Notes on scientific research. 



153 



watery solution in order to decompose the remaining campholenic acid; under these 

 circumstances by far the greater part boils from 140 to 142° (12 mm.). However, it 

 was impossible to obtain the acid in quite a pure state according to this method. 

 Accordingly, the author converted the reduced acid by heating its ammonium salt for 

 5 hours at 220 to 230° into the amide of the «-dihydrocampholenic acid (melting point 



H 2 C 



H 2 C 



CH 



HaCCCH 



CH, 



CH 



H 2 C -"" CH2 



•> H3CCCH3 



C:NOH HC 



CN 



C-CH 3 



(I) Campheroxime. 



H 2 C 

 H 2 C 



CCH 3 



(II) Campholenic nitrile. 



H 2 C 



CH 



CCH 3 



C0 2 H 



H 2 C 



H 3 C-CCH 3 



CH 2 



C0 2 H 



C(CH 3 ) 2 



(IV) /S-campholenic acid. 



CH-CH 3 



(V) cc-dihydrocampholenic acid. 



150.5°) which, on being treated with alcoholic caustic potash, turned into the a-dihydro- 

 campholenic acid, boiling from 143 to 144° (12 mm.). Its ethylester forms a pleasant 

 smelling liquid, having the specific gravity 0.9276 (^), the anilide melts at 128 to 129°. 

 These data do not tally with those of Mahla and Tiemann 1 ) for dihydrocampholenic 

 acid and its derivatives. Van Kregten obtained ^-dihydrocampholenic acid {rac.-fi- 

 campholanic acid) (VI), boiling from 136 to 137° at 10 mm., by reducing /^-campholenic 

 acid. It was purified by transforming it into its amide (melting point 157°) and by 

 saponifying the latter in the same manner as described above for a-dihydrocampholenic 

 acid. Jso-/?-J'-campholenic acid (VII) was prepared by treating /^-dihydrocampholenic 

 acid with phosphorus pentachloride till the generation of muriatic acid stopped, and 



H 2 C 



H 2 C 



CH 



HCCH 3 



CH 2 



C0 2 H 



H 2 C 



HC-CH 3 



C0 2 H 



H 2 C 



H 2 C 



CO 



HCCHs 



C(CH 3 ) 2 



(VI) /^-dihydrocampholenic acid 

 (rac. /2-campholanic acid). 



C(CH 3 ) 2 



(VII) Iso-fi-A '-campholenic acid. 



C(CH 3 ) 2 



(VIII) 1, 1, 2-Trimethyl- 

 cyclopentanone-3. 



hereupon by heating the reaction product for 2 hours on the water bath. Hereupon 

 bromine was added and the mass then poured at a low temperature into alcohol, 

 whereby the ethylester of the a-bromo-/?-dihydrocampholenic acid was formed. By 

 heating the latter with quinoline at 200°, the ethylester of the fi-A '-campholenic acid 

 was formed which on saponification gave /?-J'-campholenic acid which melts at 



') Berl. Berichte 33 (1900), 1929. 



