— 140 — 



O — CO COOR 



CH 2 



/ 

 CH q — CH 



C CH 



^ / 



C-C(CH 3 ) 2 



CH 2 — CH 2 



By saponification with alkali liquor, the unstable pulegone malonic 

 acid is obtained, and from the latter the beautifully crystallising keto- 

 dilactone of the m. p. 104 , o CO 



CH, 



CH 2 



/ 

 ■CH 



c — o- 



\ 



CH- 



■CO-CH 



/ 

 C(CH 3 ) 2 



CH 2 — CH 2 

 and from this, by the action of alcohol and sulphuric acid, pule- 

 gone malonic acid dialkyl ester. The latter is split up by absolute- 

 alcoholic sodium alcoholate, with dissolution of the carbon-linking, 

 into pulegone and sodium malonic ester, so that the dissolving action 

 of the alcoholate is opposed to its condensing action. Like in all 

 dissociations, the medium plays here also the principal part. In the 

 presence of benzene the addition predominates; in alcoholic solution, 

 the rupture. By splitting off carbon dioxide (at 203 to 204 ) there 

 is obtained from the dilactone of pulegone malonic acid, pulegone 

 acetic anhydride (m. p. 103 ) 1 ). The production of a series of deriv- 

 atives succeeded both with pulegone malonic and with pulegone 

 acetic acids. The keto - dilactone can be very readily obtained 

 in a good yield by treating dry pennyroyal oil with sodium malonic ester. 

 Attempts to produce other characteristic keto-dilactones from ring ketones 

 had negative results with tanacetone, dihydrocarvone, carone, and 

 camphorphorone, but with benzalmenthone it succeeded to some extent. 



Diosphenol. According to Kondakow and Bachtschiew 2 ), 

 the following formulae came up to the present under the consideration 

 for the constitution of diosphenol, if on the one hand C 10 H 18 O 2 , or 

 on the other C 10 H 16 2 is accepted as the gross formula : — 



/ C H 3 , C H 3 j C H 3 



CH< CH( CH( 



/ X CHO / X CHO / X CHO 



CH C CH 



H 9 C 



H 9 C 



CH-OH 



H C 



H 9 C 



COH 



CH 2 

 CH-CH, 



H 9 C 



HC 



/ 



C-OH 



CH 2 



CH.CH, 



x ) A. May and W. Konig, ibidem 345 (1906), iS 

 2 ) Comp. Report April 1901, 91. 



