Title of Invention

AN IMPROVED PROCESS FOR PREPARATION OF P,P-BISPHENOL

Abstract

An improved process for the preparation of p,p' - bisphenol A by reacting phenol with acetone in a ratio of phenol to acetone in the range of 2 : 1 to 20 : 1 (w/w) in the presence of a heteropoly acid as a catalyst in the concentration ranging between 0.1 to 5% by weight and an inhibitor selected from mercaptopropionic acid at a temperature in the range of 50 - 150°C, at a pressure ranging between 1 to 5 atmospheres, for a period ranging from 1 to 16 hrs, terminating the reaction and separating the product of the reaction mixture by known methods and recovering p,p' - bisphenol A by conventional procedures.

Full Text

The present invention relates to an improved process for the preparation of bisphenol - A. More particularly, the present invention relates to a process for producing bisphenol A from phenol and acetone at high purity, selectivity and conversion in presence of a heteropolyacid compound. Bisphenol A is an important raw material for the synthesis of epoxy resins, polycarbonates and other useful polymers. Acid catalysed condensation of phenol with acetone is the facile route for the synthesis of bisphenol A. Literature reveals that HCI is the conventional catalyst for its synthesis [Ligorati F, " Process for the production of 2,2-(4,r' - dihydroxy diphenyl) propane ", US Patent No. 4,169,211.]. In the manufacture of bisphenol A the main drawback of using HCI is its environmental pollution and waste disposal problems. Moreover HCI induces corrosion to the reactor set up in large scale preparation of bisphenols. Due to the above mentioned difficulties, hydrochloric acid is replaced by certain sulphonic acid resin catalyst. Temperature limitation is the main problem while using these resins . An ideal catalyst for the production of bisphenol A should be moderately acidic and selective whereby lesser quantities of byproducts would be formed [Yadav G D & Kirthivasan N, Applied Catalysis A: Gen, 154 (1997) 29]. Singh has showed that some solid zeolites with larger pore openings are more selective in the formation of bisphenol A even though the conversion was lower; H-ZSM-5, H.Mordenite, H-Y and RE-Y [Singh A P, Catalysis Letters 16 (1992)431]; these have been claimed to diminish the above mentioned drawbacks of the conventional catalyst. There is mention about heteropoly acids also in the literature, but details are not available [ Yamamtsu S, phosphotungstic acid, silicotungstic acid and mono- di- and tri- vanadium substituted phosphomolybdic acids. These catalysts showed high selectivity at good conversion levels to the required isomer product when compared to other standard catalysts. The object of the present is to provide a process for the preparation bisphenol-A. Another object of the present invention is to provide a process for the preparation of bisphenol-A using acid catalyst which give better selectivity and environment friendly applications. Accordingly the present invention provides an improved process for the preparation of p,p' - bisphenol A which comprises reacting phenol with acetone in a ratio of phenol to acetone in the range of 2 : 1 to 20 : 1 (w/w) in the presence of a heteropoly acid such as herein described as a catalyst in the concentration ranging between 0.1 to 5% by weight and characterized in that in presence of an initiator selected from mereaptopropionic acid at a temperature in the range of 50 - 150°C, at a pressure ranging between 1 to 5 atmospheres, for a period ranging from 1 to 16 hrs, terminating the reaction and separating the product of the reaction mixture by known methods and recovering p,p' - bisphenol A by conventional procedures. In an embodiment of the present invention the heteropoly acid used is selected from the group consisting of phosphotungstic acid, silicotungstic acid and mono- di- or tri- vanadium substituted phosphomolybdic acid. In yet another embodiment the initiator used is mereaptopropionic acid. phosphotungstic acid, silicotungstic acid and mono- di- and tri- vanadium substituted phosphomolybdic acids. These catalysts showed high selectivity at good conversion levels to the required isomer product when compared to other standard catalysts. The object of the present invention is to provide a process for the preparation of bisphenol-A. Another object of the present invention is to provide a process for the preparation of bisphenol-A using acid catalyst which gives better selectivity and environment friendly applications. Accordingly the present invention provides an improved process for the preparation of p,p '-bisphenol A which comprises reacting phenol with acetone in a ratio of phenol to acetone in the range of 2 :1 to 20 : 1 (w/w) in the presence of a heteropoly acid as