A process is provided for preparing a substituted 2,3-dihydrobenzofuran of the general formula ##STR1## in which R.sub.a is hydrogen, halogen, alkyl, straight or branched having from 1 to 4 carbon atoms, aryl, alkaryl, --OH, --OR.sub.3, --N(R.sub.d).sub.2, where R.sub.3 and R.sub.d are alkyl, straight or branched having from 1 to 4 carbon atoms; R.sub.b is alkyl, straight or branched, having from 1 to 6 carbon atoms, aryl, alkaryl; and R.sub.c is hydrogen or the same as R.sub.b, by the rearrangement of a 1,1-bis(2-hydroxybenzene) alkyl and/or aryl-ethane, in the presence of catalytic amounts of a mineral acid or organic acid such as phosphoric, sulfuric or p-toluenesulfonic, at elevated temperatures from 180.degree. to 250.degree. C., and withdrawing the resulting products from the reaction mixture as they are formed. The starting 1,1-bis(2-hydroxybenzene) alkyl and/or aryl-ethane compounds may be obtained by the catalyzed reaction of a substituted biphenol with an aldehyde. The substituted 2,3-dihydrobenzofurans are useful in the manufacture of pesticides.
