Pyrolysis of N-t-Butyl-N-alkylcarbamoyl Chlorides. A New Synthesis of Isocyanates

Abstract

A number of N-<-butyl-N-alky 1 carbamoyl chlorides have been synthesized by known methods. These compounds decompose readily at low temperature with or without catalysis to the corresponding alkyl isocyanates in high yield.

New aminoporphyrins bearing urea derivative substituents: synthesis, characterization, antibacterial and antifungal activity

“…Compared to phosgene and diphosgene, it exhibits superior properties. Generally, aliphatic and aromatic carbamoyl chlorides are prepared from amines and phosgene group compounds by a simple one-step condensation method (Scheme 1) (Tilley and Sayigh 1963;Johnson 1967 (Zare et al 2012). The reactions were clean and only the carbamoyl chlorides were detected by spectroscopic analysis of the crude products.…”

Phenyl Chloro(thionoformate): a New Dealkylating Agent of Tertiary Amines

“…analysis of the intermediate (28), prepared as above, suggested that this product was contaminated by Nbenzyl-3-(benzylamino)propanamide (29) which presumably arose by elimination of t-butylamine from (27) or (28), followed by conjugate addition of benzylamine. To improve the yield of the desired product (28), the mixture of (28) and (29) was heated in a sealed tube with t-butylamine which converted (29) into (28) (92%). The amide was then reduced with diborane affording the diamine (30), which was then methylated to give the diamine (26).…”

Mechanistic Studies of the Solvolyses of Carbamoyl Chlorides and Related Reactions

“…It was found that N - t -butyl- N -alkylcarbamoyl chlorides decomposed on heating in nitrobenzene at 100 °C or in the less polar toluene at higher temperatures to give isobutylene plus HCl together with the alkyl isocyanate, many of which could not be prepared by any of the other techniques available at that time. The favored pathway involved ionization to give a chloride ion followed by its removal of a hydrogen from the tert -butyl group, with accompanying formation of isobutylene [69]. This pathway has similarities to that proposed [70] for the decomposition of 1-adamantyl chloroformate on heating in nitrobenzene, when loss of CO 2 led to 1-adamantyl chloride (Equation (10)).…”

“…Derivatives with different alkyl groups can readily be prepared by reaction of appropriate secondary amines with phosgene [69], and there are instances where such compounds have been found to be synthetically useful. It was found that N - t -butyl- N -alkylcarbamoyl chlorides decomposed on heating in nitrobenzene at 100 °C or in the less polar toluene at higher temperatures to give isobutylene plus HCl together with the alkyl isocyanate, many of which could not be prepared by any of the other techniques available at that time.…”

“…We have earlier reviewed the decomposition of N - tert -butyl- N -alkylcarbamoyl chlorides to give alkyl isocyanate [69] and the same research group extended this work to a study of N -phenyl- N -4-isocyanatobenzylcarbamoyl chloride. In refluxing chlorobenzene, in the presence of dry hydrogen chloride, decomposition to 4-isocyanatobenzyl chloride and phenyl isocyanate was observed.…”