| abstract |
The invention comprises 6-phenyl benzoxazolyl compounds of the formula where R 1 and R 2 are the same or different and represent hydrogen or halogen or a nitrile, hydroxyl, alkyl, alkoxy, phenoxy, cycloalkyl, hydroxyalkyl, cyanoalkyl, halogenoalkyl, carboxy alkyl, phenylalkyl, phenyl, alkenyl, carboxyl, carbonamide, carboxylic acid ester, sulpho, sulphonic acid ester or sulphonamide group and B 1 represents a residue of one of the formul[mu] any of which residues may be substituted by a non-chromophoric group. Specified non- chromophoric groups include halogen, alkyl, alkoxy, carbalkoxy, sulphonic or carboxylic acid (or salts thereof), phenyl, phenylalkyl, nitrile, sulphonamide, carbonamide or amine salt groups. The compounds may be prepared by reacting an ortho-amino phenol of the formula with a compound R.CO.B 1 where R is an hydroxyl group or halogen, to give the amide which on ring closure yields the required compound. Ring closure may be effected by heating, optionally in the presence of a catalyst, e.g., boric acid, boric anhydride, ZnCl 2 or p-toluene sulphonic acid. The benzoxazolyl compounds are used as optical brighteners (see Divisions C3, C5, Dl. |