Halogens hypohalites

Hydrogen peroxide has been shown to oxidize halide ions to halogens or positive halogen species in the presence of a metal catalyst. The generated halogens/hypohalites can then oxidize hydrocarbons to form alkyl or aryl halides. 

Among the numerous mediator systems, halide ions show the broadest applicability. The internal electrochemical generation of the active species, i.e., molecular halogen, hypohalite ions, and halonium ions, is always possible by the in-cell method without... 

The latter is an exttemely reactive species. Trifluoroacetate is a good leaving group and facilitates cleavage of the O—Br bond. The acyl hypohalites are also the active halogenating species in solutions of the hypohalous acids in carboxylic acids, where they exist in equilibrium. 

O-X Alkyl perchlorates. Chlorite salts. Halogen oxides, Hypohalites, Perchloric acid, Perchloryl Compounds... 

ForCb, Bt2 and h, K. c is 4.2 x 10- 7.2 x 10 and 2.0 x 10 mol 1 respectively, thereby favouring the free halogens, whereas Kaik is 7.5 X lO, 2 X lO and 30mol I respectively, indicating a tendency to disproportionation which is overwhelming for CI2 but progressively less pronounced for Br2 and I2. In actuality the situation is somewhat more complicated because of the tendency of the hypohalite ions themselves to disproportionate further to produce the corresponding halite ions ... 

Solutions of the corresponding hypohalites can be made by the rapid disproportionation of the individual halogens in cold alkaline solutions (p. 856) ... 

In addition to the applications indicated on p. 858. hypohalous acids are useful halogenating agents for Ixjth aromatic and aliphatic compounds. HOBr and HOI are usually generated in silii. The ease of aromatic halogenation increa.ses in the sequence OCl < OBr < Ol and is facilitated by salts of Pb or Ag. Another well-known reaction of hypohalites is their cleavage of methyl ketones to form carboxylates and haloform ... 

Hypohalite ions, XO, are formed when a halogen is added to the aqueous solution of a base. Sodium hypochlorite, NaClO, is produced from the electrolysis of brine when the electrolyte is rapidly stirred, and the chlorine gas produced at the... 

Addition of Hypohalous Acids and Hypohalites (Addition of Halogen, Oxygen)... 

Halogenations are strongly catalyzed by mercuric acetate or trifluoroacetate. These conditions generate acyl hypohalites, which are the active halogenating agents. The trifluoroacetyl hypohalites are very reactive reagents. Even nitrobenzene, for example, is readily brominated by trifluoroacetyl hypobromite.19... 

Superior antimicrobial activity in alkaline pH (seawater is always above pH 8), in the presence of nitrogenous organic matter, and due to lower volatility has been documented for bromine antimicrobials3 4. The pKa acid dissociation constants for HOC1 and HOBr are 7.4 and 8.7, respectively the dissociated acids are less effective antimicrobials4,5. Undissociated hypohalous acids are more effective because they are far better halogenating agents compared to the dissociated anion (hypohalite). Table 1 shows the effect of acid dissociation on antimicrobial performance in well-controlled laboratory experiments. 

See Other HALOGEN OXIDES, HYPOHALITES, IODINE COMPOUNDS... 

Although solutions containing the hypohalous acids are produced by dissolving the halogens in water, the process must be carried out at low temperature. Hypohalites are also produced when halogens react in basic solution. 

AMINIUM PERCHLORATES CHLORITE SALTS HALOGEN OXIDES HYPOHALITES PERCHLORYL COMPOUNDS... 

In general, ketones don t undergo oxidation however, methyl ketones undergo a haloform reaction. In a haloform reaction, the oxidation converts the methyl group to a haloform molecule (usually iodoform (CHI3)), which leaves the Ccirbon backbone one carbon atom shorter. The oxidant in a haloform reaction is sodium hypohalite (NaOX), which forms by the reaction of sodium hydroxide (NaOH) with a halogen (X, where X = Cl, Br, or 1). 

A convenient procedure for the oxidation of primary and secondary alcohols was reported by Anelli and co-workers (8,9). The oxidation was carried out in CH2CI2 with an aqueous buffer at pH 8.5-9.5 utilizing 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO, 1) as the catalyst and KBr as a co-catalyst. The terminal oxidant in this system was NaOCl. The major disadvantage of using sodium hypochlorite or any other hypohalite as a stoichiometric oxidant is that for each mole of alcohol oxidized during the reaction one mole of halogenated salt is formed. Furthermore,... 

The traditional method of oxidizing hydrazine derivatives makes use of halogens or hypohalites as oxidizing agents. The techniques range from the preparation of l,l -azobis(l-cyclohexanenitrile) by the addition of bromine to an alcoholic hydrochloric acid solution of the corresponding hydrazine [89], through the use of bromine water [90, 91] to oxidations with sodium hypo-bromite [64] or sodium hypochlorite [92]. 

Until recently, in the chemistry of hypochlorites, there has been particular emphasis on the chemistry of -butyl hypochlorite. Hypochlorites in general were ignored. However, in their classical paper on the photolysis of organic nitrites,48 Barton et al. adumbrated a photochemical rearrangement of hypohalites of the type (A) —> (B) (X = any halogen). A year later applications of this principle were described... 

Hypohalites IRO-Hal) are similar to nitrates (see p. 155 in their photochemical behaviour. Ultraviolet irradiation gives an (n,Ji > excited state that cleaves to form an alkoxy radical and a halogen atom. The radical may undergo alpha-cleavage before recombination with the halogen atom occurs, and this accounts for the formation of 5-iodopentanal (5.69) from the hypoiodite of cydopentanol such hypoiodites are generated in situ from the alcohol. Iodine and merturyfll oxide. In open-chain systems the alkoxy radical can... 

CH2 CH.C=CX)n, C4H3X, where X is a halogen. Prepn is from hypohalites and vinyacetyl-ene. According to Blatt (Ref 2) these polymers are expl... 

The acyl hypohalit reaction with iodine ob a halogen component is the well-known Prevost reaction,18i0 whioh has found some application during recent years in the field of natural prodwtB.. u. . w. In thiB ease the acyl hypoholite is acetyl hypoiodite, generated by reaction of iodine with silver nitrate in glacial acetic arid (Eq. 130). 

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