Ketones reactions with hypochlorite

Methyl ketones are degraded to the next lower carboxylic acid by reaction with hypochlorite or hypobromite ions. The initial step in these reactions involves base-catalyzed halogenation. The a-haloketones are more reactive than their precursors, and rapid halogenation to the trihalo compound results. Trihalomethyl ketones are susceptible to alkaline cleavage because of the inductive stabilization provided by the halogen atoms. 

We have found that carboxylic acids are obtained advantageously from methyl ketones by reaction with hypochlorites in an aqueous medium... 

Reaction of HOCl, formed from calcium hypochlorite and CO2, with highly substituted alkenes in CH2CI2 is a convenient route to aHyUc chlorides (111). Ketones are chlorinated to a-chloroketones by reaction with HOCl Acetone initially gives CH2COCH2CI (112). Methyl ethyl ketone gives 78% CH3CHCICOCH3, 15% CH3CH2COCH2CI, and 7% dichlorides (113). 

The discovery that photolysis of hypochlorite (14) gave chloroketone (11) directly provided a short cut in this synthesis. The ketone in (11) will need to be protected during reaction with acetylene. 

The reaction can also be effected with hypochlorite ion, and this constitutes a useful method for converting methyl ketones to carboxylic acids. 

Nickel(lll) oxide, prepared from a nickel(ii) salt and sodium hypochlorite, is used for the oxidation of alkanols in aqueous alkali [46]. Residual nickel(Ii) oxide can be re-activated by reaction with sodium hypochlorite. Nickel oxides have also long been used in the manufacture of the positive pole in the Edison nickel-iron rechargeable battery, now largely superseded by die lead-acid accumulator, and in the Jungner nickel-cadmium batteries used as button cells for calculators [47]. Here, prepared nickel oxide is pressed into a holding plate of perforated nickel. Such prepared plates of nickel(lli) oxide have been proposed as reagent for the oxidation, in alkaline solution, of secondary alcohols to ketones and primary alcohols to carboxylic acids [48]. Used plates can be regenerated by anodic oxidation. 

For the sake of completeness we also note that oxygen transfer processes can be mediated by organic catalysts which can be categorized on the same basis as metal catalysts. For example, ketones catalyze a variety of oxidations with mono-peroxysulfate (KHS05) [14]. The active oxidant is the corresponding dkmrane and, hence, the reaction can be construed as involving a peroxometal pathway. Similarly, TEMPO-catalyzed oxidations of alcohols with hypochlorite [15, 16] involve an oxoammonium salt as the active oxidant, i.e. an oxometal pathway. 

Chlorination of steroid ketones has been studied in only a few cases. The reaction with elementary chlorine [iS ] is generally similar to bromination, but other sources of electrophilic chlorine have also been used. These include sulphuryl chloride, pyridine hydrochloride perchloride, and tert-butyl hypochlorite [J57]. 

Synthesis of Optically Active Epoxides. Alkaloids and alkaloid salts have been successfully used as catalysts for the asymmetric synthesis of epoxides. The use of chiral catalysts such as quinine or quinium benzylchloride (QUIBEC) have allowed access to optically active epoxides through a variety of reaction conditions, including oxidation using Hydrogen Peroxide (eq 5), Darzens condensations (eq 6), epoxidation of ketones by Sodium Hypochlorite (eq 7), halohydrin ring closure (eq 8), and cyanide addition to a-halo ketones (eq 9). Although the relative stereochemistry of most of the products has not been determined, enan-tiomerically enriched materials have been isolated. A more recent example has been published in which optically active 2,3-epoxycyclohexanone has been synthesized by oxidation with t-Butyl Hydroperoxide in the presence of QUIBEC and the absolute stereochemistry of the product established (eq 10). ... 

Aryl methyl ketones give generally high yields of acids on treatment with hypohalites [6SS, 696,698, 736. The reaction of 1,3,5-triacetylbenzene and sodium hypochlorite results in a 94% yield of trimesic acid [655], and that of methyl p-naphthyl ketone and sodium hypochlorite gives an 87-88% yield of p-naphthoic acid [695]. 4-Acetyl-4 -methoxybiphenyl is converted... 

It is known from Houben-Weyl, Methoden der organischen Chemie, volume 8, pages 415-416, that carboxylic acids can be manufactured by oxidation of methyl ketones with hypohalites in an aqueous medium. The publication recommends dispersing the ketone by means of oxidation-resistant emulsifiers or carrying out the reaction in the presence of dioxane all the examples were carried out in this way. In most cases the reaction only takes place satisfactorily with hypobromite solutions, which are more expensive and less stable than hypochlorite solutions. For this reason alone, industrial utilization of the reaction is confined to special reactions with aromatic ketones. 

Steroid (2). In this case water is needed for effective completion of the chlorination step. Chloro-3-ketosteroids (3 and 4) were obtained both from the ketones and from the corresponding alcohols by reaction with /-butyl hypochlorite in acetic acid at steam bath temperature. 

Three-membered rings with two heteroatoms are usually encountered only as reagents. Diazirines are nsefnl carbene precnrsors" - they are generally more stable than the equivalent isomeric diazo compounds, thongh they are sometimes explosive in the pure state. They can be prepared by oxidation of diaziridines that, in tnm, are available via the condensation of a ketone or aldehyde with ammonia and chloramine. Chloro-diazirines, from the reaction of amidines with hypochlorite, wiU undergo Sn2 or Sn2 displacement reactions."" ... 

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