The Reaction of Camphene and o-Cresol

Abstract

The reaction of camphene with o-cresol was carried out under various temperatures in the presence of such catalysts as boron trifluoride etherate, activated earth, aluminium chloride and cation exchange resin.
The gas chromatogram of the crude reaction product showed formation of six products and their contents varied over a wide range with the change in the catalysts and the reaction temperature.
When boron trifluoride etherate was used as a catalyst, the ratio of ortho-substituted products (CO-1, CO-3, CO-4) to para-substituted products (CO-2, CO-5, CO-6) in the adducts was 3.O4: 1.
In the case of activated earth, aluminium chloride or cation exchange resin, the ratio of the ortho to para was O.35: 1, O.51: 1, O.61: 1, respectively. The reaction at elevated temperatures gave the products which contained more para isomer in all case.
The adducts (C0-3, CO-4, CO-5, CO-6) were identified on the basis of their spectral data (NMR, 'IR, Mass) as 6-isoborny1-2-methylphenol, 6- (6'-exo-isocamphyl)-2-methylphenol, 4- camphenyly1-2-methylphenol, 4- (6'-exo-isocamphyl)-2-methylphenol respectively.
A mechanism to account for the observed results is presented.