988 
For preparing large quantities of glutaconie acid this methed is 
certainly the one to be most recommended ; it is cheap and gives 
relatively high yields. 
D. 10 grams of cumalinie acid were boiled with 60 grams of 
barium hydroxide in a reflux apparatus until the bright red liquid 
was nearly colourless, which took + 15 hours. After removing the 
barium carbonate precipitate, the filtrate was shaken with ether, the 
barium was precipitated with sulphuric acid and after filtration the 
liquid was extracted continuously with ether. 
I so obtained 1.7 gram of glutaconic acid, melting after the usual 
recrystallisation at 135°—137°. The yield amounted to 18°/, of the 
theory thus corresponding with von PecHMann’s statement. 
i. The linking of diazoacetic ethyl ester to acrylic methyl ester 
was carried out as follows. 
An equimolecular mixture of both esters was heated in a reflux 
apparatus for 2 days at + 50°. The reaction then takes place without 
any sensible generation of heat or elimination of nitrogen. 
The (generally thick-fluid) reaction product was heated in the same 
flask at + 180° and kept at this temperature until no more nitrogen 
was evolved. The residual oil was then distilled and the fraction 
107—117° at 10 m.m. was collected. The yield of the mixture of 
olutaconic acid and trimethylenedicarboxylic ester as 66°/, of the 
theoretical amount. 
The ester mixture was now boiled with 10°/, aqueous potassium 
hydroxide, slightly in excess of the theoretical quantity, until all has 
just dissolved ; the whole was acidified with sulphuric acid and con- 
tinuously extracted with ether. 
Owing to the extraordinary resemblance in properties between 
elutaconie and ¢ranstrimethylenedicarboxylic acid (in all solvents 
these acids are both more or less soluble to the same extent whilst 
the salts also do not exhibit serious differences) the separation is 
very troublesome; it further appeared that in addition to these acids 
another czs-trimethylenedicarboxylic acid was present (although in 
smaller quantities) which might have been expected theoretically. By 
fractional crystallisation from water, from ether (with or without 
addition of benzene) and from ethyl acetate, I finally sueceeded in 
obtaining the three acids in a pure condition. 
a. Transtrimethylene 1.2 dicarboaylic acid is, of the three acids, 
the one most soluble in ether and least soluble in ethyl acetate. It 
possessed all the properties communicated for this acid by BucHNer 
(loc. cit.). M.p. 175°. 
b. Glutaconic acid melts after repeated recrystallisations from ether- 
