Patent GB-743133-A (GB)
Title: Improvements in or relating to cyanine dyestuffs
Inventor: KENDALL JOHN DAVID
IPC: G03C1/12
Filed: 1953-03-13
Abstract: 3,5-Dimethyl-1:2:4-triazoles having a 1-phenyl, 1-(p-chlorophenyl) or 1-methyl substituent are prepared from diacetimide and the appropriate hydrazine.  3 - Methylthio - 5 - methyl - 1 - phenyl - 1:2:4-triazole is prepared from methyl-acetyldithio-carbamate and phenyl hydrazine. The 3-ethylthio and 3-benzylthio derivatives are similarly prepared.  The 3-methylthio compound is also prepared by methylation of the corresponding 3-mercapto derivative.  Its metho-p-toluene sulphonate may be converted by hot aqueous sodium sulphide solution into the corresponding N-methyl-thione.  The thione can be quaternized to give the original quaternary salt.  2:5 - Dimethyl - 1 - phenyl - 1:2:4 - triazole-3-thione is prepared by treating 2-methyl-1-phenylhydrazine with potassium thiocyanate to yield 2-methyl-1-phenylthiosemicarbazide, acetylating and closing the ring with ethanolic sodium ethoxide.  4:5 - Dimethyl - 1 - phenyl - 1:2:4 - triazole-3-thione is prepared by acetylating 4-methyl-1-phenylthiosemicarbazide and closing the ring by heating. 2 - 21 - Acetanilidovinyl - 3:5 - dimethyl-1:3:4-thiadiazolium iodide is prepared by refluxing 2:5-dimethyl-1:3:4-thiadiazole in methyl iodide, and then refluxing the solid obtained with diphenylformamidine and acetic anhydride.  2 - 21 - Ethylthiovinyl - 3:5 - dimethyl-1:3:4-thiadiazolium iodide is prepared by refluxing 2:3:5-trimethyl-1:3:4-thiadiazolium iodide, acetic anhydride and ethyl trithioorthoformate.  2 - 21 - Acetanilidovinyl - D 2 - thiazoline metho-p-toluene sulphonate is prepared by heating 2-methyl-D 2-thiazoline and methyl p-toluene sulphonate and refluxing the product with diphenylformamidine and acetic anhydride. Specification 425,609 and U.S.A.  Specification 2,349,179 are referred to.ALSO:Cyanine dyes of the general formula:-<FORM:0743133/IV(c)/1> wherein R1 is an alkyl, aryl or substituted aryl group, R2 is an alkyl, alkylthio or aralkylthio group, R3 is an alkyl or hydroxyalkyl group, R4 is an alkyl group, X is an acid radical, m and n are o or 1 and D1 completes a heterocyclic nucleus, or of the general formula:- <FORM:0743133/IV(c)/2> wherein R1, R2 and R3 are as above and D2 completes a heterocyclic nucleus, are prepared by condensing a triazole quaternary salt having a reactive methyl group in the 5-position with either (i) a compound of formula:- <FORM:0743133/IV(c)/3> wherein D1 R4 X and m have the above meanings and Q is a thioether, thioether vinyl or acetanilidovinyl group, or (ii) a compound of the formula:- <FORM:0743133/IV(c)/4> wherein D2 is as above and R5 is an alkyl group. Values of R1 specified include chlorophenyl.  D1 may complete a nucleus of the thiazole, oxazole or selenazole series, including their benzene and naphthalene homologues, or of the pyridine, quinoline, naphthoquinoline, indolenine, pyrimidine, quinazoline, 1:3:4-thiadiazole; thiazoline or selenazoline series. The carboxylic rings of such nuclei may carry alkyl, aryl, alkoxy, methylene dioxy or halogen substituents.  D2 may complete a rhodanine, oxarhodanine, oxindole, 5-pyrazolone, hydantoin, thiohydantoin, pseudohydantoin, pseudothiohydantoin, oxazolone or thiazolidone (including 21:11-benziminazo-2:3-thiazolid-4-one) nucleus.  The reactions are preferably carried out in the presence of a base such as pyridine, triethylamine or sodium acetate.  In the Provisional Specification the methine chain of the dyes may be substituted, and the various substituents R are defined in wider terms.  Merodicarbocyanine dyes are referred to, and further examples of the nucleus completed by D1 are given. Specification 425,609 and U.S.A. Specification 2,349,179 are referred to.