44 THE SIMPLER NATURAL BASES 



hydrogen atoms is not due to unsaturation but to ring formation ; on 

 heating, vapours are formed which give the pyrrole reaction with pine 

 wood, and these facts led Schulze and Trier [1909, 2; 1910, 2] to re- 

 gard the base as a derivative of a-pyrrolidine carboxylic acid (proline) 

 which had meanwhile been recognised as a common fission product 

 of proteins. They suggested for stachydrine the formula I, which was 



CH 



<COOCH 3 



CH 3 

 I 



soon afterwards also adopted by Engeland [1909, 3] after comparing 

 the properties of the methylation product of proline with those of 

 stachydrine as given in the literature. Finally Trier [1910] converted 

 stachydrine by distillation into the isomeric methyl ester of hygric acid 1 

 (formula II) and obtained stachydrine by hydrolysis of the methiodide 

 of this ester (formula III) ; the methiodide had already been synthesised 

 by Willstatter and Ettlinger [1903] starting from trimethylene dibro- 

 mide and ethyl malonate. 



Stachydrine, as obtained from most sources, is optically inactive, 

 but Yoshimura and Trier [1912] have recently obtained the laevo- 

 rotatory variety from Galeopsis ochroleuca ; the base prepared by 

 Engeland by methylating proline (from caseinogen) is optically active. 

 Stachydrine has an unpleasant sweetish taste and is without marked 

 physiological action ; taken by the mouth it is excreted unchanged in 

 the urine. The isomeric methyl ester of hygric acid on the other hand 

 has a convulsant action (Trier [1910]). 



Betonicine and Turicine, C 7 H 13 O 3 N. 



Schulze and Trier [1912, I, section on betaine] have found that in 

 Betonica officinalis, a Labiate closely related to Stachys, stachydrine is 

 accompanied by a base containing an additional oxygen atom, which 

 base they have named betonicine. It is the N -dimethyl derivative of 

 oxypyrrolidine-carboxylic acid (oxyproline), which occurs as a constit- 

 uent of proteins. 



The aurichloride C 7 H 13 O 8 N, HAuCl 4 accompanies stachydrine auri- 



1 Hygric acid, or N-methyl o-pyrrolidine carboxylic acid, is an oxidation product of 

 hygrine, an alkaloid accompanying cocaine in Coca leaves. 



