142 THE SIMPLER NATURAL BASES 



probably has the constitution (CH 8 ) 3 N(OH) . CH 2 . COOH, of which 

 the other substance is a cyclic anhydride. 



Betaine and its isomeride, the methyl ester of dimethyl-amino- 

 acetic acid, are interconvertible at temperatures between 135 (the 

 boiling point of the ester) and 293 ; over this range betaine is the 

 more stable and it is formed in good yield by heating the ester in a 

 sealed tube to 200. On the other hand a 50 per cent, yield of the 

 ester is obtainable by heating betaine to 300, when the ester distils 

 out. At or above 293 betaine begins to be decomposed into tri- 

 methylamine and other substances (Willstatter [1902, l]). 



Betaine is a very feeble base, forming a series of stable salts. The 

 salts with mineral acids have a strongly acidic reaction, and for this 

 reason the chloride is sold as a solid substitute for hydrochloric acid 

 under the name " acidol ". 



The chloride, C 5 H 12 O 2 NC1, forms leaflets, melting and decomposing 

 at 227-228 (243) ; it is very soluble in water and differs from the 

 hydrochlorides of most organic bases in being almost insoluble in 

 absolute alcohol (i grm. dissolves in 365 c.c. of absolute alcohol at 

 room temperature; Schulze [1909, Ch. IV, choline]). 



The iodide, C 5 H 12 O 2 NI, non-deliquescent crystals; m.p. 188-190; 

 very soluble in hot alcohol, but little in cold (Willstatter [1902, i]). 

 The periodide, C 5 H 12 O 2 NI. I 6 , loses iodine on exposure to the air 

 [StanSk, 1912]. Compounds with potassium iodide of the formulae 

 C 5 H n O 2 N . KI . 2H 2 O and (C 6 H u O 8 N)s, . KI . 2H 2 O have also been de- 

 scribed (see Willstatter [1902, i]). 



The/^Ma/,C 5 H u O 2 N . H 3 PO 4 , melts at 199-200 and decomposes 

 at 234(Andrlik [1903-4]). 



The perchlorate, C 5 H U O 2 N . HC1O 4 , is much less soluble than the 

 corresponding choline salt; at 19 17*73 parts dissolve in 100 parts 

 of water (Hofmarm, Roth, Hobold and Metzler [1910, Ch. IV, 

 choline]; Hofmann and Hobold [i9ii,Ch. IV, choline]). 



Thepicrate, C 5 H U O 2 N .C 6 H 3 O 7 N 3 , forms yellow needles ; m.p. 180- 

 181; it is suitable for the separation of the base from mixtures 

 (Schulze and Trier [1910, i]). 



^\\e.picrolonate t C 5 H n O 2 N . C 10 H 8 O 6 N 4 , forms yellow needles readily 

 soluble in alcohol and in water, and decomposes at 200 (Otori [1904, 3, 

 Ch. I]). 



The platinichloride, (C 5 H n O 2 N) 2 H 2 PtCl 6 .4H 2 O., crystallises from 

 concentrated aqueous solution in the cold in large rhomb-shaped 

 tables with truncated angles, and effloresces in air ; m.p. 242 ; insol- 

 uble in alcohol, very soluble in hot water from which it crystallises 



