Carbamyl chlorides, preparation

Ketone formation can also be avoided if one of the functional acyl halogens ia phosgene is blocked. Carbamyl chlorides, readily obtained by the reaction of phosgene with ammonia or amines, are suitable reagents for the preparation of amides ia direct Friedel-Crafts acylation of aromatics. The resulting amides can be hydroly2ed to the corresponding acids (134) ... 

The practical appHcation of this reaction has been demonstrated ia the preparation of terephthaUc acid from toluene, ia which case oxidation follows hydrolysis (135). The reaction also proceeds well with substituted carbamyl chlorides such as CgH (C2H )NCOCl. 

Nitrophenyl isocyanate has been prepared by heating -nitrophenyl carbamyl chloride. The latter has been obtained by the action of phosgene on -nitroaniline in benzene-toluene solutions, and by the action of phosphorus pentachloride on methyl jii-nitrophenylcarbamate. The preparation given above is based upon recent publications of the authors. ... 

Mesitoic acid has been prepared by carbonation of mesityl-magnesium bromide 2-4 by hydrolysis of its amide prepared by condensation of mesitylene with carbamyl chloride under the influence of aluminum chloride 6 by oxidation of isodurene with dilute nitric acid 6-7 by distillation of 2,4,6-trimethylmandelic acid (low yield) 8 by dry distillation of 2,4,6-trimethyIphenyl-glyoxylic acid 9 by oxidation of the latter with potassium permanganate 10 and by treating 2,4,6-trimethylphenylglyoxylic acid with concentrated sulfuric acid in the cold11 or with heating.12... 

Alkyl carbamates prepared from the carbamyl chlorides also react with amines to give semicarbazides [15, 17] (Eq. 25). 

Mesitoic acid has been obtained by hydrolysis of its amide which was prepared from mesitylene, carbamyl chloride, and aluminum chloride in carbon disulfide.1 It has been prepared by heating isodurene with dilute nitric acid,2,3 in small yields by the distillation of 2,4,6,-trimethylmandelic acid,4 by dry dis-... 

The submitters have prepared the following thiocarbamyl chlorides by the chlorination of the corresponding disulfides dimethylthiocarbamyl chloride, b.p. 90-95°/0.5 mm., m.p. 42.5-43.5°, carbon tetrachloride reaction medium diisopropylthio-carbamyl chloride, m.p. 69-71°, benzene reaction medium diiso-butylthiocarbamyl chloride, m.p. 46-48°, no solvent. 

Billeter prepared diethylthiocarbamyl chloride2 and other carbamyl chlorides by the reaction of the appropriate amine as amine hydrochloride with thiophosgene. The present preparation represents an adaptation of the Ritter process.6... 

Simple isocyanates containing up to twelve carbon atoms are best prepared by a vapor-phase reaction of phosgene and a primary amine reported in 1950. The reaction occurs without a catalyst at 240-350° to form carbamyl chlorides from which the isocyanates are obtained by refluxing in an inert solvent or by treating with a tertiary amine. Over-all yields range from 58% to 88%. Secondary amines are converted to disubstituted carbamyl chlorides, RjNCOCl. ... 

Asymmetric ureas, N,N dialkylurethanes, and 4,4-dialkylsemicarba-zides are available by this method. In general, the yields are excellent. Carbamyl chlorides are prepared by the action of phosgene on secondary amines (cf. method 411). 

The reaction of A(-(a-chlorobenzylidene)carbamyl chloride (180) with sodium azide gave (74JOC1226), among other products, 3,6-diphenyl-1,2,4-triazolo[3,4-6] 1,3,4-oxadiazole (182) and not the other possible product 181. The former product was unequivocally prepared (74JOC1226) by cyclization of 4-benzoylamino-5-chloro-3-phenyl-1,2,4-triazole (184) with aqueous sodium carbonate and found to be identical with that obtained by the previous method. 2-Hydrazino-l,3,4-oxadiazoles (185) with carboxylic... 

Of-Naphthoic acid has been prepared by the hydrolysis of a-naphthyl cyanide and (in poor yield) by the fusion of sodium a-naphthalenesulfonate and sodium formate. It has also been prepared by passing carbamyl chloride into naphthalene and aluminum chloride and hydrolyzing the a-napthamide thus formed.3... 

