Patent GB-730489-A (GB)
Title: Improvements in or relating to cyanine and merocyanine dyes
Inventor: KENDALL JOHN DAVID
IPC: C09B23/02
Filed: 1952-11-14
Abstract: Dyes of the following general formula are described:-  I <FORM:0730489/IV (c)/1> and II <FORM:0730489/IV (c)/2> wherein R1, R2, R3 and R4 are alkyl groups containing up to 4 carbon atoms, R5 is an alkyl group, R6 is a hydrocarbon radical or is joined via carbon and nitrogen to the nucleus D2 to form a heterocyclic nucleus, R7 is H or alkyl, X is an anion, m and n are 0 or 1 and D1 and D2 complete heterocyclic nuclei.  The dyes of formula I may be prepared by reacting a compound of formula <FORM:0730489/IV (c)/3> wherein Y is an acid radical with a compound of formula <FORM:0730489/IV (c)/4> wherein Q is a thioether or acetanilide group.  The dyes of formula II may be prepared by reacting a compound of formula III with a heterocyclic keto-methylene compound in the presence of an alkyl orthoformate or alkyl ortho acetate.  Symmetrical dyes of formula I are obtained by reacting two mols. of a compound of formula III with an alkyl orthoformate.  In place of the quaternary salt of formula III there may be used a compound of formula <FORM:0730489/IV (c)/5> and two molecular equivalents of a salt R4Y (in which case R3 = R4) and instead of the quaternary salt of formula IV the corresponding base may be used together with a quaternizing salt R5X.  D1 may complete a nucleus such as thiazole or oxazole and their benzene and naphthalene homologues, quinoline, indolenine, diazines such as pyrimidine, diazoles such as thio-b ,b 1-diazole, pyrazolenine and iminazolenine.  The carbocyclic rings of such nuclei may be substituted with alkyl, aryl, alkoxy, methylene dioxy or halogen radicals.  D2 may complete a rhodanine, pyrazole-5-one, thiohydantoin or thiazolidene (e.g. with R6, a benziminazothiazolidone) nucleus. According to the Provisional Specification the nucleus D1 may also be selenazole, an acenaphthene or anthracene homologue of thiazole, oxazole or selenazole, pyridine, a - and b -naphthoquinolines, lepidine, quinazoline, oxazoline, thiazoline, or selenazotine, and D2 may be oxarhodanine or an N-hydrocarbon derivative thereof, oxindole, hydantoin, pseudohydantoin or pseudothiohydantoin.  Further, formula II is given wherein the two nuclei are joined by = (CH-CH)p, where p is a positive integer, e.g. 1 or 2.  It is stated that the carbocyclic rings of the nuclei D1 may also be substituted with amino or hydroxy groups, that Q in formula IV may be an amino or substituted amino group, and that R1, R2 and R3 may be hydrocarbon groups, R4 may be alkyl or aralkyl and R5 may also be aralkyl, hydroxyalkyl or carboxyalkyl.ALSO:4 : 4 : 5 - trimethyl - 3 - pyrazolone is prepared by heating ethyl a ,a -dimethylacetoacetate and hydrazine hydrate under reflux, and removing the ethanol and water formed.  4 : 4 : 5 - trimethylpyrazolenine - 3 - thiol is prepared by adding phosphorus pentasulphide to 4 : 4 : 5-trimethyl-3-pyrazolone in dry xylene.  3 - Methylthio - 4 : 4 : 5 - trimethylpyrazolene is prepared by adding dimethyl sulphate to 4 : 4 : 4 : 5 - trimethylpyrazolenine - 3 - thiol dissolved in sodium hydroxide.  Similarly, ethyl a  : a  - diethylacetoacetate yields 4 : 4 - diethyl - 5 - methyl - 3 - pyrazolone and the corresponding -3-thiol.