Oxidation with sodium hypobromite

Conversion of Methyl Ketones into Carboxylic Acids with One Less Carbon [736] 

A solution of sodium hypobromite, prepared by dissolving 42 g (1.05 mol) of sodium hydroxide in 200 mL of water and adding 15 mL (47 g, 0.29 mol) of bromine at 0 C, is added over a 30-min period to a stirred solution of 15.0 g (0.066 mol) of 4-(p-methoxyphenyl)acetophenone in 150 mL of dioxane. During the addition, the temperature is allowed to rise to 35-40 °C. After being stirred for an additional 15 min, the mixture is treated with enough sodium bisulfite to destroy the excess of sodium hypobromite. Water (1 L) is added, and 200 mL of water is distilled off to remove the bromoform and some dioxane. Acidification of the hot solution and subsequent cooling yields 13.8 g (91%) of 4-(p-methoxyphenyl)benzoic acid, mp 247-248 °C. 

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The pinacolone may be employed for the preparation of trimethylacetlc acid (plvallc acid) by oxidation with sodium hypobromite solution ... 

Alicyclic hydroxamic acids undergo several specific oxidative cleavage reactions which may be of diagnostic or preparative value. In the pyrrolidine series compounds of type 66 have been oxidized with sodium hypobromite or with periodates to give y-nitroso acids (113). Ozonolysis gives the corresponding y-nitro acids. The related cyclic aldonitrone.s are also oxidized by periodate to nitroso acids, presumably via the hydroxamic acids.This periodate fission was used in the complex degradation of J -nitrones derived from aconitine. 

Aminopyrazine 1-oxide has been prepared from 3-carbamoylpyrazine 1-oxide with sodium hypobromite (108, 547a), and the interaction of iminodiacetonitrile ... 

The cuprate-mediated reaction of l-phenoxy-(2i ,7)-octadiene with propylmag-nesium chloride leads to undeca-l,6-diene, which may be selectively oxidised at the terminal double bond in a Wacker oxidation. Further oxidation with sodium hypobromite (haloform reaction) and reduction with lithium aluminium hydride then lead to (5 )-decenol, which can be esterified with acetic anhydride. The alcohol and the acetate are then mixed corresponding to their ratio in the natural pheromone composition. [187]... 

Good results are obtained by the oxidation of the commercially available cyclo-propyl methyl ketone with sodium hypobromite solution, and the preparation may be regarded as an excellent example of the oxidation of the —COCH, group to — OOH ... 

Appropriate pyrido[2,3-d]pyrimidin-5-ones with formyl groups in the 6-position have been oxiized to piromidic (68) and pipemidic (69) acids, or to intermediates for these, using moist silver oxide, chromium trioxide (potassium dichromate), potassium permanganate or, alternatively, sodium chlorite/hydroxylamine-O-sulfonic acid. 6-Acetyl groups have been similarly oxidized using sodium hypobromite in aqueous dioxane, whilst 2-acetyl groups give dimethylaminomethylene derivatives en route to 2-pyrazolylpyrido[2,3-d]pyrimidines. 

Phenoxy acetophenone, 46, 94 Phenylacetyleue, oxidative coupling to diphenyldiacetylene, 46, 39 partial reduction to styrene using palladium catalyst, 46, 90 reaction with sodium hypobromite to yield phenylbromoethyne, 46,86... 

Dicarboxyl starch can also be made by oxidation with sodium hypochlorite or hypobromite (see reference 116). Reaction with hypochlorite is accelerated by use of catalytic amounts of sodium bromide.123,124... 

Estimation.—Gravimetric Methods.—A convenient method consists in decomposing a solution of nickel salt with sodium hypobromite as explained on p. 118, and either reducing the oxide in a current of hydrogen and weighing as metallic nickel, or by ignition in air and... 

In general, the properties of these compounds and those of their benzenoid analogues are similar. Thus, isothiazole aldehydes and ketones behave normally and form the usual derivatives. Imidazole-2-carbaldehyde exists as a hydrate in aqueous solution. 4-Acetyloxazoles are oxidized to the corresponding acids with sodium hypobromite. Thiazole aldehydes undergo the benzoin and Cannizzaro reactions. Compounds with aldehyde groups to an NH group sometimes form dimers, e.g., as in the 1,2,4-triazole series 615. 

The synthesis of BENZYL ISOCYANIDE from benzaldehyde via reductive amination with 5-aminotetrazole followed by oxidation of the resultant amine with sodium hypobromite provides a general method for the synthesis of isocyanides. The preparation of BIS(2,2,2-TRICHLOROETHYL) AZODICARBOXYLATE makes available an alternative to dimethyl azodicarboxylate that is not only more reactive in Diels-Alder reactions but whose ester groups can be removed under neutral conditions. 

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