Title of Invention	"AN IMPROVED PROCESS FOR CARBONYLATION OF METHANOL FOR PRODUCING ACETATE ESTER OR MIXTURE OF CARBOXYLIC ACID AND ESTER"
Abstract	The present invention provides an improved process for carbonylation of methanol for producing acetate ester or mixture of carboxylic acid and acetate ester by contacting carbon monoxide with liquid reaction composition comprising methanol, a halogen promoter preferably methyl iodide, water and a rhodium metal complex catalyst selected from [Rh(CO)2CI(Ph2PCH2OCH3)], [Rh(CO)2CI(Ph2PCH2CH2OCH2CH3)], [Rh(CO)2(Ph2PCH2COOC2H5)CI], [Rh(CO)(Ph2PCH2CH2SC2H5)CI] or [Rh(CO)2CIL] wherein L is a ligand containing one nitrogen donor groups selected from amino phenol or amino benzoic acid or tertiary-phosphine chalcogenide containing either oxygen , sulfur or selenide donor group, in an autoclave , under the temperature range 100°C to 160°C and at a pressure of 1 to 20 bar, for a period of 30-90 min , and recovering acetate ester or a mixture of carboxylic acid and acetate ester by conventional method.

Title of Invention

"AN IMPROVED PROCESS FOR CARBONYLATION OF METHANOL FOR PRODUCING ACETATE ESTER OR MIXTURE OF CARBOXYLIC ACID AND ESTER"

Abstract

The present invention provides an improved process for carbonylation of methanol for producing acetate ester or mixture of carboxylic acid and acetate ester by contacting carbon monoxide with liquid reaction composition comprising methanol, a halogen promoter preferably methyl iodide, water and a rhodium metal complex catalyst selected from [Rh(CO)2CI(Ph2PCH2OCH3)], [Rh(CO)2CI(Ph2PCH2CH2OCH2CH3)], [Rh(CO)2(Ph2PCH2COOC2H5)CI], [Rh(CO)(Ph2PCH2CH2SC2H5)CI] or [Rh(CO)2CIL] wherein L is a ligand containing one nitrogen donor groups selected from amino phenol or amino benzoic acid or tertiary-phosphine chalcogenide containing either oxygen , sulfur or selenide donor group, in an autoclave , under the temperature range 100°C to 160°C and at a pressure of 1 to 20 bar, for a period of 30-90 min , and recovering acetate ester or a mixture of carboxylic acid and acetate ester by conventional method.

