Secondary alcohols reduction

Oxidant) was introduced into olefin to form the corresponding alcohol while another oxygen atom was reduced by two hydrogen atoms from secondary alcohol (Reductant) to form water (Scheme 1). Then, the amount of water formed during the reaction was measured by taking the hydration of 1-decene in 2-propanol catalyzed by Co(ecbo)2- It was observed then that the amount of water increased as the hydration proceeded and nearly two moles of water were formed along with one molar of hydrated product, 2-decanol. 

Oxidation-Reduction Hydration of olefins into the corresponding hydrated compounds using molecular oxygen (Oxidant) and secondary alcohol (Reductant) in the presence of a catalytic amount of bis(l,3-diketonato)cobalt(II) was descnbed in the poor section Based on the detailed observation on the hydration reaction, it was revealed that one... 

Aliphatic hydrocarbons can be prepared by the reduction of the readily accessible ketones with amalgamated zinc and concentrated hydrochloric acid (Clemmensen method of reduction). This procedure is particularly valuable for the prep>aration of hydrocarbons wdth an odd number of carbon atoms where the Wurtz reaction cannot be applied with the higher hydrocarbons some secondary alcohol is produced, which must be removed by repeated distillation from sodium. 

Clemmensen reduction of aldehydes and ketones. Upon reducing aldehydes or ketones with amalgamated zinc and concentrated hydrochloric acid, the main products are the hydrocarbons (>C=0 —> >CHj), but variable quantities of the secondary alcohols (in the case of ketones) and unsaturated substances are also formed. Examples are ... 

Unsaturated hydrocarbons are present in nearly all products of the Clemmensen reduction of aromatic ketones and must be removed, if the hydrocarbon is requiral pure, by the above process. Secondary alcohols, often produced m small amount are not appreciably steam-volatile. 

Reduction of ketones, with zinc powder and alcoholic sodium hydroxide leads to secondary alcohols, for example ... 

Secondary alcohols may be oxidised to the corresponding ketones with aluminium ferf.-butoxlde (or tsopropoxlde) In the presence of a large excess of acetone. This reaction Is known as the Oppenauer oxidation and Is the reverse of the Meerweln - Ponndorf - Verley reduction (previous Section) it may bo expressed ... 

The hydrogenolyaia of cyclopropane rings (C—C bond cleavage) has been described on p, 105. In syntheses of complex molecules reductive cleavage of alcohols, epoxides, and enol ethers of 5-keto esters are the most important examples, and some selectivity rules will be given. Primary alcohols are converted into tosylates much faster than secondary alcohols. The tosylate group is substituted by hydrogen upon treatment with LiAlH (W. Zorbach, 1961). Epoxides are also easily opened by LiAlH. The hydride ion attacks the less hindered carbon atom of the epoxide (H.B. Henhest, 1956). The reduction of sterically hindered enol ethers of 9-keto esters with lithium in ammonia leads to the a,/S-unsaturated ester and subsequently to the saturated ester in reasonable yields (R.M. Coates, 1970). Tributyltin hydride reduces halides to hydrocarbons stereoselectively in a free-radical chain reaction (L.W. Menapace, 1964) and reacts only slowly with C 0 and C—C double bonds (W.T. Brady, 1970 H.G. Kuivila, 1968). 

Reduction to alcohols (Section 15 2) Aide hydes are reduced to primary alcohols and ketones are reduced to secondary alcohols by a variety of reducing agents Catalytic hydrogenation over a metal catalyst and reduction with sodium borohydride or lithium aluminum hydride are general methods... 

Secondary alcohols (C q—for surfactant iatermediates are produced by hydrolysis of secondary alkyl borate or boroxiae esters formed when paraffin hydrocarbons are air-oxidized ia the presence of boric acid [10043-35-3] (19,20). Union Carbide Corporation operated a plant ia the United States from 1964 until 1977. A plant built by Nippon Shokubai (Japan Catalytic Chemical) ia 1972 ia Kawasaki, Japan was expanded to 30,000 t/yr capacity ia 1980 (20). The process has been operated iadustriaHy ia the USSR siace 1959 (21). Also, predominantiy primary alcohols are produced ia large volumes ia the USSR by reduction of fatty acids, or their methyl esters, from permanganate-catalyzed air oxidation of paraffin hydrocarbons (22). The paraffin oxidation is carried out ia the temperature range 150—180°C at a paraffin conversion generally below 20% to a mixture of trialkyl borate, (RO)2B, and trialkyl boroxiae, (ROBO). Unconverted paraffin is separated from the product mixture by flash distillation. After hydrolysis of residual borate esters, the boric acid is recovered for recycle and the alcohols are purified by washing and distillation (19,20). 

