— 139 

 CH 2 



ch/\co 



CH - 



-CH- CO • COOC 2 H 5 



results from condensation of pentanone and ethyl oxalate with sodium 

 and absolute alcohol; the ester boils at 14 mm. pressure at 138 to 

 139 . The corresponding isothujone oxalic ester (dimethyl- 1,5 -isopropyl- 

 4-cyclopentene-5 -one- 2 -oxalic acid ester-3) 



CCE 



H Q CC 



C,H 7 .HC 



CO 



CH- CO.COOCH, 



boils at 182 to 184 (11 mm. pressure); its semicarbazone melts at 

 168 to 169 . Thujone oxalic acid ester (methyl-2-isopropyl-5-bicylo- 

 [o, 1,3 -Jhexanone- 3 -oxalic ester- 4) boils at 168 to 170 (11 mm. 

 pressure), and yields a semicarbazone melting at 156 to 1 57°. The 

 crystals (m. p. 253,5°) separating off when the ester was boiled with 

 aniline in alcohol, were identified as oxanilide. Attempts to effect a 

 separation of carbonic oxide from cyclop entane - 2 - oxalic acid ethyl 

 ester- 1, and also from thujone oxalic ester, did not succeed, and a 

 conversion of the latter into thujone oxalic acid also failed. The 

 pentacyclic oxalic esters described behave for the rest like the derivat- 

 ives of cylohexanone, i. e., they are split up by soda liquor into the ketone 

 and oxalic acid. On the other hand, the former are, contrary to the 

 latter, are very stable when heated in vacuo , (slight inclination to split off 

 carbonic oxide), but when heated under ordinary or increased pressure, 

 they are split up into carbonic oxide, carbon dioxide, alcohol, and 

 the corresponding ketones, instead of passing over (like the hexacyclic 

 compounds) into the /? - keto - carboxylic esters. This difference in 

 the behaviour of cyclic ketone - oxalic esters, when heat is applied, 

 enables us to ascertain whether a CH 2 - group, adjacent to the CO- 

 group, is situated in a cyclopentane or in a cyclohexane ring. 



Pulegone. In connection with previous researches for the know- 

 ledge of addition -processes 1 ), D. Vorlander 2 ) and his collaborators 

 have also made experiments with pulegone. The action of sodium 

 malonic ester on pulegone 3 ) takes place as follows: In the presence 

 of benzene or ether, the anhydride of an alkyl ester acid of pulegone 

 malonic acid is formed, probably as follows: 



*) Liebig's Annalen 341 (1905), 1. 



2 ) Ibidem 345 (1906), 155. 



3 ) D. Vorlander and Fr. Kothner, ibidem 345 (1906), 158. 