Full Text	The present invention relates to an improved process for carbonylation of methanol for producing acetate ester or mixture of carboxylic acid and acetate ester using rhodium complex catalyst. The present invention particularly provides an improved process for carbonylation of methanol to acetic acid and / or its derivatives especially methyl acetate using a catalyst precursor such as [Rh(CO)2ClL] where L is a tertiary-phosphine chalcogenide or a ether phosphine or a nitrogen donor ligand. More particularly the catalyst precursor is [Rh(COD)ClL] where L is tertiary-phosphine chalcogenide. The carbonylation reaction was carried out under CO pressure (1-20 bar) in the temperature range 100 - 160 °C for a period 30 - 90 minutes. hi our co-pending patent Pat. Appl. No 206/DEL/2001 What is status application we haye disclosed claimed a process for the preparation of novel rhodium.complexes which can used for the carbonylation of methanol for producing carboxylic acid and its ester. Since the first report of catalysis by [Rh(CO)2I2]- (F.E.Paulik and J.F.Roth, J.Chem.Soc. Chem.Comm., 1968, 1578), there has been little improvement on the intrinsic activity of the catalyst. Attempt to develop new catalysis species have been hampered by the relatively harsh condition under which the reaction is conducted commercially (150-200 °C, 25-45 atm., in the presence of I-) because under such conditions, virtually any source of rhodium will be converted to [Rh(CO)2l2]~ (D. Forster, J. Am. Chem. Soc., 1976, 98, 846). Reference may be made to U.S. Pat. No. 3769327 Indian equepment issued to F.E.Paulik et.al. wherein methanol is carbonylated with carbon monoxide gas at 175°C and 1000 psig pressure to acetic acid using the catalyst [Rh(CO)2l2]• The process is similar to existing industrial condition for conducting the reaction. The draw back of the process is that it involves sufficient high pressure and temperature for maintaining high absolute reaction rates. U.S.Pat. 4,990,654 issued to Wegman et.al. discloses production of acetate ester from alcohol using rhodiuym complex catalysts. The process comprises catalytic reaction of a mixture of methanol and ethanol and carbon monoxide in contact with a homogeneous catalyst of rhodium complex containing the ligands like Ph2P(CH2)nP(O)Ph2 (Ph = phenyl, n = 1-4) or Ph2P(CH2)nCOOR (R = alkyl/aryl). The reaction was carried out at a temperature up to 130°C and reaction pressure up to about 250 psig. The main draw back of the process is that the conversion of methanol was 70 %. Reference may be made to Wegman et.al. (J. Chem. Soc. Chem. Comm., 1987, 1891) wherein carbonylation in presence of catalyst [Rh(CO)2Cl(Ph2P(CH2)2P(O)Ph2)] was carried out at 80°C and 50 psig CO. The turnover frequency was 400 h"1. U.S.Pat. 5488153 issued to Baker et.al. discloses a process for the liquid phase carbonylation of methanol in presence of CO, a halogen promoter ( eg. CH3T), water, rhodium complexes of Ph2PCH2P(S)Ph2 or 2-(diphenylphosphino)-thiophenol. The reaction was performed in the temperature range of 25 - 250°C and at a pressure in the range 10 to 200 bar. The carbonylation rate was found to be considerably higher i.e. about 6 times higher than that in absence of the ligand in the system.The main draw back of the process is that it involves higher temperature and pressure for the reaction. Baker et.al.(J. Chem. Soc. Chem. Soc., 1995, 197) also discloses that a catalyst cis- RhI(CO)Ph2PCH2P(S)Pl2 is about 8 times more active than the classic Monsanto catalyst [Rh(CO)2l2]- for carbonylation of methanol at 185°C and at 70 bar pressure. Again, the main draw back of the above process is that it involves high temperature and pressure. In another disclosure, Dilworth et.al. (J.Chem.Soc.ChemComm., 1995, 1579) claimed that use of thofium(l) vomplrcrd containing phosphino-thiolate and thioether ligands resulted about 4 times higher rate in carbonylation of methanol to ethanoic acid than that of [Rh(CO)2l2]-. The reaction was carried out at 185°C and at 70 bar pressure. The drawback of the process is that it involves high temperature and pressure. Reference may be made to U.S. pat No. 5973197 issued to Denis et.al., wherein a method for preparing carboxylic acids by carbonylation of an alcohol in presence of rhodium complex catalyst. The carbonylation reaction was conducted at a temperature in the range 150° - 250°C and 1-100 bar pressure. Again, the drawback is that the above process involves high temperature and pressure. The main object of the present invention is to provide an improved process for carbonylation of methanol for producing acetate ester or a mixture of carboxylic acid and ester which obviates the drawbacks as mentioned above. Another object of the present invention is to provide an improved process which involves rhodium complex catalysts containing phosphine chalcogenides or ether-phosphine or nitrogen donor ligands like amino phenol and amino benzole acid. Still another object of the present invention is to provide a process for carbonylation of methanol at comparatively lower temperature and pressure. Accordingly the present invention provides an improved process for carbonylation of methanol for producing acetate ester or mixture of carboxylic acid and acetate ester characterized in that the reaction is carried out in presence a halogen promoter and rhodium metal complex catalyst at a temperature range 100°C to 160°C , which comprises contacting carbon monoxide with liquid reaction composition comprising methanol, a halogen promoter preferably methyl iodide, water and a rhodium metal complex catalyst such as herein described , in an autoclave , under the said temperature range 100°C to 160°C and at a pressure of 1 to 20 bar, for a period of 30-90 min , and recovering acetate ester or a mixture of carboxylic acid and acetate ester by conventional method. In an embodiment of the present invention the carbonylation reaction is exemplified by the reaction of methanol with carbon monoxide to form methyl acetate or a mixture of acetic acid and methyl acetate. In another embodiment of the present invention, the rhodium metal complex used may be [Rh(CO)2ClL] contains the ligand L which comprises a triphenylphosphine chalcogenide or a ether phosphine or a nitrogen donor ligand such as amino-phenol or amino-benzoic acid. In yet another embodiment of the present invention, the rhodium metal complex may be [Rh(COD)ClL] contains the ligand L which comprises a triphenyl phosphine chalcogenide. In another embodiment of the present invention, the metal complex [Rh(CO)2(Ph2PCH2COOC2H5)Cl] contains the ligand which comprises "Soft"-phosphorous and "Hard"-oxygen donors. The complex show two equally intense carbonyl absorption bands at 1985 and 2070 cm-1 attributable to cw-disposition of the two carbonyl groups. 31PNMR shows at 8 28.3 ppm. In yet another embodiment of the present invention, the metal complex [Rh(CO)(Ph2PCH2CH2SC2H5)Cl] where the ligand contains "Soft"-phosphorous and "Soft"-sulphur donors. The complex shows a. vCO value at 1970 cm"1 and 31P NMR shows at 8 70 ppm. Still in another embodiment of the present invention, the metal complex catalyst may be added directly to the catalytic system or may be generated in-situ by reacting [Rh(CO)2Cl]2 and the appropriate ligand L. The catalytic reaction was carried out in a 150 ml capacity teflon coated pressure reactor (Make Berghof, Model Heizug 75-150, Germany). The reactants such as methanol (3.16 ml, 0.078 mol), methyl iodide (1 ml, 0.006 mol), water (1 ml, 0.055 mol) and [Rh(CO)2CI]2 (10 mg, 0.025 m mol) or [Rh(COD)Cl]2 ( 12 mg, 0.025 mmol) and ligand L (0.05 - 0.10 m mol) were taken in to the reaction vessel. Optionally, the metal complex [Rh(CO)2ClL] or [Rh(COD)ClL] as synthesized was added to the catalytic system. The reaction vessel was purged with CO gas for about 5 minutes and then pressured with CO gas up to 6 bar (0.036 mol at about 30°C). The temperature of the reactor was raised to 100 - 160°C and the corresponding pressure were in the range 10 to 20 bar. The reaction was allowed for 30 to 90 minutes. After the catalytic reaction, the reaction products were collected and analysed by Gas Liquid Chromatography. More than 30 years after the discovery, the Monsanto catalyst [Rh(CO)2I2]- is still the preferred commercial catalyst for carbonylation of methanol to acetic acid. It is known that the complexes which are more electron rich than [Rh(CO)2I2]- will contribute higher carbonylation rate. In the present invention , the catalyst [Rh(CO)2ClL] where L is a triphenylphosphine chalcogenide or ether phosphine or a nitrogen donor contribute higher electron density on the central metal atom which in turn becomes more reactive for carbonylation reaction. Moreover, the phosphine ether and the nitrogen donor ligand also contains a second function such as -OR (R = Me, Et) or -OH or -COOH functional group in its molecule, v/hich may take part in coordination forming