Patent GB-955962-A (GB)
Title: Improvements in or relating to new sensitizing dyes and sensitized photographic emulsions
Inventor: DEPOORTER HENRI
IPC: C09B23/10
Filed: 1959-10-13
Abstract: 2-methyl benzimidazolium quaternary salts of the general formula: <FORM:0955962/C2/1> wherein R12 and R13 are hydrogen, chlorine bromine, fluorine or cyano but at least one must be cyano, R1 and R3 are alkyl, substituted alkyl, cycloalkyl, allyl, aryl, substituted aryl, benzyl or substituted benzyl groups and X is an anion, are prepared by quaternization of the corresponding bases. Examples are given of the quaternization of 1-ethyl -2- methyl -5- cyano benzimidazole with ethyl iodide, ethylene bromohydrine (the product may be acetylated on the hydroxyethyl group with acetic anhydride), N-(bromo-acetyl)-methane sulphonamide, 1;3-dioxathiane-2; 2-dioxide, N-acetyl -3- bromo-propanesulphonamide or N-acetyl -4- bromo-butane-sulphonamide, of the quaternization of 1-(b -acetoxyethyl) -2- methyl -5- cyano-benzimidazole with ethylene bromohydrine (the product may be acetylated as above), and of the quaternization of 1-ethyl -2- methyl -5- chloro (or fluoro) -6- cyano benzimidazole with ethyl iodide. The appropriate bases are described in Specification 955,961  1; 3-Diethyl -2- (b -phenylimino-ethylidene) -5-cyano benzimidazoline is prepared by heating 1;3-diethyl -2- methyl -5- cyano-benzimidazolium iodide and diphenylformamidine on an oil bath, suspending the 2-(b -anilidovinyl)- derivative thus formed in acetone, and adding aqueous sodium hydroxide. The product is dissolved in acetone, and toluene p-sulphonyl chloride is added to give 1;3-diethyl -2- [b -(p.-tolusulphoanilido) vinyl] -5- cyano-benzimidazolium chloride. The corresponding 5-chloro- and 5;6-dichloro-benzimidazoline and its p-tolusulpho-chloride are prepared similarly.  Specifications 904,332 and 955,964 also are referred to.ALSO:Cyanine and merocyanine dyes are described which contain a benzimidazole nucleus substituted in the 5- or 6-position by a cyano group. The other of these two positions may have a fluoro, bromo, chloro or cyano substituent. Examples are given of the preparation of such dyes by reacting the appropriately substituted 2-methyl-benzimidazolium salts with ethyl orthoformate to give symmetrical carbocyanine dyes, with cyclammonium salts having a reactive alkylmercapto group such as 1-ethyl-2-ethylmercapto-quinolinium ethosulphate or 2-methylmercapto - 3 - methyl - benzoxazolium p-tolusulphonate to give mono-methine dyes, or with cyclammonium salts such as thiazolinium salts having a reactive b -acetanilidovinyl group (or b -anilidovinyl group in the presence of acetic anhydride), or with cyclammonium salts such as 5 : 6 - dichlorobenzimidazolium or 5 - chloro- or 5-cyano-benzimidazolium salts having a reactive b -(p-tolusulpho-anilido) vinyl group, or with heterocyclic nitrogen bases such as benzoxazoline, benzselenazoline and benzthiazoline having a reactive b -phenylimino group in the presence of acetic anhydride, to give carbocyanine dyes. Merocyanine dyes are prepared by reacting 1 : 3-diethyl-2-methyl-5-cyano-benzimidazolium iodide with 3-ethyl-5-acetanilido-methylidene rhodanine or with 1-methyl-3-ethyl-5-acetanilido-methylidene-2-thiohydantoin. The substituent on one of the nitrogen atoms of the benzimidazole nucleus may be ethyl, b -hydroxyethyl or b -acetoxyethyl, and that on the other nitrogen atom may be ethyl, b -hydroxyethyl, b -acetoxyethyl, g -(acetylsulphonamido) propyl or g -(acetylsulphonamido) butyl, or it may be an ion of the g -sulphopropyl or methylsulphonylcarbamylmethyl group to give an anhydro dye.  The Provisional Specification refers to styryl and complex merocyanine dyes.  Specifications 904,332, 955,961, and 955,964 are referred to.