Title of Invention	"AN IMPROVED PROCESS FOR THE PREPARATION OF 1,4 BUTENEDIOL"
Abstract	The present invention deals with the selective hydrogenation of 1.4-butenediol in presence of suitable catalyst over alkali or alkaline earth metals which gives high selectivity of the hydrogenated substance.

Full Text

This invention relates to an improved process for the preparation of 1,4 butenediol. More particularly it'relates to selective liquid phase hydrogenation of 1,4 butynediol to 1,4 butenediol in a basic medium in the presence of platinum catalyst supported on alkaline earth carbonate. 1,4 butenediol is a very useful intermediate in the production of pesticide, insecticide, vitamin B6. Being unsaturated diol it can be used in synthesis of many organic products such as tetrahydrofuran, n-methyl pyrrolidione, y-butyrolactone etc. It is also used as an additive in paper industry, as a stabilizer in resin manufacture, as a lubricant for bearing system and in the synthesis of allyl phosphates. In the prior art, the uses of a number of catalysts are described for producing 1,4 butenediol by hydrogenation of 1,4 butynediol. Most of these patents are based on the combination of palladium with one or more mixed compounds of copper, zinc, calcium, cadmium, lead, alumna, mercury, tellurium, gallium etc. An improved process for the selective hydrogenation of acetylinic compound is described in GBA 871,804 in a suspension method using Pd catalyst which has been treated with the salt solutions of Zn, Cd, Hg, Ga, Th, In, or Ga. The process is carried out at milder conditions with 97% selectivity for cis 1 ^-butenediol and 3% to the trans form. Moreover, for this process additional amines are used. Lindlar catalyst (lead doped Pd catalyst) is also used for the selective hydrogenation of the acetylinic compounds as described in US patent No. 2,681,938. The drawback of this process is use of additional amines such as pyridine to obtain good selectivity for 1,4-butenediol. Yet another DE patent (DE 1,213,839) describes a process for the partial hydrogenation of water miscible acetylinic compounds using Pd catalyst doped with Zn salts and ammonia. But this catalyst suffers from a major drawback of short lifetime due to poisoning. The hydrogenation of butynediol in an inert solvent using Pd/Al2O3 catalyst which has been treated with carbon monoxide is described in DE -A 2,619,660. The disadvantage of this process is that the catalyst is treated with carbon monoxide gas, which is highly toxic and difficult to handle. US Patent No. 2,961,471 describes a process for partial hydrogenation of 1,4- butynediol using Raney nickel catalyst. A low selectivity for 1,4-butenediol is obtained using this catalyst. In another US Patent No. 2,953,604 -IS described a process for reduction of 1,4 butynediol to 1,4 butenediol using Pd containing charcoal and copper catalyst with 81% selectivity for 1,4 butenediol. The drawback of the process is the formation of large amount of side products. Another US Patent No. 4,001,344 describes a catalyst for the preparation of 1,4 butenediol by hydrogenation of 1,4 butynediol by use of palladium mixed with y-Al2O3 along with both zinc and cadmium or either zinc or cadmium together with bismuth or tellurium at 65°-72°C and 4-12.5 bars hydrogen pressure . The disadvantage of the said process is the formation of that a large amount of residues (7.5-12 %) which lowers the selectivity of 1,4 butenediol to 88 %. In addition to these patents, US Patent Nos. 5,521,139 and 5,728,900 describe the catalyst and a process for the preparation of 1,4 butenediol by the hydrogenation of 1,4 butynediol over a Pd containing catalyst. It teaches use of fixed bed catalyst, which was prepared by applying Pd and Pb or Pd and Cd successively, by vapor deposition or sputtering, to a metal gauze or a metal foil acting as a support. In this process also a selectivity obtained for cis 1,4 butenediol is 98 %. The disadvantage of these processes is that a trans butenediol with residues are also obtained. All the above said processes for the hydrogenation of butynediol to butenediol suffers from the disadvantages such as high temperatures and pressures. The formation of side products and residues have also been reported which affect the efficiency of the process and the recovery of pure 1,4 butenediol is difficult. In addition, another drawback is that the catalyst used for these processes contain more than two metals alongwith other/ promoters like organic amines. Their preparation becomes cumbersome. All these processes using catalysts reported do not give complete selectivity to the desired product 1,4 butenediol. Also these catalysts suffer from short life due to fast deactivation because of poisoing. The above patent survey shows that the process for the hydrogenation of 1,4 butynediol was reported using mainly palladium or nickel based catalyst But there is no report available on the use of platinum based catalyst for this industrially important process. It is, therefore, interesting to study the process for the selective production of 1,4 butenediol using platinum containing catalyst. The main object of the