a chelate as and when required in the catalytic system and thus enhancing stabilization of the catalyst. On the other hand the higher activity of the complexes [Rh(COD)ClL] (L = PPh3O or PPh3S or PPh3Se) over [Rh(CO)2l2]- may be due to higher nucleophilicity of the rhodium center caused by the presence of (i) COD molecule which is lesser n - acceptor as compared to CO molecule and (ii) phosphine chalcogenides are stronger donor as compared to iodine atom. The following examples are given by way of illustration of the present invention and therefore should not be construed to limit the scope of the present invention. EXAMPLE -1 Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and [Rh(CO)2Cl]2 (10 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (0.7 % wt/.wt) and methyl acetate (15.5 % wt./wt.) and the Turn Over Number (TON) was 233 per 30 min. (calculated on the basis of conversion of methanol). EXAMPLE - 2 Methanol (3.16 rnl), methyl iodide (1 ml), water (1 ml), [Rh(CO)2Cl]2 (10 mg) and Ph3PO (15.0 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (less than 0.1 % wt./wt) and methyl acetate (50 % wt./wt.) and the Turn Over Number (TON) was 720 per 30 min (calculated on the basis of conversion of methanol). EXAMPLE - 3 Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and [Rh(CO)2Cl(Ph3PO)] (24 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (less than 0.1 % wt./wt) and methyl acetate (49.6 % wt./wt.) and the Turn Over Number (TON) was 715 per 30 min (calculated on the basis of conversion of methanol). EXAMPLE - 4 Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml), [Rh(CO)2Cl]2 (10 mg) and Ph3PS (16.0 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for about about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (2.5 % wt.wt) and methyl acetate (76.5 % wt./wt.) and the Turn Over Number (TON) was 1138 per 30 min. (calculated on the basis of conversion of methanol). EXAMPLE - 5 Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and [Rh(CO)2Cl(Ph3PS)] (25 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 °C and the corresponding pressure was about 15 atm. The reaction was allowed for about about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (2.5 % wt/.wt) and methyl acetate (77.1 % wt./wt.) and the Turn Over Number (TON) was 1147 per 30 min. (calculated on the basis of conversion of methanol). EXAMPLE - 6 Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml), [Rh(CO)2Cl]2 (10 mg) and Ph3PSe (18.0 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized v/ith carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (2.2 % wt/.wt) and methyl acetate (58.8 % wt./wt.) and the Turn Over Number (TON) was 878 per 30 min (calculated on the basis of conversion of methanol). EXAMPLE - 7 Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and [Rh(CO)2Cl(Ph3PSe)] (27 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 °C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (2.2 % wt/.wt) and methyl acetate (58.2 % wt./wt.) and the Turn Over Number (TON) was 870 per 30 min (calculated on the basis of conversion of methanol). EXAMPLE - 8 Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and [Rh(COD)Cl]2 (12.3 mg), were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 °C and the corresponding pressure was about 15 arm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (less than 0.1 % wt/wt) and methyl acetate (9.9 % wt./wt.) and the Turn Over Number (TON) was 143 per 30 min (calculated on the basis of conversion of methanol). EXAMPLE - 9 Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and [Rh(COD)Cl]2 (12.3 mg) and PhaPO (15 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (8.9 % wt/.wt) and methyl acetate (41.1 % wt./wt.) and the Turn Over Number (TON) was 720 per 30 min (calculated on the basis of conversion of methanol). EXAMPLE -10 Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and [Rh(COD)Cl(Ph3PO)] (27 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic; acid (9.1 % wt/.wt) and methyl acetate (41.7 % wt./wt.) and the Turn Over Number (TON) was 732 per 30 min (calculated on the basis of conversion of methanol). EXAMPLE-11 Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and [Rh(COD)Cl]2 (12.3 mg) and PhaPS (16 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (23.1 % wt/.wt) and methyl acetate (75.4 % wt./wt.) and the Turn Over Number (TON) was 1418 per 30 min. (calculated on the basis of conversion of methanol). EXAMPLE -12 Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and [Rh(COD)Cl(Ph3PS)] (28 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 °C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (22.8 % wt/.wt) and methyl acetate (74.7 % wt./wt.) and the Turn Over Number (TON) was 1406 per 30 min. (calculated on the basis of conversion of methanol). EXAMPLE -13 Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and [Rh(COD)Cl]2 (12.3 mg) and Ph3PSe (18 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (25 % wt/..wt) and methyl acetate (66.8 % wt./wt.) and the Turn Over Number (TON) was 1325 per 30 min.(calculated on the basis of conversion of methanol). EXAMPLE -14 Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and [Rh(COD)Cl(Ph3PSe)] (30 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (25.3 % wt/.wt) and methyl acetate (67.6 % wt./wt.) and the Turn Over Number (TON) was 1341 per 30 min. (calculated on the basis of conversion of methanol). EXAMPLE -15 [Rh(CO)2Cl]2 (10 mg), methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and Ph2PCH2OCH3 (25.0 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 25°C). The temperature was raised to about 130° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 60 minutes. After the catalytic reaction, the product was collected and analyzed by Gas Chromatography. The product was a mixture of acetic acid (8 % wt./wt) and methyl acetate (29 % wt./wt.) and the Turn Over Number (TON) was 538 per 60 minutes. EXAMPLE -16 [Rh(CO)2(Ph2PCH2OCH3)Cl] (22 mg), methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 25°C). The temperature was raised to about 130°C and the corresponding pressure was about 15 atm. The reaction was allowed for about 60 minutes. After the catalytic reaction, the product was collected and analyzed by Gas Chromatography. The product was a mixture of acetic acid (8 wt./wt) and methyl acetate (31 wt./wt.) and the Turn Over Number (TON) was 561 per 60 minutes. EXAMPLE -17 [Rh(CO)2Cl]2 (10 mg), Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and Ph2PCH2CH2OC2H5 (28.0 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 25°C). The temperature was raised to about 130° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 90 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (41 % wt./wt) and methyl acetate (59 % wt./wt.) and the Turn Over Number (TON) was 1440 per 60 minutes. EXAMPLE -18 [Rh(CO)2(Ph2PCH2CH2COOC2H5)Cl] (23 mg), methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 25°C). The temperature was raised to about 130° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 60 minutes. After the catalytic reaction, the product was collected and analyzed by Gas Chromatography. The product was a mixture of acetic acid (46 wt/wt) and methyl acetate (53 wt/wt) and the Turn Over Number (TON) was 1423 per 60 minutes. EXAMPLE -19 Methanol (3 ml), methyl iodide (1 ml), water (1 ml), [Rh(CO)2Cl]2 (10 mg), m-aminophenol (10.9 mg) were charged into a 150 ml capacity high pressure autoclave(Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 3 minute. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at 30°C). The temperature was raised to about 120 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The main product was a mixture of acetic acid (about 3 % wt./wt.) and methyl acetate (about 30 % wt./wt.). The TON (calculated on methanol conversion) was 320 per 30 min. EXAMPLE - 20 Methanol (3 ml), methyl iodide (1 ml), water (1 ml), [Rh(CO)2Cl]2 (10 mg), m-aminophenol (10.9 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equiped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 3 minute. The autoclave was then pressurised with carbon monoxide gas up to 6 bar (0.036 mol at 30°C). The temperature was raised to about 150°C and the corresponding pressure was about 20 atm. The reaction was allowed for 90 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The main product was a mixture of acetic acid (about 60 % wt./wt.) and methyl acetate (about 30 % wt./wt.). The TON (calculated on methanol conversion) was 1365 per hour. EXAMPLE - 21 Methanol (3 ml), methyl iodide (1 ml), water (1 ml), [Rh(CO)2Cl(m-aminophenol)] (15.6 mg), were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equiped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 3 minute. The autoclave was then pressurised with carbon monoxide gas up to 6 bar (0.036 mol at 30°C). The temperature was raised to about 150 ° C and the corresponding pressure was about 20 atm. The reaction was allowed for 90 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The main product was a mixture of acetic acid (about 59 % wt./wt.) and methyl acetate (about 32 % wt./wt.). The TON (calculated on methanol conversion) was 1371 per hour. EXAMPLE - 22 Methanol (3 ml), methyl iodide (1 ml), water (1 ml), [Rh(CO)2Cl]2 (10 mg), m-aminobenzoic acid (13.7 mg) were charged into a 150 ml capacity high pressure autoclave(Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 3 minute. