DE1934086A1 - Ortho-benzoylbenzoic acid prepn - Google Patents

Abstract

Benzoylbenzoic acid prepn. Oxidation of indanes of formula:- (R1, R2, R3 are each alkyl; R1 and/or R3 can be H), oxidised with HNO3 and/or Cr-VI compounds gives, simply and economically, better yields of high-purity o-benzoylbenzoic acid (valuable for syntheses, especially for anthraquinone) without formation of considerable quantities of o-acetylbenzophenone. Temperature for HNO3 oxidation is 50 - 250 degrees C. Less than 1.5 x stoichiometric requirement of Cr-VI compounds is preferred. In a preferred method, at least 10% stoichiometric requirement of alkaline bichromate is added simultaneously to the HNO3.

Description

Process for the preparation of o-benzoyl-benzoic acid The invention relates to a process for the preparation of o-benzoylbenzoic acid by oxidation of indanes with ghrom-VI compounds.

It is from Ullmann's Encyklopedia of Technical Chemistry, Volume 3, Page 660, it is known that phthalic anhydride and benzene can be used in the presence of aluminum chloride can convert in a Friedel-Crafts reaction to o-Benzoyl-benzoeskurs. Disadvantageous in this process is the uneconomically high consumption of catalyst.

Also in the oxidation of 1-methyl-) phenyl-indane with a large excess chromic acid produces o-benzoylbenzoic acid, but only in unsatisfactory yield and in a mixture with a high proportion of by-products> e.g. p-acetylbenzophenone (Journal of Organe Chemistry5 Volume 19 (1954), pages 17 ff .; Journal of the Ämerican Chemical Society, Volume 72 (1950), pages 4918 ff.). This result is explained at least in part from the influence of the oxidation medium on the o-benzoyl-benzoic acid formed. If o-benzoylbenzoic acid is oxidized under the conditions of this process, in this way, only 45 ffi of the raw material is returned unreacted, the main part is thus destroyed by the oxidation medium (J. Am. Chem. Soc., loc. cit., p 4920). If you start from 1.1.3-trimethyl-3-phenyl-indane as the starting material, this must be Oxidation process can be modified, but also provides the modified fixed process only moderate yields of o-benzoyl-benzoic acid and a high proportion of o-acetylbenzophenone (Reports of the German Chemical Society, Volume 90 (1957), pages 1208 ff.).

It has now been found that o-benzoylbenzoic acid is advantageously obtained by oxidation of indanes with chromium VI compounds if tndanes of the general formula in which R1, R2, X3 can be the same or different and each represent an alkyl radical, R1 and / or R3 can also each denote a hydrogen atom, with chromium VI compounds in less than 1.5 times the stoichiometric amount, based on Indane, oxidized.

If 1-methyl-3-phenyl-indane is used, the reaction can be represented by the following formula: Compared to the known processes, the process according to the invention provides o-benzoylbenzoic acid in a simple and economical way in better yield and very high purity and without the formation of substantial amounts of o-acetylbenzophenone. In view of the prior art, these advantageous results are surprising; if a smaller amount of oxidizing agent had been used, an additional substantial proportion of by-products that were not completely oxidized, for example o-acetylbenzophenone, should have been expected.

The indanes used as starting materials I can be obtained by dimerization of unsubstituted or substituted styrenes, e.g. according to those mentioned in the above Publications or in Rabjohn, Organic Syntheses, Collective Volume IV (John Wiley Inc., New York 1963), pages 665 ff.

Preferred indanes I are those whose formula R1, R2, R> are the same or can be different and in each case an alkyl radical with 1 to 8, in particular 1 to 4 carbon atoms, R1 and / or R3 in addition each one Can denote hydrogen atom. Suitable indanes I are, for example, 1-methyl-, 1,3-dimethyl-, 1.1. 3-trimethyl-, 1-propyl-, l-isobutyl-3-phenylindane.

The reaction is usually carried out at a temperature between 50 and 2500C, preferably between 90 and 1100C.

You work without pressure or under pressure, e.g. at a pressure of up to 100 at, in general at the pressure under the reaction conditions, The reaction can be carried out continuously or batchwise.

The starting material 1 with chromium VI compounds is used in less than 1.5 times, preferably less than 1.15 times, in particular in the 0.1 to 1.1 times the stoichiometric amount, based on starting material 1, to. as Chromium-Vi compounds come into question: mono- and polychrome acids, e.g. di-, tri-, Tetrachromic acids, as well as their anhydrides and salts. As salts are beneficial Alkali and alkaline earth chromates and dichromates, in particular sodium and potassium chromate or bichromate, is used.

