38064-12-9

Upstream product

• 30289-28-2 N-methoxy-N-methylcarbamoyl chloride 
• 108-95-2 phenol 
• 6638-79-5 N,O-dimethylhydroxylamine*hydrochloride 
• 1885-14-9 phenyl chloroformate 

Relevant academic research and scientific papers

One-Pot Synthesis of O -Aryl Carbamates

A simple, versatile, one-pot procedure for the synthesis of substituted O-aryl carbamates has been developed, and a protocol is henceforth described. N-Substituted carbamoyl chloride is formed in situ and subsequently reacted with a substituted phenol, avoiding the direct manipulation of sensitive reactants. This procedure offers an economical and efficient route to many compounds of interest.

Kinetics and mechanism of base-catalysed degradations of substituted aryl-N-hydroxycarbamates, their N-methyl and N-phenyl analogues

The kinetics and mechanism of the degradation reactions of substituted phenyl N-hydroxycarbamates and their N-methyl and N-phenyl analogues have been studied at pseudo-first-order reaction conditions in aqueous buffers and sodium hydroxide solutions at 20°C and 60°C and at I = 1 mol·1 -1. The dependence of log kobs on pH for phenyl N-hydroxycarbamates at pH 13 is linear with the unit slope; at pH 10-12 log kobs is pH independent. The Bronsted coefficient βlg is about -1 (pH 7-13) and -1.53 (pH > 13) indicating that the degradation reaction of phenyl N-hydroxycarbamates follows an ElcB mechanism giving the corresponding phenol/phenolate and HO-N=C=O. The latter species undergoes further decomposition to give carbonate, nitrogen and ammonia as final products. In contrast to the phenyl N-hydroxycarbamates the N-methyl derivatives at pH 7-9 undergo degradation to the corresponding phenol/phenolate, carbonate and methylamine via a concerted mechanism (βlg is about - 0.75). The only exception is 4-nitrophenyl N-hydroxy-N-methylcarbamate in which the predominant break down pathway proceeds via the Smiles rearrangement to give sodium N-methyl-(4-nitrophenoxy)carbamate. At pH > 9 the reaction of N-hydroxy-N-methylcarbamates is kinetically complex: the dependence of absorbance on time is not exponential and it proceeds as a consecutive two-step reaction. N-Hydroxy-N-phenylcarbamate under the same conditions undergoes degradation to phenol, carbonate, aniline and azoxybenzene.

KINETICS AND MECHANISM OF HYDROLYSIS OF ARYL N-METHOXYCARBAMATES AND THEIR DERIVATIVES

Hydrolysis kinetics have been studied of 3- and 4-substituted phenyl N-methoxycarbamates and their N-methyl derivatives in aqueous buffers at 60 deg C.The N-methyl derivatives show linear dependence of the rate constants on concentration of hydroxyl ion in the pH range measured.Hydrolysis of aryl N-methoxycarbamates is independent of hydroxyl ion concentration at higher pH values.Logarithms of the rate constants have been correlated with the substituent constants ?.The calculated values 0.9 for N-methyl derivatives, 4.5 and 3.3 for aryl N-methoxy-carbamates in theregions of linear pH-dependency and pH-independency, respectively, suggest that the hydrolysis follows the BAc2 and ElcB mechanisms in the case of the N-methyl derivatives and aryl N-methoxycarbamates, respectively.Difference between the two ρ constants for the hydrolysis of aryl N-methoxycarbamates agrees with the found value ρ=1.2 for dissociation constants of these compounds.The elimination mechanism has been confirmed by reaction of the isocyanate formed with added aniline to give the respective urea.