Patent GB-486780-A (GB)
Title: Improvements in the manufacture and production of heterocyclic nitrogen compounds containing aldehyde groups
Filed: 1936-12-09
Abstract: Heterocyclic nitrogen compounds containing an aldehyde group are made by causing formamidines of the general formula <FORM:0486780/IV/1> [R and R1 = aryl, R2 = alkyl, aralkyl or aryl or the radicle <FORM:0486780/IV/2> is a member of a saturated ring] to react with heterocyclic nitrogen compounds containing a reactive methyl or methylene group in the form of their ammonium salts or the corresponding pseudo bases and splitting the polymethine compounds obtained with alkalies.  The intermediate polymethine compounds are yellow basic dyes.  The aldehydes are intermediates for the preparation of polymethine dyes, e.g. according to Specifications 438,603, 448,936, and 462,238.  In examples: (1) 1 : 3 : 3-trimethyl-2-methyleneindoline-o -aldehyde is made by heating 2 : 3 : 3-trimethylindolenine bromomethylate with N-methyldiphenylformamidine in acetic anhydride, rendering alkaline with caustic soda and steam distilling to remove the free base; (2) N - ethyl - 2 - methylenequinoline - o  - aldehyde is similarly made from 2-methylquinoline iodoethylate but with intermediate isolation of the dyestuff; (3) N-methyl-m -methylenebenzthiazole-o -aldehyde is made from 2-methylbenzthiazole dimethyl sulphate as in (2); a corresponding benzobenzthiazole - o  - aldehyde is similarly made from 2-methyl-b -naphthiazole dimethyl sulphate; (4) the aldehyde of (1) (containing a little 2-methylindoline) is made by condensing 2 : 3 : 3-trimethylindolenine bromomethylate with 2-methylindolinylphenylformamidine as above and splitting the resulting dyestuff with alkali; the corresponding 5-methoxy-o -aldehyde is obtained from 5-methoxy-2 : 3 : 3-trimethylindolenine bromomethylate; (5) 1 3 : 3-trimethyl-2-methylene-b  - naphthindolenine - o  - aldehyde is made from 2 : 3 : 3-trimethyl-b -naphthindolenine bromomethylate and 1 : 2 : 3 : 4 - tetrahydroquinolylphenylformamidine as above, separating the intermediate dyestuff (which dyes cotton mordanted with tannic acid, acetate artificial silk and wool in yellow shades) and subjecting it to alkaline steam distillation; (6) the aldehyde of (1) is made from 2 : 3 : 3-trimethylindolenine iodomethylate and triphenylformamidine as in the previous examples.  N-cyclohexyl-, N-benzyl- and N-p-tolyl-diphenylformamidine and 2-methylindolinyl-m-tolylformamidine are also specified as starting materials as well as the alkyl halide, dialkyl sulphate and p-toluenesulphonic acid alkyl ester addition compounds to 2 : 3 : 3-trimethylindolenine, 2 : 3 : 3-trimethyl-b -naphthindolenine, 2- and 4-methylquinoline, methyl-a -and b  - naphthoquinolines, 2 - methylbenzthiazole, 2 - methyl - b  - naphthiazole, 2 - methylbenzoxazole and 2-methylbenzselenazole and the stable pseudo bases containing methylene groups obtainable from the said compounds by action of alkalies, e.g. 1 : 3 : 3-trimethyl-2-methyleneindoline. Specification 344,409 also is referred to.  The above formamidines may be made by condensing the formyl compound of a primary aromatic amine with secondary aromatic or heterocyclic nitrogen compounds in the presence of chlorides of phosphorus.