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at 30°C). The temperature was raised to about 120 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The main product was a mixture of acetic acid (about 2 % wt./wt.) and methyl acetate (about 31 % wt./wt.). The TON (calculated on methanol conversion) was 342 per 30 min. EXAMPLE - 23 Methanol (3 ml), methyl iodide (1 ml), water (1 ml), [Rh(CO)2Cl(m-aminobenzoic acid)] (17.06 mg), were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 3 minute. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at 30°C). The temperature was raised to about 120 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The main product was a mixture of acetic acid (about 2 % wt./wt.) and methyl acetate (about 32 % wt./wt.). The TON (calculated on methanol conversion) was 352 per 30 min. EXAMPLE - 24 Methanol (3 ml), methyl iodide (1 ml), water (1 ml), [Rh(CO)2Cl]2 (10 mg), m-amino /benzoic acid (13.7 mg) were charged into a 150 ml capacity high pressure autoclave(Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 3 minute. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at 30°C). The temperature was raised to about 150 ° C and the corresponding pressure was about 20 atm. The reaction was allowed for 90 minutes. After the catalytic reaction, the product was collected and analyzed by Gas Liquid Chromatography. The main product was a mixture of acetic acid (about 50 % wt./wt.) and methyl acetate (about 42 % wt./wt.). The TON (calculated on methanol conversion) was 1327 per 90 min. EXAMPLE -25 [Rh(CO)2Cl]2 (10 mg), Methanol (3.10 ml), methyl iodide (1 ml), water (1 ml) and Ph2PCH2COOC2H5 (15.0 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 10 bar (0.06 mol at about 30°C). The temperature was raised to about 130° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas Chromatography. The product was a mixture of acetic acid (11 % wt./wt) and methyl acetate (33 % wt./wt.) and the Turn Over Number (TON) was 1050 per 30 minutes. EXAMPLE -26 [Rh(CO)2(Ph2PCH2COOC2H5)Cl] (24 mg), Methanol (3.10 ml), methyl iodide (1 ml), water (1 ml) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 10 bar (0.06 mol at about 30°C). The temperature was raised to about 130° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas Chromatography. The product was a mixture of acetic acid (8 % wt./wt) and methyl acetate (34 % wt./wt.) and the Turn Over Number (TON) was 1034 per 30 minutes. EXAMPLE - 27 [Rh(CO)2Cl]2 (10 mg), Methanol (3.10 ml), methyl iodide (1 ml), water (1 ml) and Ph2PCH2COOC2H5 (15.0 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 10 bar (0.06 mol at about 30°C). The temperature was raised to about 160° C and the corresponding pressure was about 20 atm. The reaction was allowed for about 90 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (49 % wt./wt) and methyl acetate (51 % wt./wt.) and the Turn Over Number (TON) was 2400 per 90 minutes. EXAMPLE -28 [Rh(CO)2 (Ph;-PCH2COOC2H5)Cl] (24 mg), Methanol (3.10 ml), methyl iodide (1 ml), water (1 ml) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 10 bar (0.06 mol at about 30°C). The temperature was raised to about 160° C and the corresponding pressure was about 20 atm. The reaction was allowed for about 90 minutes. After the catalytic reaction, the product was collected and analyzed by Gas Chromatography. The product was a mixture of acetic acid (47 % wt/wt) and methyl acetate (52 % wt/wt) and the Turn Over Number (TON) was 2394 per 90 minutes. EXAMPLE - 29 [Rh(CO)2Cl]2 (10 mg), Methanol (3.10 ml), methyl iodide (1 ml), water (1 ml) and Ph2PCH2CH2SC2H5 (15 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 10 bar (0.06 mol at about 30°C). The temperature was raised to about 130 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (4 % wt.wt) and methyl acetate (19 % wt./wt.) and the Turn Over Number (TON) was 552 per 30 minutes. EXAMPLE - 30 [Rh(CO)(Ph2PCH2CH2SC2H5)Cl] (24 mg), Methanol (3.10 ml), methyl iodide (1 ml), water (1 ml) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 10 bar (0.06 mol at about 30°C). The temperature was raised to about 130 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (3 % wt/.wt) and methyl acetate (21 % wt./wt.) and the Turn Over Number (TON) was 567 per 30 minutes. EXAMPLE - 31 [Rh(CO)2Cl]2 (10 mg), Methanol (3.10 ml), methyl iodide (1 ml), water (1 ml) and Ph2PCH2CH2SC2H5 (15 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 10 bar (0.06 mol at about 30°C). The temperature was raised to about 160° C and the corresponding pressure was about 20 atm. The reaction was allowed for about 90 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (46 % wt.wt) and methyl acetate (44 % wt./wt.) and the Turn Over Number (TON) was 2180 per 90 minutes. EXAMPLE - 32 [Rh(CO)(Ph2PCH2CH2SC2H5)Cl] (24 mg), Methanol (3.10 ml), methyl iodide (1 ml), water (1 ml) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 10 bar (0.06 mol at about 30°C). The temperature was raised to about 160 ° C and the corresponding pressure was about 20 atm. The reaction was allowed for about 90 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (51 % wt/.wt) and methyl acetate (40 % wt./wt.) and the Turn Over Number (TON) was 2191 per 90 minutes. In summary, the metal complexes [Rh(CO)2ClL] or [Rh(COD)ClL] where L is triphenyl phosphine chalcogenide or ether phosphine or nitrogen donor ligands like amino phenol and amino-benzoic acid, which enhances the electron density at the central metal atom and subsequently enhances the activity for carbonylation reaction. Due to the presence of different types of donor such as "Hard oxygen" or "Soft sulfur" or Soft selenium" the complexes behave differently and thus exhibiting different results. Moreover, the selectivity depends up on the temperature and pressure of the carbonylation reaction. In summary, the active metal complexes [Rh(CO)2(Ph2PCH2COOC2H5)Cl] or [Rh(CO)2(Ph2PCH2CSC2H5)Cl] were generated by reacting [Rh(CO)2Cl]2 with ligand Ph2PCH2COOC2H5 or Ph2PCH2CH2SC2H5 respectively. The ligands in these complexes contribute high electron density on the central rnetal atom and subsequently facilitate the catalytic reaction. Moreover, the metal complexes show hemilabile character by dissociating the weakly Rh-O or Rh-S bond and thus creating vacancy for substrate bonding which will lead catalytic reaction at comparatively low temperature and pressure. The hemilabile nature of the [Rh(CO)2(Ph2PCH2COOC2H5)Cl] and [Rh(CO)(Ph2PCH2CH2SC2H5)Cl] complexes facilitate the catalytic reaction. The main advantages of the present invention are : (i) The carbonylation reaction can be carried at a temperature below 160°C and pressure below 20 bar. (ii) The metal complexes [Rh(CO)2CL] or [Rh(COD)ClL] can be added directly to the catalytic system or can be generated in-situ by reacting [Rh(CO)2C]2 or [Rh(COD)Cl]2 with appropriate ligand L. Claim: 1. An improved process for carbonylation of methanol for producing acetate ester or mixture of carboxylic acid and acetate ester characterized in that the reaction is carried out in presence a halogen promoter and rhodium metal complex catalyst at a temperature range 100°C to 160°C , which comprises contacting carbon monoxide with liquid reaction composition comprising methanol, a halogen promoter preferably methyl iodide, water and a rhodium metal complex catalyst such as herein described , in an autoclave , under the said temperature range 100°C to 160°C and at a pressure of 1 to 20 bar, for a period of 30-90 min , and recovering acetate ester or a mixture of carboxylic acid and acetate ester by conventional method. 2. A process as claimed in claim 1 wherein the rhodium metal complex catalyst is selected from [Rh(CO)2CI(Ph2PCH2OCH3)], [Rh(CO)2CI(Ph2PCH2CH20CH2CH3)], [Rh(CO)2(Ph2PCH2COOC2H5)CI], [Rh(CO)(Ph2PCH2CH2SC2H5)CI] or [Rh(CO)2CIL] wherein L is a ligand containing one nitrogen donor groups selected from amino phenol or amino benzoic acid or tertiary-phosphine chalcogenide containing either oxygen , sulfur or selenide donor group. 3. A process claimed in claims 1-3, wherein the tertiary-phosphine chalcogenide ligand is selected from PhsPO, PhaPS and Ph3PSe. 4. A process as claimed in claims 1 - 4, wherein the amino phenol or amino benzoic acid ligand is selected from m-amino phenol , m-amino benzoic acid. 5. An improved process for carbonylation of methanol for producing acetate ester or a mixture of carboxylic acid or acetate ester substantially as herein described with reference to the examples.

