Abstract: An industrially advantageous process for producing 5,7-dichloro-4-hydroxyquinoline (DCHQ) useful as an intermediate for agrohorticultural bactericides. The process comprises (i) hydrolyzing 3-cyano- or 3-ethoxycarbonyl-5,7-dichloro-4-hydroxyquinoline into 5,7-dichloro-3-carboxy-4-hydroxyquinoline (DCQA) in the presence of hydrochloric, sulfuric or phosphoric acid and (ii) decarboxylating the formed DCQA into DCHQ in the presence of sulfuric or phosphoric acid. In particular, this process comprises continuously conducting the hydrolysis of 5,7-dichloro-3-ethoxycarbonyl-4-hydroxyquinoline and the decarboxylation of the hydrolyzate in the presence of sulfuric acid having a specified concentration. The invention also relates to a process for producing DCQA by hydrolyzing 3-cyano- or 3-ethoxycarbonyl-5,7-dichloro-4-hydroxyquinoline in the presence of hydrochloric, sulfuric or phosphoric acid and a process for producing DCHQ by decarboxylating DCQA in the presence of sulfuric or phosphoric acid.

Abstract: A method for halogenating an aromatic compound, which comprises reacting the aromatic compound of the formula (I): ##STR1## wherein X is a hydroxyl group, an amino group or an acylamino group, each of Z.sub.1 and Z.sub.2 is a hydrogen atom or a halogen atom, one of R and Y is a hydrogen atom and the other is a nitro group, a cyano group or a trifluoromethyl group, and Q is a nitrogen atom or --C(T).dbd. (wherein T is a hydrogen atom, a halogen atom, a nitro group, a cyano group or a trifluoromethyl group), with a halogenating agent to obtain a 3-halogenoaromatic compound of the formula (II): ##STR2## wherein one of R' and Y' is a halogen atom and the other is a nitro group, a cyano group or a trifluoromethyl group, and X, Z.sub.1, Z.sub.2 and Q are as defined above.

Abstract: A process for producing 3,5-difluoroaniline, which comprises reacting a benzonitrile compound of the formula (I): ##STR1## wherein each of X.sub.1, X.sub.2 and X.sub.3 is hydrogen, chlorine, bromine or a cyano group, provided that at least one of X.sub.1 to X.sub.3 is a cyano group, with a mineral acid for hydrolysis and decarboxylation to obtain an aniline compound of the formula (II): ##STR2## wherein each of X.sub.4, X.sub.5 and X.sub.6 is hydrogen, chlorine or bromine, provided that at least one of X.sub.4 to X.sub.6 is hydrogen, and in the case of a compound of the formula (II) wherein X.sub.4, X.sub.5 and X.sub.6 are not simultaneously hydrogen, reacting such a compound with hydrogen in a presence of a catalyst for reduction to obtain 3,5 -difluoroaniline.