990 
unsaturated acid’) is interesting because it again shows the slight 
difference in energy between S-ring and double bond, a fact also 
already noticed by others”) The difference in tension in the 3-rings 
and 2-rings is not so considerable by a long way as demanded by 
the ring-tension theory of von Baryer. That this theory does not 
hold good has been demonstrated by me previously by means of 
quantitative measurements. *) 
Properties of glutaconic acid. 
The properties of this acid have already been frequently described; 
attention may be called to a few facts only. 
a. The melting point, after keeping the acid for months over 
phosphorus pentoxide in vacuum is still quite unchanged. Hence, 
there is no question of anhydride formation in these circumstances. 
4. On evaporating an aqueous solution of the acid we obtain 
beside a little g-oxyglutarie acid a brown sticky mass, from which 
is extracted by ether a very impure brown-coloured glutaconie acid. 
The acid, therefore, appears to partly resinify. 
ce. With ferric chloride no discoloration takes place in aleoholie 
solution, but in aqueous solution a brownish-red coloration occurs. 
Contrary to Coyrap and Gurnzeir’s statement’) this solution remains 
unchanged on boiling and no ferrie bydroxide is deposited. 
Attempt to find a new synthesis of glutaconie acid. 
By Trorpe and RoGerson’) g-alkyl derivatives of glutaconie acid 
have been prepared by condensation of Na-cyanacetic ester with 
acetylacetic ester or alkyl! derivatives thereof, for instance 
1 { Me 
ni ue 
CHNa + CH — EtOOC.CNa(CN)—CMe=:CH—COO Et 
| | 
COOKt COOEt (Ethyl « cyano p methylglutaconate). 
On saponification with strong hydrochloric acid these esters yielded 
the desired acid in varying quantity often beside pyridine derivatives. 
1) The unsaturated condition of glutaconic acid is also shown by the conversion 
into dibromo-acid dioxyglutanie acid, with bromine and potassium permanganate, 
respectively. 
2) BGESEKEN: Overzicht der koolwaterstoffen I, p. 209 and 266. 
5) Handelingen XVe Ned. Natuur- en Geneesk. Kongres, p. 234. 
4) Ann. 222, 254 (1883). 
5) Soc. 87, 1685 (1905). 
