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Lithium borohydride (LiBH 4) is a borohydride and known in organic synthesis as a reducing agent for esters.Although less common than the related sodium borohydride, the lithium salt offers some advantages, being a stronger reducing agent and highly soluble in ethers, whilst remaining safer to handle than lithium aluminium hydride.
An ester of carboxylic acid.R stands for any group (organic or inorganic) and R′ stands for organyl group.. In chemistry, an ester is a compound derived from an acid (organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group (−OH) of that acid is replaced by an organyl group (−R).
The final step in the reduction of carboxylic acids and esters is hydrolysis of the aluminium alcoxide. [8] Esters (and amides) are more easily reduced than the parent carboxylic acids. Their reduction affords alcohols and amines, respectively. [9] The idealized equation for the reduction of an ester by lithium aluminium hydride is:
It has also been shown to reduce aromatic esters to the corresponding alcohols as shown in eq 6 and 7. LiBHEt 3 also reduces pyridine and isoquinolines to piperidines and tetrahydroisoquinolines respectively. [7] The reduction of β-hydroxysulfinyl imines with catecholborane and LiBHEt 3 produces anti-1,3-amino alcohols shown in (8). [8]
The selectivity of this reagent is illustrated by its reduction of all three methylcyclohexanones to the less stable methylcyclohexanols in >98% yield. Under certain conditions, L-selectride can selectively reduce enones by conjugate addition of hydride, owing to the greater steric hindrance the bulky hydride reagent experiences at the carbonyl ...
The Bouveault–Blanc reduction is a chemical reaction in which an ester is reduced to primary alcohols using absolute ethanol and sodium metal. [1] It was first reported by Louis Bouveault and Gustave Louis Blanc in 1903. [2] [3] [4] Bouveault and Blanc demonstrated the reduction of ethyl oleate and n-butyl oleate to oleyl alcohol. [5]
The reaction is performed in aprotic solvents with a high boiling point, such as benzene and toluene, in an oxygen-free atmosphere (as even traces of oxygen interfere with the reaction path and reduce the yield). Protic solvents effect the Bouveault-Blanc ester reduction rather than condensation.
[1] [2] This is an example of a reductive decarboxylation. Using this reaction it is possible to remove carboxylic acid moieties from alkyl groups and replace them with other functional groups . [ 3 ] [ 4 ] (See Scheme 1) This reaction is named after its developer, the British chemist and Nobel laureate Sir Derek Barton (1918–1998).