Notes on scientific research. 135 



camphene formula (I). W. N. Haworth and A. T. King 1 ) have now tried to ascertain 

 the constitution of camphene chemically, by the synthesis of camphenic acid and its 

 products of resolution. Aschan' 2 ) some time ago obtained dehydrocamphenic acid by 

 treating monobromocamphenic acid with alkali. With nitric acid this dehydrocamphenic 

 acid can be oxidised into a lactone, which Aschan regards as the lactone of ","-dimethyl- 

 ,c?-hydroxy-adipic-/?-carboxylic acid. Haworth and King have endeavoured to synthethise 

 this lactone. They started from ethyl «-ketoglutarate (II), which they condensed with ethyl 

 «-bromoisobutyrate (III), whereby ethyl /^-hydroxy-^^-dimethylbutane-^/^fV-tricarboxylate 

 (IV) was generated. 



CH>COC0 2 C 2 H 5 



| + C(CH 3 ) 2 Br-C0 2 C,H 5 — ► 



CH 2 C0 2 C 2 H 5 



in. 

 C0 2 C 2 H 5 



CH 2 • C (OH) C (CH 8 ) 8 • CO* C 2 H, 

 i 



CH 2 C0 2 C 2 H 5 

 i. IV. 



This ester they hydrolysed with 15 p. c. hydrochloric acid. The free lactonic acid, C 9 H 12 0«, 

 melts at 159°; when heated to about 165° it is converted into its anhydride, m. p. 104°. 

 It is not identical with the lactonic acid m. p. 256° which was obtained by Aschan as 

 the degradation product of camphenic acid; hence the formula assigned to his acid 

 by Aschan is untenable. 



On the reduction of camphene, see p. 134. 



Pinene. It will be remembered that some time ago G. G. Henderson and 

 M. M. ). Sutherland 3 ) oxidised camphene with hydrogen peroxide. They have recently 

 also treated pinene with this oxidising agent 4 ) and have obtained as reaction-products 

 compounds which can be no longer derived from the pinene-ring. The pinene was 

 separated from American turpentine oil by repeated fractional steam distillation (b. p. 155 

 to 156° 5 ) and was oxidised in a solution of glacial acetic acid with 30 p. c. aqueous 

 solution of hydrogen peroxide at 40 to 60°. From the neutral reaction-products the 

 authors obtained with bisulphite an aldehyde d Hi 6 O (semicarbazone, m. p. 190 to 191°), 

 which proved to be exactly similar to the body of the same structure 6 ) obtained from 

 pinene by oxidation with chromyl chloride. After removal of the aldehyde the authors 

 isolated from the reaction-mass free a-terpineol (m. p. 35°; phenylurethane, m. p. 113°) 

 and terpinyl acetate, as well as bornyl acetate (b'orneol, m. p. 203°), dipentene (tetra- 

 bromide, m. p. 125°), and a body CioH 20 3 , m. p. 95 to 96°, which was not volatilisable 

 with steam, and which is most probably menthane-1, 4, 8-triol (trihydroxyterpane). 

 Trihydroxyterpane was already known as an oxidation product of J 4(8) -menthenol-l 

 (/-terpineol) 7 ), but so far it does not appear to have been observed as a derivative of 

 pinene. 



Pio glycol or ketone, such as is afforded by camphene upon oxidation with hydrogen 

 peroxide was yielded by pinene. 



x ) Journ. Chem. Soc. 101 (1912), 1975. — 2 ) Liebigs Annalen 375 (1910), 336; Report April 1911, 1SS. — 

 3 ) Comp. Journ. chem. Soc. 99 (1911), 1539; Report October 1911, 134. — 4 ) Journ. chem. Soc. 101 (1912), 22SS. — 

 5 ) Judging from the b. p. this body should be a-pinene. — 6 ) Comp. Report October 1903, S5. — ') Baeyer 

 and Blau, Berl. Berichte 28 (1895), 2296. 



