Ketones, methyl with hypoiodites

Another variant of the synthesis of the diacid (126) starts from 17a-ketones methylated at 0 3 (125). Here the opening of ring D is carried out either by the action of alkali-metal hypoiodites (Schemes 7, 80) or by the formation from (125) of the 17-oxime by the action of isoamyl nitrite with subsequent Beckmann rearrangement and hydrolysis (Scheme 113). 

For years the iodoform test was a laboratory method for the identification of a methyl ketone (a ketone where one of the R groups is a methyl group). A positive test produced the compound iodoform. Iodoform, CHI3, is a yellow precipitate with a characteristic odor. The oxidation utilizes sodium hypoiodite, which is generated in situ by the reaction of iodine with sodium hydroxide. Figure 10-35 shows an example of the iodoform test. 

The vast majority of the preparative oxidations of methyl ketones are carried out with alkaline hypochlorites or hypobromites. The same effect can be achieved by alkaline hypoiodites, but examples are scarce. One example is the opening of the D ring of benzyl estrone to benzyl marrianolic... 

Hypoiodites are used for qualitative tests for methyl ketones (Lieben test). For this purpose, a compound to be tested is stirred with an aqueous solution of sodium hydroxide (80 mol/mol of methyl ketone). Iodine (4.5 mol of 12) is added portionwise with stirring, and the mixture is set aside for 20 min at 25 °C before acidification. In the presence of a methyl keto group, a yellow heavy precipitate of iodoform settles at the bottom of the test tube. Iodoform can be identified easily not only by its characteristic smell but also by its melting point (120-123 °C) [1173], This test applies not only to methyl ketones but to any compound that can be converted in the reaction medium into a species containing the COCH3 group, for example, isopropyl or ethyl alcohol. 

In problem (b), the product desired is benzoic acid which is synthesized by the oxidation of methyl ketones. This reaction involves sodium hypoiodite (NaOI) and sulfuric acid (HaSOi,) wherein NaOI has the special property of only attacking the methyl group on methyl ketones. The methyl group is then tri-halogenated with the iodine and the -CI3 group is replaced by an -C a portion. This compound formed is known as the intermediate and must be treated with concentrated sulfuric acid to complete the oxidation to a carboxylic acid. Problem (b) can now be solved illustrating the entire synthesis ... 

OBr [Pg.134]

A mixture of cyclohexyl methyl ketone and a soln. of Na-hypoiodite (prepared from iodine, NaOH, KI, and water) containing 3 times the theoretical amount of alkali warmed 4 hrs. at 50-60° with vigorous stirring cyclohexylglycolic... 

Two-carbon ring expansions of the five-, six,- and seven-membered rings of P-indanone, P-tetralone, and P-suberone can be achieved via a sensitized [2-1-2]-photoaddition of the trimethylsilyl enol ethers of the cyclic ketones with acrylonitrile or methyl acrylate followed by P-fragmentation of the alkoxyl radicals generated from the hypoiodites of the resulting cyclobutanols and mercury(ll) oxide-iodine, as outlined in Scheme 72. The ring expansion of the cyclobutanol derived from P-indanone enol ether and acrylonitrile gave an a,P-unsaturated nitrile. 

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