Carbamyl chlorides amines

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) ... 

Hlasta and Deng have developed a two-step solid-phase method for the decoration of azoles at C-2 [188]. First, imidazole was loaded onto a polystyrene-bound carbamyl chloride via a benzaldehyde bridge (Fig. 40). The 2-substi-tuted imidazole was efficiently cleaved in good yields in the presence of various nucleophiles (i.e., water, alcohols, and amines), trifluoroacetic acid, and boron trifluoride under microwave irradiation in a closed vessel at 120 °C for 5 min. 

Carbamate herbicides, 13 320 Carbamates, 13 108 amine, 16 359 Carbamic acid nitrile, 3 158 Carbamide derivatives, as cellulose solvents, 11 272 Carbamodiimide, 8 158 Carbamoylated gelatin, 12 444 Carbamoyl-methylphosphoryl family, extractants of, 10 789 Carbamyl chlorides, 12 180 Carbanion coordination, 13 656—657 Carbanions, 21 101... 

Carbamyl chlorides, available by the reaction of phosgene on secondary amines, can react with hydrazines to give good yields of 1,1-dialkylsemi-carbazides [31] (Eq. 24). 

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

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). 

Ureas from amines and carbamyl chlorides NH —y NCONRa... 

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 . 

Commercially, isocyanates are exclusively produced from amines and phosgene. The synthesis proceeds in two stages in order to suppress the formation of polyureas. In the first stage (cold phosgenization), a solution or suspension of amine at 0 C is reacted with an excess of phosgene to produce a mixture of carbamyl chloride and carbamyl chloride hydrochloride ... 

Insufficient phosgene produces polyureas and the amine hydrochloride. In the second stage, more phosgene is added at 60-70° C to the carbamyl chloride suspension, and the isocyanate is formed by hydrochloride elimination (hot phosgenization) ... 

Procedure C [93] Formation of diastereomeric allophanates from (4R, 5S-c s-4,5-diphenyl-2-oxazolidone-3-carbamyl chloride (DOCC) Heat a mixture of DOCC (1 mM), the amine (1.1 mM), triethylamine (1.1 mM) and dry benzene (3 ml) under reflux for approximately 3 h. Cool, dilute with ether and partition with hydrochloric acid (IM) and finally water. Evaporate the organic phase and dissolve the residue in a solvent suitable for chromatography. 

In the second stage, more phosgene is added to the suspension of amine hydrochloride and carbamyl chloride at 60-70" C, thereby forming isocyanate through the elimination of HCl (hot phosgenization). The isocyanate 0=C=N—R—N=C=0 is purified by distillation. 

The commercially most important reaction of phosgene, covering 85% of its use, is with primary amines to form carbamyl chlorides, from which isocanates are formed by elimination of hydrogen chloride at elevated temperatures... 

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