ree for cater et dihpdiggcitroneliol cote Or Be observed in this reduction, iy 
4 eit was likewise impossible to reduce phytochemically the double bond -CH:CH- 
previous experiments with allyl alcohol and cinnamic acid. The yield of cicotel 
amounted in the best case to 59.4 per cent. of the theoretically possible quantity. This 
a transformation of citronellal into citronellol by means of a vegetable organism is, the 
authors think, interesting not only for plant physiologists but likewise for the chemistry 
> “of aromatics. They take it that phytochemical reductions contribute in part to the 
development of the “bouquet”. 
a 
a 
x 
= 
-A good many years ago, F. D. Dodge’), when treating citronellal in moist ethereal 
solution with phosphorus pentoxide, obtained a compound which he called citronellal 
phosphoric acid. On discussing this body in his book “Die dtherischen Ole” (vol.-I, 
page 614, Leipzig 1906) F. W. Semmler expresses the opinion that the citronellal 
phosphoric acid really is an isopulegol derivative, for the reactions of the aldehyde 
; sroup have disappeared. Dodge2), in the meantime, has come to the same conclusion, — | 
for in a recently appeared publication he proposes for the citronellal phosphoric acid - 
» the name of isopulegol phosphonic acid. It is a strong monobasic acid and affords a 
series of well defined salts which, generally speaking, crystallize easily. It is sparingly 
soluble in water, but easily in alcohol and chloroform; m. p. 181 to 182°. At a com- 
paratively low temperature, the sodium salt decomposes, forming isopulegol, which was 
characterized by oxidation to isopulegone; semicarbazone, m.p. about 171°. The acid 
is not saponifiable with either hot alcoholic potash lye or hot dilute suphuric acid, 
_which indicates that the PO; group is combined directly with a carbon atom. 
Normal phosphonic acids are dibasic, whereas the isopulegol phosphonic acid is 
monobasic. It was impossible to obtain a di-potassium salt. The ready formation of — 
isopulegol on dry distillation points to the presence of a secondary hydroxyl group in the — 
acid; on the other hand, the acid cannot be acetylated or oxidized with either chromic acid 
or dilute potassium permanganate solution, so that the presence of a hydroxyl group 
(except a tertiary one) seems to be excluded. There cannot be any carbonyl group either 
in the molecule, for the acid neither forms an oxime nor a phenylhydrazone. Although 
isopulegol shows the behaviour of an unsaturated secondary alcohol, the zsopulegol phos- 
phonic acid appears as a saturated compound. The solution of its sodium salt does not 
discolour bromine water. The position of the phosphonic group is not yet known. 
As may be seen, the structure of the isopulegol phosphonic acid is still rather 
uncertain, and we think it questionable whether we have really to deal with an ‘so- 
— __pulegol derivative at all. 
In any case, the isopulegol phosphonic acid is a characteristic derivative of citronellal 
and may possibly be used as a proof of its presence. Dodge tried to prove the presence 
of citronellal as isopulegol phosphonic acid in normal and terpeneless lemon oils, but 
without result, from which he deduces that the content of citronellal in lemon oil is 
but inconsiderable. jaa 
The transformation of anisaldehyde into anisic acid with the aid of persulphate | 
has been discussed on page 79 of this Report. 
‘ 
i yaa : : Sader hanes 
a 0-Vamillin. E. Rupp and K. Linck*) prepared a series of derivatives of o-vanillin, 
4 which had oy. been described already some years ago by Noelting*). However, the 
1) Americ. chem. Journ. 12 (1890), 553. — ) Journ. Americ. chem. Soc. 87 (1915), 2756. — %) Arch. der 
: Pharm. 25% (1915), 33. — *) Chem. Zentralbl. 1910, J. 1880; Report October 1910, 195. 
