The methyl betaïne of nicotinic acid is identical with the alkaloid trigonelline, which was discovered in 1885 by E. Jahns in the seeds of Trigonella faenum-graecum (Ber., 1885, 18, p. 2518). It has also been obtained from nicotine by A. Pictet by oxidizing the methyl hydroxide of nicotine with potassium permanganate (Ber., 1897, 30, p. 2117).
Substances closely related to betaïne are choline, neurine and muscarine. Choline (bilineurine, sincaline), (Gr. χολή, bile), C5H15NO2 or HO·CH2·CH2·N(CH3)3·OH, first isolated by A. Strecker in 1862 (Ann. 123, p. 353; 148, p. 76), is found in the bile, in brain substance, and in yolk of egg in the form of lecithin, a complex ester of glycerin with phosphoric acid and the fatty acids. It is also found in combination with sinapic acid in sinapin, the glucoside obtained from white mustard, and can be obtained from this glucoside by hydrolysis with baryta water,
| C16H23NO5 + 2H2O | = | C5H15NO2 | + | C11H12O5. |
| Sinapin. | Choline. | Sinapic acid. |
It can be synthetically prepared by the action of trimethylamine on an aqueous solution of ethylene oxide (A. Wurtz, Ann. Suppl., 1868, 6, p. 201). It forms deliquescent crystals of strongly alkaline reaction, and absorbs carbon dioxide from the air. It is not poisonous. By continued boiling of its aqueous solution, it is resolved into glycol and trimethylamine.
Neurine, trimethyl vinyl ammonium hydroxide (Gr. νεῦρον, nerve), CH2 : CH·N(CH3)3·OH, is a product of the putrefaction of albumen. It may be prepared by the action of moist silver oxide on ethylene dibromide and trimethylamine,
CH2Br·CH2Br → CH2Br·CH2N(CH3)3Br → CH2 : CH·N(CH3)3·OH.
It is a crystalline solid, very soluble in water, and is strongly basic and very poisonous. Muscarine, C5H15NO3, is an exceedingly poisonous substance found in many fungi. It may be obtained synthetically by oxidizing choline with dilute nitric acid (O. Schmiedeberg, Jahresb., 1876, p. 804). The exact constitution has not yet been definitely determined.