— 115 — 
Thujone, tanacetone. Up to the present, the following formulae 
have been proposed for tanacetone: 
CH. 
CH. 
CH 
CH 
CH 
CO 
CH„ 
CHg CH. 
Semmler 
CH3 CH, 
Fromm 
C Hg C Hg 
Kondakow. 
In a recent work, Semmler^) objects to the constitutional formulae 
drawn up by Fromm and Kondakow. Against the latter it is only 
mentioned for the present that through it tanacetone is drawn into 
closer relation to carone, which would render various conversions diffi- 
cult to explain. Between Semmler's and Fro mm 's formulae, the 
presence or absence of a methylene-group in addition to the carbonyl- 
group, can be decisive. As Semmler now, by condensation of tana- 
cetone with benzaldehyde, could produce a benzylidene tanacetone, 
(boiling point 178° at 9 mm; dgQO = 1,0298; Uj^go^ = i?5728), this 
proves in favour of his formula that a methylene-group is contiguous 
to the carbonyl-group. The degradation-products show that no con- 
version has taken place during the condensation. Benzylidene tana- 
cetone can be split up by oxidation with potassium permanganate, 
into homotanacetone dicarbonic acid and benzoic acid: 
CH, CH 
CH — CHg + CgH^COOH. 
CH. 
CH — C. 
CH. 
COOH COOH 
This acid yields an anhydride, exactly like tanacetone dicarbonic 
acid; it has no double-linking, and is not attacked by potassium per- 
manganate in the cold. The acid ^QH^gO^, obtained by Wallach 
by oxidation of tanacetone with alkaline bromine solution, is possibly 
identic with homotanacetone dicarbonic acid. Of the derivatives of 
benzylidene tanacetone which are also described, the product obtained 
by the action of hydro xylamine (melting point 138° to 140^) is 
interesting in so far as it is no oxime, but an addition-product. 
L) Berliner Berichte 36 (1903), 4367. 
8* 
