DE671903C - Process for the preparation of trifluoromethylbenzenesulfonic acids - Google Patents

Description

Process for the preparation of trifluoromethylhenzenesulfonic acids Bei Attempts to produce the as yet unknown sulfonic acids of trifluoromethylbenzenes, it is observed that the most common sulfonating agents such as concentrated Sulfuric acid or chlorosulfonic acid, fail. It doesn't find any, sulfonation either instead of or the trifluoromethyl radical is attacked, so that the reaction products Carboxylic acids or sulfocarboxylic acids obtained.

It has now been found that trifluoromiethylbenzenesulfonic acids can be added , Passes, running w;. At Triluonnethylbenzole with sulfur trioxide, optionally in Treated the presence of a little monohydrate as a thinning agent; on such trifluoromethylbenzenes, which: hold a free nitro or amino group, is as determined by experiments the procedure was not applicable.

The new sulfonic acids can .as intermediate: enprodukte, z. B. on the Dye area, find use. EXAMPLE 1 Leaves triuromethylbenzene in 46 parts 125 parts are added with stirring at temperatures below 0 ° within half an hour 65% oleum leg drops. After 15 to 2 hours of standing, the reaction mass 1n 150o ccm of saturated saline solution and the precipitated sodium salt the TriflLiorm @ ethylb; enzenesulfonic acid sucked off. It becomes more saturated with little Washed saline and dried.

The sodium salt is easily soluble in water, @ it crystallizes out concentrated aqueous solution in thin, shiny flakes. The barium salt is relatively sparingly soluble in cold water. @Es crystallizes from hot water with 1 mol of crystal water in needles.

The aniline salt of the acid crystallizes from water in the form of wider, white needles from F. toi to 2o2 ° (uncorr.).

The sulfonic acid group has probably entered in the m-position to the trifluoromethyl group. EXAMPLE 2 80 parts of sulfur trioxide are introduced into 146 parts of trifluoromethylbenzene at ordinary temperature. The liquid turns yellow-brown with green fluorescence. After a long time. Standing (2q. To 48 hours) it is poured slowly. in a saturated saline solution and works on, as described in example i. EXAMPLE 3 125 parts of 65% strength oleum are slowly added dropwise with stirring to 18 parts of i-trifluoromethyl-q-chlorobenzene at temperatures below 0 °. After: about: 20 hours of standing, the reaction mass is in, saturated boil: - Zn. saline solution -entered. The precipitated sodium salt of sulfonic acid, probably i-trifluoromethyl-4-, chlorobenzene-3-sulfo s crystallized from hot water in Plates with 1 mole of water of crystallization. The Baü1L @ T Salt, which is rather difficult to dissolve in hot water, crystallizes in regular thin plates.

Example 4 In 1 7 6 parts by weight of i-trifluoromethyl-3-methoxybenzene one passes in at a temperature below 80 parts by weight of sulfur trioxide and lets stand in ice for about 12 hours. The reaction mass is then transferred to saturated Be saline solution and make alkaline with dehydrated sodium carbonate. The excreted Product is filtered off and dried.

During sulphonation, the methoxy group is saponified for the most part, so that mainly i-oxy-3-trifluoromethylberizolsulfonic acid sodium is formed. In addition, an i-methoxy-3-tri $ uormethylbenzenesulfonic acid is also obtained in a minor amount in the form of their sodium salt.

Example 5 In a solution of 40 parts by weight of .i-aoetylamino-3-trifluoromethylbenzene in 50 parts by weight of tetrachloroethane is left slowly at ordinary temperature and drop in 30 parts by weight of 65% strength oleum with thorough stirring. It will then slowly heated to 145 'and kept at this temperature for 1 hour. After cooling down one carries in saturated saline solution and putscht - the precipitated i-acetylamino-3-trifluoromethylb, enzenesulfonic acid Sodium.

Claims (1)

PATENT CLAIM: Process for the production of Trifluorm, ethylbenzenesulfonic acids, characterized in that trifluoromethylbenzenes, with the exception of those which contain a free amino or nitro group, with sulfur trioxide, optionally treated in the presence of a little monohydrate as a diluent.