Patent GB-1047796-A (GB)
Title: Triphenylmethane dyes
IPC: C07D233/54
Filed: 1964-06-23
Abstract: The invention comprises a leuco dye of the formula <FORM:1047796/C4-C5/1> where R1 and R2 are alkyl groups containing from 1 to 12 carbon atoms, 2-cyanoethyl, 2-hydroxy-ethyl, 3-hydroxypropyl, alkoxy alkyl groups containing from 2 to 8 carbon atoms, aralkyl or aryl groups; R3 is methyl, ethyl or fluorine; X is hydrogen, hydroxy or cyano; and Q is 2-thienyl, 2-furyl, 3,4-methylenedioxy-phenyl, 2-methoxy-4-(C1 to C8)-alkoxyphenyl, 3,4-di-(C1 to C8) alkoxyphenyl or <FORM:1047796/C4-C5/2> where R4 is an alkyl, aralkyl, aryl or substituted aralkyl group containing from 1 to 8 carbon atoms, the substituents of said substituted aralkyl being fluoro, chlori, alkyl or alkoxy substituents and R5 is hydrogen or an alkyl group containing from 1 to 4 carbon atoms, and oxidized, coloured forms thereof, and a leuco dye-salt of the formula <FORM:1047796/C4-C5/3> where M is hydrogen and A an anion, or M is a metal and A is an anion or anions which satisfy the valence of M and which together with M form a Lewis acid, and n is 1 or 2.  The coloured dyes which are formed by oxidation of the leuco dye or salts have the formula <FORM:1047796/C4-C5/4> The leuco compounds in which X is hydrogen may be made by condensation of (a) 2-thiophene-carboxaldehyde, 2-furaldehyde or a correspondingly substituted benzaldehyde with an N,N-disubstituted-3-methyl (or ethyl or fluoro) aniline; (b) an acetal of the aldehydes named in (a) with an N,N-disubstituted-m-toluidine; or (c) a bis-[4-N,N-disubstituted amino-2-ethyl (or fluoro or methyl phenyl] methanol with a phenyl alkyl (or aryl or aralkyl) sulphide.  The corresponding methanols (X is OH) may be prepared by oxidizing the methanes in an alkaline medium or by alkaline hydrolysis of the oxidized dye, and the corresponding cyanomethanes (X is CN) may be made by treating the oxidized dye with alkali metal cyanide.  Some of the dyes may be made directly from a phenone R1R2N.C6H3(CH3).CO.Q and a N,N-dialkyl-m-toluidine. The leuco compounds may be oxidized to the dyes with lead dioxide, chloranil, sodium dichromate, manganese dioxide or nitrosyl sulphuric acid.  The substituted methanols and cyanomethanes are converted to the dyes by acid hydrolysis.ALSO:The invention comprises a leuco dye of the formula <FORM:1047796/C2/1> where R1 and R2 are alkyl groups containing from 1 to 12 carbon atoms, 2-cyanoethyl, 2-hydroxy-ethyl, 3-hydroxypropyl, alkoxy alkyl groups containing from 2 to 8 carbon atoms, aralkyl or aryl groups; R3 is methyl, ethyl or flourine; X is hydrogen, hydroxy or cyano; and Q is 2-thienyl, 2-furyl, 3,4-methylene-dioxyphenyl, 2 - methoxy - 4 - (C1 to C8)-alkoxyphenyl, 3,4-di-(C1 to C8) alkoxyphenyl or <FORM:1047796/C2/2> where R4 is an alkyl, aralkyl, aryl or substituted aralkyl group containing from 1 to 8 carbon atoms, the substituents of said substituted aralkyl being fluoro, chloro, alkyl or alkoxy substituents and R5 is hydrogen or an alkyl group containing from 1 to 4 carbon atoms, and a leuco dye-salt of the formula <FORM:1047796/C2/3> where M is hydrogen and A an anion, or M is a metal and A is an anion or anions which satisfy the valence of M and which together with M form a Lewis acid, and n is 1 or 2. The leuco compounds in which X is hydrogen may be made by condensation of (a) 2-thiophene - carboxaldehyde, 2 - furaldehyde or a correspondingly substituted benzaldehyde with an N,N-disubstituted-3-methyl (or ethyl or flouro) aniline; (b) an acetal of the aldehydes named in (a) with an N,N-disubstituted-m-toluidine; or (c) a bis-[4-N,N-disubstituted amino-2-ethyl (or fluoro or methyl) phenyl] methanol with a phenyl alkyl (or aryl or aralkyl) sulphide.  The corresponding methanols (X is OH) may be prepared by oxidizing the methanes in an alkaline medium or by alkaline hydrolysis of the oxidized dye, and the corresponding cyanomethanes (X is CN) may be made by treating the oxidized dye with alkali metal cyanide.