Patent GB-511940-A (GB)
Title: Improvements in and relating to the production of carbocyanine-like dyestuffs and tothe sensitising of photographic silver halide emulsions
IPC: C09B23/01
Filed: 1937-11-23
Abstract: 511,940. Sensitizing dyes. GEVAERT PHOTO-PRODUCTEN N.V. Nov. 23, 1937, Nos. 32293 and 32294. Convention dates, Nov. 23, 1936, and Nov. 28, 1936. [Class 2 (iii)] [Also in Group XX] Carbocyanine-like dyes are made by reacting an orthoester, aldehyde, imidothioester or amidine with a compound of the general formula where X and X<1> are heterocyclic nuclei containing nitrogen, the nitrogen being connected with an anion to form a quaternary ammonium salt, the -CH2- groups being linked in the alpha- or y-positions relative to the respective nitrogen atoms, M is methylene or substituted methylene and n is a whole number, with the exclusion of dyes made by condensing a compound of the formula in which X 0 or S, Y = halogen or any desired acid residue, n-1 = 1, 2 or 3 and R = alkyl with an orthoformic acid ester. The products contain in the molecule, two heterorings linked by the ring system in which A = methine or substituted methine, M = methylene of substituted methylene and n is a whole number. They are used for sensitizing photographic silver halide emulsions. In the examples (1)-(5) the following compounds are heated with orthoformic acid triethylester in pyridine ; alpha: # [2 : 2<1>-dibenzothiazolyl] ethane diiodiethylate, alpha : 1 [2 : 2<1>-dibenzoselenazolyl] butane diiodoethylate, alpha : # [2 : 2<1>-dibenzoxazolyl] ethane di(ethylsulphate), alpha : y [2 : 21- diquinolyl] propane diiodoethylate and alpha: y [2 :2<1>-diquinolyl] #-phenylpropane diiodoethylate, (6) alpha-# [2 : 2<1>-dibenzothiazolyl] butane diiodoethylate is heated with diphenylformamidine in presence of sodium acetate and acetic anhydride. Specification 405,309 is referred to. The heterocyclic bases used as starting materials may be made as follows : (1) when X and X<1> are benzthiazole or naphththiazole residues by condensing di-basic acid chlorides, e.g., adipyl chloride with o-aminoarylmercaptans, (2) when X and X<1> are benzselenazole residues by condensing with a selenomercaptan, (3) when X and X<1> are benzoxazole residues by condensing di-basic acid amides, e.g., adipamide with o-aminophenol. The Specification as open to inspection under Sect. 91 comprises, the preparation of carbocyanine-like dyes by reacting a condensing agent which contains a reactive methine or substituted methine group with compounds of the first formula above and also comprises silver halide emulsions sensitized with the dyes however obtained. In further examples the following compounds are heated in pyridine with orthoformic acid triethylester : alpha : #-[2 : 2<1>-dibenzothiazolyl] butane diiodoethylate, alpha: y-[dibenzothiazolyl] propane diiodoethylate, alpha : # [2 : 2<1>-dibenzothiazolyl] pentane diiodoethylate, alpha : #-[2 : 2<1>-dibenzoxazolyl] butane di (ethylsulphate) : alpha : y-[2 : 2<1>- dibenzthiazolyl] propane diiodoethylate is also condensed with orthoacetic acid triethylester. Additional spectrograms are given. This subject-matter does not appear in the Specification as accepted.