Process for selectively hydroesterifying diolefin

#1. Technical Field

#This invention relates to a process for selective hydroesterification. More particularly, the invention relates to a process for producing unsaturated acid or its ester by selectively hydroesterifying diolefin.

#Furthermore, the invention relates to a process for selectively hydroesterifying only diolefin in a material which contains certain monoolefins.

#The present invention is described in the following with reference to examples.

#To a 2 liter three-neck flask equipped with a dropping funnel, a reflux condenser and a stirrer was added 25.5 g (1.05 mole) of metallic magnesium and it was dried sufficiently by supplying dry nitrogen gas. After that, 50 ml of tetrahydrofuran which had been dried with a molecular sieve 5A, was put into the flask and the contents were stirred vigorously. A solution of 183 g (1.0 mole) of 3-vinylbenzene bromide in 500 ml of dried tetrahydrofuran was then dropped little by little over 2 hours. The reaction temperature was maintained 75.degree. to 80.degree. C. and, after the addition of the solution, the stirring was continued for further 1 hour as it stands. Into the thus obtained Grignard reagent of 3-vinylphenylmagnesium bromide, a solution of 122.6 g (1.02 mole) of acetophenone in 500 ml of dried tetrahydrofuran was dropped little by little over 2 hours. The reaction temperature was maintained at 75.degree. to 80.degree. C. and, after the dropping, the stirring was continued for further 1 hour as it stands. The reaction mixture was then poured into 3 liter of an aqueous solution of 75 g of ammonium chloride and it was left to stand still for 20 hours and an oily layer was recovered to obtain 1-(3-vinylphenyl)-1-phenylethyl alcohol in a yield of 89% (acetophenone basis) by distilling off the tetrahydrofuran.

#To a 300 ml three-neck flask with a distillation column and a dropping funnel was added 81 g of potassium hydrogensulfate and the pressure was reduced to 15 to 20 mm Hg. The obtained alcohol was then dropped into the flask little by little over 2 hours. The water produced by dehydration and oily components were recovered from the top of the distillation column and 1-(3-vinylphenyl)-1-phenylethylene was obtained in a yield of 100% (on the basis of raw material alcohol) from the oily layer by a separatory funnel. The dehydration reaction was carried out at a temperature of 200.degree. to 250.degree. c.