4-Chlorophenyl isocyanate is used in the preparation of isothiocyanates. Aryl isocyanates undergo [2+2] cycloaddition reactions with dihydrofuran to give bicyclic ?-lactams in high yield.
일반 설명
Colorless to yellow liquid or crystals. Used as an intermediate in pesticide and pharmaceutical manufacture.
반응 프로필
Isocyanates and thioisocyanates are incompatible with many classes of compounds, reacting exothermically to release toxic gases. Reactions with amines, aldehydes, alcohols, alkali metals, ketones, mercaptans, strong oxidizers, hydrides, phenols, and peroxides can cause vigorous releases of heat. Acids and bases initiate polymerization reactions in these materials. Some isocyanates react with water to form amines and liberate carbon dioxide. Base-catalysed reactions of isocyanates with alcohols should be carried out in inert solvents. Such reactions in the absence of solvents often occur with explosive violence, [Wischmeyer(1969)].
Safety Profile
Poison by ingestion and
inhalation. Unspecified human systemic
effects. A severe eye and moderate skin
irritant. A flammable liquid when exposed to
heat or flame. Dangerous, can explode on
distillation. When heated to decomposition
it emits toxic fumes of Cl-, CN-, and NOx.
Purification Methods
Purify the isocyanate by recrystallisation from pet ether (b 30-40o) or better by fractional distillation. TOXIC irritant. [Beilstein 12 H 616, 12 III 1376, 12 IV 1213.]
