Poly(oxyalkylene) substituted xanthene colorant and method for making the same

A xanthene colorant comprising a compound having the structure:

• ##STR12## where Y is a poly(oxyalkylene) substituent having a straight or branched polymer chain of from 3 to 200 monomer units selected from ethylene oxide, propylene oxide, butylene oxide and glycidol;
• R.sub.1 and R.sub.2 are independently selected from H, C1-C4 alkyl, C1-C4 alkoxy, Cl, Br and I;
• X is selected from H, SO.sub.3 --, CO.sub.2 -- and COOR.sub.3, where R.sub.3 is C1-C4 alkyl or aryl;
• and
• each Z is independently selected from SO.sub.3 --, CO.sub.2 --, COOR.sub.4, Cl and OH, where R.sub.4 is C1-C4 alkyl or aryl, and n is 0, 1, or 2.

A method of manufacturing a poly(oxyalkylene) substituted xanthene colorant comprising the steps of:

• (a) providing an aqueous solution of a triphenyl methane colorant, having
• (i) a first phenyl group substituted with an amino group in a position para to a central carbon, said amino group further having first and second substituents identified as Y, which are characterized by a straight or branched poly(oxyalkylene) chain of from 3 to 200 monomer units selected from ethylene oxide, propylene oxide, butylene oxide and glycidol;
• said first phenyl group is also substituted with an alkoxy group in a position ortho to said central carbon, wherein said alkoxy group has 1 to 4 carbon atoms, said first phenyl group is optionally methyl or ethyl substituted;
• (ii) said triphenyl methane colorant further having a second phenyl group substituted with an amino group in a position para to said central carbon, said amino group further having first and second substituents selected from H, C1-C20 alkyl, aryl and Y, provided that if one of said substituents is Y, the other cannot be H;
• said second phenyl group is also substituted with an hydroxyl or alkoxy group in a position ortho to said central carbon, wherein said alkoxy group has 1 to 4 carbon atoms, said second phenyl group is optionally methyl or ethyl substituted;
• (iii) said triphenyl methane further having a third phenyl group which is optionally substituted with up to three groups selected from SO.sub.3 --, CO.sub.2 and COOR, where R is C.sub.1-4 alkyl;
• (b) providing a pH of less than 7 is said solution;
• and
• (c) heating said solution to a temperature of 150.degree. C. or greater, causing a ring closure reaction and formation of an ether linkage between said ortho positions on said first and second phenyl groups.