Standard Oil Company (indiana)

Amoco Corporation

Houssam M Naim

George E Kuhlmann

Nicholas C Huie

David A Palmer

Hobe Schroeder

Stephen J Pietsch

A continuous process for the production of methacrylic acid ester of a C.sub.1 to C.sub.4 saturated aliphatic alcohol in the presence of a catalyst is disclosed. This process contemplates continuously introducing into a plug-flow reactor a feed stream containing methacrylic acid, a C.sub.1 to C.sub.4 saturated aliphatic alcohol in stoichiometric exesss relative to the methacrylic acid present, an esterification catalyst, and a liquid organic substance having a volatility no greater than that of methacrylic acid. The feed stream thus introduced into the plug-flow reactor is preferably maintained at substantially atmospheric pressure, while the contained methacrylic acid reactant is held at an esterification temperature and for a time period sufficient to esterify at least a portion of the introduced methacrylic acid. The admixture thus produced is continuously fractionated, preferably in a distillation zone or column, into a vaporized distillate stream and a liquid bottoms stream. The distillate stream has a relatively greater methacrylic acid ester content than the bottoms stream. A portion of the bottoms stream, constituted primarily by the liquid organic substance and the esterification catalyst, is recycled to the reactor while the remainder is purged.

Continuous process for production of methacrylic acid ester of C.sub.1

An improved two-step catalytic neat oxidation of liquid xylene is provided wherein there is no separation of oxidation products from the first oxidation step nor minimum limitation imposed on the liquid o-xylene concentration entering the second step according to the prior two-step oxidations of o-xylene. Rather the first step is conducted under conditions such that the liquid effluent from the first step contains from 6 up to 30 weight percent liquid o-xylene and from 8 up to 40 weight percent o-phthalic acid and such effluent is directly oxidized with air in the second step. By such improved two-step oxidation there is obtained a liquid product containing o-phthalic acid in yields of up to 85-87% of the theoretical yield and also containing impurities separable from o-phthalic acid after it has been converted to its anhydride in vapor form and the anhydride vapors are separated from water vapor. Such two step neat oxidation of liquid o-xylene provides a route to phthalic anhydride commercially competitive with routes starting with the vapor phase oxidation of o-xylene.

Continuous production of ortho-phthalic acid product by two-step

Phthalic anhydride of commercially acceptable quality can be produced continuously in yields of from about 80 up to about 83 mole percent (% of theoretical) through a combination of steps starting with the neat oxidation of liquid o-xylene with air in the presence of the catalysis provided by cobalt, manganese and bromine. Said oxidation is conducted in two steps wherein the first step is conducted under mild conditions and short residence time to provide a liquid effluent containing 8 to 40 weight percent o-phthalic acid and 6 to 30 weight percent o-xylene and the second step oxidizes such liquid effluent composition under more vigorous conditions including higher reaction temperature and longer residence time until substantially all of the o-xylene and precursors of o-phthalic acid have been converted to o-phthalic acid. Thereafter the second liquid oxidation effluent is subjected to simultaneous rapid dehydration and phthalic anhydride evaporation followed by contact of the resulting mixture of vapors first with a noble metal catalyst to remove bromine contamination and then with a reflux liquid in a fractionation system to remove water as part of a top fraction and provide a liquid partially purified anhydride as the bottom fraction which is heated with a catalytic amount of KOH to remove phthalide and finally the phthalide-free liquid partially purified anhydride is fractionated to obtain, in known manner, high purity phthalic anhydride product.

Production of liquid ortho-phthalic acid and its conversion to high

Phthalic anhydride of commercially acceptable quality can be produced continuously in yields of from about 80 up to about 83 mole percent (% of theoretical) through a combination of steps starting with the neat oxidation of liquid o-xylene with air in the presence of catalysis provided by cobalt, manganese and bromine. Said oxidation is conducted in two steps wherein the first step is conducted under mild conditions and short residence time to provide a liquid effluent containing 8 to 40 weight percent o-phthalic acid and 6 to 30 weight percent o-xylene and the second step oxidizes such liquid effluent composition under more vigorous conditions including higher reaction temperature and longer residence time until substantially all the o-xylene and precursors of o-phthalic acid have been converted to o-phthalic acid. Thereafter, the second liquid oxidation effluent is subjected to simultaneous rapid dehydration and phthalic anhydride evaporation followed by contact of the resulting mixture of vapors with a reflux liquid in a fractionation system to remove water as part of the top fraction and provide a liquid partially purified anhydride as a separate bottom fraction, heating said liquid anhydride with a catalytic amount of KOH to remove phthalide and then fractionating the phthalide-free liquid partially purified anhydride to obtain, in known manner, high purity phthalic anhydride product.

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Naperville, IL, United States of America

Houssam M Naim