Full Text

The present invention relates to an improved process for carbonylation of methanol for producing acetate ester or mixture of carboxylic acid and acetate ester using rhodium complex catalyst.
The present invention particularly provides an improved process for carbonylation
of methanol to acetic acid and / or its derivatives especially methyl acetate using a
catalyst precursor such as [Rh(CO)2ClL] where L is a tertiary-phosphine chalcogenide
or a ether phosphine or a nitrogen donor ligand. More particularly the catalyst precursor
is [Rh(COD)ClL] where L is tertiary-phosphine chalcogenide. The carbonylation reaction
was carried out under CO pressure (1-20 bar) in the temperature range 100 - 160 °C for a
period 30 - 90 minutes.
hi our co-pending patent Pat. Appl. No 206/DEL/2001 What is status application
we haye disclosed claimed a process for the preparation of novel rhodium.complexes which can used for the carbonylation of methanol for producing carboxylic acid and its ester.
Since the first report of catalysis by [Rh(CO)2I2]- (F.E.Paulik and J.F.Roth,
J.Chem.Soc. Chem.Comm., 1968, 1578), there has been little improvement on the
intrinsic activity of the catalyst. Attempt to develop new catalysis species have been
hampered by the relatively harsh condition under which the reaction is conducted
commercially (150-200 °C, 25-45 atm., in the presence of I-) because under such
conditions, virtually any source of rhodium will be converted to [Rh(CO)2l2]~ (D. Forster,
J. Am. Chem. Soc., 1976, 98, 846).
Reference may be made to U.S. Pat. No. 3769327 Indian equepment issued to F.E.Paulik et.al. wherein methanol is carbonylated with carbon monoxide gas at 175°C and 1000 psig pressure to acetic acid using the catalyst [Rh(CO)2l2]• The process is similar to existing
industrial condition for conducting the reaction. The draw back of the process is that it involves sufficient high pressure and temperature for maintaining high absolute reaction rates.
U.S.Pat. 4,990,654 issued to Wegman et.al. discloses production of acetate ester from alcohol using rhodiuym complex catalysts. The process comprises catalytic reaction of a mixture of methanol and ethanol and carbon monoxide in contact with a homogeneous catalyst of rhodium complex containing the ligands like Ph2P(CH2)nP(O)Ph2 (Ph = phenyl, n = 1-4) or Ph2P(CH2)nCOOR (R = alkyl/aryl). The reaction was carried out at a temperature up to 130°C and reaction pressure up to about 250 psig. The main draw back of the process is that the conversion of methanol was 70 %.
Reference may be made to Wegman et.al. (J. Chem. Soc. Chem. Comm., 1987, 1891) wherein carbonylation in presence of catalyst [Rh(CO)2Cl(Ph2P(CH2)2P(O)Ph2)] was carried out at 80°C and 50 psig CO. The turnover frequency was 400 h"1.
U.S.Pat. 5488153 issued to Baker et.al. discloses a process for the liquid phase
carbonylation of methanol in presence of CO, a halogen promoter ( eg. CH3T), water, rhodium complexes of Ph2PCH2P(S)Ph2 or 2-(diphenylphosphino)-thiophenol. The reaction was performed in the temperature range of 25 - 250°C and at a pressure in the range 10 to 200 bar. The carbonylation rate was found to be considerably higher i.e. about 6 times higher than that in absence of the ligand in the system.The main draw back of the process is that it involves higher temperature and pressure for the reaction.
Baker et.al.(J. Chem. Soc. Chem. Soc., 1995, 197) also discloses that a catalyst cis-
RhI(CO)Ph2PCH2P(S)Pl2 is about 8 times more active than the classic Monsanto catalyst
[Rh(CO)2l2]- for carbonylation of methanol at 185°C and at 70 bar pressure. Again, the main draw back of the above process is that it involves high temperature and pressure.
In another disclosure, Dilworth et.al. (J.Chem.Soc.ChemComm., 1995, 1579) claimed that use of thofium(l) vomplrcrd containing phosphino-thiolate and thioether ligands resulted about 4 times higher rate in carbonylation of methanol to ethanoic acid than that of [Rh(CO)2l2]-. The reaction was carried out at 185°C and at 70 bar pressure. The drawback of the process is that it involves high temperature and pressure.
Reference may be made to U.S. pat No. 5973197 issued to Denis et.al., wherein a method for preparing carboxylic acids by carbonylation of an alcohol in presence of rhodium complex catalyst. The carbonylation reaction was conducted at a temperature in the range 150° - 250°C and 1-100 bar pressure. Again, the drawback is that the above process involves high temperature and pressure.
The main object of the present invention is to provide an improved process for carbonylation of methanol for producing acetate ester or a mixture of carboxylic acid and ester which obviates the drawbacks as mentioned above.
Another object of the present invention is to provide an improved process which involves rhodium complex catalysts containing phosphine chalcogenides or ether-phosphine or nitrogen donor ligands like amino phenol and amino benzole acid.
Still another object of the present invention is to provide a process for carbonylation of methanol at comparatively lower temperature and pressure.
Accordingly the present invention provides an improved process for carbonylation of methanol for producing acetate ester or mixture of carboxylic acid and acetate ester characterized in that the reaction is carried out in presence a halogen promoter and rhodium metal complex catalyst at a temperature range 100°C to 160°C , which comprises contacting carbon monoxide with liquid reaction composition comprising methanol, a halogen promoter
preferably methyl iodide, water and a rhodium metal complex catalyst such as herein described , in an autoclave , under the said temperature range 100°C to 160°C and at a pressure of 1 to 20 bar, for a period of 30-90 min , and recovering acetate ester or a mixture of carboxylic acid and acetate ester by conventional method.
In an embodiment of the present invention the carbonylation reaction is exemplified by the reaction of methanol with carbon monoxide to form methyl acetate or a mixture of acetic acid and methyl acetate.
In another embodiment of the present invention, the rhodium metal complex used may be [Rh(CO)2ClL] contains the ligand L which comprises a triphenylphosphine chalcogenide or a ether phosphine or a nitrogen donor ligand such as amino-phenol or amino-benzoic acid.
In yet another embodiment of the present invention, the rhodium metal complex may be [Rh(COD)ClL] contains the ligand L which comprises a triphenyl phosphine chalcogenide.
In another embodiment of the present invention, the metal complex [Rh(CO)2(Ph2PCH2COOC2H5)Cl] contains the ligand which comprises "Soft"-phosphorous and "Hard"-oxygen donors. The complex show two equally intense carbonyl absorption bands at 1985 and 2070 cm-1 attributable to cw-disposition of the two carbonyl groups. 31PNMR shows at 8 28.3 ppm.
In yet another embodiment of the present invention, the metal complex [Rh(CO)(Ph2PCH2CH2SC2H5)Cl] where the ligand contains "Soft"-phosphorous and "Soft"-sulphur donors. The complex shows a. vCO value at 1970 cm"1 and 31P NMR shows at 8 70 ppm.
Still in another embodiment of the present invention, the metal complex catalyst may be added directly to the catalytic system or may be generated in-situ by reacting [Rh(CO)2Cl]2 and the appropriate ligand L.
The catalytic reaction was carried out in a 150 ml capacity teflon coated pressure reactor (Make Berghof, Model Heizug 75-150, Germany). The reactants such as methanol (3.16 ml, 0.078 mol), methyl iodide (1 ml, 0.006 mol), water (1 ml, 0.055 mol) and [Rh(CO)2CI]2 (10 mg, 0.025 m mol) or [Rh(COD)Cl]2 ( 12 mg, 0.025 mmol) and ligand L (0.05 - 0.10 m mol) were taken in to the reaction vessel. Optionally, the metal complex [Rh(CO)2ClL] or [Rh(COD)ClL] as synthesized was added to the catalytic system. The reaction vessel was purged with CO gas for about 5 minutes and then pressured with CO gas up to 6 bar (0.036 mol at about 30°C). The temperature of the reactor was raised to 100 - 160°C and the corresponding pressure were in the range 10 to 20 bar. The reaction was allowed for 30 to 90 minutes. After the catalytic reaction, the reaction products were collected and analysed by Gas Liquid Chromatography.
More than 30 years after the discovery, the Monsanto catalyst [Rh(CO)2I2]- is still the preferred commercial catalyst for carbonylation of methanol to acetic acid. It is known that the complexes which are more electron rich than [Rh(CO)2I2]- will contribute higher carbonylation rate. In the present invention , the catalyst [Rh(CO)2ClL] where L is a triphenylphosphine chalcogenide or ether phosphine or a nitrogen donor contribute higher electron density on the central metal atom which in turn becomes more reactive for carbonylation reaction. Moreover, the phosphine ether and the nitrogen donor ligand also contains a second function such as -OR (R = Me, Et) or -OH or -COOH functional group in its molecule, v/hich may take part in coordination forming a chelate as and when
required in the catalytic system and thus enhancing stabilization of the catalyst. On the other hand the higher activity of the complexes [Rh(COD)ClL] (L = PPh3O or PPh3S or PPh3Se) over [Rh(CO)2l2]- may be due to higher nucleophilicity of the rhodium center caused by the presence of (i) COD molecule which is lesser n - acceptor as compared to CO molecule and (ii) phosphine chalcogenides are stronger donor as compared to iodine atom. The following examples are given by way of illustration of the present invention and therefore should not be construed to limit the scope of the present invention.
EXAMPLE -1
Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and [Rh(CO)2Cl]2 (10 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (0.7 % wt/.wt) and methyl acetate (15.5 % wt./wt.) and the Turn Over Number (TON) was 233 per 30 min. (calculated on the basis of conversion of methanol).
EXAMPLE - 2
Methanol (3.16 rnl), methyl iodide (1 ml), water (1 ml), [Rh(CO)2Cl]2 (10 mg) and Ph3PO (15.0 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof,
Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (less than 0.1 % wt./wt) and methyl acetate (50 % wt./wt.) and the Turn Over Number (TON) was 720 per 30 min (calculated on the basis of conversion of methanol).
EXAMPLE - 3
Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and [Rh(CO)2Cl(Ph3PO)] (24 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (less than 0.1 % wt./wt) and methyl acetate (49.6 % wt./wt.) and the Turn Over Number (TON) was 715 per 30 min (calculated on the basis of conversion of methanol).
EXAMPLE - 4
Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml), [Rh(CO)2Cl]2 (10 mg) and Ph3PS (16.0 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for about about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (2.5 % wt.wt) and methyl acetate (76.5 % wt./wt.) and the Turn Over Number (TON) was 1138 per 30 min. (calculated on the basis of conversion of methanol).
EXAMPLE - 5
Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and [Rh(CO)2Cl(Ph3PS)] (25 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 °C and the corresponding pressure was about 15 atm. The reaction was allowed for about about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The
product was a mixture of acetic acid (2.5 % wt/.wt) and methyl acetate (77.1 % wt./wt.) and the Turn Over Number (TON) was 1147 per 30 min. (calculated on the basis of conversion of methanol).
EXAMPLE - 6
Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml), [Rh(CO)2Cl]2 (10 mg) and Ph3PSe (18.0 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized v/ith carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (2.2 % wt/.wt) and methyl acetate (58.8 % wt./wt.) and the Turn Over Number (TON) was 878 per 30 min (calculated on the basis of conversion of methanol).
EXAMPLE - 7
Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and [Rh(CO)2Cl(Ph3PSe)] (27 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 °C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic
reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (2.2 % wt/.wt) and methyl acetate (58.2 % wt./wt.) and the Turn Over Number (TON) was 870 per 30 min (calculated on the basis of conversion of methanol).
EXAMPLE - 8
Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and [Rh(COD)Cl]2 (12.3 mg), were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 °C and the corresponding pressure was about 15 arm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (less than 0.1 % wt/wt) and methyl acetate (9.9 % wt./wt.) and the Turn Over Number (TON) was 143 per 30 min (calculated on the basis of conversion of methanol).
EXAMPLE - 9
Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and [Rh(COD)Cl]2 (12.3 mg) and PhaPO (15 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 ° C and the
corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (8.9 % wt/.wt) and methyl acetate (41.1 % wt./wt.) and the Turn Over Number (TON) was 720 per 30 min (calculated on the basis of conversion of methanol).
EXAMPLE -10
Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and [Rh(COD)Cl(Ph3PO)] (27 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic; acid (9.1 % wt/.wt) and methyl acetate (41.7 % wt./wt.) and the Turn Over Number (TON) was 732 per 30 min (calculated on the basis of conversion of methanol).
