Method for preparing an insect repellent agent

Abstract

The present invention relates to a method for preparing p-menthane-3,8-diol, characterised in that it comprises the following steps: a. preparation of an aqueous solution comprising between 0.05% and 5% by mass, preferably between 0.05% and 2% by mass, preferentially between 0.05% and 1% by mass, even more preferentially between 0.05% and 0.5% by mass of an ammonium salt, the said ammonium salt being characterised in that it is selected from the group formed by an amino acid ammonium salt, and in particular an amino acid hydrochloride, a vitamin B ammonium salt, and in particular a vitamin B hydrochloride, an ammonium salt of an amino acid ester, and an ammonium salt of a vitamin B ester, or is defined by the following formula (I): wherein Rrepresents a benzyl, optionally substituted, or Rrepresents an alkyl, either linear or branched, optionally cyclical, saturated or unsaturated, optionally substituted, comprising from 1 to 10 carbon atoms, preferably from 1 to 6 carbon atoms, preferentially from 2 to 4 carbon atoms, and R, Rand Rrepresent a hydrogen or a methyl group, and X represents a chlorine atom, bromine atom or an OR' group, R′ being an alkyl group comprising from 1 to 10 carbon atoms, b. adding of citronellal to the aqueous solution obtained in the step a), and obtaining a mixture; c. stirring and heating of the mixture obtained in the step b); d. decanting of the reaction medium obtained at the end of step c) and obtaining at least two phases; and e. separation of the said at least two phases obtained in the step d), and obtaining at least one aqueous phase and at least one organic phase, the said organic phase comprising at least p-menthane-3,8-diol.