Some terpenoids with single carbon–carbon double bonds such
as menthomenthene and carvomenthene were also detected.
These products also were found in the esterification of the biooil,
as shown in Fig. S2 in Supporting information. These compounds
could have been produced by the aromatization of a-terpinene
and the hydrogenation of a-terpinene (Scheme S1).
According to the results shown in Fig. 3, the production of a-terpineol
and terpinolene reached a maximum at 170 C.