The reaction is usually carried out in the presence of a solvent such as organic and preferably inorganic acids carried out.

It is advantageous to use sulfuric acid, expediently in the form of a 10 to 80% strength by weight aqueous solution and / or nitric acid, expediently in the form a 10 to 65% strength by weight aqueous solution.

There are organic acids, e.g. alkanecarboxylic acids such as acetic acid and PropionsEure.zur application, one obtains lower yields of end product. In general the reaction is carried out in a ratio of 1.5 to 50 mol sulfuric acid (calc. 100 %) per 1 mole of chromium VI Connection carried out.

In a preferred embodiment of the process, one uses Nitric acid not only as a solvent, but also as one with the chromium VI compound oxidizing agent acting in combination. The amount of chromium VI compound can be Surprisingly, significantly reduced in the case of such combined oxidations without a poorer yield of end product being obtained.

The preferred combined oxidation is therefore particularly economical Advantages. It is advantageous to use 3 to 50 mol of nitric acid (calc. 100%) per 1 Moles of chromium (VI) compound and 0.1 to 1.1 times, preferably 0.1 to q.3 times stoichiometric amount of chromium VI compound, based on starting material I.

The reaction can be carried out as follows: A mixture of starting material I, chromium VI compound and nitric acid of the above concentration is approx. Maintained at the reaction temperature for 2 to 8 hours. It is advantageous to lay out the starting material I and nitric acid or sulfuric acid and adds the chromium VI compound in portions in the corresponding acid for 0.2 to 4 hours. Then the reaction mixture cooled down. The end product can be extracted from it in the usual way, e.g. by filtration or Can be isolated from decanting.

According to the method of the invention. connection that can be established a valuable starting material for numerous syntheses (see e.g.

Ullmanns Eneyklopadie der Technischen Chemie, Volume 3, pages 660 ff.). It is of particular importance as a starting material for the production of anthraquinone. The method according to the invention opens up an elegant way of producing Anthraquinone, based on the cheap styrene.

By reaction with glycerine under reducing conditions (Annali di Chimica Applicata, Volume 22 (1932), pages 691 ff.) one receives another Base material for dyes, benzanthrone.

The parts listed in the following examples are parts by weight, Example 1 In a mixture of 20 parts of i-methyl-3-phenylindane and 60 parts of sulfuric acid (40% by weight) is a mixture of 70 parts of chromium VI oxide for 4 hours at 100-105 ° C and 380 parts of sulfuric acid (40Gew.ffi) were added. The mixture is then held with thorough mixing for 4 hours at 100-105 ° C, then cooled, diluted with 400 parts of water and sucks the mixture off. The filter material is dissolved in 1000 parts of sodium hydroxide solution entered, the mixture is heated to 100 ° C and filtered. The filtrate is acidified whereby the end product precipitates. 20 parts (92% of theory) of o-benzoylbenzoic acid are obtained. M.p. 1200 (from benzene / cyclohexane).

Example 2 In a mixture of 20 parts of 1-methyl-3-phenylindane and 100 parts of nitric acid (40% by weight) becomes a mixture for 5 hours at 100-1050 of 20 parts of sodium dichromate and 50 parts of nitric acid (40% by weight) were added. Then keep the mixture with thorough mixing for 4 hours at 100-1050C, then it is cooled, diluted with 400 parts of water and the mixture is filtered off with suction. The filter material is added to 1000 parts of 1N sodium hydroxide solution, the mixture is heated to 1000C and filtered. The filtrate is acidified, whereby the end product precipitates. You get 20.8 parts (95% of theory) of o-benzoylbenzoic acid.

Example 3 The reaction is carried out as in Example 2 with 20% by weight nitric acid carried out. 16.4 parts of o-benzoylbenzoic acid (75% of theory) are obtained.

Example 4 The reaction is carried out as in Example 2 with 10 parts of sodium dichromate carried out.

Yield: 16.1 parts of o-benzoylbenzoic acid (74% of theory).

Claims (2)

Claim 1) Process for the preparation of o-benzoylbenzoic acid by oxyaction of indanes with chromium VI compounds, characterized in that indanes of the general formula are used in which R1, R2, R3 can be the same or different and Jewells are an alkyl radical, R1 and / or R3 can also each denote a hydrogen atom, with chromium VI compounds in less than 1.5 times the stoichiometric amount, based on Indane, oxidized. 2) Method according to claim 1, characterized in that the implementation is carried out with a combination of chromium VI compounds and nitric acid.