DEC0009592MA - - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

Registration date: July 1, 1954 Announced on March 29, 1956

GERMAN PATENT OFFICE

In the patent application C 8258 IVb / 120 is a Process for the production of aromatic carboxylic acids from corresponding oxygen-free or low-oxygen compounds with side chains by treatment with aqueous hypochlorite solution been described in aqueous emulsion.

It has been found that this procedure can also be carried out with the greatest success at its core Halogen, nitro and / or oxy-substituted aromatic compounds with side chains can apply. The corresponding carboxylic acids are obtained in a very smooth conversion, more excellent Yield and purity.

For the preparation of the aromatic carboxylic acids are suitable by halogen, nitro and or or Oxy-substituted aromatic compounds with side chains, e.g. B. toluenes, xylenes, ethylbenzenes, Diethylbenzenes, triethylbenzenes, phenylethyl alcohols, phenylacetaldehydes, phenylmethyl ketones as well as the z. B. crude available in the oxidation of these compounds with air Mixtures, in addition to unchanged starting material and substituted terephthalic acids also contain substituted alcoholic, aldehydic and other oxygen-containing compounds.

The process is carried out, for example, in such a way that the substituted one to be oxidized aromatic compound with the aid of an emulsifier in an alkaline agent by stirring

509 699/498

C 9592 IVb / 12 ο

is emulsified, whereupon chlorine is passed in with continued vigorous stirring. Is the one to be oxidized aromatic compound, so it will

: ■, expediently first in a suitable, against Chlorine and hypochlorite solvents that are as stable as possible under the working conditions, e.g. Benzene or cyclohexane, dissolved, whereupon the resulting solution is emulsified in water and mixed with Hypochlorite is treated! The one to be oxidized

ίο aromatic compound can also be emulsified in Form be treated with separately prepared aqueous hypochlorite solution.

The emulsifiers used are those that are effective against hypochlorite and chlorine the .Working conditions are as stable as possible, z. B. sulfonates long-chain paraffins or alkylated Naphthalenes. In general, about 1 percent by weight of the emulsifier, based on weight, is sufficient on the aromatic compound to be oxidized, if necessary during the treatment used emulsifiers continuously or temporarily given in.

Depending on the starting material used, the treatment with hypochlorite is either heated or cooled, which has to be clarified in individual cases by means of a preliminary test. It is also useful during the treatment for an intensive mixing of the components, e.g. B. by stirring or sonication, to care. Treatment with hypochlorite is stopped as soon as the smell of Hypochlorite has disappeared. It can be of advantage to use the., Hypochlorite in a somewhat lower than the theoretically required amount to be used, and a certain small proportion. on unchanged starting material in the end product to be taken into account, because the end point of the treatment is easier to recognize than if you works with an excess of hypochlorite.

Example 1 :

An emulsion is prepared from 66 parts in a known manner by treating with air in 3, 5-D1-chloro-i-ethylbenzene anoxidized in the presence of cobalt salts (33% of which is used for the oxidation of 3, 5-dichloro-i-ethylbenzene to 3, 5-D1-chlorobenzoic acid required theoretical amount of oxygen were absorbed), 1000 parts Sodium hypochlorite solution with 168 parts of active chlorine, 30 parts of sodium hydroxide and 1 part of one Paraffin sulfonate, which is produced by sulfochlorination of higher molecular weight paraffin hydrocarbons Fischer-Tropsch synthesis and subsequent

soap was made. One warms under Stir at 75 to 85 ° until the hypochlorite odor has disappeared and acidifies, 3,5-dichlorobenzoic acid precipitating in 85% yield. After recrystallizing once the acid is melting point pure.

Example 2

An emulsion is made from 1000 parts of sodium hypochlorite solution with 155 parts of active chlorine, 30 parts of sodium hydroxide, 50 parts in 4-chloro-i-ethylbenzene anoxidized in a known manner with air in the presence of cobalt salts (with 30% of the amount used for the oxidation of 4-chloro-ethylbenzene the amount of oxygen required for 4-chlorobenzoic acid) and r part of an emulsifier according to Example 1. It is used at a temperature of 75 to 85 ° up to Disappearance of the hypochlorite odor, stirred intensively. The solution is acidified in The 4-chlorobenzoic acid is usually separated off in a yield of 87%.

Example 3

An emulsion forth of 1000 parts of sodium hypochlorite active with 155 parts of chlorine, 50 parts of sodium hydroxide, 100 parts of p-nitrotoluene, which was oxidized in a known manner in the presence of cobalt salts with air (in which 3o ^o / o of the oxidation of p-nitrotoluene ; the amount of oxygen required for p-nitrobenzoic acid was taken up) and. 1 part · of an emulsifier according to Example 1. The mixture is stirred at 75 to 85 ° until the odor of hypochlorite has disappeared. The p-nitrobenzoic acid can be separated off in good yield by acidification. In a corresponding manner, the cresols which have been partially oxidized with air are obtained by treatment with hypochlorites in emulsion to give the corresponding oxybenzoic acids.

Claims (1)

PATENT CLAIM: Process for the preparation of aromatic carboxylic acids by oxidation of aromatic compounds which carry side chains with hypochlorites in an aqueous emulsion according to patent application C8258 IVb / 120, characterized in that the starting compounds in the nucleus are aromatic substituted ^{by halogen, nitro and / or: oxy groups} Compounds ,, which carry side chains ,, can be used.