JPS6234747B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing styrene glycol ester by liquid phase oxidation of styrene using a Co--Cu--Br catalyst. Conventionally, various liquid phase oxidation of styrene using metal catalysts such as transition metals have been proposed. For example, in Japanese Patent Publication No. 44-8484, a palladium-based catalyst was used, and in Japanese Patent Publication No. 43813 and No. 43814, styrene was oxidized in liquid phase with molecular oxygen using an alkali metal nitrate or a copper-containing metal nitrate, respectively. , which manufactures styrene glycol ester. It is also known that Co-Br catalysts or Cu-Br catalysts are effective as oxidation catalysts in liquid phase oxidation reactions using molecular oxygen. Furthermore, the present inventors have already announced that benzyl ester can be produced by liquid-phase oxidation of toluene using a Co-Cu-Br catalyst. However, in the oxidation reaction of hydrocarbons, various oxides such as aldehydes, alcohols, and carboxylic acids are generally produced, and the production ratio of these oxides varies greatly depending on the oxidation catalyst, reaction conditions, etc. The same holds true depending on the type of substrate in the oxidation reaction. The present inventors completed the present invention as a result of research into a method for producing styrene glycol ester selectively over styrene. That is, the present invention is a method for producing styrene glycol ester, which is characterized by carrying out liquid phase oxidation of styrene in a fatty acid with molecular oxygen in the coexistence of a cobalt salt, a copper salt, and a bromine compound. In the present invention, cobalt salt to be coexisting,
Any copper salt and bromine compound can be selected as long as they are soluble in the reaction medium fatty acid under reaction conditions. Therefore, cobalt salts and copper salts include, for example, cobalt, copper bromides, hydroxides, sulfates, hydrochlorides, and other bromides, inorganic acid salts, and also formates, acetates, propionates, etc. Organic acid salts of can also be used. However, in the present invention, since the substrate styrene is oxidized in a fatty acid, a salt of the fatty acid is preferable, and as described later, acetic acid is preferable as the fatty acid, so cobalt acetate and copper acetate are more preferable. Examples of the bromine compound include organic bromides such as hydrogen bromide, ethyl bromide, and ethylene dibromide, and metal bromides such as alkali metals such as cobalt, copper, sodium, and potassium. Among these, preferred are alkali metal bromides, and particularly preferred is sodium bromide. The coexistence ratio of cobalt salts, copper salts, and bromine compounds that should coexist is Co:Cu:Br=1:0.1 ~
10:1 to 20, more preferably 1:0.5 to
2:4-10. Further, in order to sufficiently increase the oxidation reaction rate, it is desirable that the cobalt salt, copper salt, and bromine compound to be present in the fatty acid have a concentration of 0.01 to 1 mol/each in the fatty acid. In addition, in the present invention, it is necessary to coexist cobalt salts and copper salts as metal components in addition to bromine compounds, but in addition to these, 50% or more of various transition metal compounds such as manganese, cerium, nickel, etc. The presence of salts will not affect the reaction,
Rather, the reaction rate can be increased. Although the present invention performs liquid phase oxidation in fatty acids,
Examples of fatty acids include unsubstituted aliphatic monocarboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, and caproic acid, and lower alkoxy or chloroacetic acids such as acetoacetic acid, chloroacetic acid, and chloropropionic acid. Examples include substituted fatty acid monocarboxylic acids such as substituted monocarboxylic acids,
Acetic acid is suitable from the viewpoint of oxidative stability. Molecular oxygen is introduced into the reaction system mixed with another inert gas, such as nitrogen, or in the form of air,
Can oxidize styrene. In addition, in the present invention, it is advantageous to carry out the reaction under pressure in order to obtain a sufficient reaction rate. At low reaction pressures, α-phenylacetate is produced and styrene polymerization occurs, so it is preferable. Normally, an oxygen partial pressure of 1 Kg/cm ² is sufficient. The reaction time is not particularly limited, but may be from 10 minutes to 10 hours. Furthermore, the oxidation reaction temperature is preferably 100 to 200°C; if this range is exceeded, the yield of styrene glycol ester will decrease. However, at reaction temperatures lower than this range, styrene bromides such as styrene dibromide are produced, but since these styrene bromides easily turn into styrene glycol esters when reacted with acids, they can be regarded as reaction intermediates. Also,
Therefore, even at a relatively low reaction temperature, the ultimate yield of styrene glycol ester does not decrease much compared to a high temperature. In the present invention, styrene is oxidized in a fatty acid to form a styrene glycol ester of the fatty acid, but the styrene glycol ester is easily hydrolyzed into styrene glycol and the fatty acid by a conventional method. Furthermore, the styrene glycol ester or styrene glycol of the present invention is useful as a raw material for plasticizers, thickeners, wetting agents, alkyd resins, unsaturated polyester resins, and the like. Next, the present invention will be specifically explained in detail with reference to Examples. The reaction conditions for the experiments indicated by each experiment number and the analytical values of the reaction products in the reactions are summarized in the following table. Examples (Experiment numbers 1 to 3) In a titanium magnetic rotation induction autoclave with an internal volume of 200 ml, 43.8 mmol of styrene and acetic acid were added.
60 ml was added, and cobalt acetate, copper acetate and sodium bromide were further added to the concentrations shown in the table below. Next, air was introduced, and the reaction was started by stirring at the air pressure and reaction temperature shown in the table below. After reacting for 60 minutes, an internal standard substance was added to the reaction mixture, and the reaction product was analyzed by gas chromatography. The results are shown in the table below. Comparative examples (experiment numbers 4 to 7) In experiment number 4, cobalt acetate and sodium bromide, in experiment number 5, copper acetate and sodium bromide,
Further, the reaction was carried out in the same manner as in Experiment No. 1, except that only cobalt acetate was used in Experiment No. 6, and only copper acetate was used in Experiment No. 7. 【table】

Claims (1)

[Claims] 1. In the presence of a cobalt salt, a copper salt and a bromine compound, styrene is treated with molecular oxygen from the group consisting of unsubstituted aliphatic monocarboxylic acids, lower alkoxy-substituted monocarboxylic acids and chloro-substituted monocarboxylic acids. A method for producing styrene glycol ester, which comprises liquid phase oxidation of selected fatty acids. 2. Production of styrene glycol ester according to claim 1, wherein the cobalt salt, copper salt, and bromine compound are cobalt acetate, copper acetate, and alkali metal bromide, respectively, and the fatty acid is acetic acid. Method. 3. The method for producing styrene glycol ester according to claim 2, wherein the alkali metal bromide is sodium bromide.