a catalyst in the concentration ranging between 0.1 to 5% by weight and an initiator, at a temperature in the range of 50-150°C, at a pressure ranging between 1 to 5 atmospheres, for a period ranging from 1 to 16 hrs, terminating the reaction and separating the product of the reaction mixture by known methods and recovering the desired product by conventional procedures. In an embodiment of the present invention the heteropoly acid used is selected from the group consisting of phosphotungstic acid, silicotungstic acid and mono- di- or tri-vanadium substituted phosphomolybdic acid. In yet another embodiment the initiator used is mercaptopropionic acid. In yet another embodiment the heteropoly acid catalyst use is recovered by adding potassium chloride and is recyclable. In yet another embodiment the selectivity for p,p'-bisphenol A is in the range of 90- 100%. The process of the present invention is described with reference to examples hereinbelow which are illustrative only and should not be construed to limit the scope of present invention in any manner. Example 1 A mixture of phenol (30.1 g) and acetone (1.85 g), catalyst HCl gas (0.2 g) and initiator (2-3 drops of mercaptopropionic acid) were taken in a 100 ml round bottomed flask and the reaction mixture was magnetically stirred and heated to 80°C at one atmospheric pressure under reflux conditions. The reaction was stopped after 6 hrs., product poured into cold water (250 ml) , the upper layer separated and aqueous layer extracted with toluene (50 ml, 3 times), the organic layers mixed and analysed by gas chromatography for the quantification of the reaction products and unreacted phenol and acetone. Example 2 A mixture of phenol (30.1 g) and acetone (1.85 g), catalyst HCl gas (0.4 g) and initiator (2-3 drops of mercaptopropionic acid) were taken in a 100 ml round bottomed flask and the reaction mixture was magnetically stirred and heated to 70°C at one atmospheric into cold water (250 ml) , the upper layer separated and aqueous layer extracted with toluene (50 ml, 3 times), the organic layers mixed and analysed by gas chromatography for the quantification of the reaction products and unreacted phenol and acetone. Example 3 A mixture of phenol (30.1 g) and acetone (1.85 g), catalyst phosphotungstic acid (0.2 g in 0.2 ml water) and initiator (2-3 drops of mercaptopropionic acid) were taken in a 100 ml round bottomed flask and the reaction mixture was magnetically stirred and heated to 60°C at one atmospheric pressure under reflux conditions. The reaction was stopped after 6 hrs., product poured into cold water (250 ml) , the upper layer separated and aqueous layer extracted with toluene (50 ml, 3 times), the organic layers mixed and washed with a 5% solution of KCl (25 ml), the layers again separated and organic layer analysed by gas chromatography for the quantification of the reaction products and unreacted phenol and acetone. Example 4 A mixture of phenol (30.1 g) and acetone (1.85 g), catalyst phosphotungstic acid (0.4 g in 0.4 ml water) and initiator (2-3 drops of mercaptopropionic acid) were taken in a 100 ml round bottomed flask and the reaction mixture was magnetically stirred and heated to 85°C at one atmospheric pressure under reflux conditions. The reaction was stopped after 16 hrs., product poured into cold water (250 ml) , the upper layer separated and aqueous layer extracted with toluene (50 ml, 3 times), the organic layers mixed and analysed by gas chromatography for the quantification of the reaction products and unreacted phenol and acetone. Example 5 A mixture of phenol (30.1 g) and acetone (1.85 g), catalyst silicotungstic acid (0.2 g in 0.2 ml water) and initiator (2-3 drops of mercaptopropionic acid) were taken in a 100 ml round bottomed flask and the reaction mixture was magnetically stirred and heated to 85°C at one atmospheric pressure under reflux conditions. The reaction was stopped after 6 hrs., product poured into cold water (250 ml) , the upper layer separated and aqueous layer extracted with toluene (50 ml, 3 times), the organic layers mixed and washed with a 5% solution of KC1 (25 ml), the layers again separated and organic layer analysed by gas chromatography for the quantification of the reaction products and unreacted phenol and acetone. Example 6 A mixture of phenol (30.1 g) and acetone (1.85 g), catalyst monovanadium substituted (Vi) phosphomolybdic acid (0.2 g) and initiator (2-3 drops of mercaptopropionic acid) were taken in a 100 ml round bottomed flask and the reaction mixture was magnetically stirred and heated to 80°C at one atmospheric pressure under reflux conditions. The reaction was stopped after 6 hrs., product poured into cold water (250 ml) , the upper layer separated and aqueous layer extracted with toluene (50 ml, 