Ketones to hydrocarbons

Low-valent nitrogen and phosphorus compounds are used to remove hetero atoms from organic compounds. Important examples are the Wolff-Kishner type reduction of ketones to hydrocarbons (R.L. Augustine, 1968 D. Todd, 1948 R.O. Hutchins, 1973B) and Barton s olefin synthesis (p. 35) both using hydrazine derivatives. 

Reduction of Aldehydes and Ketones to Hydrocarbons. Deep hydrogenation of aldehydes and ketones removes the oxygen functionahty and produces the parent hydrocarbons. 

WOLFF - KISHNER HUANG MINLON Reduction Reduction ol ketones to hydrocarbons by heating with NHaNH2 and aqueous KOH (Wotff-Kishnei) or KOH in ethytene glycol (Huang-Minlon)... 

Two techniques, electrochemical reduction (section IIl-C) and Clem-mensen reduction (section ITI-D), have previously been recommended for the direct reduction of isolated ketones to hydrocarbons. Since the applicability of these methods is limited to compounds which can withstand strongly acidic reaction conditions or to cases where isotope scrambling is not a problem, it is desirable to provide milder alternative procedures. Two of the methods discussed in this section, desulfurization of mercaptal derivatives with deuterated Raney nickel (section IV-A) and metal deuteride reduction of tosylhydrazone derivatives (section IV-B), permit the replacement of a carbonyl oxygen by deuterium under neutral or alkaline conditions. 

For the reduction of aliphatic ketones to hydrocarbons several methods are available reduction with triethylsilane and boron trifluoride [772], Clemmensen reduction [160, 758] (p. 28), Wolff-Kizhner reduction [280, 281, 759] (p. 34), reduction of p-toluenesulfonylhydrazones with sodium borohydride [785], sodium cyanoborohydride [57i] or borane [786] (p. 134), desulfurization of dithioketals (jaeicaipioles) [799,823] (pp. 130,131) and electroreduction [824]. 

Reduction of aromatic ketones to hydrocarbons occurs very easily as the carbonyl group is directly attached to an aromatic ring. In these cases reduction produces benzylic-type alcohols which are readily hydrogenolyzed to hydrocarbons. This happens during catalytic hydrogenations as well as in chemical reductions. 

However, most frequently used methods for reduction of aromatic ketones to hydrocarbons are, as in the case of other ketones, Clemmensen reduction [160, 161, 758, 843, 844] Procedure 31, p. 213), Wolff-Kizhner reduction [280,281,282, 759, 774,845] Procedure 45, p. 216), or reduction of p-toluene-sulfonylhydrazones of the ketones with lithium aluminum hydride [811, 812] or with borane and benzoic acid [786]. 

Reduction of ketones to hydrocarbons has been used to elucidate the carbon skeleton of the ketone mol-... 

We now have methods of reducing ketones to hydrocarbons in acidic, alkaline, and neutral solutions. This is useful since we may have molecules which are sensitive to some of these conditions. Which methods would you use for these reactions ... 

Rhodium(II) acetate catalyzes C—H insertion, olefin addition, heteroatom-H insertion, and ylide formation of a-diazocarbonyls via a rhodium carbenoid species (144—147). Intramolecular cyclopentane formation via C—H insertion occurs with retention of stereochemistry (143). Chiral rhodium (TT) carboxamides catalyze enantioselective cyclopropanation and intramolecular C—N insertions of CC-diazoketones (148). Other reactions catalyzed by rhodium complexes include double-bond migration (140), hydrogenation of aromatic aldehydes and ketones to hydrocarbons (150), homologation of esters (151), carbonylation of formaldehyde (152) and amines (140), reductive carbonylation of dimethyl ether or methyl acetate to 1,1-diacetoxy ethane (153), decarbonylation of aldehydes (140), water gas shift reaction (69,154), C—C skeletal rearrangements (132,140), oxidation of olefins to ketones (155) and aldehydes (156), and oxidation of substituted anthracenes to anthraquinones (157). Rhodium-catalyzed hydrosilation of olefins, alkynes, carbonyls, alcohols, and imines is facile and may also be accomplished enantioselectively (140). Rhodium complexes are moderately active alkene and alkyne polymerization catalysts (140). In some cases polymer-supported versions of homogeneous rhodium catalysts have improved activity, compared to their homogenous counterparts. This is the case for the conversion of alkenes direcdy to alcohols under oxo conditions by rhodium—amine polymer catalysts... 

REDUCTION OF KETONES TO HYDROCARBONS WITH TRIETHYLSILANE m-NITROETHYLBENZENE... 

Catalytic hydrogenation of alkyl aryl ketones and diaryl ketones to hydrocarbons is most convenient provided that high-pressure apparatus is available. Coppoalumina and copper-chromium oxide catalysts have been used. At 100-130° alcohols are formed, but at 180-250° excellent yields of the corresponding hydrocarbons are obtained. ... 

Three common procedures are available for the transformation of aldehydes and ketones to hydrocarbons (1) reduction by zinc and hydrochloric acid (Clemmensen), (2) reduction by hydrazine in the presence of a base (Wolff-Kishner), and (3) catalytic hydrogenation. In view of the complicated mixtures obtained by the polyalkylation of benzene by the Friedel-Crafts reaction (method 1), reduction of alkyl aryl ketones is the most reliable method for the preparation of di- and poly-alkylbenzenes. 

Reduction of ketones to hydrocarbons by heating with NH2NH2 and aqueous KOH (Wolff-Kishner) or KOH in ethylene glycol (Huang Minion) (see 1st edition). 

Reduction of aldehydes or ketones to hydrocarbons can be accomplished using the Clemmensen reaction (Zn/Hg/HCI), the Wolff-Kishner reaction (hydrazine, KOH), Raney nickel/Hj reduction of a dithioacetal, or palladium-catalyzed hydrogenolysis (aryl ketones only). 

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