GB1001061A - Improvements in or relating to sensitized photographic silver halide emulsions and to new sensitizing dyes - Google Patents

Abstract

The invention relates to methine dyes containing a 1 : 2-condensed benzimidazole nucleus of one of the following formulae and joined to the methine chain by the bonds shown:- <FORM:1001061/C4-C5/1> and <FORM:1001061/C4-C5/2> <FORM:1001061/C4-C5/3> and <FORM:1001061/C4-C5/4> wherein A is -CH2-, -CH2-CH2-, -CH2-O- or <FORM:1001061/C4-C5/5> R2 is an alkyl, aryl or benzyl group, any of which may be substituted or a cycloalkyl or allyl group, R0 is an alkylene-O-SO3(-) radical or a A-W-N"-"-V-B radical wherein A, B, W and V are as defined in Specification 904,332 and V1-V4 are hydrogen or halogen atoms or alkyl, substituted alkyl, nitrile, carboxyl, carbalkoxy, amino, acylamino or N-substituted saturated heterocyclic sulphonamido groups or V2 and V3 together complete a fused-on benzene ring. The dyes are prepared from the quaternary salts of the formulae <FORM:1001061/C4-C5/6> <FORM:1001061/C4-C5/7> wherein X is an anion or from the corresponding betaines, where R2 = R0- and X is absent, by the usual methods. Symmetrical dyes having two nuclei of formula I linked by a chain of one or three methine groups are prepared by condensing a quaternary salt of formula VIII with ethyl orthoformate or 1 : 3: 3-triethoxy-1-propene. Dyes of formula IV <FORM:1001061/C4-C5/8> wherein R1 has the same definition as R2, m is 1 or 2 and Z completes a 5- or 6-membered heterocyclic ring, and the corresponding betaines where R2 is R0- and X is absent, are prepared by condensing a quaternary salt of the formula VIII (or the corresponding betaine) with a quaternary salt of a heterocyclic base such as a thiazolinium, selenazolinium or benzimidazolinium (which may have a 5-chloro-, 5 : 6-dichloro- or 5-cyano substituent) salt having a reactive b -anilinovinyl, b -acetanilidovinyl, or N-p-tolusulphonyl-b -anilidovinyl group, or with a heterocyclic base such as 2: 3-dihydrobenzoxazole or 2: 3-dihydrobenzselenazole having a reactive b -phenylimino-ethylidene group. By using quaternary salts of the formula IX instead of those of formula VIII with such intermediates, tri-nuclear methine dyes are obtained. Dyes of formula VI <FORM:1001061/C4-C5/9> wherein e is 1 or 2 and P and Q together complete a heterocyclic ketomethylene nucleus are prepared by condensing quaternary salts of formula VIII with compounds such as 3-ethyl-5-acetanilidomethylene-2-thio-2: 4-thiazolidine-dione or the corresponding oxazolidine and 3 - ethyl - 5 - acetanilidopropenylidene - 2 - thio - 2: 4-thiazolidine-dione. By using quaternary salts of formula IX instead of those of formula VIII with such intermediates, trinuclear methine dyes are obtained. The dyes of formula VI having a thio group on the ketomethylene nucleus may be quaternized, e.g. with dimethyl sulphate and reacted with further ketomethylene compounds such as 3-ethyl-rhodanine or with quaternary salts having a reactive methyl group such as 2: 5-dimethyl-3-ethyl-benzthiazolium methosulphate to give complex trinuclear methine dyes. Monomethine dyes are also prepared by reacting the quaternary salts of formula VIII with dialkylaminobenzaldehydes. Tables are given of suitable intermediates of formulae VIII and IX and of dyes made therefrom wherein one or more of V1-V4 is selected from methyl, trifluoromethyl, chloro, bromo, fluoro, cyano, nitro, carboxy, carbethoxy, amino, acetylamino, 1-pyrrolidino-sulphonyl and 1-piperidino-sulphonyl, R2 is methyl, ethyl, b - hydroxyethyl, b - carboxyethel, b - acetoxyethyl, N - acetyl - sulphonamidopropyl, N - acetyl-sulphonamidobutyl or methylsulphonyl-carbamyl-methyl, and R0- is sulphato-propyl or an anion derived from one of the specified groups of the formula A-W-NH-V-B.ALSO:2; 3 - Dihydro - 1H - pyrrolo - [1; 2a]benzimidazoles whih may be substituted in the benzene ring are prepared by reacting pyrrolidine with a o-dinitro- or o-halogeno-nitrobenzene, optionally substituted with any of the groups required in the benzene ring of the product, to give an N-(2-nitrophenyl)-pyrrolidine, reducing the nitro group to the corresponding amine, diazotizing and reacting with sodium azide to give the N-(2-azodophenyl)-pyrrolidine, and then cyclizing this with nitrobenzene. Similar reactions may be carried out with piperidine or tetrahydro-1,4-oxazine in place of pyrrolidine to give 1; 2; 3; 4 - tetrahydropyridino[1; 2-a]-benzimidazoles or 3; 4 - dihydro - 1H - 1; 4-oxazine[4; 3-a]benzimidazoles respectively. The substituent in the benzine ring may be chloro, bromo, fluoro, cyano, methyl, trifluoromethyl or carbethoxy. In certain cases a chlorosulphonyl substitutent is present, and this also reacts with the heterocyclic base to give a pyrrolidino-sulphonyl or piperidino-sulphonyl substituent in the product. The carbethoxy substituents may be hydrolysed to carboxyl groups in the final product. The products may be nitrated to introduce a nitro group into the 7 - position of the 2; 3 - dihydro - 1H - pyrrolo-[1; 2-a]benzimidazoles or a similar position of the other nuclei, and this may be reduced to give the amine. This amino group may be acylated, e.g. with acetic anhydride or replaced by groups such as chloro, fluoro and cyano by diazotization followed by a Sandmeyer reaction or by the Schiemann reaction. 6 - Cyano - 2; 3 - dihydro - 1H - pyrrolo-[1; 2-a]benzimidazole is prepared by refluxing the corresponding 6-bromoderivative with cuprous cyanide in nitrobenzene, cooling and adding a solution of sodium cyanide. 6,11 - Dihydro - benzimidazolo[1; 2-b]isoquinoline is prepared by heating 3; 6-dihydro-4; 5-benzo-2-pyrone with o-phenylene diamine in a sealed tube at 250 DEG C. Any of the above bases as well as 1; 2; 3; 4; 8; 9; 10; 11 - octahydro - dipyrido[1; 2 - a; 11; 21 - a1] - benzo[1; 2 - d: 51; 41 - d1] - diemidazole may be quaternized by heating them with a quarternating agent such as methyl or ethyl iodide, b -hydroxyethyl bromide (these quaternary salts may be subsequently acetylated with acetic anhydride), b -carboxyethyl bromide, N - acetyl - 3 - bromopropane - sulphonamide, N - acetyl - 4 - brombutane - sulphonamide, N - bromoacetyl - methane - sulphonamide or the betaine of g -hydroxypropylsulphate. 5 - Ethyl - 8 - chloro - 1; 2; 3; 4 - tetrahydropyridino[1; 2 - a]benzimidazolium iodide is prepared by hydrogenation of the quaternary salt from ethyl iodide and 8-chloro-pyridino[1;2-a]-benzimidazole which itself has been prepared from the corresponding 8-amino compound by diazotization followed by a Sandmeyer reaction with cuprous chloride.