244 



SCIENCE PROGRESS 



of the methyl group by the action of chlorosulphonic acid. Both 

 of these observations point to the opening of the — C(CH 3 ) 2 — 

 chain and the production of a terpene-like derivative of cyclo- 

 hexane. It has been suggested : that the first product is a 

 hydroxymenthone (or its chloride or sulphate) formed by the 

 addition to the camphor molecule of a molecule of water (or 

 HC1 or H 2 S0 4 ), and that this may part with the elements of a 

 molecule of water in such a way as — 



(1) To reproduce a molecule of camphor, or 



(2) Give rise to a molecule of dihydrocarvone and so provide 

 an opportunity of sulphonating the methyl group, or 



(3) Give rise to a molecule of eucarvone, the enolic form of 

 which would be optically inactive and so provide a 

 mechanism for racemising the whole of the compounds 

 in equilibrium with it, whilst 



(4) Finally the wandering from the side-chain into the ring 

 of the double bond of the dihydrocarvone or dihydro- 

 eucarvone would lead to the production of carvenone as 

 recorded by Bredt. 



These operations are set out in the following scheme, which 



bears all the evidences of being absolutely correct in its main 



outlines, although some of the details may perhaps be open to 



criticism. 



CMe.OH CMe, 



CHj — CH CHo 



I 

 CMe 2 



I 

 CH 2 — CMe — CO 



Camphor 





CH 2 — CH CH, 



CH— CHMe— CO 



Hydroxymenthone 



CH,=CMe 



CH 2 — CH- 



-CH, 



CH 2 — CMe=C(OH) 



Dihydroeucarvone 

 (inactive enolic form) 



CHMe, 



CH,- 



CH 2 -CH- 



CH 2 



CH,— C 



=CH 



CH 2 — CHMe— CO 



Dihydrocarvone 



-CH — CH 2 HO. SO,. CH 2 . CMe. OH 



CH 2 — CHMe— CO 



Carvenone 



HO.S0 2 .CH,CMe 



CH 2 



Camphor ir-sulphonic acid 



<- 



CHt 



-CH- 



-CH, 



CMe— CO CH, 



-CHMe— CO 



Dihydrocarvone + H2S0 4 



1 Armstrong and Lowry, loc. cit. 



