Patent GB-640127-A (GB)
Title: Improvements in or relating to the production of cyanine dyestuffs and to the sensitising of photographic emulsions
Inventor: DOYLE FRANK PETER
IPC: G03C1/12
Filed: 1948-05-19
Abstract: a -Carbethoxymalondialdehyde mono-anil is prepared by refluxing together a solution obtained by adding a suspension of ethyl anilinomethyleneacetate in dry ether and ethyl formate in portions to sodium powder in dry ether.  Ethyl anilinomethyleneacetate is prepared by adding an aqueous solution of sodio formyl ethyl acetate to a solution of aniline in acetic acid and water.  Ethyl a -formyl-b -ethylthioacrylate is prepared by reacting a mixture of ethyl b -ethylthioacrylate, ethyl formate, and dry ether with sodium powder in ether, and heating.  Ethyl b -ethylthioacrylate is prepared by passing HCl gas through a cooled mixture of sodio formyl ethyl acetate, ethyl mercaptan, and ether, allowing to stand, and pouring into dilute sodium carbonate solution.  a -(n-Propylcarboxy)-malondialdehyde mono-anil is prepared by refluxing a mixture obtained by adding in portions a suspension of n-propyl anilinomethyleneacetate, dry ether, and ethyl formate to sodium powder in dry ether.  n-Propyl anilinomethyleneacetate is prepared by adding an aqueous solution of sodio formyl-n-propyl acetate to a solution of aniline in acetic acid and water.  a -Cyanomalondialdehyde mono-anil is prepared by refluxing a mixture obtained by adding a suspension of anilinomethylene acetonitrile in dry ether and ethyl formate to sodium powder in dry ether. Anilinomethylene acetonitrile is prepared by adding an aqueous solution of sodium formyl acetonitrile to a solution of aniline in acetic acid and water.ALSO:Cyanine dyes are prepared by condensing a compound of the general formula <FORM:0640127/IV (c)/1> wherein R1 is CN or COOR and X is SR or NHR, R being a hydrocarbon group, with a heterocyclic nitrogen compound containing a reactive methylene group, e.g. with a compound of the general formula <FORM:0640127/IV (c)/2> wherein R2 is alkyl, hydroxyalkyl, or aralkyl, R3 is H, alkyl, or aralkyl, Y1 is an acid radical, D1 is the residue of a 5- or 6-membered ring, and n is 0 or 1, or with a compound of the general formula <FORM:0640127/IV (c)/3> wherein R4 is H, or an alkyl, aralkyl, or aryl group, and D2 is the residue of a heterocyclic keto-methylene nitrogen ring.  The condensation may be effected in the presence of a base (e.g. pyridine, triethylamine, or sodium acetate), with or without an acid anhydride (e.g. acetic anhydride). Where R2 is a hydroxyalkyl group, it may be acylated during the reaction. Where D1 is the residue of a polycyclic compound, the carbocyclic rings may be substituted by one or more alkyl, aryl, amino, hydroxy, alkoxy, or methylene-dioxy groups or halogen atoms. Bis - 2 - (3 - ethylbenzthiazole) - g  - carbethoxypentamethinecyanine iodide is prepared either by refluxing together a -carbethoxymalondialdehyde mono-anil, 2-methylbenzthiazole ethiodide, and pyridine, and adding triethylamine, or by heating together ethyl a -formyl-b -ethylthioacrylate, 2-methylbenzthiazole, and pyridine.  Bis - 2 - (1 - ethylquinoline) - g -carbethoxypentamethinecyanine iodide, bis - 2-(1 : 3 : 3 - trimethylindolenine) - g  - carbethoxypentamethinecyanineiodide, bis - 2 - (3 - b -acetoxyethylbenzthiazole) - g  - carbethoxypentamethinecyanine iodide, bis-2-(3-b -acetoxyethyl-5-chlorobenzthiazole) - g  - carbethoxypentamethinecyanineiodide, bis - 2 - (3 - b  - acetoxyethylbenzthiazole) - g  - (n - propylcarboxy) - pentamethinecyanine iodide, bis - 2 - (1 - b  - acetoxyethylquinoline) - g  - (n - propylcarboxy) - pentamethinecyanine iodide, bis - 2 - (3 - ethyl benzthiazole) - g  - cyanopentamethinecyanine iodide, a  : g  - bis - 5 - (3 - ethyl - 5 - thio - 4-ketotetrahydrothiazole) - b  - cyanopropene, bis-5 - (3 - ethyl - 5 - thio - 4 - ketotetrahydrothiazole)-b  - cyanopropene, bis - 2 - (3 - b  - acetoxyethylbenzthiazole) - g  - cyanopentamethinecyanine iodide, and bis - 2 - (3 - ethylbenzselenazole)-g  - carbethoxypentamethinecyanine iodide are similarly prepared.