Amine reactions with isocyanate

The catalysis of isocyanate reactions has been extensively studied because of its critical importance in many of these processes. Noncatalyzed (or rather, self-catalyzed) reactions may sometimes be fast enough in practice isocyanate reactions with amines are so fast that only recent studies using stopped-flow methods could lead to useful data [255, 256], metallic or tertiary amine catalysts being ineffective in this case. 

I. S. Bechara, The Mechanism of Tin-Amine Synergism in the Catalysis of Isocyanate Reaction with Alcohols, in Urethane Chemistry and Applications, ACS Symposium Series 172, K. N. Edwards, (Ed.), American Chemical Society, Washington, DC, 1981. 

The procedure may be adapted for the preparation of other acyl isocyanates (i.e., dichloroacetyl, trichloroacetyl, phenyl-acetyl, diphenylacetyl, benzoyl, etc) and is generally more convenient than the reaction of acid chlorides with silver cyan-ate3 4 Acyl isocyanates react with amines, alcohols, and mer-captans to yield acyl ureas, carbamates, and thiocarbamates. 

Symmetrical carbodiimides, i.e., molecules with the same substituent on both nitrogen atoms, are best prepared from alkyl or aryl isocyanates in the presence of a phospholene oxide catalyst, the byproduct being carbon dioxide gas. No solvent is required for this reaction. Unsymmetrical carbodiimides or alkylarylcarbodiimides are also obtained from isocyanates, either by reaction with amines and subsequent dehydration of the intermediate... 

It appears, then, that isocyanate and isothiocyanate CDAs are useful in LC resolutions of amines. Several of these agents are commercially available, and many others can be readOy prepared from a variety of commercially available optically active primary amines. The stereochemical stability of these CDAs is excellent, their reaction with amines is rapid and convenient, and the derivatives are readily and sensitively detected. These reagents are likely, therefore, to enjoy continued popularity. 

There are a few other chemical reactions on the wood surface that could make important contributions. One is that of moisture on the surface of wood to form an unstable carbamic acid group that quickly decomposes to form a primary amine with evolution of carbon dioxide. The primary amine formed has active hydrogens reactive to isocyanate. Other successive reactions ensue leading first to disub-stituted ureas and then to biurets. Furthermore, isocyanate reaction with urethane to form allophanates, and trimerization of isocyanates to form isocyanurate are also possible to variable extents, under the conditions of bonding. The different reactions are summarized in Scheme 2. 

The Mechanism of Tin—Amine Synergism in the Catalysis of Isocyanate Reaction with Alcohols... 

CAPRYLIC ACID or -CAPRYLIC ACID ( 1 24-07-2) CgHjsOi CH3(CH2)jCOOH Forms explosive mixture with air (flash point 230°F/110°C). Violent reaction with amines, strong oxidizers, fiirfuryl alcohol (explosion), hypochlorites, isocyanides, nitromethane, chromic acid, nitric acid, hydrogen peroxide, phosphorus pentaoxide, all bases (exothermic reaction) sulfuric acid. Reacts with azo/diazo compounds, dithiocarbamates, dithionites (forming sulfur dioxide) isocyanates, mercaptans, nitrides, nitrates, sulfides. 

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