Title of Invention

"AN IMPROVED PROCESS FOR THE PREPARATION OF 1,4-BUTANEDIOL"

Abstract

An improved process for the preparation of 1,4-butanediol by adding Ni-AI alloy to a solution of 2-butene-1,4-diol in aqueous metal hydroxide in the concentration range of 5 to 20% at a temperature ranging from 5 to 50°C, stirring the reaction mixture further for a period of 1 to 6 hr, separating the solid by conventional method, saturating the filtrate with salt, extracting the product in an organic solvent, isolating the product, 1,4-butanediol by known methods.

Full Text

This invention relates to an improved process for the preparation of 1,4-butanediol. More particularly it describes a process for 1,4-butanediol by reduction of 2-butene-l,4-diol. Still more particularly, the present invention relates to an improved process for the preparation of 1,4-butanediol by the reduction of 2-butene~l,4-diol using nickel-aluminium (Ni~Al) alloy. 1,4~Butanediol is an important intermediate in the manufacture of polyethers, polyols, copolyester ethers, elastomers, thermoplastic polyurethanes, and spandex fibers (M. L Morgan, Chem. & Industry, 1997, 166]. In a prior art various methods have been demonstrated for the preparation of 1,4-butanediol. In one of the method, acetylene is reacted with formaldehyde to get 1,4-butynediol, which on two stage hydrogenation in presence of Pd on alumina resulted in the formation of 1,4~butanediol along with small amount of 4~hydroxybutyraldehyde and 2-butene-l,4-diol {Ger (east) DD 26539, (1989)}. In another method, 1,4-butanediol is prepared by hydrogenation of 2-butene~l,4-diol in presence of catalysts containing metal salts of Fe, Co, Ca, Cr, Ti and Ni impregnated on silica gel, at 10 atm. pressure and 80°C temperature 0apan Kokai 7449910 (1972)}. In yet another method, 1,4~butanediol is obtained in three step process from 1,3~butadiene by acetoxylation, hydrogenation followed by hydrolysis (a) US 3,922, 300 (1975); b) US 4,225,729 (1980)}. In yet another method, 1,4-butanediol is prepared from epoxybutene {US 3,932,468 (1975)}. ARCO has developed a three step process for 1,4~butanediol from propylene oxide, which includes isomerization of propylene oxide to allyl alcohol at 250 ~ 300°C and about 10 bar pressure, hydroformylation of allyl alcohol to 4~hydroxybutyraldehyde and hydrogenation of 4-hydroxybutyraldehyde to 1,4-butanediol {(a) US 4,567,305 (1986); b) EP Appl No. 129802 Al (1984); c) US 4,537,997 (1985); d) US 4,465,873 (1984)}. In a similar method allyl ethers on hydroformulation, hydrogenation followed by hydrolysis gave 1,4~ butanediol {(a) EP Appl. No. 18163 (1980); b) EP Appl. No. 18164 (1980)}. In a yet another process, 1,4-butanediol is obtained as by product along with tetrahydrofuran, is based on vapor phase hydrogenation of maleic anhydride or succenic anhydride, {(a) EP Appl. No. 147219 B1 (1989); (b) US 4,810,807(1989)}. In a yet another process 1,4-butanediol is produced as a mixture of 1,2- and 1,4-butanediol, by reacting, 1,3-butadiene with tert-butylhydroperoxide in the presence of a cobalt on silica catalyst, followed by catalytic hydrogenation of di (tert-butylperoxy)butene obtained at 200-1300 psi H2 pressure {S. C. Tang and K. Tex, US 4,384,146 (1983)}. The hydrogenation of 1,4-butynediol and 2-butene-1,4-diol over various palladium catalysts are carried out to get 1,4-butanediol [Bull. Chem. Soc. Japan, 1958, 31, 343]. In most of the prior arts described above involves more steps and are less selective, and moreover lead to the formation of mixture of products from which desired product, 1,4-butanediol, has to be separated. The drawback of some of the prior art are the hydrogenation step is carried out at very high pressure and temperature. The main object of this invention is to provide an improved process for the preparation of 1,4-butanediol with very high selectivity and which do not have the limitations of the prior art processes, described hereinabove. Another object of this invention is to provide a process for the preparation of 1,4-butanediol, wherein the reduction of 2-butene-1,4-diol can be carried out at lower temperature and at atmospheric pressure. Accordingly the present invention provides an improved process for the preparation of 1,4-butanediol, which comprises of adding Ni-AI alloy to a solution of 2-butene-1,4-diol in aqueous metal hydroxide in the concentration range of 5 to 20% at a temperature ranging from 5 to 50 ° C, stirring the reaction mixture further for a period of 1 to 6 hr., separating the solid by conventional method, saturating the filtrate with salt, extracting the product in an organic solvent, isolating the product, 1,4-butanediol by known methods. In an embodiment of the present invention, the metal hydroxide may be selected from hydroxides of Na or K. In another embodiment, the concentration of the