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The cyanide source can be potassium cyanide (KCN), sodium cyanide (NaCN) or trimethylsilyl cyanide ((CH 3) 3 SiCN). With aromatic aldehydes such as benzaldehyde, the benzoin condensation is a competing reaction. The reaction is used in carbohydrate chemistry as a chain extension method for example that of D-xylose.
Cyanide is unstable in water, but the reaction is slow until about 170 °C. It undergoes hydrolysis to give ammonia and formate, which are far less toxic than cyanide: [14] CN − + 2 H 2 O → HCO − 2 + NH 3. Cyanide hydrolase is an enzyme that catalyzes this reaction.
In this reaction, the nucleophilic CN − ion attacks the electrophilic carbonyl carbon in the ketone, followed by protonation by HCN, thereby regenerating the cyanide anion. Cyanohydrins are also prepared by displacement of sulfite by cyanide salts: [2] Cyanohydrins are intermediates in the Strecker amino acid synthesis.
Cyanation of ketones or aldehydes yields the corresponding cyanohydrins, which can be done directly with the cyanide ion (the cyanohydrin reaction) or by using bisulfite, followed by displacement of sulfite: [3] [4] Cyanation of aldehyde with bisulfite. A related reaction is hydrocyanation, which installs the elements of H-CN.
Lithium aluminium hydride, commonly abbreviated to LAH, is an inorganic compound with the chemical formula Li[Al H 4] or LiAlH 4.It is a white solid, discovered by Finholt, Bond and Schlesinger in 1947. [4]
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.
The reaction mechanism was proposed in 1903 by A. J. Lapworth. [7] In the first step in this reaction, the cyanide anion (as sodium cyanide ) reacts with the aldehyde in a nucleophilic addition . Rearrangement of the intermediate results in polarity reversal of the carbonyl group, which then adds to the second carbonyl group in a second ...
The change of enthalpy of this reaction is equal to -481.06 kJ. [3] The heat provided by the main reaction serves as a catalyst for other side reactions. CH 4 + H 2 O → CO + 3 H 2 2 CH 4 + 3 O 2 → 2 CO + 4 H 2 O 4 NH 3 + 3 O 2 → 2 N 2 + 6 H 2 O. These side reactions can be minimized by only short exposures to the catalyst of the order of ...