Patent GB-561172-A (GB)
Title: Improvements in and relating to dye bases and photographic emulsions containing them
IPC: C09B23/01
Filed: 1941-12-16
Abstract: A hemicyanine dye base of the formula shown in Fig. 1, wherein L represents a methine group (including substituted methine), m 0 or 1, n 0, 1, 2, or 3, R an alkyl or aryl radical, R1 an aryl radical, and Z the non-metallic atoms necessary to complete a heterocylic nucleus, is prepared by treating with an acid-binding agent a hemicyanine dye of the formula shown in Fig. 2. X represents an acid radical, preferably a halogen atom.  The acid-binding agent may be an alkaline metal hydroxide.  The reaction may be carried out in a liquid diluent, e.g. acetone, which is a solvent for the base but not for the dye.  3 - Ethyl - 2 - phenyliminobenzthiazoline is prepared by suspending 2-anilinobenzthiazole ethiodide in acetone, and adding aqueous sodium hydroxide.  The acetone is distilled from the acetone layer, and the residue stirred with water.  The base crystallizes.  3 - Ethyl - 2 - (2 - phenyliminoethylidene) - benzthiazole, 1 - methyl - 4 - (2 - phenylimino-ethylidene) - 1 : 4 - dihydroquinoline, 3 - methyl - 2 - (2 - phenyliminoethylidene) - thiazolidine, 1 - ethyl - 2 - (2 - phenyliminoethylidene) - 1 : 2 - dihydroquinoline, 1 - ethyl - 2 - (2 - phenyliminoethylidene) - b  - naphthathiazoline, 3 - ethyl - 2 - [2 - (b  - naphthylimino) - propylidene] - benzthiazoline, 1 - ethyl - 2 - [2 - (b  - naphthylimino) - propylidene] - b  - naphthathiazoline, 2 - [2 - (p - anisylimino) - propylidene] - 1 - ethyl - b  - naph <FORM:0561172/IV/1> <FORM:0561172/IV/2> <FORM:0561172/IV/3> <FORM:0561172/IV/4> thathiazoline, 1 - ethyl - 2 - [2 - p - tolylimino) - propylidene] - b  - naphthathiazoline, 2 - [2 - p - chlorophenylimino) - butylidene] - 3 - ethylbenzselenazoline, 1 - ethyl - 2 - (2 - phenyliminopropylidene) - b  - naphthathiazoline, 3 - ethyl - 2 - (4 - phenylimino - 2 - butenylidene) - benzthiazoline, and 3 - ethyl - 2 - (6 - phenylimino - 2 : 4 - hexadienylidene)-benzthiazoline are similarly prepared.  2 - Anilinobenzthiazole ethiodide is prepared by heating together in a sealed tube 2-anilinobenzthiazole and ethyl iodide.  Hemicyanine dyes of the formula shown in Fig. 5, wherein R, R1, X, and Z have the same meanings as in Figs. 1 and 2 and R11 represents an alkyl group are prepared by treating a cyclammonium quaternary salt containing in the a -position a chloropropenyl or chloro-1-butenyl group with a primary aromatic amine.  Hemicyanine dye bases of the formula shown in Fig. 4, wherein R, R1, R11, X and Z have the same meanings as in Fig. 5 may be incorporated in photographic silver halide emulsions as sensitizers, and may be incorporated in the washed finished emulsion or by bathing the coated plate or film.  Sensitizing data are given. The dye bases may be used in the preparation of light filters. Samples have been furnished under Sect. 2 (5) of (a) 1-ethyl-2-(21-phenyliminopropylidene) - b  - naphthathiazoline using triethylamine, (b) 1 - ethyl - 2 - (21 - phenyliminopropylidene) - b - naphthathiazoline using pyridine, and (c) 2 - (21 - p - anisyliminopropylidene) - 1 - ethyl - b  - naphthathiazoline using triethylamine.  Specifications 447,748 and 533,425 are referred to. The Specification as open to inspection under Sect. 91 refers also to the use of the bases for dyeing cellulose acetate yarn and to the preparation of 3 - phenyl - 2 - (21 - phenyliminoethylidene) - benzthiazole from 2 - (2 - anilinovinyl) - benzthiazole pheniodide, of the latter by condensing 2 - methyl - 3 - phenylbenzthiazolium iodide with diphenylformanidine, and of 2 - methyl - 3 - phenylbenzthiazolium iodide by hydrolyzing 2-dicarbethoxymethylene-3-phenylbenzthiazoline in presence of HC2, and converting to the iodide.  Specification 551,824 is referred to. This subject-matter does not appear in the Specification as accepted.