present invention is to provide an improved process for the preparation of 1,4 butenediol at a milder reaction conditions using novel efficient and selective catalyst which comprises of only platinum on a suitable support without poisoning for the selective production of 1,4 butenediol by hydrogenation of 1,4 butynediol. Another object is to provide a process with 100 % selectivity for production of cis 1,4 butenediol. The present process gives 100% conversion of butynediol with 100 % selectivity to 1,4 butenediol at milder conditions. Moreover, the pure 1,4 butenediol is recovered merely by the separation of the catalyst. Accordingly the present invention provides an improved process for preparation of 1,4 butenediol which comprises hydrogenating aqueous solution of 1,4 butynediol under stirring conditions, over a supported Pt catalyst in basic medium at a temperature ranging between 20 to 110°C under hydrogen atmosphere, cooling the reaction mixture to room temperature, separating the catalyst by conventional methods to obtain 1,4 butenediol. In one of the embodiment of the present invention, the supported platinum catalyst used is prepared as per the procedure claimed and described in our copending patent application no 125/DEL03 please mouide Patent application no. In yet another embodiment the concentration of 1,4 butynediol in aqueous medium is in the range of 10-70%. In yet another embodiment the pH of the reaction mixture is maintained, preferably 8-10 by adding a base preferably ammonia. In yet another embodiment the hydrogen pressure may be in the range of 100-900 psig , preferably 200-700 psig. In still another embodiment the temperature of the reactions is preferably in the range 30°C to 90°C. In still another embodiment the temperature of the reaction mey be in the range of 20°C to llO°C. The present invention achieves 100% conversion for 1,4 butynediol with 100% selectivity for cis 1,4 butenediol at milder conditions. At higher temperatures, 1,4 butynediol is converted completely but less selectivity ( In the present invention, the catalyst is prepared by impregnating platinum precursor with support (viz. CaCO3,MgCO3 or BaCO3) in basic medium (pH=7-12),stirred in water and is heated in the temperature range between 60°C to 120°C,preferably between 70°C to 90°C.The mixture is then reduced by adding formaldehyde. This solution is stirred/iltered washed and dried in the temperature range between 100°C to 250°C,preferably 140°C to 200°C in static air for a period ranging between 5 to 12 hours. The detailed description for the catalyst preparation is described in our copending patent application (NCL 125/DEL/03). The hydrogenation of 1,4 butynediol to 1,4 butenediol was carried out in zn autoclave under stirring conditions in the presence of a Pt containing catalyst suspended in a mixture of 1,4 butynediol in water at a temperature and H2 pressure which mentioned in the examples. The mixture is made alkaline (pH = 8-10) by adding ammonia. Before pressurizing an autoclave, be ensured that no air is present inside the autoclave. The hydrogenation is complete when the absorption of hydrogen is stopped or unchanged. After the reaction was complete, the reactor was cooled below ambient temperature and the contents were discharged and analyzed die reaction mixture by gas chromatograph. The process of the invention is described by following examples which are illustrative only and should not be construed to limit the scope of the invention in any manner. Example 1 This example illustrates the procedure for the preparation of platinum supported catalyst as follows. The catalyst is prepared by impregnating platium precursor, with support ( viz. MgCO3 or BaCO3) in basic medium, stirred in water and is heated at 80°C. The mixture is then reduced by adding formaldehyde. This solution is stirred, filtered washed and dried at 150°C static air for 10 hrs. Example 2 This example illustrates the performance or the use of the 1% Pt / MgCO3 catalyst in the hydrogenation of 1,4 butynediol to 1,4 butenediol. The catalyst is prepared by impregnating platium precursor with MgCO3 support in basic medium, stirred in water and is heated at 80°C. The mixture is then reduced by adding formaldehyde. This solution is stirred, filtered washed and dried at 150°C static air for 10 hrs. The reaction in presence of this catalyst was carried out in an autoclave as per the procedure given earlier. The reaction was carried out at the following reaction condition: Cone, of 1,4 Butynediol in water : 20 % Wt. of catalyst : O.13 gms Temperature : 50 °C H2 Pressure : 350psig. The following results were obtained. Conversion of 1,4 butynediol : 100% Selectivity for cis 1,4 butenediol : 99.8 % Example 3' This example illustrates the performance or use of the 1% Pt/CaCO3 catalyst in the hydrogenation of 1,4 butynediol. The catalyst is prepared by impregnating platium precursor with CaCO3 support in basic medium, stirred in water and is heated at 80°C. The mixture is then reduced by adding formaldehyde. This solution is stirred, filtered washed and dried at 150°C static air for 10 hrs. The hydrogenation reaction in presence of