Abstract: A process for preparing a disazo dye represented by the following formula: ##STR1## wherein R.sup.1 and R.sup.2 each represents a hydrogen atom, a halogen atom, a nitro group, a trifluoromethyl group, a lower alkoxycarbonyl group or a lower alkylsulfonyl group, R.sup.3 represents a lower alkyl or allyl group which may optionally have a substituent or substituents, and R.sup.4 represents a lower alkyl or allyl group having a substituent or substituents, which comprises diazotizing an amine represented by the following formula: ##STR2## wherein R.sup.1 and R.sup.2 are the same as defined above, and coupling the diazotized product with a bis(N,N-di-substituted anilino)methane represented by the following formula: ##STR3## wherein R.sup.3 and R.sup.4 are the same as defined above.

Abstract: This invention relates to thiazoleazophenylaminoethyl carbonyloxy-C.sub.8 -C.sub.10 -alkyl compounds useful as dyes for polyester fibers represented by the formula: ##STR1## wherein X represents hydrogen, chlorine, methyl, methoxy or ethoxy; Y represents methyl, acetylamino or propionylamino; and R.sup.1 represents C.sub.8 -C.sub.10 alkyl.

Abstract: A monoazo dye for synthetic fibers, particularly polyester fibers, which can dye the fiber clear blue with excellent fastness to sublimation, fastness to light, resistance for after finish and alkali discharge.

Abstract: Monoazo dyes for dyeing polyester fibers represented by the formula: ##STR1## wherein D represents a substituted or unsubstituted thiazolyl, benzothiazolyl, thiadiazolyl or pyridyl group, X represents a hydrogen atom, a chlorine atom, a methyl group, a methoxy group or an acylamino group, Y represents a hydrogen atom, a chlorine atom, a methyl group, an alkoxy group or an alkoxyalkyl group, R.sup.1 represents a hydrogen atom, a substituted or unsubstituted alkyl, alkenyl or aryl group, and R.sup.2 represents a phenoxymethyl group, a phenoxyethyl group, a benzyl group or a tetrahydrofurfuryl group.Fibers which can be dyed with the azo dyes of the present invention include polyester fibers such as polyethylene terephthalate, a polycondensate between terephthalic acid and 1,4-bis (hydroxymethyl) cyclohexane or the like and blended or mixed fibers of the above-described polyester fibers with natural fibers such as cotton, silk or wool.