aqueous solution of metal hydroxide may be 5 to 20%. In yet another embodiment, the organic solvent used for the extraction may be selected from ethyl acetate, ethers, chlorinated hydrocarbons such as dichloromethane, chloroform, dichloethane and the like. The process of the present invention is described hereinbelow with reference to the examples, which are illustrative only and should not be construed to limit the scope of the invention in any manner. Example 1 To a solution of 2~butene-l,4-diol (5.0 g) in aqueous sodium hydroxide (20%, 30 ml), nickel-aluminium (Ni~Al) alloy powder (2.0 g) is added slowly at 5~10°C with stirring. The reaction mixture is allowed to come to room temperature and stirred at this temperature for 1 hr. It is filtered to remove the solid residue from the reaction mixture. The filtrate is saturated with sodium chloride and extracted with ethyl acetate. The ethyl acetate portion is dried over anhydrous sodium sulfate and the solvent is removed by distillation. The residue is distilled under reduced pressure to get 1,4~butanediol as a colorless oil. Example 2 To a solution of 2~butene-l,4~diol (5.0 g) in aqueous sodium hydroxide (10%, 30 ml), nickel-aluminium (Ni-Al) alloy powder (2.0 g) is added slowly at 5~10°C with stirring. The reaction mixture is allowed to come to room temperature and stirred at this temperature for 3 hr. It is filtered to remove the solid residue from the reaction mixture. The filtrate is saturated with sodium chloride and extracted with diethyl ether. The ether portion is dried over anhydrous sodium sulfate and the solvent is removed by distillation. The residue is distilled under reduced pressure to get 1,4~butanediol as a colorless oil. Example 3 To a solution of 2~butene~l,4~diol (5.0 g) in aqueous potassium hydroxide (20%, 30 ml), nickel-aluminium (Ni-Al) alloy powder (2.0 g) is added slowly at 5-10°C with stirring. The reaction mixture is allowed to come to room temperature and stirred at this temperature for 1 hr. It is filtered to remove the solid residue from the reaction mixture. The filtrate is saturated with ammonium chloride and extracted with chloroform. The chloroform portion is dried over anhydrous sodium sulfate and the solvent is removed by distillation. The residue is distilled under reduced pressure to get 1,4~butanediol as a colorless oil. Example 4- To a solution of 2-butene-l,4~diol (5.0 g) in aqueous sodium hydroxide (20%, 50 ml), nickel-aluminium (Ni~Al) alloy powder (0.5 g) is added slowly at 5~10°C with stirring. The reaction mixture is allowed to come to room temperature and stirred at this temperature for 4 hr. It is filtered to remove the solid residue from the reaction mixture. The filtrate is saturated with sodium chloride and extracted with ethyl acetate. The ethyl acetate portion is dried over anhydrous sodium sulfate and the solvent is removed by distillation. The residue is distilled under reduced pressure to get 1,4-butanediol as a colorless oil with 40% selectivity and 60% conversion. Example 5~ To a solution of 2~butene-l,4~diol (5.0 g) in aqueous sodium hydroxide (20%, 30 ml), nickel~aluminium (Ni~Al) alloy powder (2.0g) is added slowly at 5~10°C with stirring. The reaction mixture is heated to 50°C and stirred at this temperature for 2 hr. The reaction mixture is cooled to room temperature and filtered to remove the solid. The filtrate is saturated with sodium chloride and extracted with dichloromethane. The dichloromethane portion is dried over anhydrous sodium sulfate and the solvent is removed by distillation. The residue is distilled under reduced pressure to get 1,4-butanediol as a colorless oil. claim : 1. An improved process for the preparation of 1,4-butanediol, which comprises of adding Ni-AI alloy to a solution of 2-butene-1,4-diol in aqueous metal hydroxide in the concentration range of 5 to 20% at a temperature ranging from 5 to 50°C, stirring the reaction mixture further for a period of 1 to 6 hr., separating the solid by conventional method, saturating the filtrate with salt, extracting the product in an organic solvent, isolating the product, 1,4-butanediol by known methods. 2. An improved process as claimed in claim 1, wherein the metal hydroxide used is hydroxides of Na or K. 3. An improved process as claimed in claims 1-2 wherein the organic solvent used for extraction is ethyl acetate, ethers, chlorinated hydrocarbons selected from dichloromethane, chloroform, dichloethane. 4. An improved process for the preparation of 1,4-butanediol as substantially described herein with the reference to the examples.

Documents:

507-del-1998-abstract.pdf

507-del-1998-claims.pdf

507-del-1998-correspondence-others.pdf

507-del-1998-correspondence-po.pdf

507-del-1998-description (complete).pdf

507-del-1998-form-1.pdf

507-del-1998-form-19.pdf

507-del-1998-form-2.pdf

507-del-1998-petition-137.pdf