Abstract: An azo compound of the formula:A--N.dbd.N--B--N.dbd.N--Dwherein:A is (i) a phenyl group containing at least two unsaturated electron-withdrawing groups in ortho or para positions with respect to the azo link, (ii) an aromatic heterocycle, or (iii) the residue of an aromatic coupling component having a group displaceable by a diazotized aromatic amine;B is an substituted or unsubstituted thien-2,5-ylene or thiazol-2,5-ylene group; andD is the residue of an aromatic coupling component having a group displaceable by a diazotized aromatic amine.The azo compound has a significant absorption band extending into the near infra-red region of the spectrum and has utility in applications, such as solar screening, electronic, optical character recognition, printing, reprographic and security systems, where enhanced infra-red absorption is necessary or desirable.

Abstract: Novel reactive dyes particularly suitable for the dyeing and printing of cellulose-containing fiber materials which give, in combination with a high color yield, dyeings and prints having good fastness properties, said dyes having the formula ##STR1## in which D is the radical of a diazo component, Q is a substituted or unsubstituted phenyl or naphthyl radical or a substituted or unsubstituted aromatic heterocyclic radical and A.sub.1 and A.sub.2 independently of one another are a radical of the formula ##STR2## in which R.sub.1 and R.sub.2 independently of one another are hydrogen, substituted or unsubstituted C.sub.1 -C.sub.6 alkyl or substituted or unsubstituted aryl, or R.sub.1 and R.sub.2 together with the N atom form a further substituted or unsubstituted heterocyclic 5- or 6-ring, with the proviso that at least one of the radicals A.sub.1, A.sub.2 and D has a fiber-reactive group.