Patent GB-555935-A (GB)
Title: Improvements in or relating to dyestuff intermediates
IPC: C07D277/10
Filed: 1942-03-02
Abstract: 555,935. Dye intermediates. KENDALL, J. D. March 2, 1942, No. 2699. [Class 2 (iii)] Dye intermediates of the formula where D 1  is the residue of a 5- or 6-membered heterocyclic nitrogen ring, R is H or an alkyl or aralkyl group, R 1  and R 2  are each an alkyl or aralkyl group, X is a p-toluenesulphonate group and n is 0 or 1 are prepared by condensing an alkyl or aralkyl-p-toluenesulphonate quaternary salt of a 5- or 6-membered heterocyclic nitrogen compound containing a, reactive methyl or mono-substituted methyl group in the α- or γ- position to the heterocyclic quaternary nitrogen atom with an ester of trithioorthoformic acid, the condensation being effected in presence of a non-basic solvent for the reactants. The intermediate may be converted to a salt with another acid by adding it to a solution of a salt of such acid. In a modification, the alkyl or aralkyl quaternary salt used is other than an alkyl or aralkyl p-toluenesulphonate, and a large excess of the' ester of trithioorthoformic acid is used ; the intermediate is separated from the trinuclear cyanine dye also formed, e.g. by fractional crystallization. The solvent may be acetic or propionic anhydride, and the ethyl ester of trithioorthoformic acid used. The heterocyclic nitrogen compound may be a thiazole, oxazole, selenazole or a polycyclic homologue (e.g. of the benzne,e naphthalene, acenaphthene, or anthracene series) ; pyridine or a polycyclic. homologue (e.g. quinoline, or α- or #-naphthaquinoline) ; or a lepidine, indolenine, diazine (e.g. a pyrimidine or quinazoline), diazole (e.g. thio-#:#<SP>1</SP>- diazole), oxazoline, thiazoline, or selenazoline. The polycyclic compounds may be substituted in the carbocyclic rings with one or more .groups, e.g. alkyl, aryl, amino, hydroxy, alkoxy, or methylene-dioxy, or by halogen atoms. The groups R, R 1  and R 2  may be methyl, ethyl, propyl, butyl, benzyl, or naphthylmethyl groups. In example 1, 1- #-ethylthiovinyl-benzthiazole-methyl-p-toluenesulphonate is prepared by adding ethyl trithioorthoformate and acetic anhydride to the product obtained by fusing together 1-methylbenzthiazole and methyl p-toluenesulphonate, and boiling. The corresponding methiodide (example 2) is prepared by pouring the reaction solution according to example 1 into potassium iodide solution. The reaction may be effected with propionic anhydride. The methiodide may also be obtained by boiling together 1-methylbenzthiazole methiodide, ethyl trithio-orthoformate, and acetic anhydride, extracting the filtered solid with methyl alcohol, and separating the methiodide from the methyl alcohol extract. The corresponding ethiodide is prepared similarly using the product obtained by fusing together 1-methylbenzthiazole and ethyl p-toluenesulphonate. 2-#-ethylthio-vinyl-quinoline methiodide, 1- #-ethylthio-vinyl-benzoxazole methiodide, 4-#-ethylthio-vinyl-quinoline methiodide, 1- #- ethylvinyl-thiazoline-methyl-p-toluenesulphonate, and 1-#-ethylthio-isopropenyl-benzthiazole methiodide are similarly prepared. 1- #-ethylthiovinyl-2:2<SP>1</SP>-dimethylindolenine methiodide is prepared by heating together 1-methylene-2:2<SP>1</SP>- dimethyl - N - methyl - dihydroindole, p - - toluenesulphonic acid monohydrate, and acetic acid, adding ethyl trithio - ortho formate, boiling, distilling off acetic anhydride, and pouring an ethyl alcohol solution of the residue into potassium iodide solution. 1 - # - benzylthio - vinyl - benzthiazole methiodide is prepared similarly to example 2 using benzyl trithio orthoformate. Specification 555,936 is referred to. 1 - - methylene - 2 : 2<SP>1</SP> - dimethyl - N - methylindole is prepared by steam-distilling a mixture of alkali and 1 : 3 : 3 - trimethylindolenine methiodide. Benzyl trithio - orthoformate is prepared by passing dry HC1 into a cooled mixture of ethyl formate and benzyl mercaptan. According to the Provisional Specification, R may also be an aryl group, and R 2  may be an aryl group (e.g. phenyl or naphthyl), and may be substituted with alkyl, aryl, amino, hydroxy, or alkoxy groups, or halogen atoms.