SUBJECTS hydrocyanic acid

The discovery of Liebig, that when hydrocyanic acid was mixed with sulphide of ammonium, and subjected to a moderate degree of heat, a compound— snlphocyanide of ammonium—was formed, which possessed the property of giving an intense blood-red color with the sesquisalts of iron, afforded a test for hydrocyanic acid, which is equal, if not superior, to any at present known, Dr, Pereira remarks —When the acid is in small quantity, and mixed with solids or... 

These may be isolated by steam distillation. It is usual to make two such distillations, the first from acid solution, the second from alkaline. About 50-100 gm of tissue is homogenized, mixed with an equal quantity of water, acidified with tartaric acid and steam-distilled until a volume ecpial to the original sample taken has been collected. This distillate will contain neutral and acidic compounds such as hydrocyanic acid, phenol, and phosphorus. The tissue slurry is now made alkaline with sodium hydroxide solution and again subjected to steam distillation. This second distillate will contain basic compounds. The tip of the condenser should be immersed in dilute hydrochloric acid to trap the more volatile bases. The plant alkaloids most likely to be present are nicotine, coniine, arecoline, ephedrine, and sparteine, but a number of synthetic drugs, notably amjihetamine and other sympathomimetic bases, also occur in this fraction. Pethidine may also be isolated by steam distillation. The... 

Regulatory Status. Howers are GRAS (American, 182.10 and 182.20 European, 182.20) leaves have been approved for use in alcoholic beverages only, with the provision that hydrocyanic acid (HCN) should not exceed 25 ppm (0.0025%) in the flavor ( 172.510). S. nigra flowers are subject of a German therapeutic monograph allowed as a diaphoretic and to increase bronchial secretion in the treatment of colds. ... 

The addition of cyanide to an aldehyde or ketone (hydrocyanation) is an old reaction, but it has been the subject of renewed interest since Reetz s discovery that a chiral Lewis acid could be used to catalyze the asymmetric addition of trimethyl-silylcyanide to isobutyraldehyde ([91] reviews [59,92]). The general process, illustrated in Scheme 4.7, usually employs trimethylsilylcyanide because hydrogen cyanide itself catalyzes the addition as well (nonselectively). Most of the catalysts are chiral titanium complexes some of the more selective examples are shown in Table 4.6. A clear mechanistic picture of the titanium catalyzed additions nis not yet emerged. ... 

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