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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Isocyanide (3) attacks to re-face and si-face of 8E and 8Z and produces intermediate nitrilium ion 9R and 9S having one more stereocenter.
8E was 3.8 kcal/mol more stable than 8Z isomer and consequently has better chance to exist in equilibrium and approach isocyanide (3).
Lentijo et al., "Fluorophobic effect in metallomesogens-the synthesis and mesomorphism of Ag, Au, Cu, Fe, Pd, and Pt fluorous isocyanide complexes," European Journal of Inorganic Chemistry, vol.
The biosynthesis of sesquiterpene isocyanides and isothiocyanates in the marine sponge Acanthella cavernosa (Dendy): evidence for dietary transfer to the dorid nudibranch Phyllidiella pustulosa.
Marine isocyanides and related natural products--structure, biosynthesis and ecology.
The chemistry of the isocyanides is profoundly different from the rest of organic chemistry, because the functional group of the isocyanides is the only one that contains a divalent carbon atom [C.sup.II], and their practically irreversible reactions correspond to exothermic conversions of the [C.sup.II] into the [C.sup.IV] [1].
In the usual organic chemistry only a few MCRs are known, and each reaction produces compounds with a similar skeleton and only different substituents, whereas in the chemistry of the isocyanides a much greater variation of MCRs is known.
This synthesis uses a visible light-promoted insertion of vinyl isocyanides 87 with diphenyliodonium tetrafluoroborate 88 at room temperature to prepare six multisubstituted ring-fluorinated, trifluoromethylated, and fluoroarylated isoquinoline derivatives 89.
Related (disilene)palladium complexes with isocyanide ligands 75a, 75b, and 76 are synthesized by the reactions of 70b and 74 with the corresponding isocyanide (eqs [30] and [31]) in high yields.
Moghimi, "Catalytic multicomponent reactions based on isocyanides," Journal of the Iranian Chemical Society, vol.
Isocyanide, or isonitrile, chemistry attracted much attention at the end of the 20th century when the stable carbene began being used for diversity-oriented synthesis, high throughput screening, and drug discovery.