Isonitriles

Isinortriles? Wait. The correct term is isonitriles, also called isocyanides. They are organic compounds defined by the isocyano group with the connectivity -N≡C. The general structure is R-N≡C, where R is an alkyl or aryl substituent attached to the nitrogen. This arrangement places the NC group as a distinct functional unit from nitriles, which have the opposite connectivity (-C≡N). Isonitriles are valued in organic synthesis for their unique reactivity, but many examples have strong, unpleasant odors and can be toxic.

The isocyanide group features a highly reactive carbon center, which behaves as a nucleophilic carbon in many reactions. In infrared spectroscopy, the NC triple bond typically shows a strong absorption near 2140–2160 cm−1. Isonitriles are generally reactive toward nucleophiles and can be sensitive to air and moisture; many are handled under inert atmosphere and stored in appropriate solvents to minimize decomposition or polymerization.

Synthesis of isonitriles commonly involves dehydration of primary formamides (R-NH-CHO) with phosphoryl chloride (POCl3) in the presence of a base (such as pyridine) to furnish R-NC. Other methods include alternative dehydrative routes and catalytic transformations. The choice of method depends on the substrate and desired scale.

Reactivity and applications are broad. Isonitriles serve as versatile one-carbon building blocks in multicomponent reactions, notably the Ugi four-component reaction and the Passerini reaction, enabling rapid assembly of complex molecules. They are used in natural product synthesis, medicinal chemistry, and some areas of polymer and organometallic chemistry, reflecting their unique mode of carbon and nitrogen connectivity.

Safety and handling: many isonitriles have foul odors and can be toxic; methyl isocyanate is especially hazardous. They require appropriate ventilation, protective equipment, and careful storage away from oxidizers and moisture.