Preparation of a mixture of an alkyl 3-chloroanthranilate and an alkyl 6-chloroanthranilate

A process for the preparation of a mixture of an alkyl 3-chloroanthranilate of the formula ##STR16## and an alkyl 6-chloroanthranilate of the formula ##STR17## where R is alkyl, in a ratio of from 2.9 to 3.1 moles of the one ester to one mole of the other ester, wherein

• (a 1) 3-chlorophthalic anhydride is reacted, optionally in the presence of a catalyst selected from the group consisting of bromine, bromides, iodine, iodides and/or an amide of the formula ##STR18## where R.sup.1 is a sulfonic acid group, a sulfonate radical or a sulfonamide group, R.sup.2 is hydrogen, an aliphatic radical, chlorine or bromine, X is chlorine, bromine or hydrogen, R.sup.1 and R.sup.2 may also, conjointly with the adjacent nitrogen, be members of a heterocyclic radical which contains, adjacent to the nitrogen, one or more sulfone groups or phosphonyl groups of the formula ##STR19## where R.sup.3 is hydrogen or an alkali metal atom, and R.sup.1 and R.sup.2 together may also be ##STR20## where R.sup.4 is alkylene or ##STR21## R.sup.5 is hydrogen, chlorine or bromine and R.sup.6 is an aliphatic radical, with ammonia and an alkali metal hypochlorite in the presence of an alkali metal hydroxide at from 0.degree. to 100.degree. C., and thereafter
• (a 2) the resulting mixture of 8-chloroisatoic anhydride of the formula ##STR22## and 5-chloroisatoic anhydride of the formula ##STR23## is esterified-with an alkanol of the formula
• ROH III
• where R has the above meaning, in the presence of an esterification catalyst, or
• (b 1) 3-chlorophthalic anhydride is reacted with ammonia or formamide and thereafter
• (b 2) the resulting 3-chlorophthalimide is reacted, optionally in the presence of a catalyst selected from the group consisting of bromine, bromides, iodine, iodides and/or an amide of the formula ##STR24## where R.sup.1 is a sulfonic acid group, a sulfonate radical or a sulfonamide group, R.sup.2 is hydrogen, an aliphatic radical, chlorine or bromine, X is chlorine, bromine or hydrogen, R.sup.1 and R.sup.2 may also, conjointly with the adjacent nitrogen, be members of a heterocyclic radical which contains, adjacent to the nitrogen, one or more sulfone groups or phosphonyl groups of the formula ##STR25## where R.sup.3 is hydrogen or an alkali metal atom, and R.sup.1 and R.sup.2 together may also be ##STR26## where R.sup.4 is alkylene or ##STR27## R.sup.5 is hydrogen, chlorine or bromine and R.sup.6 is an aliphatic radical, with an alkali metal hypochlorite in the presence of an alkali metal hydroxide at from 0.degree. to 100.degree. C., after which
• (b 3) the resulting mixture of 8-chloroisatoic anhydride of the formula ##STR28## and 5-chloroisatoic anhydride of the formula ##STR29## is esterified with an alkanol of the formula
• ROH III
• where R has the above meaning, in the presence of an esterification catalyst.