Patent GB-885520-A (GB)
Title: Diazacarbocyanine bases
Inventor: KENDALL JOHN DAVID
IPC: C09B26/02
Filed: 1958-06-25
Abstract: 2-Benzoyl-1-methylbenziminazole is prepared by refluxing mandelic acid and o-methylaminoaniline in hydrochloric acid and making the solution alkaline with ammonia to give 1-methyl-2-a -hydroxybenzyl-benziminazole.  The latter is then oxidized with sodium dichromate in acetic acid to give the required ketone.  By using lactic acid instead of mandelic acid, 1-methyl-2-a -hydroxyethyl-benziminazole is formed which is then oxidised to 2-acetyl-1-methylbenziminazole.  The o-methylamino-aniline may be replaced by o-phenylene diamine in the above series of reactions to give 2-a -hydroxybenzyl-benziminazole or 2-a -hydroxyethyl-benziminazole, which are then oxidised to 2-benzoyl-benziminazole and 2-acetyl-benziminazole, respectively. 2-Benzoyl-benzthiazole is prepared by heating mandelic acid and o-amino-thiophenol to give 2-a -hydroxybenzyl-benzthiazole which is then oxidized as above.  By using lactic acid or a -hydroxy-n-butyric acid in place of mandelic acid, 2-a -hydroxyethyl-benzthiazole or 2-a -hydroxypropyl-benzthiazole respectively are first produced, and these are then oxidized to 2-acetyl-benzthiazole or 2-propionyl-benzthiazole respectively.  2-Acetylquinoline is prepared by adding ethyl quinaldinate and ethyl acetate to sodium ethoxide in dry toluene, and heating the solid intermediate which separates with conc. sulphuric acid.  By using ethyl phenylacetate in place of ethyl acetate, 2-phenylacetylquinoline is obtained, decarboxylation being effected with hydrochloric acid instead of sulphuric acid, however. 4-Benzoylpyridine is prepared from isonicotinyl chloride and benzene as described for the 2-benzoyl-pyridine in Berichte, 1915, 48, 2047. 2-Hydrazone - 1 : 2 - dihydro - 1 - methyl - quinoline is prepared by refluxing 1-methyl-2-methylthio-quinoline toluene p-sulphonate and ethyl hydrazinoformate in water in the presence of triethylamine to give the 2-carbethoxyhydrazone derivative.  The latter is hydrolyzed and decarboxylated by refluxing with conc. hydrochloric acid to give the required product.  6 - Ethoxy - 2 - hydrazono - 3 - methylbenzthiazoline is similarly prepared, hydrolysis of the carbethoxyhydrazone being effected by boiling either with conc. hydrochloric acid or with 40% aqueous sodium hydroxides.  The following hydrazones are similarly prepared via their respective carbethoxyhydrazones: 2 - Hydrazono-6 - methoxy - 3 - methylbenzthiazoline, 2 - hydrazono - 5 : 6 - dimethoxy - 3 - methylbenzthiazoline, 2 - hydrazono - 3 - methyl - 5 - methylthio - D 4 - 1 : 3 : 4 - thiadiazoline and 2 - hydrazono - 5 - chloro - 3 - methylbenzthiazoline.  4 - Hydrazone - 1 : 4 - dihydro - 1 - methylquinoline is prepared by heating 4-methylthio-quinoline metho toluene-p-sulphonate with hydrazine hydrate.  2 - Hydrazino - 4,6 - dimethyl - pyrimidine is prepared by treating hydrazine hydrate with 2-chloro-4,6-dimethyl pyrimidine in ethanol. 3-Hydrazino-6-phenyl-pyridazine is similarly prepared from 3-chloro-6-phenyl-pyridazine.  U.S.A. Specification 2,073,600 is referred to.ALSO:Diazacarbocyanine bases, suitable for dyeing polymeric materials comprising at least 85% of acrylonitrile units, have the general formula <FORM:0885520/IV (c)/1> wherein R1 is hydrogen, alkyl, aryl or aralkyl, R2 is alkyl, aryl or aralkyl, m and n are 0 or 1 and D1 and D2 complete 5- or 6-membered heterocyclic nuclei.  The dye bases are prepared by condensing a ketone of the general formula <FORM:0885520/IV (c)/2> with a hydrazone of the formula <FORM:0885520/IV (c)/3> alternatively, dye bases of formula I wherein R1 is an alkyl group can be prepared by alkylating (e.g. with an alkyl halide) the corresponding compounds wherein R1 is hydrogen, which latter compounds may exist in the tautomeric form having the formula <FORM:0885520/IV (c)/4> Examples are given of the preparation of dye bases of formula I wherein R1 is H1 methyl or ethyl, R2 is methyl, ethyl, phenyl or benzyl, D1 completes a benzthiazole (which may be substituted in the benzene ring), benzimidazole, 2- or 4-quinolene, 5 - methylthio - 11,31,4 - thiadiazole - 2, 41,6-dimethyl-2-pyrimidine or 6-phenyl-3-pyridazine nucleus, and D2 completes a benzimidazole, 1-methyl-benzimidazole, 2- or 4-pyridine, 2-quinoline, or benzthiazole nucleus.  An example is given of the dyeing of polyacrylonitrile in hot aqueous acetic acid in the presence of a condensation product from olein alcohol and ethylene oxide. U.S.A. Specification 2,073,600 is referred to.