Patent GB-571231-A (GB)
Title: Improvements in or relating to photographic materials
Filed: 1943-12-08
Abstract: A silver halide emulsion contains as a super-sensitizing combination a dye of the formula I <FORM:0571231/IV/1> and a dye of the formula II <FORM:0571231/IV/2> where R1, R2, R3, R5 and R6 ar substituted or unsubstituted alkyl or aralkyl groups, R4 and R7 are H or alkyl or aralkyl groups; D1, D2, D3 and D4 are residues of 5- or 6-membered heterocyclic nitrogen nuclei: n is 0 or 1; and X and Y are acid radicals.  The substituted alkyl-groups may be hydroxyalkyl groups. The residues D1, D2, D3 and D4 may be residues of thiazoles, oxazoles, selenazoles and their polycyclic homologues, pyridine and its polycyclic homologues, lepidines, indolenines, diazines such as pyrimidines and quinazolines, diazoles such as thio-b .b 1-diazole, oxazolines, thiazolines, and selenazolines.  The polycyclic compounds may be substituted in the carbocyclic rings with one or more groups such as alkyl, aryl, amino, hydroxy, alkoxy, or methylenedioxy, or by halogen atoms.  Dyes of formula I specified are 3 : 31-di-(hydroxyethyl)-9 - methylthiadicarbocyanine iodide, 3 - ethyl - 31 : 9-diamethylthiaselenadicarbocyanine iodide, 3 : 31 - diethyl - 9 - methylthiadicarbocyanine iodide, 3 : 31-diethyl-5 : 51 : 9 - trimethylthiadicarbocyanine iodide, 3 : 9 - dimethyl - 31 - ethylthiadicarbocyanine iodide, 3 : 31 : 9 - triethylthiadicarbocyanine iodide, 3 : 31 - dimethyl - 9 - ethylthiadicarbocyanine iodide, 2 : 11 : 8 - trimethylthiaquinodicarbocyanine iodide, and 3 : 31 : 9 : 12 - tetramethylthiadicarbocyanine iodide.  Dyes of formula II specified are 3 : 31-diethyl - 9 - methylthiacarbocyanine bromide, 3 : 31 : 9-triethyl-5 : 51-dichlorothiacarbocyanine chloride, 3 : 31-diethyl-9-methyl - 4 : 5 : 41 : 51-dibenzthiacarbocyanine bromide, 3 : 3 31 - di - ethylthiacarbocyanine iodide, 3 : 31-di-(hydroxy ethyl)-9-methylthiacarbocyanine iodide, 3 : 31-diethyl-9-methyl-4 : 5 : 41 : 51-tetroxydimethylenethiacarbocyanine iodide, 3 : 31 - diethyl - 9 - methylselenacarbocyanine iodide, and 3 : 31 : 9-triethylselenacarbocyanine iodide.  Data are given for speeds to daylight and to red light of emulsions containing combinations of the dyes.  The emulsion binder may be gelatin, polyvinyl alcohol, polyvinyl acetals, or part-hydrolysed cellulose esters. Specification 553,144 is referred to.  3 : 31 - Diethyl - 9 - methyl - 5 : 6 : 51 : 61 - di - (methylenedioxy) - thiacarbocyanine iodide is made by condensing 2-methyl-5 : 6-methylene-dioxybenzthiazole ethiodide with ethyl ortho-acetate in presence of pyridine.  3 : 3 - Diethyl - 5 : 51 - 9 - triethylthiadiocarbo - cyanin iodide is prepared by boiling together 1-(o -methyl-o -ethylthiobutadienyl)-5-methyl-benzthiazole ethochloride, 1 - methylbenzthia - zole ethiodide, ethyl alcohol and triethylamine.  3 : 9 - Dimethyl - 31 - ethylthiadicarbocyanine iodide, 3 : 31 : 9-triethylthiadicarbocyanine iodide and 3 : 31 - dimethyl - 9 - ethylthiadicarbocyanine iodide are similarly prepared. 2 : 11 : 8 - Trimethylthiaquinodicarbocyanine iodide is prepared by boiling 2-o -methyl-o -ethylthiobutadienylquinoline methochloride with 1-methylbenzthiazole methiodide in presence of ethyl alcohol and sodium acetate.