Hypohalites, alkaline

The reaction is applicable to the preparation of amines from amides of aliphatic aromatic, aryl-aliphatic and heterocyclic acids. A further example is given in Section IV,170 in connexion with the preparation of anthranilic acid from phthal-imide. It may be mentioned that for aliphatic monoamides containing more than eight carbon atoms aqueous alkaline hypohalite gives poor yields of the amines. Good results are obtained by treatment of the amide (C > 8) in methanol with sodium methoxide and bromine, followed by hydrolysis of the resulting N-alkyl methyl carbamate ... 

The main example presented will be the alkaline-hypohalite method as it is the easiest to acquire the necessary chemicals. It Is of interest to note that the alkaline-halide method is much easier to perform, process- wise, in that it is more forgiving of sloppy technique. 

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

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. 

The anion of this acid results from the oxidation of red phosphorus wiih hypohalites in alkaline solution ... 

The finely divided metal is soluble in hypohalites if an excess of alkali is present. At red heat, the metal combines with C z to form the dichlondc. Ruthenium(VIIl) oxide is formed when an alkaline ruthenium solution is treated with a strong oxidant, such as chlorine, or bromate ion when the Ru is in acid solution,... 

The oxidation of a methyl ketone to a carboxylic acid can be effected by the use of the haloform reaction. This involves treatment of the methyl ketone with an alkaline hypohalite reagent. A trihalomethyl ketone is initially formed which then undergoes hydrolysis under the basic conditions used. 

The availability of a-dioximes, which makes them the most common source of furazans also accounts for their widespread use in furoxan preparations. Divers oxidizing agents have been employed, including alkaline hypohalites, potassium ferricyanide, lead tetraacetate, oxides of nitrogen, cerium(IV) ion, AModosuccinimide (80H(14)1279), and phenyl-iodine(III) bistrifluoroacetate. Electrochemical oxidation has also been reported. 

Reaction of hydrogen peroxide with hypohalites has been examined in acidic solutions and, very much less completely, under alkaline conditions. The reaction of hydrogen peroxide and chlorine in hydrochloric acid proceeds according to equation (16), with a rate law (17)... 

The action of the hypohalites is generally far more drastic in alkaline solution than in acid or neutral media. As the values of the oxidation potentials (Table I) do not predict this result, the effect may be attributed in part to the action of alkali on the sugars. The oxidation is not con-... 

The hypohalite oxidations are easy to carry out. The methyl ketones, pure or dissolved in dioxane, are added to cooled or warm solutions of hypohalites in water. The reverse order of addition has also been used [736], An exothermic reaction ensues, and the haloform starts forming a heavy organic layer. The excess hypohalite is destroyed by sodium bisulfite, the heavy layer is separated, the residual haloform is removed by steam distillation, and the aqueous solution of the alkaline salt of the carboxylic acid is treated with sulfuric or hydrochloric acid (equation 420). 

Diraethyldihydroresorcinol (dimedone) is converted into 3,3-di-methylglutaric acid on treatment with sodium hypochlorite or sodium hy-pobromite. As a p-diketone, it suffers alkaline hydrolysis to 3,3-dimethyl-5-ketohexanoic acid, which undergoes regular hypohalite degradation of the methyl ketone end (equation 429) [735. Both the hydrolytic opening of the ring and the hypohalite reaction are accomplished in one step [699],... 

The Hofmann reaction involves the conversion of carboxylic primary amides to primary amines or their derivatives. Generally, alkaline hypohalites or a combination of halogens and alkaline hydroxides are used in aqueous solutions. The rearrangement generally occurs by heating. The intermediate isocyanates are easily hydrolyzed to amines under the reaction conditions, as shown in Scheme 3. When sodium methoxide in methanol is used in place of aqueous alkaline hydroxide, the corresponding methylurethanes are formed and may be hydrolyzed to yield amines. 

Chakrabartly, S. K. Alkaline Hypohalite Oxidations, in Oxidation in Organic Chemistry, Part C (ed. Trahanovsky, W. S.), 343-370 (Academic Press, New York, 1978). 

Hofmann Reaction.72 In contrast to the molecular rearrangements which have been discussed, the Hofmann reaction proceeds in an alkaline medium. In this reaction an amide is treated with a hypohalite solution, and, under the usual conditions of the reaction, an amine with one less carbon atom is obtained ... 

Several prespotter formulations are disclosed in the patent literature. Acidic compositions that contain a mixture of nonionic surfactants and hydrotropes [163], thickened alkaline products with hypohalite bleaches [164,165], and enzyme-containing formulas [ 166] have all been developed for use as prespotters. Although... 

The procedure for chlorination, bromination, and iodination of acetylenes in alkaline hypohalite solution432 is applicable to alkynes, alkynols, and acetylenemonocarboxylic acids with at least one hydrogen on the C=C group. 

Gaseous alkynes are passed into alkaline (up to 23% referred to KOH) hypo-halite solution at 0°. Liquid alkynes or solutions of solid ones in light petroleum are shaken or stirred with the hypohalite solution at room temperature, sometimes with addition of an emulsifier. The necessary hypohalite solutions are prepared as follows 432... 

Alkali cleaves, a ,a>trihalomethyl ketones to trihalomethanes and carboxylic acids. This haloform reaction 714 also occurs directly if alkaline hypohalite solution is allowed to react with a methyl ketone and has preparative importance as a method of obtaining carboxylic acids from methyl ketones. 

Hypohalites in water or alkaline solutions are effective in producing a number of different types of halogenation. The controlling factor in many of these reactions is hydrogen-ion concentration. 

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