Bromamine-T, oxidation

As with chlorine-containing oxidants, JV-bromo species have been used to oxidize sulphoxides to sulphones (with no bromine incorporation) through the initial formation of a bromosulphonium ion, by nucleophilic attack of the sulphoxide sulphur atom on the electrophilic halogen atom. Such reactions involve JV-bromosuccinimide ° bromamine-T, iV-bromoacetamide ° and iV-bromobenzenesulphonamide. All reported studies were of a kinetic nature and yields were not quoted. In acid solution all oxidations occurred at or around room temperature with the nucleophilic attack on the electrophilic bromine atom being the rate-limiting step. In alkaline solution a catalyst such as osmium tetroxide is required for the reaction to proceed . ... 

H, Cl, Br, NO2, Me, MeO) by bromamine-B, catalysed in the presence of HCl in 30% aqueous methanol by RuCls have been smdied and a biphasic Hammett a-relationship derived. A kinetic study of the ruthenium(in)-catalysed oxidation of aliphatic primary amines by sodium A-bromo-j -toluenesulfonamide (bromamine-T, BAT) in hydrochloric acid medium has been undertaken and the mechanism of the reaction discussed. A concerted hydrogen-atom transfer one-electron transfer mechanism is proposed for the ruthenium(in)-catalysed oxidation of 2-methylpentane-2,4-diol by alkaline hexacyanoferrate(III). The kinetics of the oxidation of propane-... 

Kinetic studies of the oxidation of aspirin by bromamine-T, A-bromosuccinimide (NBS), and A-bromophthalimide (NBP) support a mechanism in which the unpro-tonated oxidant is the active species. " The ultimate product of the reaction is 2,4,6-tribromophenol, which arises through decarboxylation, bromination and loss of acetic acid. The NBP and NBS oxidations of -hydroxy acids are found to be similar in mechanism. 

Catalysis of the oxidation of allyl and crotyl alcohols with chloramine-T, 375 chloramine-B, bromamine-T, and bromamine-B Catalysis of the chloramine-T oxidation of glycolic and lactic acids 376... 

The kinetics of oxidation of caffeine by sodium IV-bromo-p-toluenesulfonamide (bromamine-T) in dilute HC1 have been studied.138 In the oxidation of a-phenylbenzenemethanols by bromamine-T catalysed by ruthenium(III), the reaction constant p is —2.1 for electron-releasing substituents.139 It is proposed that the... 

An alternative oxidation using O2 and a RuCls catalyst converted pyridine to pyridine A-oxide. Bromamine-T and RuCls in aq. acetonitrile also oxidizes pyridine to the A-oxide. Tertiary amines are oxidized to the A-oxide with O2 and Fe203 in the presence of an aliphatic aldehyde. " Oxygen and a cobalt-Schiff base complex also oxidzes tertiary amines, including pyridine. ... 

The application of a different N-halogen source was described by Branco, Prab-hakar and coworkers [20]. In this case, acrylic acid derivatives underwent amination in the presence of bromamine-T to yield the corresponding aziridines as the major products. Aminobrominated side products were also observed in some cases. Scheme 4.3 shows a representative example for the oxidation of dimethyl acrylamide (Eq. (4.9)). The reactions were also investigated in the presence of stoichiometric amounts of palladium, as for example for methyl acrylate, which gave the corresponding aziridine as the only product [21]. The mechanism of this aziridination remains uncertain as both Pd(II) and Pd(IV) intermediates have been suggested, although without definite proof... 

More recently, an oxidation procedure with sodium percarbonate as the oxidant and MTO as the catalyst for the efficient oxidation of pyridines to the N-oxides was reported [125]. The latter system also worked well with N,N-dialkylated anilines to give the corresponding N-oxides. The same research group had previously reported a related Re-catalyzed N-oxidation with bromamine-T as the terminal oxidant [126]. 

The uncatalysed and Ru(ni) catalysed oxidations of niacin by bromamine-B in HCl has an inverse fractional order in HCl. The catalysed reaction is fractional order in Ru(III). The similarly catalysed bromamine-T (BAT) oxidation of trans-4-(aminomethyl) cyclohexanecarboxylic acid (Tx) in HCl to 4-formylcyclohexane-l-carboxylic acid is fractional orders in Tx, H+ ion and para-toluenesulfonamide (PTS). 

The RUCI3-catalysed oxidation of levocarnitine (LC) by bromamine-T is fractional order in LC and H+ ions. The rates are accelerated by increasing Ru(IIl) and dielectric constant and retarded by PTS. ... 

Two papers on the kinetics of oxidation of D-glucose by pyridiitium chlorochromate CC) have t peared, and the oxidation of L-arabinose, D-lyxose, D-tibose, and D-xylose by sodium N-bromo-p-toluene (bromamine T) in alkaline media has been examined. An investigation of the Ru04-catalysed oxidation of aldoses by alkaline iV-bromoacetamide is referred to in Chapter 16. 

The oxidation of DL-methionine by sodium iV-chlorotoluene-p-sulfonamide (CAT) in alkaline medium catalysed by OSO4 shows a first-order dependence each on CAT and methionine, an inverse fl actional-order dependence on HO , and a fractional-order dependance on 0s04. " The oxidation of mono-, di-, and tri-ethanolamine (MEA, DEA, and TEA, respectively) by CAT " and sodium A-bromotoluenesulfonamide (bromamine-T, BAT) " in alkaline buffer is first order in oxidant and fractional order each in substrate and HO. The oxidation rate increased in the order di- > tri- > mono- and suitable mechanisms consistent with the kinetic data have been proposed. Osmium(Vni)-catalysed oxidation of propane-1,3-diol by CAT in alkaline medium proceeds via hydride-ion abstraction fi om the a-carbon of the diol. " ... 

A primary kinetic isotope effect (kn/ko = 6.03 at 298 K) was observed for the oxidation of formic and oxalic acids by benzyltrimethylammonium tribromide (BTMAB) to carbon dioxide. The kinetics of oxidation of pyridoxine to pyridoxal by broma-mine-T and bromamine-B ° and caffeine by bromamine-B have been investigated. 

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