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Sodium borohydride, also known as sodium tetrahydridoborate and sodium tetrahydroborate, [5] is an inorganic compound with the formula Na B H 4 (sometimes written as Na[BH 4]). It is a white crystalline solid, usually encountered as an aqueous basic solution. Sodium borohydride is a reducing agent that finds application in papermaking and dye ...
For example, sodium cyanoborohydride is generally incapable of reducing amides, ethers, esters and lactones, nitriles, or epoxides. [8] Therefore, it can selectively reduce some functionalities in the presence of others. Some examples of selective reduction include: Reduction of iminium ions in the presence of carbonyls [8]
Since, aldehydes reduce more easily than ketones, they require milder reagents and milder conditions. At the other extreme, carboxylic acids, amides, and esters are poorly electrophilic and require strong reducing agents. [17] The idealized equation for the reduction of a ketone by sodium borohydride is: 4 RCOR' + NaBH 4 → NaB(OCHRR') 4
The intermediate imine can be isolated or reacted in-situ with a suitable reducing agent (e.g., sodium borohydride) to produce the amine product. [2] Intramolecular reductive amination can also occur to afford a cyclic amine product if the amine and carbonyl are on the same molecule of starting material. [4]
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.
Normal bases are also nucleophiles, but often chemists seek the proton-removing ability of a base without any other functions. Typical non-nucleophilic bases are bulky, such that protons can attach to the basic center but alkylation and complexation is inhibited.
Ball-and-stick model of the tetrahydroborate anion, [BH 4] −. Borohydride refers to the anion [B H 4] −, which is also called tetrahydridoborate, and its salts. [1] Borohydride or hydroborate is also the term used for compounds containing [BH 4−n X n] −, where n is an integer from 0 to 3, for example cyanoborohydride or cyanotrihydroborate [BH 3 (CN)] − and triethylborohydride or ...
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.