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LiCl is removed by filtration from an ethereal solution of LAH, with subsequent precipitation of LAH to yield a product containing around 1% w/w LiCl. [10] An alternative preparation starts from LiH, and metallic Al instead of AlCl 3. Catalyzed by a small quantity of TiCl 3 (0.2%), the reaction proceeds well using dimethylether as solvent. This ...
The hardness of the borohydride is increased by replacing hydride groups with alkoxide groups, a reaction catalyzed by the cerium salt by increasing the electrophilicity of the carbonyl group. This is selective for ketones because they are more Lewis basic. In one application, a ketone is selectively reduced in the presence of an aldehyde.
The McMurry reaction of benzophenone. 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.
Sodium borohydride and lithium aluminium hydride are commonly used for the reduction of organic compounds. [3] [4] These two reagents are on the extremes of reactivity—whereas lithium aluminium hydride reacts with nearly all reducible functional groups, sodium borohydride reacts with a much more limited range of functional groups.
At low temperatures (below -60°C), the solution solidifies to a glassy pulverizable substance with no sharp melting point. SMEAH is a versatile hydride reducing agent. It readily converts epoxides, aldehydes, ketones, carboxylic acids, esters, acyl halides, and anhydrides to the corresponding 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.
Lithium borohydride reacts with water to produce hydrogen. This reaction can be used for hydrogen generation. [8] Although this reaction is usually spontaneous and violent, somewhat-stable aqueous solutions of lithium borohydride can be prepared at low temperature if degassed, distilled water is used and exposure to oxygen is carefully avoided. [9]