Isocyanates carboxylic acid amide

N-Subst. carboxylic acid amides from isocyanates Carboxylic acid amides from acylisocyanates... 

Isocyanates are quite reactive and they react with compounds which contain active hydrogen such as hydroxy, amine, carboxylic acids, amide, urea, etc. They can also undergo addition reaction ... 

The other procedure10 illustrates a general method for conversion of carboxylic acids into the corresponding nitriles. Treatment of cinnamic acid (4) with chlorosulfonyl isocyanate gives the carboxylic acid amide N-sulfonyl chloride (5). As above, treatment of (5) with DMF gives cinnamonitrile (6) in 78-87% yield. 

We selected a novel approach to design a masked or blocked aliphatic diisocyanate based on the fact that 1,3-disubstituted ureas undergo facile thermal dissociation to produce an isocyanate and an amine derivative. ) In the dissociation of mono acyl and aroyl ureas an isocyanate and a carboxylic acid amide is simultaneously produced. If the urea group is part of a cyclic system both fragments are parts of the same molecule. 

Recyclization does not occur because the reaction of aliphatic isocyanates with carboxylic acid amide groups occurs only under very severe conditions. 

The reactivity of different isocyanates varies widely, and the most reactive NCO groups can react with almost any compound that contains an active hydrogen [1, 2, 16]. The reactivity of the nucleophilic groups also varies primary amines are more reactive towards NCO than primary alcohols, followed by water, secondary and tertiary alcohols, other urethanes, carboxylic acids, and carboxylic acid amides in that order [16]. The isocyanate will, of course, react with the water present in the EPI formulation to form amines followed by further reactions producing urea and biuret. The mechanism of this reaction is shown in Pig. 5. As can be seen from the reaction mechanism CO2 is a byproduct of this reaction. 

Although there are many alternative routes for the synthesis of isocyanates [24] (see also Chapter 4), none are as simple or as attractive as the carbonylation of primary amines with phosgene. This is reflected by the widespread employment of phosgene in the industrial manufacture of isocyanates the use of phosgene continues despite numerous attempts to And suitable alternatives (see Chapter 4). However, acyl isocyanates such as 10 cannot normally be prepared by the reaction of phosgene with the corresponding carboxylic acid amide, since the phosgene... 

Isocyanates from carboxylic acid amides GONHg N C O... 

Aromatic isocyanates react with regular olefins only in the presence of metal catalysts. For example, reaction of ethylene with phenyl isocyanate in the presence of liganded nickel (o) catalysts under argon in THF at -20 °C affords a five-membered ring metalla-cycle, which on hydrolysis gives a Af-substituted carboxylic acid amide. Heating of the metallacycle causes jS-elimination with formation of Af-substituted acrylic acid amides Diolefines and allenes also undergo this reaction with phenyl isocyanate. From 1,1-bis-p-dimethylaminophenylethylene and p-nitrophenyl isocyanate a linear 1 1 adduct is obtained... 

The insertion of isocyanates into C-H bonds is also well known. Olefins, alkanes, aromatic and heteroaromatic compounds are known to react with isocyanates to give N-substituted carboxylic acid amides. Often the formation of the linear adduct is the result of a [2+2] cycloaddition reaction and subsequent rearrangement. Electron donating groups on the aromatic nucleus on the one side and electron withdrawing groups on the isocyanate enhance the reactivity of both components. Lewis acids, such as aluminum chloride, are supplied successfully as catalysts... 

Alkyl and aryl magnesium halides react with isocyanates to give the substituted carboxylic acid amides 263 after hydrolysis . 

Organoaluminum compounds also undergo insertion reaction with isocyanates. For example, aluminum trialkyls react with alkyl and aryl isocyanates to give carboxylic acid amides after hydrolysis . Alkyl aluminum chlorides react similarly . Aluminium trichloride also forms insertion products with isocyanates Diethylaluminum ethyl thiolate or dimethylamide react with equimolar amounts of alkyl or aryl isocyanates to give the expected insertion products 274. ... 

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