N‐bromosuccinimide oxidation of dipeptides and their amino acids: Synthesis, kinetics and mechanistic studies

Abstract

Dipeptides (DP), namely valyl-glycine (Val-Gly), alanyl-proline (Ala-Pro), and valyl-proline (Val-Pro) were synthesized by classical solution phase methods and characterized. The kinetics of oxidation of amino acids (AA) and DP by N-bromosuccinimide (NBS) was studied in the presence of perchlorate ions in acidic medium at 28 • C. The reaction was followed spectrophotometrically at λ max = 240 nm. The reactions follow identical kinetics, being first order each in [NBS] , and ionic strength was observed. Effects of varying dielectric constant of the medium and addition of anions such as chloride and perchlorate were studied. Activation parameters have been computed. The oxidation products of the reaction were isolated and characterized. The proposed mechanism is consistent with the experimental results. An apparent correlation was noted between the rate of oxidation of AA and DP.

Use of Bromine and Bromo-Organic Compounds in Organic Synthesis

“…Many kinetic and mechanistic studies were carried out by different researchers for different oxidation reactions by using NBS as the oxidizing agent. For example, kinetic and mechanistic studies on the oxidation of cycloheptanol in acid solution, oxidation of digol, − oxidation of amino acids and peptides, − oxidation of various sugars, − and oxidation of different acids − such as ethylenediaminetetraacetic acid, , aspartic acid, malic acid, and citric acid were reported. Similar studies were undertaken for the oxidation of allyl alcohol, − benzyl ethers, benzhydrols, amines and amino alcohols, − glycols, , cardiotoxin II,nitrones and N ,α-diphenylnitrones, , dibenzyl sulfoxide, and substituted aromatic acetals .…”

Oxidation and Reduction

“…The relative reactivity has been correlated in terms of hydrophobicity. 163 The Ru(III)-and Ir(III)-catalysed oxidation of malic acid with NBS show identical kinetics. A suitable mechanism in conformity with the observed kinetics has been proposed.…”

Fast and Facile Etching of Gold Nanorods by N-Halosuccinimides: Toward Multicolorimetric Identification and Quantification of 20 Natural Amino Acids

“…Elemental bromine and chlorine are among the well-known and widely used reagents in organic chemistry on account of their great potential in halogenation and oxidation of diverse substrates. , However, the integration of extreme toxicity and high volatility in these reagents has been always a matter of serious concern to the safety of the researcher. , The discovery of N-bromosuccinimide (NBS) and N-chlorosuccinimide (NCS) as the solid-state mild alternatives of bromine and chlorine not only resolved the foregoing challenge but enabled the scientists to gain a better insight into different halogenation and oxidation mechanisms and to unravel countless synthetic pathways thereafter. , In fact, NBS and NCS are considered as mild sources of halogen radicals (i.e., Br • , Cl • ) in radical substitution reactions. ,, Furthermore, depending on the structure of the target substrate, these reagents can also act as halonium sources (i.e., Br + , Cl + ) in electrophilic addition , and electrophilic substitution reactions. , In either case, the produced intermediates are strong oxidizing agents and can engender redox reactions with the substrate. , Therefore, thanks to the versatility of NBS and NCS reactions with a myriad of analytically valuable organic compounds such as biomolecules, − it would be of special interest to assess the potentiality of NBS and NCS in the etching of AuNRs.…”