Kinetics of the chlorination of secondary amines by N‐chlorosuccinimide

2014

J. Phys. Org. Chem.

The chlorination reactions of nitrogenous organic compounds (2,2,2-trifluoroethylamine, benzylamine, glycine, and dimethylamine) by tert-butyl hypochlorite ( t BuOCl) were studied at 25°C, ionic strength 0.5 M and under isolation conditions. The kinetic results obtained in the formation processes of the corresponding N-chloramines in acid medium (pH = 5-7) are summarized in this paper. Kinetic studies showed a first order with respect to t BuOCl concentration. The chlorination reactions involving benzylamine, glycine and dimethylamine were all first order with respect to nitrogenous compound concentration and approximately À1 order with respect to proton concentration. The reaction with 2,2,2-trifluoroethylamine was more complex, and the order of reaction with respect to the amine varied with pH. 952-959 Scheme 4. Protonation equilibrium of tert-butyl hypochlorite ( t BuOCl) Scheme 5. Ionization equilibrium of primary and secondary nitrogenous compounds in aqueous solution REACTIONS OF CHLORINATION

Section: Introductionmentioning

confidence: 97%

Reactions of chlorination withtert-butyl hypochlorite (^TBuOCl)

2014

J. Phys. Org. Chem.

“…N ‐Chloro compounds are reagents that are frequently used in the intermediate steps of the synthesis of organic compounds . Sodium hypochlorite, N ‐chlorosuccinimide (NCS), chloramine‐T, chloramine‐B, and tert‐butyl hypochlorite are some of the most common reagents used to obtain N ‐chloro compounds . All of them contain one electrophile chlorine atom, positive chlorine, able to react with amino acids, amines, amides, and other nitrogenous compounds to form the corresponding N ‐chloro compound.…”

Section: Introductionmentioning

confidence: 99%

Kinetic study of the formation of N‐chloro compounds using N‐chlorosuccinimide

J of Physical Organic Chem

et al. 2014

b Second-order rate constants were determined for the chlorination reaction of 2,2,2-trifluoethylamine and benzylamine with N-chlorosuccinimide at 25°C and an ionic strength of 0.5 M. These reactions were found to be of first order in both reagents. According to the experimental results, a mechanism reaction was proposed in which a chlorine atom is transferred between both nitrogenous compounds. Kinetics studies demonstrate that the hydrolysis process of the chlorinating agent does not interfere in the chlorination process, under the experimental conditions used in the present work. Free-energy relationships were established using the results obtained in the present work and others available in the literature for chlorination reactions with N-chlorosuccinimide, being the pK a range included between 5.7 and 11.22.

“…The most commonly used reagents for the preparation of N‐chloro compounds are among others: sodium hypochlorite, N‐chlorosuccinimide, Chloramine‐T (CAT), Chloramine‐B (CAB) and tert‐butylhypochlorite ( t BuOCl) . All of them contain a chlorine atom electrophile, positive chlorine, able to react with the amino groups (R 1 R 2 NH) of amino acids, amines, amides and other nitrogenous compounds, to form the corresponding N‐chloro compounds, in a reaction in that takes place the process of breaking a NH bond and formation of the NCl bond.…”

Section: Introductionmentioning

confidence: 99%

Use of N-chloro-N-methyl-p-toluenesulfonamide in N-chlorination reactions

2013

J. Phys. Org. Chem.

Second-order rate constants (k 2 ) were determined for the addition of ten nitrogenous organic compounds (benzylamine, 2,2,2-trifluoethylamine chlorhidrate, methylamine chlorhidrate, glycine ethyl ester chlorhidrate, glycine, glycylglycine chlorhidrate, morpholine, pyperidine, pyperazine and dimethylamine) to the N-chloro-Nmethyl-p-toluenesulfonamide (NCNMPT) in the formation reaction of N-chloramines in aqueous solution at 25 C and ionic strength 0.5 M. The series of nucleophiles considered is structurally very varied and covers five pK a units.The kinetic behaviour is similar for all compounds, being the elementary step the transfer of chlorine from the NCNMPT molecule to the nitrogen of the free amino group. These reactions were found first order in both reagents. The values of the rate constants indicate that the more basic amines produce N-chloramines more readily.Rate constants for the nucleophilic attack are shown to correlate with literature data for some of these nitrogenous organic compounds in their reaction with N-methyl-N-nitroso-p-toluenesulfonamide. Both reactions involve that the rate determining step is the attack of nitrogenous compounds upon electrophilic centre (Cl or else NO group).NCNMPT is a particularly interesting substrate, for which has not hitherto been published kinetic information, that allows us to assess the efficiency and the competitiveness of this reaction and compare it with other agents with a Cl + atom. a calculated from empirical equations of Hall for primary and secondary amines. b calculated by extrapolation of the linear correlation between N + and n, considering N + = 4.40.