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Aldehydes and ketones [31] can also be reduced to alcohols by LAH, but this is usually done using milder reagents such as Na[BH 4]; α, β-unsaturated ketones are reduced to allylic alcohols. [32] When epoxides are reduced using LAH, the reagent attacks the less hindered end of the epoxide, usually producing a secondary or tertiary alcohol.
Some amides can be reduced to aldehydes in the Sonn-Müller method, but most routes to aldehydes involve a well-chosen organometallic reductant. Lithium aluminum hydride reduces an excess of N,N-disubstituted amides to an aldehyde: [citation needed] R(CO)NRR' + LiAlH 4 → RCHO + HNRR' With further reduction the alcohol is obtained.
Aldehydes and ketones can be reduced respectively to primary and secondary alcohols. In deoxygenation , the alcohol group can be further reduced and removed altogether by replacement with H. Two broad strategies exist for carbonyl reduction.
The McMurry reaction is an organic reaction in which two ketone or aldehyde groups are coupled to form an alkene using a titanium chloride compound such as titanium(III) chloride and a reducing agent. The reaction is named after its co-discoverer, John E. McMurry.
Enantioselective ketone reductions convert prochiral ketones into chiral, non-racemic alcohols and are used heavily for the synthesis of stereodefined alcohols. [ 1 ] Carbonyl reduction, the net addition of H 2 across a carbon-oxygen double bond, is an important way to prepare alcohols.
Ethylene glycol protects a ketone (as an acetal) during an ester reduction, vs. unprotected reduction to a diol. A protecting group or protective group is introduced into a molecule by chemical modification of a functional group to obtain chemoselectivity in a subsequent chemical reaction. It plays an important role in multistep organic ...
The mechanism for the reduction of a nitrile to an aldehyde with DIBAL-H. The hydride reagent Diisobutylaluminium hydride, or DIBAL-H, is commonly used to convert nitriles to the aldehyde. [14] Regarding the proposed mechanism, DIBAL forms a Lewis acid-base adduct with the nitrile by formation of an N-Al bond. The hydride is then transferred to ...
The Weinreb–Nahm ketone synthesis. The major advantage of this method over addition of organometallic reagents to more typical acyl compounds is that it avoids the common problem of over-addition. For these latter reactions, two equivalents of the incoming group add to form an alcohol rather than a ketone or aldehyde. This occurs even if the ...