With imidazole being an essential pharmacophore, the solid-phase synthesis of non-annelated imidazoles has been reported in several publications ]50-52]. Houghten et al. devised a plethora of imidazole syntheses, but used exclusively the experimentally difficult HF cleavage ]53-55, and citations therein]. The preparation of 1,2,4-trisubstituted imidazoles via the solid-phase synthesis of N-alkyl-N-(]3-keto)amides using a carbazate linker has been demonstrated [67]. An approach for the preparation of 2-substituted azoles in a traceless fashion using a polystyrene-carbamyl chloride resin has been described by Deng and Hlasta [58]. 

Nicotine has been prepared in one step by ring expansion of cyclopropyl 3-pyridyl ketone Phthalimidines can be obtained by intramolecular Friedel-Crafts ring closure of carbamyl chlorides . Easy preparations of 2-methylindoles from ar. amines and 2,3-dibromopro-pene through N-(2-bromallyl)anilines and of 1-azaadamantanes from N-tosylpiperidone enamines through 3-azabicyclo[3.3.1]non-9-ones have been reported. 3-Hydroxypyridinium salts have been prepared by a new method, the chlorine oxidation of N-monosubst. 2-(a-amino-alkyl)furans . 

Eneisocyanates have been prepared in good yields from azirines via car-bonylation, and from carbamyl chlorides via thermolysis. "... 

Carbamic Acids. The esters of carbamic add or substituted carbamic acids (urethans) do not react readily with hydrazine, but the corresponding carbamyl chlorides do. The semicarbazide or substituted semi-carbazides that result yield carbamyl azides with nitrous acid. Most carbamyl azides are prepared more conveniently from the carbamyl chlorides and sodium azide. Monosubstituted carbamyl azides can also be synthesized from isocyanates and hydrazoic acid. -... 

Phosgene condensed into an ice-cold, stirred soln. of o-dichlorobenzene and tributylamine, then fert-butyl-n-butylamine added during 10 min., after 1.15 hrs. heated at 120-145° for 1 hr., cooled to 90°, a second mole of tributylamine added to the mixture containing the intermediate carbamyl chloride, then heated 1 hr. at 175° and 1 hr. at 200° with distillation of the product n-butyl isocyanate. Y 87%.—Isocyanates otherwise not readily accessible can be prepared by this method. F. e., also with isolation of the intermediate, s. J. N. Tilley and A. A. R. Sayigh, J. Org. Chem. 28, 2076 (1963). 

Ulrich H (1997) Chemistry and technology of isocyanates. Wiley, Chichester Slocombe RJ, Hardy EE, Saunders JH, Jenkins RL (1950) Phosgene derivatives, the preparation of isocyanates, carbamyl chlorides and cyanuric acid. J Am Chem Soc 72 (5) 1888-1891... 

N-Heterocyclic amides have been efficiently prepared by homo-lytic carbamylation with formamide. Under mild conditions amides can be converted into nitriles with pyrophosphoryl chloride Another mild, efficient, and novel method is the oxidation of lactams to imides with peroxy acids or hydroperoxides in the presence of transition metal ions... 

Pyrolysis of pyridine derivatives is a method for allylic and benzylic deamination the preparation of nitriles from aldehydes, and the preparation of isocyanates from acid chlorides or hydrazides Flash vacuum pyrolysis continues to yield interesting reactions and products. Recently, it has been reported that quite sensitive acetylene derivatives can be obtained by this method from 4-alkylideneisoxazol-5(4H)-ones by ring degradation. On the other hand, 2 carbamyl azide molecules cyclize under these conditions to form l,2,4-triazolidine-3,5-dione 1,2-ylids . 2H-Cyclohepta[b]furan-2-ones have been obtained by ring expansion of phenyl propiolates... 

Trifluoroacetic acid added slowly at ca. 30° to a stirred mixture of tert-butanol and Na-cyanate in benzene, and stirring continued 3 hrs. or overnight in the loosely stoppered container /er -butyl carbamate. Y 69-92%.—Garbamates of tert. alcohols hitherto difficult to prepare can be obtained by this simple method.—Similarly in methylene chloride for 18 hrs. Cyclohexanone oxime cyclohexanone oxime carbamate. Y 90%. F. e., also carbamylation of phenols and mercaptans, s. B. Loev and M. F. Kormendy, J. Org. Chem. 28, 3421 (1963). 

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