GB835892A - Manufacture of diaryloxazole derivatives - Google Patents

Abstract

The invention comprises a process for making diaryloxazoles of formula <FORM:0835892/IV (b)/1> in which R1 and R2 are aryl residues and R3\t is an organic bridge member with at least one double bond between two carbon atoms, and also the new compounds of the above formula in which R1 and R2 contain at least one alkyl group having up to 4 carbon atoms and in at least one of the residues R1 and R2 the alkyl group or groups contain a total of at least 2 carbon atoms. The diaryl oxazoles are made by heating a compound of formula <FORM:0835892/IV (b)/2> with an agent that splits off water, e.g. sulphur trioxide or zinc chloride, to a temperature in the range 140-180 DEG C. When sulphur trioxide is used sulphonation also takes place. The starting materials are obtained by condensing dihalides of unsaturated dicarboxylic acids, e.g. thiophene-2,5-dicarboxylic acid, with primary aryl amines having an hydroxyl group in the ortho position to the amino group, in accordance with the process described and claimed in Specification 835,891. Examples are given of the preparation of the compounds of formul <FORM:0835892/IV (b)/3> a ,b - di - [5 - methylbenzoxazolyl - (2)] - ethylene disulphonic acid and its sodium salt, a ,b -di-[benzoxazolyl-(2)]-ethylene disulphonic acid, and <FORM:0835892/IV (b)/4> The products are optical brightening agents (see Group IV (c)), and may be used in the treatment of paper and cardboard (see Group VIII) and acetyl cellulose films (see Group IV (a)).ALSO:Diaryloxazoles of formula <FORM:0835892/IV(c)/1> in which R1 and R2 are aryl residues and R3 an organic bridge member with at least one double bond between 2 carbon atoms are made by heating a compound of formula <FORM:0835892/IV(c)/2> with an agent that splits off water, e.g. sulphur trioxide or zinc chloride, to a temperature in the range 140-180 DEG C. When sulphur trioxide is used sulphonation also takes place. Compounds in which R1 and R2 contain at least one alkyl group having up to 4 carbon atoms, the alkyl group or groups containing at least 2 carbon atoms, are claimed per se. The products are brightening agents. Examples are given of the preparation of <FORM:0835892/IV(c)/3> a .b - di - [5 - methylbenzoxazolyl - (2)] - ethylene disulphonic acid and its sodium salt, a .b -di-[benzoxazolyl-(2)]-ethylene disulphonic acid and <FORM:0835892/IV(c)/4>ALSO:Compounds of the formula <FORM:0835892/IV (a)/1> in which R1 and R2 are aryl residues and R3\t an organic bridge member with at least one double bond between 2 carbon atoms, are used for the optical brightening of nitro cellulose lacquers and acetyl cellulose films. In an example 0.25 part of a -b -di-[5-methylbenzoxazolyl - (2)] - ethylene is added to 100 parts of an acetyl cellulose mass containing 24% of acetyl cellulose. The film produced from this mass has a brighter appearance than one containing no oxazole compound.