EXAMPLE-11
Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and [Rh(COD)Cl]2 (12.3 mg) and PhaPS (16 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6
bar (0.036 mol at about 30°C). The temperature was raised to about 130 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (23.1 % wt/.wt) and methyl acetate (75.4 % wt./wt.) and the Turn Over Number (TON) was 1418 per 30 min. (calculated on the basis of conversion of methanol).
EXAMPLE -12
Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and [Rh(COD)Cl(Ph3PS)] (28 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 °C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (22.8 % wt/.wt) and methyl acetate (74.7 % wt./wt.) and the Turn Over Number (TON) was 1406 per 30 min. (calculated on the basis of conversion of methanol).
EXAMPLE -13
Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and [Rh(COD)Cl]2 (12.3 mg) and Ph3PSe (18 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for
about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (25 % wt/..wt) and methyl acetate (66.8 % wt./wt.) and the Turn Over Number (TON) was 1325 per 30 min.(calculated on the basis of conversion of methanol).
EXAMPLE -14
Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and [Rh(COD)Cl(Ph3PSe)] (30 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 30°C). The temperature was raised to about 130 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (25.3 % wt/.wt) and methyl acetate (67.6 % wt./wt.) and the Turn Over Number (TON) was 1341 per 30 min. (calculated on the basis of conversion of methanol).
EXAMPLE -15
[Rh(CO)2Cl]2 (10 mg), methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and Ph2PCH2OCH3 (25.0 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating
arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 25°C). The temperature was raised to about 130° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 60 minutes. After the catalytic reaction, the product was collected and analyzed by Gas Chromatography. The product was a mixture of acetic acid (8 % wt./wt) and methyl acetate (29 % wt./wt.) and the Turn Over Number (TON) was 538 per 60 minutes.
EXAMPLE -16
[Rh(CO)2(Ph2PCH2OCH3)Cl] (22 mg), methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 25°C). The temperature was raised to about 130°C and the corresponding pressure was about 15 atm. The reaction was allowed for about 60 minutes. After the catalytic reaction, the product was collected and analyzed by Gas Chromatography. The product was a mixture of acetic acid (8 wt./wt) and methyl acetate (31 wt./wt.) and the Turn Over Number (TON) was 561 per 60 minutes.
EXAMPLE -17
[Rh(CO)2Cl]2 (10 mg), Methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) and Ph2PCH2CH2OC2H5 (28.0 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for
about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 25°C). The temperature was raised to about 130° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 90 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (41 % wt./wt) and methyl acetate (59 % wt./wt.) and the Turn Over Number (TON) was 1440 per 60 minutes.
EXAMPLE -18
[Rh(CO)2(Ph2PCH2CH2COOC2H5)Cl] (23 mg), methanol (3.16 ml), methyl iodide (1 ml), water (1 ml) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at about 25°C). The temperature was raised to about 130° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 60 minutes. After the catalytic reaction, the product was collected and analyzed by Gas Chromatography. The product was a mixture of acetic acid (46 wt/wt) and methyl acetate (53 wt/wt) and the Turn Over Number (TON) was 1423 per 60 minutes.
EXAMPLE -19
Methanol (3 ml), methyl iodide (1 ml), water (1 ml), [Rh(CO)2Cl]2 (10 mg), m-aminophenol (10.9 mg) were charged into a 150 ml capacity high pressure autoclave(Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 3 minute. The autoclave was then pressurized with carbon monoxide gas up to 6
bar (0.036 mol at 30°C). The temperature was raised to about 120 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The main product was a mixture of acetic acid (about 3 % wt./wt.) and methyl acetate (about 30 % wt./wt.). The TON (calculated on methanol conversion) was 320 per 30 min.
EXAMPLE - 20
Methanol (3 ml), methyl iodide (1 ml), water (1 ml), [Rh(CO)2Cl]2 (10 mg), m-aminophenol (10.9 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equiped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 3 minute. The autoclave was then pressurised with carbon monoxide gas up to 6 bar (0.036 mol at 30°C). The temperature was raised to about 150°C and the corresponding pressure was about 20 atm. The reaction was allowed for 90 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The main product was a mixture of acetic acid (about 60 % wt./wt.) and methyl acetate (about 30 % wt./wt.). The TON (calculated on methanol conversion) was 1365 per hour.
EXAMPLE - 21
Methanol (3 ml), methyl iodide (1 ml), water (1 ml), [Rh(CO)2Cl(m-aminophenol)] (15.6 mg), were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equiped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 3 minute.
The autoclave was then pressurised with carbon monoxide gas up to 6 bar (0.036 mol at 30°C). The temperature was raised to about 150 ° C and the corresponding pressure was about 20 atm. The reaction was allowed for 90 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The main product was a mixture of acetic acid (about 59 % wt./wt.) and methyl acetate (about 32 % wt./wt.). The TON (calculated on methanol conversion) was 1371 per hour.
EXAMPLE - 22
Methanol (3 ml), methyl iodide (1 ml), water (1 ml), [Rh(CO)2Cl]2 (10 mg), m-aminobenzoic acid (13.7 mg) were charged into a 150 ml capacity high pressure autoclave(Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 3 minute. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at 30°C). The temperature was raised to about 120 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The main product was a mixture of acetic acid (about 2 % wt./wt.) and methyl acetate (about 31 % wt./wt.). The TON (calculated on methanol conversion) was 342 per 30 min.
EXAMPLE - 23
Methanol (3 ml), methyl iodide (1 ml), water (1 ml), [Rh(CO)2Cl(m-aminobenzoic acid)] (17.06 mg), were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for
about 3 minute. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at 30°C). The temperature was raised to about 120 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The main product was a mixture of acetic acid (about 2 % wt./wt.) and methyl acetate (about 32 % wt./wt.). The TON (calculated on methanol conversion) was 352 per 30 min.
EXAMPLE - 24
Methanol (3 ml), methyl iodide (1 ml), water (1 ml), [Rh(CO)2Cl]2 (10 mg), m-amino /benzoic acid (13.7 mg) were charged into a 150 ml capacity high pressure autoclave(Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 3 minute. The autoclave was then pressurized with carbon monoxide gas up to 6 bar (0.036 mol at 30°C). The temperature was raised to about 150 ° C and the corresponding pressure was about 20 atm. The reaction was allowed for 90 minutes. After the catalytic reaction, the product was collected and analyzed by Gas Liquid Chromatography. The main product was a mixture of acetic acid (about 50 % wt./wt.) and methyl acetate (about 42 % wt./wt.). The TON (calculated on methanol conversion) was 1327 per 90 min.
EXAMPLE -25
[Rh(CO)2Cl]2 (10 mg), Methanol (3.10 ml), methyl iodide (1 ml), water (1 ml) and Ph2PCH2COOC2H5 (15.0 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating
arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 10 bar (0.06 mol at about 30°C). The temperature was raised to about 130° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas Chromatography. The product was a mixture of acetic acid (11 % wt./wt) and methyl acetate (33 % wt./wt.) and the Turn Over Number (TON) was 1050 per 30 minutes.
EXAMPLE -26
[Rh(CO)2(Ph2PCH2COOC2H5)Cl] (24 mg), Methanol (3.10 ml), methyl iodide (1 ml), water (1 ml) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 10 bar (0.06 mol at about 30°C). The temperature was raised to about 130° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas Chromatography. The product was a mixture of acetic acid (8 % wt./wt) and methyl acetate (34 % wt./wt.) and the Turn Over Number (TON) was 1034 per 30 minutes.
EXAMPLE - 27
[Rh(CO)2Cl]2 (10 mg), Methanol (3.10 ml), methyl iodide (1 ml), water (1 ml) and Ph2PCH2COOC2H5 (15.0 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating
arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 10 bar (0.06 mol at about 30°C). The temperature was raised to about 160° C and the corresponding pressure was about 20 atm. The reaction was allowed for about 90 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (49 % wt./wt) and methyl acetate (51 % wt./wt.) and the Turn Over Number (TON) was 2400 per 90 minutes.
EXAMPLE -28
[Rh(CO)2 (Ph;-PCH2COOC2H5)Cl] (24 mg), Methanol (3.10 ml), methyl iodide (1 ml), water (1 ml) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 10 bar (0.06 mol at about 30°C). The temperature was raised to about 160° C and the corresponding pressure was about 20 atm. The reaction was allowed for about 90 minutes. After the catalytic reaction, the product was collected and analyzed by Gas Chromatography. The product was a mixture of acetic acid (47 % wt/wt) and methyl acetate (52 % wt/wt) and the Turn Over Number (TON) was 2394 per 90 minutes.
EXAMPLE - 29
[Rh(CO)2Cl]2 (10 mg), Methanol (3.10 ml), methyl iodide (1 ml), water (1 ml) and Ph2PCH2CH2SC2H5 (15 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for
about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 10 bar (0.06 mol at about 30°C). The temperature was raised to about 130 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (4 % wt.wt) and methyl acetate (19 % wt./wt.) and the Turn Over Number (TON) was 552 per 30 minutes.
EXAMPLE - 30
[Rh(CO)(Ph2PCH2CH2SC2H5)Cl] (24 mg), Methanol (3.10 ml), methyl iodide (1 ml), water (1 ml) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 10 bar (0.06 mol at about 30°C). The temperature was raised to about 130 ° C and the corresponding pressure was about 15 atm. The reaction was allowed for about 30 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (3 % wt/.wt) and methyl acetate (21 % wt./wt.) and the Turn Over Number (TON) was 567 per 30 minutes.
EXAMPLE - 31
[Rh(CO)2Cl]2 (10 mg), Methanol (3.10 ml), methyl iodide (1 ml), water (1 ml) and Ph2PCH2CH2SC2H5 (15 mg) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 10
bar (0.06 mol at about 30°C). The temperature was raised to about 160° C and the corresponding pressure was about 20 atm. The reaction was allowed for about 90 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (46 % wt.wt) and methyl acetate (44 % wt./wt.) and the Turn Over Number (TON) was 2180 per 90 minutes.
EXAMPLE - 32 [Rh(CO)(Ph2PCH2CH2SC2H5)Cl] (24 mg), Methanol (3.10 ml), methyl iodide
(1 ml), water (1 ml) were charged into a 150 ml capacity high pressure autoclave (Berghof, Germany) which was equipped with magnet-drive stirrer and heating arrangement. The reaction vessel (autoclave) was purged with carbon monoxide gas for about 5 minutes. The autoclave was then pressurized with carbon monoxide gas up to 10 bar (0.06 mol at about 30°C). The temperature was raised to about 160 ° C and the corresponding pressure was about 20 atm. The reaction was allowed for about 90 minutes. After the catalytic reaction, the product was collected and analyzed by Gas chromatography. The product was a mixture of acetic acid (51 % wt/.wt) and methyl acetate (40 % wt./wt.) and the Turn Over Number (TON) was 2191 per 90 minutes.
In summary, the metal complexes [Rh(CO)2ClL] or [Rh(COD)ClL] where L is triphenyl phosphine chalcogenide or ether phosphine or nitrogen donor ligands like amino phenol and amino-benzoic acid, which enhances the electron density at the central metal atom and subsequently enhances the activity for carbonylation reaction. Due to the presence of different types of donor such as "Hard oxygen" or "Soft sulfur" or Soft selenium" the complexes behave differently and thus exhibiting different results.
Moreover, the selectivity depends up on the temperature and pressure of the carbonylation reaction.
In summary, the active metal complexes [Rh(CO)2(Ph2PCH2COOC2H5)Cl] or [Rh(CO)2(Ph2PCH2CSC2H5)Cl] were generated by reacting [Rh(CO)2Cl]2 with ligand Ph2PCH2COOC2H5 or Ph2PCH2CH2SC2H5 respectively. The ligands in these complexes contribute high electron density on the central rnetal atom and subsequently facilitate the catalytic reaction. Moreover, the metal complexes show hemilabile character by dissociating the weakly Rh-O or Rh-S bond and thus creating vacancy for substrate bonding which will lead catalytic reaction at comparatively low temperature and pressure.
The hemilabile nature of the [Rh(CO)2(Ph2PCH2COOC2H5)Cl] and
[Rh(CO)(Ph2PCH2CH2SC2H5)Cl] complexes facilitate the catalytic reaction.
The main advantages of the present invention are :
(i) The carbonylation reaction can be carried at a temperature below 160°C and pressure
below 20 bar.
(ii) The metal complexes [Rh(CO)2CL] or [Rh(COD)ClL] can be added directly to the
catalytic system or can be generated in-situ by reacting [Rh(CO)2C]2 or [Rh(COD)Cl]2
with appropriate ligand L.