this catalyst was carried out in an autoclave as per the procedure given earlier. The reaction was carried out at the following reaction condition: Cone, of 1,4 Butynediol in water : 10 % Wt. of catalyst : 0.065 gms Temperature : 50 °C HZ Pressure : 350 psig. The following results were obtained. Conversion of 1,4 butynediol : 100% Selectivity for cis 1,4 butenediol : 100% Example 4 The reaction was carried out at the following reaction condition: Catalyst : 1 %Pt/CaCO3 Wt. of catalyst : 0.13 gms Cone, of 1,4 Butynediol in water : 20 % Temperature : 50 °C Ha Pressure : 350 psig. The following results were obtained. Conversion of 1,4 butynediol : 100% Selectivity for cis 1,4 butenediol : 100% Example 5 The reaction was carried out at the following reaction condition: Catalyst : 1 %Pt/CaC03 Wt. of catalyst : 0.13 gms Cone, of 1,4 Butynediol in water : 20 % Temperature : 50 °C Ha Pressure : 500 psig. The following results were obtained. Conversion of 1,4 butynediol : 100 % Selectivity for cis 1,4 butenediol : 100 % Example 6 The reaction was carried out at the following reaction condition: Catalyst : !%Pt/CaCO3 Wt. of catalyst : 0.13 gms Cone, of 1,4 Butynediol in water : 20 % Temperature : 80 °C HZ Pressure : 350 psig. The following results were obtained. Conversion of 1,4 butynediol : 100 % Selectivity for cis 1,4 butenediol : 97.2 % Side products : 2.8 Example 7 The reaction was carried out at the following reaction condition: Catalyst : !%Pt/CaCO3 Wt. of catalyst : 0.13 gms Cone, of 1,4 Butynediol in water : 20 % Temperature : 80 °C HI Pressure : 500 psig. The following results were obtained. Conversion of 1,4 butynediol : 100% Selectivity for cis 1,4 butenediol : 95.7 % Side products : 4.3 Example 8 The reaction was carried out at the following reaction condition: Catalyst : 1%Pt/CaCO3 Wt. of catalyst : 0.23 gms Cone, of 1,4 Butynediol in water : 35 % Temperature : 50 °C H2 Pressure : 350psig. The following results were obtained. Conversion of 1,4 butynediol : 100% Selectivity for cis 1,4 butenediol : 100 % Example 9 The reaction was carried out at the following reaction condition: Catalyst : 1 %Pt/CaCO3 Wt. of catalyst : 0.46 gms Cone, of 1,4 Butynediol in water : 70 % Temperature : 50 °C H2 Pressure : 350psig. The following results were obtained. Conversion of 1,4 butynediol : 100 % Selectivity for cis 1,4 butenediol : 83.4 % Example 10 This example illustrates the performance or use of the 1 % Pt/ BaCO3 catalyst in the hydrogenation of 1,4 butynediol to 1,4 butenediol. The catalyst is prepared by impregnating platium precursor with BaCO3 support in basic medium, stirred in water and is heated at 80°C. The mixture is then reduced by adding formaldehyde. This solution is stirred, filtered washed and dried at 150°C static air for lOhrs. The reaction in presence of this catalyst was carried out in an autoclave as per the procedure given earlier. The reaction was carried out at the following reaction condition: Cone, of 1,4 Butynediol in water : 20 % Wt. of catalyst : 0.13 gms Temperature : 50 °C Ha Pressure : 350psig. The following results were obtained. Conversion of 1,4 butynediol : 100 % Selectivity for cis 1,4 butenediol : 99.9 % The present invention gives following advantages over any other known processes. • Selective hydrogenation of 1,4 butynediol to 1,4 butenediol is achieved using novel 1 % Pt/MgCO3, 1 % Pt/CaC03 and 1% Pt/BaCO3 catalysts without poisoning. • Results obtained under milder reaction conditions. • Easy separation of the product 1,4 butenediol in the pure from. The catalyst can be easily separated from the reaction mixture. We Claim: 1 An improved process as claimed in claim l,wherein the temperature of the reaction may be in the range of 20°C-110°C.preferably 30°-90°C An improved process for preparation of 1,4-butenediol which comprises hydrogenating aqueous solution of 1,4-butynedioj under stirring conditions, over a supported Pt catalyst in basic medium at a temperature ranging between 20° to 110°C under hydrogen atmosphere at a pH ranging between 7 to 12,cooling the reaction mixture to room temperature, separating the catalyst by conventional methods to obtain 1,4-butenediol. 2. An improved procecs as claimed in claim 1, wherein the concentration of 1,4 butynediol in aqueous medium is in the range of 10-70%,preferably 20- 50%. 3. An improved process as claimed in claim 1, wherein pH of the reaction mixture is maintained at preferably 8-10 by adding a base preferably ammonia. 4. An improved process as claimed in claim 1,wherein the hydrogen pressure may be in the range of 100-900 psig .preferably 200-700 psig. 5. An improved process as claimed in claim 1, wherein the temperature of the reactions is preferably in the range 30°C to 90°C. 6. A process for the hydrogenation of 1,4-butynediol as substantially described herein before with reference to the examples.

Documents:

216-del-2000-abstract.pdf

216-del-2000-claims.pdf

216-del-2000-correspondence-others.pdf

216-del-2000-correspondence-po.pdf

216-del-2000-description (complete).pdf

216-del-2000-form-1.pdf

216-del-2000-form-13.pdf

216-del-2000-form-19.pdf

216-del-2000-form-2.pdf

216-del-2000-form-3.pdf