Processes for preparing ortho-substituted benzoic acids

A process for preparing ortho-substituted benzoic acids of formula (I):

• ##STR3## wherein:
• R.sup.1 is a group which may be introduced by electrophilic substitution of an aromatic lithio derivative;
• R.sup.2 is a fluorine, chlorine or bromine atom;
• R.sup.3 is a fluorine, chlorine, bromine or hydrogen atom or a group selected from R.sup.6, --OR.sup.6 and --SR.sup.6,
• R.sup.4 and R.sup.5 are independently hydrogen, fluorine, chlorine, bromine, or a straight- or branched-chain alkyl group having from one to six carbon atoms optionally substituted by one or more fluorine atoms;
• R.sup.6 is a straight- or branched-chain alkyl group having from one to six carbon atoms optionally substituted by one or more halogen atoms;
• with the proviso that when R.sup.4 is fluorine, chlorine or bromine and R.sup.5 is hydrogen, R.sup.2 and R.sup.4 represent the same group;
• which comprises the reaction of a compound of formula (II):
• ##STR4## wherein R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are as defined above, with a lithiating reagent, followed by the reaction of the ortho-lithiated compound thus obtained with an electrophilic reagent to introduce the group R.sup.1.