— 57 — 



Oxidation with permanganate of potassium resulted in establishing 

 the formation of the following bodies: terephthalic acid (m. p. of the 

 methylester 140°), p-tolylmethylketone (m. p. of the semicarbazone 204 to 

 205°, on very gradual heating) and p-acetylbenzoic acid (m. p. of the 

 benzylidene compound 232 to 233°). The authors also oxidised curcumone 

 with hypobromous acid. Besides bromoform and unattacked curcumone 

 the reaction liquid contained an acid volatilisable with steam, which was 

 purified by means of the calcium salt. This body gave the following 

 constants: m. p. 33 to 34°, b. p. 168 to 170° (12 mm.), [«] D20O +31,15° (9,9° 

 solution in alcohol). The acid answered to the formula Ci 2 Hi 6 2 ; it was 

 therefore formed from curcumone Ci8Hi 8 3 by the oxidation of the 

 group • CO • CH 3 into COOH. The authors have given to this acid the name 

 of curcumic acid, and they regard it as not impossible that it may be 

 identical with the turmerinic acid of Jackson and Menke 1 ). 



The residue of the steam distillation of curcumic acid contained a 

 small proportion of an acid which, after being regenerated from its calcium 

 salt, crystallised out in large, lustrous needles, m. p. 150 to 151°, and is 

 probably a hydroxycurcumic acid. When heated with permanganate it 

 yielded terephthalic acid. 



When oxidised with permanganate of potassium, curcumic acid gives 

 rise to p-tolylmethylketone (m. p. of the semicarbazone 204 to 205°), which 

 volatilises with steam. A dicarboxylic acid, Ci 2 H 14 4 , m. p. 226 to 228°, 

 was detected in the residue of the steam distillation. It is not impossible 

 that this acid may be identical with the apoturmerinic acid described by 

 Jackson and Menke. 



The results of oxidation recorded above admit the possibility of one 

 of the three following formula? for curcumic acid, viz., — 



I. H 3 C<(^)>CH(CH3)CH 2 CH 2 G0 2 H 



^-Methyl-^-p-tolyl-n-butyric acid, 



II. H 3 C/~^>CH(CH 3 )CH(CH 3 )C0 2 H 



a ) /?-Dimethyl-/?-p-tolyl-propionic acid , 



III. H 8 C<7)>C(CH 3 )(C 2 H5)C0 2 H 



Methylethyl-p-tolylacetic acid. 



By substituting the carboxyl group in these acids by the group CO-CHs.., 

 the corresponding formulae for curcumone are arrived at. 



The synthesis of /-methyl-/-p-tolylbutyric acid showed that this body 

 was altogether different from curcumic acid-). When oxidised with per- 

 manganate of potassium it yielded the lactone of p-tolylmethyH'-hydroxy- 

 butyric acid, which is not obtainable from curcumic acid. 



2 ) Proceedings of the American Academy of Arts and Sciences 1883, 215. 

 2 ) Berl. Berichte 44 (1911), 584. 



