NOTES ON SCIENTIFIC RESEARCH. BA 
densation-product remained in the shape of dark-yellow needles. In a pure state it 
melts between 137 and 138°. The compound has the empirical formula CsgH26Qz. 
With piperonal (heliotropin), sodium laevulate forms a condensation-product, CogH220x, 
melting at 187°, with cinnamaldehyde another of the formula C.;H»,O;, melting at 106°. 
In a paper by J. Kendall and W. A. Gibbons‘) on the addition compounds of aldehydes 
and ketones with organic acids, which lies generally speaking in the physico-chemical 
domain, the following solid derivatives are described; benzaldehyde-trichloroacetic acid, 
C,HgO, CCl;CO2.H (m. p. 8,4°), anisaldehyde-trichloroacetic acid, CsHsQO2, CCl;CO.H 
(m. p. 30,99), vanillin-trichloroacetic acid, CsHsO3, 2CCl;CO.2H (m. p. 14,3°) and piperonal 
(heliotropin)-trichloroacetic acid CsHsO;, 2CCl;CO.H (m. p. 37,49), CsH.O3s, CCl;CO.H 
(m. p. 35°). 
Citronellal. Following up the investigations of Ciamician and Silber, repeatedly 
discussed in our Reports, regarding the exposure of terpenes to the light, E. Sernagiotto ”) 
examined citronellal as to its behaviour in direct sunlight and in the presence of 
oxygen. It yielded under these circumstances acetic acid, 6-methylhexoic acid, menthone 
(semicarbazone, m. p. 184 to 185°), a ketone apparently unknown so far, CioHisO (Semi- 
carbazone, m. p. 206 to 207°), isopulegol (identified by its oxidization to zsopulegone), 
acetone, @-methyladipic acid (m. p. 84°), and dihydroxycitronellic acid, an oil which 
cannot be crystallized. As may be seen, citronellal, on autoxidation in the light, 
yields on the one hand isomerization products, which also result by the action of acids 
or acetic anhydride, such as isopulegol, and oxidation products of the bodies formed 
through isomerization, such as menthone, which is likewise obtained on oxidizing with 
chromic acid. On the other hand, true oxidation products result, e. g. dihydroxy- 
citronellic acid, obtainable also by oxidation with potassium permanganate, and 
3-methyladipic acid, which also results by oxidation with chromic acid mixture. 
As to the composition of commercial citronellal, see page 74 of this Report. 
Benzaldehyde. When O. Doebner described at the time his well known reaction’), 
he ascribed the structure expressed by formula I to the phenylnaphthacinchonic acid, 
which forms for instance by the action of benzaldehyde and j-naphthylamine on 
eee Loves gu in 
ee coe 
oat ROK EIS 
Be \ Cats Nee aes 
(1) Phenylnaphtha- (Il) a-Phenyl-@-naphtha- 
cinchonic acid. quinoline. UID) Dipheuyipyeraine: 
dicarboxylic acid. 
peruvic acid. The proof of the correctness of this opinion has now been given by 
R. Ciusa and G. Buogo’), who oxidized the «-phenyl-?-naphthaquinoline (II), formed 
from cinchonic acid, with potassium permanganate dissolved in acetone to diphenyl- 
pyridinedicarboxylic acid (Ill). | 
*) Journ. Americ. Chem. Soc. 87 (1915), 149. — %) Atti R. Accad. dei Lincei, Roma (5) 24 (1915), 850; 
Chem. Zentralbl. 1916, Il. 468. — *) Berl. Berichte 27 (1894), 352; Report April 1894, 27. — +) Atti R. Accad. 
dei Lincet, Roma (5), 28, Il. (1914), 262, 265; Chem. Zentralbl. 1916, 1. 746, 747. 
6 