3 times), the organic layers mixed and washed with a 5% solution of KC1 (25 ml), the layers again separated and organic layer analysed by gas chromatography for the quantification of the reaction products and unreacted phenol and acetone. Example 7 A mixture of phenol (30.1 g) and acetone (1.85 g), catalyst divanadium substituted (V2) phosphomolybdic acid (0.2 g) and initiator (2-3 drops of mercaptopropionic acid) were taken in a 100 ml round bottomed flask and the reaction mixture was magnetically stirred and heated to 90°C at one atmospheric pressure under reflux conditions. The reaction was stopped after 6 hrs., product poured into cold water (250 ml) , the upper layer separated and aqueous layer extracted with toluene (50 ml, 3 times), the organic layers mixed and washed with a 5% solution of KC1 (25 ml), the layers again separated and organic layer analysed by gas chromatography for the quantification of the reaction products and unreacted phenol and acetone. Example 8 A mixture of phenol (30.1 g) and acetone (1.85 g), catalyst trivanadium substituted (V3) phosphomolybdic acid (0.2 g) and initiator (2-3 drops of mercaptopropionic acid) were taken in a 100 ml round bottomed flask and the reaction mixture was magnetically stirred and heated to 80°C at one atmospheric pressure under reflux conditions. The reaction was stopped after 6 hrs., product poured into cold water (250 ml), the upper layer separated and aqueous layer extracted with toluene (50 ml, 3 times), the organic layers mixed and washed with a 5% solution of KC1 (25 ml), the layers again separated and organic layer analysed by gas chromatography for the quantification of the reaction products and unreacted phenol and acetone. Example 9 The potassium salt of the heteropoly acid, separated upon adding KCl as a crystalline solid, is filtered out and washed with cold water and dried. Free heteropoly acid is extracted into diethyl ether after acidifying the salt with hydrochloric acid. The ether layer was later evaporated to get the free heteropoly acid, which is recycled as catalyst. The results and major findings are reported in tables 1, 2 and 3 mentioned below. Tables Table 1- Effect of conversion and selectivity, by using 0.6 % of the catalyst for 6 hours. Catalyst Acetone conversion (%) Selectivity (%) HC1 gas 90 Vi 65 v2 62 v3 60 PY* 93 ST* 91 para/ortho 87 94 97 100 95 96 V1 = H4[PMo11V04o]. xH20 V2=H5[PMoloV04o].xH20 V3 = H6[PMo9V04o]. xH20 PT = H3[PWi204o]. 31 H20 (phosphotungstic acid) ST = H4[SiWi204o]. 24 H20 (silicotungstic acid) * PT and ST in water Table 2 - Effect of conversion and selectivity, by using 1.25 % of the catalyst for 6 hours Catalyst Acetone conversion (%) Selectivity (%) para/ortho HC1 gas 94 88 Vi 74 96 V2 64 97 V3 61 100 PT* 96 97 ST* 95 98 Catalyst abbreviation same as in Table 1 Table 3- Effect of 16 hours reaction time on conversion and selectivity by using 0.6 and 1.25 wt% of the catalyst Acetone conversion ■ (%) Selectivity (° /o) Catalyst 0.6 (wt %) 1.25 (wt%) 0.6 (wt %) 1.25 (wt%) HC1 gas 90 94 87 88 V, 66 76 94 96 v2 63 65 97 97 v3 61 62 100 100 p'T* 95 97 95 97 ST* 92 95 96 98 Catalyst abbreviation same as in Table 1 We Claim: 1. An improved process for the preparation of p,p' - bisphenol A which comprises reacting phenol with acetone in a ratio of phenol to acetone in the range of 2 : 1 to 20 : 1 (w/w) in the presence of a heteropoly acid such as herein described as a catalyst in the concentration ranging between 0.1 to 5% by weight and characterized in that in presence of an initiator selected from mercaptopropionic acid at a temperature in the range of 50 - 150°C, at a pressure ranging between 1 to 5 atmospheres, for a period ranging from 1 to 16 hrs, terminating the reaction and separating the product of the reaction mixture by known methods and recovering p,p' - bisphenol A by conventional procedures. 2. A improved process as a claimed in claim 1, wherein the heteropoly acid used is selected from the group consisting of phosphotungstic acid, silicotungstic acid and mono - di - or tri- vanadium substituted phosphomolybdic acid. 3. An improved process for the preparation of bisphenol A as substantially described hereinbefore with reference to examples accompanying this specification.

Documents:

167-DEL-2002-Abstract-29-05-2008.pdf

167-DEL-2002-Claims (23-06-2008).pdf

167-DEL-2002-Claims-29-05-2008.pdf

167-DEL-2002-Correspondence-Others (23-06-2008).pdf

167-del-2002-description (complete)-23-06-2008.pdf

167-del-2002-description (complete)-29-05-2008.pdf

167-DEL-2002-Form-1 (23-06-2008).pdf

167-DEL-2002-Form-1-29-05-2008.pdf

167-DEL-2002-Form-2 (23-06-2008).pdf

abstract.pdf

claims.pdf

correspondence-others.pdf

correspondence-po.pdf

description complete.pdf

form-1.pdf

form-18.pdf

form-2.pdf

form-3.pdf