Isocyanides


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Isocyanides

 

(isonitriles, carbylamines), organic compounds with the general formula R—N≡C structural isomers of the cyanides (esters of hydrocyanic acid, R—C≡N).

Isonitriles are colorless liquids with a specific, offensive odor. They are extremely toxic. The properties of some of them are given in Table 1.

Isocyanides are insoluble in water but soluble in alcohol and ether. They are resistant to the action of alkalies, but dilute acids rapidly hydrolyze them to primary amines (RNH2) and formic

Table 1.
*(at 40 mm Hg)
IsocyanidesBoiling point
(°C)
Density
(g/cm3)(t°C)
Methyl isocyanide  
CH3 NC. . . . . . . . . . . . . .59.60.756 (7°)
Ethyl isocyanide  
C2H5 NC. . . . . . . . . . . . . .79.00.744 (25°)
Isopropyl isocyanide  
(CH3)2CHNC . . . . . . . . . . . . .87.00.760 (0°)
Phenyl isocyanide  
C6H5NC . . . . . . . . . . . . . . .78.0*0.975 (20°)

acid (HCOOH). Mercuric oxide oxidizes them to isocyanates (R—N=C=0). When treated with sulfur they form esters of isothiocyanic acid (R—N=C=S). Treatment with chlorine yields carbylamine chloride (R—N=CCl2). Catalytically activated hydrogen reduces them to a methylamino group Isocyanides. Heat isomerizes isocyanides to cyanides.

Isocyanides can be prepared by treating a mixture of chloroform (CHCI3) and a primary amine (RNH2) with an alcoholic alkali solution. The reaction provides a very sensitive qualitative means of detecting both amines and chloroform (as well as bromoform, CHBr3), since the isocyanide formed is readily detected by its powerful characteristic smell (Hofmann test). Isocyanides are also prepared by the action of POCI3 on formic acid monoalkylamides and by alkylating (by means of alkyl iodides) the silver, mercury, or lead salts of hydrocyanic acid (HCN).

Certain isocyanides are used to synthesize various nitrogen-containing substances (amides, nitriles, amino acids). Isocyanides were discovered by A. Hofmann in 1866.

V. N. FROSIN

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In 1959 Ugi and co-workers introduced the U-4CR of the isocyanides [1, 4, 5], which is since 1962 quoted as the Ugi reaction [5].
2000, 112, 3300-3344; Multicomponent reactions with isocyanides.
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Since 1995 the chemistry of the MCRs and the libraries of the isocyanides are the most often used reactions of forming chemical products and their libraries [9] in order to find thus new desirable products with pharmaceutical potential.
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The simultaneous a-addition of cations and anions onto isocyanides.
Multicomponent reactions and their libraries, a new type of organic chemistry of the isocyanides and phosphorus derivatives.