Title of Invention | AN IMPROVED PROCESS FOR THE PREPARATION OF CYANOFYRIDINES |
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Abstract | 1. All employed process for the preperation of cyanop- yrideines which comprises passing a feed consisting of a picoline or 4 -picolines in a molar ratio of 1:1 ammonia to 1 :20 water and air / oxygen in the range of 30 cc per minute to 100 cc per minute over a crystal- line, porous silica alumino phosphate (SAPO) catalyst prepared by the process such as herein described at a temperature in the range of 300-450 0C and weight hourly space velocity of liquid feed products in the range of 0.25 to1.0 per hour recovering by conventional methods to obtain cyanopyridines. |
Full Text | This invention relates to an improved process for the preparation of cyanopyridines. This invention particularly relates to an improved process for the preparation of nitriles such as 3-cyanopyridine and 4-cyanopyridine from 3-picoline and 4-picoline respectively. According to the process of the present invention, 3- or 4- picoline is reacted with ammonia and air in the presence of a catalyst selected from crystalline, porous silico-aluminophosphates(SAPO). The process of preparing the above catalyst has been described and claimed in oui copending application number 9/Del/95. In the presently known process, 3- and 4- cyanopyridines can be synthesized from ammoxidation of 3- and 4-picolines over amorphous V2 05 or VOPO4 supported over various supports like Al2 03 ,SiO2 -Al203 ,Cr2 03 ,TiO2 . The conventional catalysts have been amorphous in nature and not shape-selective catalysts. These cata lysts have been employed in mostly fixed bed reactors. The following patents have discussed the preparation of nitriles of present intere ' e.g. Eur.Pat; Appl. EP 37173 (1981), US Patent 4876348 (1989),US Patent 4603 207 (1S86), Eur. Pat 0037123A1 (1981), Brit. Patent 77746 (1957), Ger. (East) DDPatent 241903 (1985), US Patent 3981879 (1976), US Patent 2839535 (1958), US Patent 2510605 (1950) , US Patent 3981879 (1976) . In these inventions the yield of nitrile may or may not be highly selective. Particularly high-boiling products, CO,CO2 were formed, due to the amorphous nature of the catalysts. The high-boling products create environmental and disposal problems. The reaction of 3-picoline or 4-picoline was carried out over V2 O5 -Al2 O3 ,mixed oxides of V,Cr,Ti,Sb,Al or Si.The yield of 3-cyanopyridine varied from 50 to 85%; while the yield of 4-cyanopyridine was to 90%. The other products were the high boiling compounds,CO and CO2 . The object of the present inven- tion is to develop selective and particularly provide an improved process for the preparation of nitriles employing porous active catalytic materials. The other objective of the invention is to provide a process for the preparation of nitriles wherein the formation of CO, CO2 and high-boiling products are minimized. Accordingly, the present invention provides an improved process for the preparation of cyanopyridines from respective picolines in 50-85% yields by ammoxida- tion in one step with very high selectivity over SAPO catalysts at a temperature in the range of 350 to 4500 C and weight hourly space velocity in the range of 0.25 to 1.0 per hour. Accordingly, the present invention provides an improved process for the preparation of cyanopyridines which comprises passing a feed consisting of 3-picoline or 4-picolines in a molar ratio of 1:1 ammonia to 1:20 water and air / oxygen in the range of 3 0 cc per minute to 100 cc per minute over a crystalline, porous silica alumino phosphate (SAPO) catalyst prepared by the process such as herein described at a temperature in o the range of 300-450 C and weight hourly space velocity of liquid feed products in the range of 0.25 to 1.0 per hour recovering by conventional methods to obtain cyanopyri dines . In an embodiment of the present invention the molar ratio of picolines and ammonia used may ranges from 1:1 to 1:20. The feed ratio of air / oxygen gas may be in the range of 3 0 - 100 cc. per minute. The catalysts are prepared in general in the following way. Al2 (SO4 )3 , H3 PO4 , Na 2 SiO3 ,with or without NaCl anc tetrapropylammonium bromide (TPA) or tetrabu-tylammonium bromide (TBA) used as a template,are mixed in distilled water in the pH range of 7.0 to 12.0. The slurry is mixed for atleast 2 hrs at room temperature with constant stirring and the pH is adjusted by aqueous ammonia. The slurry was put into an autoclave for autoclaving under autogeneous pressure in the tempera- ture range of 150 to 220 C for 24 hrs to 80 hrs till complete crystallization was achieved. The mixture was filtered and washed with distilled water.The solid catalyse was dried in oven at 12 00 C over night. The organic template was removed by the