Claim:
1. An improved process for carbonylation of methanol for producing acetate
ester or mixture of carboxylic acid and acetate ester characterized in that
the reaction is carried out in presence a halogen promoter and rhodium
metal complex catalyst at a temperature range 100°C to 160°C , which
comprises contacting carbon monoxide with liquid reaction composition
comprising methanol, a halogen promoter preferably methyl iodide, water
and a rhodium metal complex catalyst such as herein described , in an
autoclave , under the said temperature range 100°C to 160°C and at a
pressure of 1 to 20 bar, for a period of 30-90 min , and recovering
acetate ester or a mixture of carboxylic acid and acetate ester by
conventional method.
2. A process as claimed in claim 1 wherein the rhodium metal
complex catalyst is selected from [Rh(CO)2CI(Ph2PCH2OCH3)],
[Rh(CO)2CI(Ph2PCH2CH20CH2CH3)], [Rh(CO)2(Ph2PCH2COOC2H5)CI],
[Rh(CO)(Ph2PCH2CH2SC2H5)CI] or [Rh(CO)2CIL] wherein L is a ligand
containing one nitrogen donor groups selected from amino phenol or
amino benzoic acid or tertiary-phosphine chalcogenide containing either
oxygen , sulfur or selenide donor group.
3. A process claimed in claims 1-3, wherein the tertiary-phosphine
chalcogenide ligand is selected from PhsPO, PhaPS and Ph3PSe.
4. A process as claimed in claims 1 - 4, wherein the amino phenol or amino
benzoic acid ligand is selected from m-amino phenol , m-amino benzoic
acid.
5. An improved process for carbonylation of methanol for producing acetate
ester or a mixture of carboxylic acid or acetate ester substantially as
herein described with reference to the examples.

