Patent GB-553264-A (GB)
Title: Improvements in or relating to dyestuff intermediates
IPC: C07D209/10
Filed: 1941-11-06
Abstract: 553,264. Sulphur compounds. KENDALL, J. D., WOOD, H. W., and MAJER, J. R. Nov. 6, 1941, No. 15050/42. Divided out of 553,143. Samples furnished. [Class 2 (iii)] A dye intermediate of the formula is prepared by reacting a compound of the formula (where D is the residue of a (5- or 6-membered heterocyclic nitrogen nucleus, R 1  is an alkyl, or aralkyl group, R 2  and R 3  are hydrocarbon groups (e.g. alkyl, aryl, or aralkyl groups, R 4  is an alkyl or aralkyl group, A is an acid radical and n is 0 or 1) with an alkyl or aralkyl mercaptan, in the presence of a strong acid (e.g. dry hydrochloric acid gas, other than hydrohalic acids, nitric acid, sulphuric acid, phosphoric acid, or p-toluenesulphonic acid). The heterocyclic nitrogen nucleus completed by D may be a substituted or unsubstituted thiazole, thiazoline oxazole, oxazoline, selenazole, selenazoline, pyridine, quinoline, lepidine, indolenine, diazine (e.g. pyrimidine), thiodiazole, or quinazoline, the corresponding substituted or unsubstituted polycyclic compounds (e.g. benzthiazoles, naphthathiazoles, or anthrathiazoles), or the diazines described in Specification 425,609. R 1  is preferably a lower alkyl group (e.g. methyl, ethyl, propyl, or butyl) or, if aralkyl, benzyl R 2 , R 3 , and R 4  are also preferably lower alkyl groups. The quaternary salts obtained may be converted to quaternary salts of other acids by treatment with suitable, e.g. alkali metal, salts. Chlorides may be converted to bromides or iodides by treatment with potassium bromide or iodide. In example 1, 1-diacetylmethylene-2-methyldihydrobenz - thiazole, methyl alcohol, and ethyl mercaptan are mixed together and dry hydrochloric acid gas passed therethrough. When solution is completed, more ethyl mercaptan is added and the solution saturated with hydrochloric acid gas. After standing, and filtering, the filtrate is evaporated under reduced pressure to yield the dye intermediate. The solid filtered off is 1-(acetyl-methylene)-2-methyldihydrobenzthiazole hydrochloride. Dye intermediates may be obtained by similarly reacting (a) 1-benzoylacetyl - methylene - 2 - methyldihydrobenzthiazole, methyl alcohol (solvent), and ethyl mercaptan, (1 - (benzoylmethylene) - 2 - methyl - dihydro - benzthiazole) hydrochloride is a byproduct. (b) 1-methyl - 2 - diacetylmethy - lene - 1:2 - dihydroquinoline and ethyl mercaptan, (c) 1 - # - dipropionylmethylene - 2 - methyldihydrobenzthiazole and ethylmercaptan, and (d) 2-diacetylmethylene-1:3:3-trimethyldihydroindolenine and ethyl mercaptan, using dry hydrochloric acid gas in each case. Dyes are prepared by condensing the dye intermediates with quaternary salts of heterocyclic nitrogen compounds containing in the α- or γ-position to the quaternary nitrogen atom a reactive methyl, mono-substituted methyl, or external methylene group, or with heterocyclic nitrogen keto - methylene com - pounds (e.g. rhodanic acid, hydantoin, pyrazole- 5-ones, or oxindoles), or with other cyclic ketomethylene compounds. Samples have been furnished under Sect. 2 (5) of (a) an intermediate obtained by the reaction of 2-( #-diacetylmethylene)-2-methyldihydrothiazoline, ethyl mercaptan, and sulphuric acid, and of (b) an intermediate obtained by the reaction of 4-(#-diacetylmethylene)-2-methyldihydroquinoline, ethyl mercaptan, and sulphuric acid.