activation of the catalyse at 400-550 0 C for 5-15 hrs. Then the calcined material was modified by promoters like Sb 2 O 3 or oxides of the elements active as promoters in the respective reactions. Basically in aluminophosphate molecular sieves the Al:P atomic ratio is 1:1. We have substituted P partially by Si as discussed and claimed in the copending patent number 1459/Del/95. Al also may be :stituted partially by Si with the corresponding variation in the atomic ratio. The above said reactions were carried out in a tubular,down-flow pyrex reactor with 20 mm internal diametei:. The reaction mixture was fed from top using syringe pump(Sage Instruments,USA). The product was cooled by using ice-cooled water and collected at the bottom. The required number of ice-cooled traps were used to collect the total amount of products. The products were analysed by using SE-30 (5%) and OV-17 columns.The analysis was confirmed by mass spectra and GC-mass. The ammoxidation of 4-picoline with ammonia was carried out in presence of air or (02 ) at 420 0C with 0.5 hr -1 W.H.S.V. and 4 gm of catalyst like SAPO(TPA), SAPO(TBA), SAPO-37 (18-30 mesh). 4-Picoline was diluted with water in 1:3 volume ratio. The feed rate of ammonia was 30-35 cc per min and the rate of air was 60 cc per min. The following reaction parameters were varied,reaction temperature, 4-picoline : NH 3 , 4-pico- line:H 2 0, W.H.S.V., etc. The ammoxidation of 3-picoline with ammonia was carried out in presence of air (0 2 ) at 420 0C with 0.5hr-1 W.H.S.V. and 4gm of catalyst. 3-Picoline was diluted with water using 1:3 by volume ratio. The feed rate of ammonia gas was 3 5 cc per min and rate of air was 60 cc per min. With the increase of ammonia in the feed there was increase in the yield of 3-cyanopyridine to about 60.8 wt%. The various reaction parameters like reaction temperature, weight hourly space velocity, picoline to ammonia and water ratio in the feed were varied. The following examples are given to illustrate the process of the present invention,however these should not be construed to limit the scope of invention. EXAMPLE - 1 In the reaction of 0.477 gm per hr 4- picoline,0.228 gm (30 cc per min) ammonia,1.5 gm per hr of water,6 0 cc per min of air over 4 gm SAPO(TPA) at 420 o C and 0.5 hr-1 W.H.S.V. of liquid feed; the yield of 4- cyanop- yridine was 39.9 % based on 4- picoline at 41.7 % conversion of 4- picoline. EXAMPLE In the reaction of 0.477 gm per hr 4- picoline,0.228 gm (30 cc per min) ammonia,1.5 gm per hr of wateater,60 as per min of air over 4 gm SAPO(TBA) at 420 0C and 0.5 ar W.H.S.V. of liquid feed; the yield of 4- cyanop- yridine was 44.0 % based on 4- picoline at 45.2 % conversion of 4- picoline. EXAMPLE In the reaction of 0.477 gm per hr 3- picoline,0.228 gm (30 cc per min) ammonia,1.5 gm per hr of water,60 cc per min of air over 4 gm SAPO(TPA) at 420 0 C and 0.5 hr-1 W.H.S.V. of liquid feed; the yield of 3- cyanop- yridine was 10.1 % based on 3 - picoline at 13.5 % conversion of 3- picoline. WE CLAIM : 1. An improved process for the preparation of cyanop- yridines which comprises passing a feed consisting of 3-picolme or 4-picoiines in a molar ratio of 1:1 ammonia to 1:20 water and air / oxygen in the range of 3 0 cc per minute to 100 cc per minute over a crystal line, porous silica alumino phosphate (SAPO) catalyst prepared by the process such as herein described at a o temperature in the range of 300-450 C and weight hourly space velocity of liquid feed products in the range of 0.25 to 1.0 per hour recovering by conventional meth- to obtain cyanopyridines. 2. An improved process as claimed in claim 1 wherein the feed ratio of air or oxygen gas is 60 cc per min preferably. 3. An improved process for the preparation of cyanopyridines substantially as herein described with reference to the examples. |
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956-del-1995-correspondence-others.pdf
956-del-1995-correspondence-po.pdf
956-del-1995-description (complete).pdf
Patent Number | 190432 | |||||||||||||||||||||
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Indian Patent Application Number | 956/DEL/1995 | |||||||||||||||||||||
PG Journal Number | 30/2003 | |||||||||||||||||||||
Publication Date | 26-Jul-2003 | |||||||||||||||||||||
Grant Date | 24-Feb-2004 | |||||||||||||||||||||
Date of Filing | 25-May-1995 | |||||||||||||||||||||
Name of Patentee | COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH | |||||||||||||||||||||
Applicant Address | RAFI MARG, NEW DELHI 110 001,INDIA | |||||||||||||||||||||
Inventors:
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PCT International Classification Number | C07C 121/00 | |||||||||||||||||||||
PCT International Application Number | N/A | |||||||||||||||||||||
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