Documents:

211-del-2001-abstract.pdf

211-del-2001-claims.pdf

211-del-2001-correspondence-others.pdf

211-del-2001-correspondence-po.pdf

211-del-2001-description (complete).pdf

211-del-2001-form-1.pdf

211-del-2001-form-19.pdf

211-del-2001-form-2.pdf

211-del-2001-form-3.pdf

« Previous Patent

Next Patent »

Patent Number

231070

Indian Patent Application Number

211/DEL/2001

PG Journal Number

13/2009

Publication Date

27-Mar-2009

Grant Date

28-Feb-2009

Date of Filing

27-Feb-2001

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG,NEW DELHI,110001,INDIA

Inventors:

#	Inventor's Name	Inventor's Address
1	NANDINI KUMARI	REGIONAL RESEARCH LOBORATORY,JORHAT-785006,ASSAM,INDIA
2	DILIP KONWAR	REGIONAL RESEARCH LOBORATORY,JORHAT-785006,ASSAM,INDIA
3	MADAN GOPAL PATHAK	REGIONAL RESEARCH LOBORATORY,JORHAT-785006,ASSAM,INDIA
4	DIPAK KUMAR DUTTA	REGIONAL RESEARCH LOBORATORY,JORHAT-785006,ASSAM,INDIA
5	PANKAN DAS,	REGIONAL RESEARCH LOBORATORY,JORHAT-785006,ASSAM,INDIA
6	MANAB SHARMA	REGIONAL RESEARCH LOBORATORY,JORHAT-785006,ASSAM,INDIA

PCT International Classification Number

C07C 51/12

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA