DE947167C - Process for the preparation of 1-aminobenzophenonesulphone-2-carboxylic acids or their esters - Google Patents

Description

Process for the preparation of 1-aminobenzopheno-nsulfone-2-carboxylic acids or their esters It has been found that new, valuable compounds of the benzophenone sulfone series can be obtained obtained when 2-methylbenzophenone sulfones are nitrated by conventional methods, the i-nitro -?, - methylbenzophenone sulfones obtained according to also known per se Methods converted into the corresponding isoxazole derivatives and the latter, expedient in an alkaline or acidic medium, with water or organic oxy compounds.

The claimed reactions proceed according to the following general scheme: where R is hydrogen or an alkyl, aryl, aralkyl or cycloalkyl group. The corresponding i-Anünobenzophenonsulfoncarbonsäuren (R = 11) or their esters (R = alkyl, cycloalkyl, aralkyl or aryl) are obtained in this way. If the starting material used is not the unsubstituted 2-methylbenzophenone sulfone, as formulated above, but its substitution products, for example its alkyl, halogen, nitro and / or alkylsulfonyl derivatives, the correspondingly substituted i-an-linobenzophenonesulfone-z -carboxylic acids or their esters. The esters can also be prepared by subsequent esterification of the carboxylic acids in a manner known per se, for. B. via the acid chlorides or isatoic anhydrides.

The nitration is carried out in the usual way, for. B. with nitrating acid or by adding nitric acid or nitrates, such as potassium or sodium nitrate, in the solution or suspension of 2-methylbenzophenone sulfone in 960 /, sulfuric acid or in monohydrate. At an ordinary or moderately elevated temperature, generally only one nitro group occurs, namely in the position i adjacent to the C 0 group; at higher temperatures, further nitro groups can enter.

The nitration mixture is worked up by diluting it with Water; the yields are consistently very good. Obtained by recrystallization the nitro compounds in analytically pure form; if necessary, one succeeds in doing this Separation into isomeric dinitro compounds.

To convert the i-nitro-2-methyl-benzophenone sulfones into the isoxazole derivatives, they are treated with oleum of about 60 to 65 0 /, S 0, content at temperatures between about 0 and 10 '.

The isoxazoles are then z. B. with dilute aqueous alkali heated until it is completely dissolved. When acidifying the solution obtained the i-amino-I; enzophenonsulfon-2-carboxylic acid formed precipitates. It arises immediately if the isoxazole, optionally in a solvent or diluent, heated with dilute mineral acids. If one uses the isoxazole derivatives with aliphatic, cycloaliphatic, araliphatic or aromatic oxy compounds, such as methanol, Ethanol, butanol, benzyl alcohol, cyclohexanol or phenol, with the addition of less Quantities of alkaline agents, such as potassium eyanide, are heated to give the corresponding amounts Ester.

The new benzophenone sulfone derivatives obtained in this way are valuable intermediates for dyes and pharmaceutical products, you can also use them as such are used to dye Acetatreyon and polyamide, polyurethane and polyester fibers, which give them a very strong, clear and real color using the dispersion process.

The parts mentioned in the examples are parts by weight. Example i In a solution of 3o parts of 2-methylbenzophenonsulfone (prepared in a known manner by condensing thio- or dithiogalicylic acid with toluene in concentrated sulfuric acid to form 2-methylthioxanthone and oxidizing the latter with hydrogen peroxide in glacial acetic acid or with a persulfate in concentrated sulfuric acid) in 36o parts of concentrated sulfuric acid are introduced in portions at 0 to 5 ' with stirring, 26.5 parts of potassium nitrate. The mixture is stirred for about 6 hours at 20 to 25 minutes, then poured onto ice, filtered off with suction, washed and dried. Recrystallization from chlorobenzene gives the i-nitro-2-i-riethylbenzophenone sulfone as colorless crystals with a melting point of 265 to 266 '.

4 parts of this nitro compound are stirred in portions into 80 parts of 60% strength oleum under carbon dioxide at 0 to 10 '. After about 30 minutes, it is poured onto ice, washed neutral and dried. The isoxazole derivative obtained in good yield forms a yellow powder which, after recrystallization from o-dichlorobenzene egg 238 to 239 ', melts.

A suspension of 4 parts of the isoxazole derivative in 3 times the weight of 2- to 50% strength sodium hydroxide solution is gradually heated to the boil and refluxed until everything has dissolved. The dark brown solution is then acidified with hydrochloric acid, the precipitated i-an) inobenzophenonsulfon-2-oxy-genic acid is filtered off with suction, and it is washed and dried. It forms a brownish-yellow, alkali-soluble powder with a temperature of 287 to 289 '. In concentrated sulfuric acid it gives a red color reaction with formaldehyde.

Example 2 4 parts of the isoxazole derivative prepared according to Example i, paragraphs i and 2, are refluxed with 2 parts of potassium cyanide and 40 parts of absolute ethanol for 2 to 3 hours. After cooling, the i-aminobenzophenonesulfon-2-ca #bonic acid ethyl ester crystallizes out in the form of yellow prisms. It melts at 23o to 231 'and gives a red color reaction in concentrated sulfuric acid with formaldehyde.

With n-butanol instead of ethanol, the n-butyl ester is obtained with a melting point of 115 to 11: 6 '.

EXAMPLE 3 100 parts of the i-aniinobenzophenonesulfone-2-carboxylic acid prepared according to Example i, paragraphs 1, 2 and 3 are treated with phosgene7 in 100 parts of nitrobenzene for 4 hours at 1 to 12 minutes. The entstan 'dene Isatosäureanhydridderivat crystallized from in the cold in sand-colored needles; F. 295 to 300 ' (dec.).

5 parts of this isatoic anhydride derivative are briefly refluxed with 100 parts of ethylene glycol. In the cold, the glycol ester crystallizes out of the filtered yellow-brown solution in almost quantitative yield in yellow prisms; F. 7.16 to 217 '.

With phenol instead of glycol one obtains the phenol ester with a melting point of 292 to 293 '.

Example 4 5 parts of the i-nitro-2, -methylbenzophenone sulfone prepared according to example i, paragraph i, are mixed with 45 parts of nitrating acid (Hp, S 0, - H N 0, = 49: 5 ) for 8 to 10 hours at 70 to 75 minutes 1) stirred. Then you suck off the precipitated crystal pulp and wash it neutral. The dinitro derivative obtained in this way melts at 336 'after drying. When the filtrate is diluted with water, an isomeric dinitro compound from F, 24o to 242 'precipitates.

4 parts of the higher-melting dinitro compound are stirred into no parts 60% oleum under carbon dioxide at 0 to 10%. Stirring is continued for about 30 minutes at about 10 ', then diluted first with 220 parts of go0 /, sulfuric acid and finally poured onto ice. The yellow x-nitrobenzophenonesulfon-i (N) - -, - isoxazole thus obtained melts at 25o to 251 '(with decomposition).

3 parts of this isoxazole derivative are heated with about 12 parts of 50% strength sodium hydroxide solution on a water bath until everything has dissolved, and the x-nitro-i-aminobenzophenonesulfone-2-carboxylic acid is precipitated from the clear reddish-brown solution with hydrochloric acid. It is washed neutral with ice water. After drying, it forms a red-brown powder from the decomposition point 248 to 249 '. The isomeric x-nitro-i: -aminobenzophenonesulfone-2-carboxylic acid is obtained from the lower-melting dinitro compound (see paragraph i) with an analogous treatment via the yellow isoxazole derivative from the decomposition point 25o to 254 '.

Claims (1)

PATENT CLAIM: A process for the preparation of i-aminobenzophenonesulfone-2-carboxylic acids or their esters, characterized in that 2-methylbenzophenonesulfones are nitrated by methods known per se, the i-nitro-2-methylbenzophenonesulfones obtained by methods likewise known per se into the corresponding isoxazole derivatives and the latter is reacted with water or organic oxy compounds and, in the case of the reaction with water, the carboxylic acids obtained are optionally esterified by methods known per se.