Cyanide reaction with

Addition of cyanide leads to the reversible formation of a cyanohydrin. Only a catalytic amount of the cyanide anion in the presence of hydrogen cyanide is required (as the cyanide anion is regenerated). 

The position of the equilibrium depends on the structure of the carbonyl compound. Nucleophilic addition is favoured by small alkyl groups attached to the carbonyl group and also by electron-withdrawing groups (e.g. CC13), which increase the 8+ character of the carbonyl carbon atom (see Section 8.3.1). 

Cyanohydrins are useful because they can be converted into other functional groups, e.g. hydroxy acids (see Section 9.9 for the reaction mechanism). 

The reaction of cyanide with aromatic aldehydes leads to the benzoin condensation reaction. The product from this reaction is called benzoin. 

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The thiosulfate reaction with cyanide to give thiocyanate is the basis for the use of thiosulfate as an antidote in cyanide poisoning ... 

It is often advantageous to proceed to a desired product through two nucleophilic displacements rather than directly when one can exploit a difference in the reactivity of two leaving groups. An example is the conversion of 4-chloro-2,6-dimethoxypyrimidine (109) (not satisfactorily reactive with sulfanilamide anion) by means of trimethylamine into the more reactive trimethylammonio derivative 110. Conversion of chloro-quinohnes and -pyrimi-dines into nitriles is best accomplished by conversion (with sulfite) into the sulfonic acids before reaction with cyanide. 

The a-bromo or a-chloro carboxylic acids 2 are versatile intermediates for further synthetic transformations. For example they can be converted into a-hydroxy carboxylic acids by reaction with water by reaction with cyanide a-cyanocarboxylic acids 7 are obtained, which can be further converted to... 

The HOI would be rapidly reduced by iodide and the Mn(V) species would be expected either to disproportionate or to oxidise further iodide. This reaction scheme has features in common with the analogous reaction with cyanide ion discussed below. 

Figure 14.24 Fluorescent silica nanobubbles have been created using gold nanoparticle seeds that initially are coated by adsorption with a fluorescent dye. The particles then are capped by a layer of silica by polymerizing TEOS and entrapping the dye molecules within it. Finally, the gold core is dissolved by reaction with cyanide, leaving behind hollow fluorescent silica nanobubbles.

However, selenium and tellurium do not react with hydrogen, so the hydrogen compounds are prepared by reacting the elements with a metal, then treating it with an acid. Selenium and tellurium undergo addition reactions with cyanides to yield selenocyanates and tellurocyanates ... 

Reissert compounds (>70%), derived from benzimidazole, phthalazine, quinoline and isoquinoline, have been prepared by a simple catalysed one-pot N-acylation of the appropriate heterocycle, followed by reaction with cyanide ion [e.g. 101-103],... 

Long-lived homogeneous Pd(0)f4 [L = P(Ph)3] catalysts for the cyanation of aryl chlorides (295) (X = Cl) have been developed, which are activated by cathodic reduction (Scheme 113) [433]. A high temperature, 130 °C, and a high-boihng solvent, dimethylformamide, are required because Pd does not insert into the aryl C—Cl bond at lower temperatures. Cat-alytically inactive metal species formed in undesirable side reactions with cyanide are electrochemically restored to a catalytically... 

Consequently, the triplet lifetime of 2-nitrothiophene in water is ca. 5 10 s and ca. 10 s in 0-01 M KCN. Owing to the extremely fast reaction with cyanide ion, the triplet lifetime, which in water is reasonably long, appears to be considerably reduced in the presence of even moderate cyanide concentrations. 

This is a synthetically useful procedure because the a-halo acids are useful starting materials for other reactions. For example, the addition of hydroxide ion leads to the replacement of the halogen with an -OH group. The reaction with ammonia replaces the halogen with -NH2. The reaction with cyanide ion, CN , converts the halide to a nitrile. Figure 12-33 illustrates this reaction. 

Elemental composition Ni 53.00%, C 21.69%, N 25.30%. The compound may be identified by x-ray and selective chemical reactions with cyanide ions. Nickel may be analyzed in an acidified aqueous solution after it is solubilized with concentrated nitric acid or aqua regia (See Nickel). 

Elemental composition Ag 75.26%, Cl 24.74%. The salt is dissolved in concentrated sulfuric acid, diluted, and analyzed for silver (see Silver). Solid powder may be characterized by its physical properties and its reaction with cyanide ion, forming the complex ion [Ag(CN)2]. ... 

Notably, as illustrated in Scheme 124, enantiofaces of aldehydes can be differentiated by a chiral rhenium template to result in stereoselective reaction with cyanide ion (297). The rhenium Lewis acid element forms stereoisomeric it complexes with aldehydes, which are convertible via... 

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