— H4 — 



tetrahydrocuminic aldehyde, but 5 to io°/ (calculated as semicar- 

 bazone) of a ketone C 9 H 14 (boiling point 103 to 106 at 15 mm. 

 pressure, 220 to 224 at atmospheric pressure; d 0,9387; n D26° 1,4788), 

 which possessed an odour greatly resembling that of the aldehyde and 

 whose semicarbazone melts at 183 to 1 84 . The unsaturated ketone 

 combines with sodium bisulphite, and in alcoholic-ammoniacal solution 

 with sulphuretted hydrogen into a sulphur compound which melts at 

 121 to 122 . It can be reduced with sodium and alcohol or moist 

 ether to a saturated alcohol, which can be oxidised to a saturated 

 ketone C 9 H 16 O, which again is split up by chromic acid into /?- 

 isopropyl adipic acid. It follows from this that the ketone C 9 H u O 

 formed from /?-phellandrene by oxidation with free oxygen, is A 2 - 

 isopropyl-(i)-hexenone-(4) : 



CH 2 — CH 2 — C = CH 2 CH 2 — CH 2 — CO 



r 1 1 1 



C 3 H 7 — CH— CH CH 2 C 3 H 7 — CH — CH = CH 



/?-phellandrene isopropylhexenone 



CH 2 — CH 2 - CO CH 2 — CH 2 — COOH 



II I 



C 3 H 7 — CH — CH 2 — CH 2 C 3 H 7 — CH — CH 2 — COOH 



isopropylhexanone /S-isopropyladipic acid 



The progress of the oxidation shows that the oxidation of un- 

 saturated compounds by means of free oxygen proceeds in a totally 

 different manner from that with potassium permanganate. Whereas, 

 if the last-named agent is employed, it commences with the addition 

 of hydroxyls, in the "autoxidation" superoxides are first of all formed, 

 with absorption of oxygen. Of both oxidising agents the semicyclic 

 linking is more readily attacked than the purely cyclic one. 



Isopropyl-(i)-hexenone-(4) could (as Wallach surmised) also be 

 obtained from the above-named glycol by oxidation with chromic acid. 



The odour of the ketones produced by Wallach induces him to 

 believe that the position of the oxygen towards the isopropyl -group 

 influences the odour of cyclic ketones in such manner, that the ortho- 

 position brings about the odour of menthone, the meta-position that 

 of carvone, and the para-position a cuminal-like odour. 



The base x ) previously obtained by reduction of nitro-/?-phellandrene 

 of which it was still doubtful whether it was a di- or a tetrahydro- 

 cuminylamine, was now recognised as identical with th^ tetrahydro base 

 which can be produced from tetrahydrocuminaldoxime. 



Semmler's proposal, to designate the terpenes which, like-/?-phel- 

 landrene, contain a semi-cyclic :C H 2 -group, as pseudo terpenes, is 



% ) Liebig's Annalen 340 (1905), 8; Report October 1905,. 97. 