Reduction. Most ketones are readily reduced to the corresponding secondary alcohol by a variety of hydrogenation processes. The most commonly used catalysts are palladium, platinum, and nickel For example, 4-methyl-2-pentanol (methyl isobutyl carbinol) is commercially produced by the catalytic reduction of 4-methyl-2-pentanone (methyl isobutyl ketone) over nickel. 

The reaction between perfluoraarylmagnesium halides and esters of dicar-boxyltc acids gives, besides the expected keto esters, secondary alcohols as reduction products [29, 30, 31] (equation 10) Such a reduction is enhanced by higher temperature The hydrogen necessary for reduction comes from the solvent, diethyl ether, which is dehydrogenated to ethyl vinyl ether, which has been identified as a by-product in a similar reaction of perfluoroalkyllithium compound [52]... 

The reduction of ketones to secondary alcohols and of aldehydes to primary alcohols using aluminum alkoxides is called the Meerw>ein-Ponndorf-Verley reduction. The reverse reaction also is of synthetic value, and is called the Oppenauer oxidation. ... 

The constitution of verbenone has been established by its reduction to the corresponding saturated secondary alcohol, dihydroverbenol, and into the corresponding saturated ketone, or dihydroverbenone. 

The solvent for ammonia may have an important influence. In reduction of C,o unsaturated dinitriles to primary amines over ruthenium-on-alumina, ammonia-/-butanol proved the preferred system normal alcohols gave poor rates and secondary alcohols produced N-alkylated products 18). 

Identify the target alcohol as primary, secondary, or tertiary. A primary alcohol can be prepared by reduction of an aldehyde, an ester, or a carboxylic acid a secondary alcohol can be prepared by reduction of a ketone and a tertiary alcohol can t be prepared by reduction. 

Perhaps the most valuable reaction of alcohols is their oxidation to yield car-bony compounds—the opposite of the reduction of carbonyl compounds to yield alcohols. Primary alcohols yield aldehydes or carboxylic acids, secondary alcohols yield ketones, but tertiary alcohols don t normally react with most oxidizing agents. 

Alcohols are among the most versatile of all organic compounds. They occur widely in nature, are important industrial 7, and have an unusually rich chemistry. The most widely used methods of alcohol synthesis start with carbonyl compounds. Aldehydes, ketones, esters, and carboxylic acids are reduced by reaction with LiAlH4. Aldehydes, esters, and carboxylic acids yield primary alcohols (RCH2OH) on reduction ketones yield secondary alcohols (R2CHOH). 

Aldehydes and ketones are among the most important of ail compounds, both in biochemistry and in the chemical industry. AUdehydes are normally prepared in the laboratory by oxidation of primary alcohols or by partial reduction of esters. Ketones are similarly prepared by oxidation of secondary alcohols or by addition of diorganocopper reagents to acid chlorides. 

The cydization to structurally defined, soluble LPPP then takes place in a two-step sequence, consisting of reduction of the keto group followed by ring closure of the secondary alcohol groups of 14 in a Friedcl-Crafts-type alkylation. 

Asymmetric hydrogenolysis of epoxides has received relatively little attention despite the utility such processes might hold for the preparation of chiral secondary alcohol products. Chan et al. showed that epoxysuccinate disodium salt was reduced by use of a rhodium norbornadiene catalyst in methanol/water at room temperature to give the corresponding secondary alcohol in 62% ee (Scheme 7.31) [58]. Reduction with D2 afforded a labeled product consistent with direct epoxide C-O bond cleavage and no isomerization to the ketone or enol before reduction. 

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