Cyanides reactions, metal cyanide reagents

Miscellaneous Reactions. Sodium bisulfite adds to acetaldehyde to form a white crystalline addition compound, insoluble in ethyl alcohol and ether. This bisulfite addition compound is frequendy used to isolate and purify acetaldehyde, which may be regenerated with dilute acid. Hydrocyanic acid adds to acetaldehyde in the presence of an alkaU catalyst to form cyanohydrin the cyanohydrin may also be prepared from sodium cyanide and the bisulfite addition compound. Acrylonittile [107-13-1] (qv) can be made from acetaldehyde and hydrocyanic acid by heating the cyanohydrin that is formed to 600—700°C (77). Alanine [302-72-7] can be prepared by the reaction of an ammonium salt and an alkaU metal cyanide with acetaldehyde this is a general method for the preparation of a-amino acids called the Strecker amino acids synthesis. Grignard reagents add readily to acetaldehyde, the final product being a secondary alcohol. Thioacetaldehyde [2765-04-0] is formed by reaction of acetaldehyde with hydrogen sulfide thioacetaldehyde polymerizes readily to the trimer. 

Cyanide reagents have been traditionally used in the metal-finishing industry and the reaction,... 

The preparation and reactions of metal cluster ions containing three or more different elements is an area with a paucity of results. The metal cyanides of Zn, Cd (258), Cu, and Ag (259) have been subjected to a LA-FT-ICR study and the Cu and Ag complex ions reacted with various reagents (2,256). The [M (CN) ]+ and [M (CN) +11 ions of copper, where n = 1-5, were calculated to be linear using the density functional method. The silver ions were assumed to have similar structures. The anions [M (CN) +1 of both copper and silver were unreactive to a variety of donor molecules but the cations M (CN) H + reacted with various donor molecules. In each case, where reactions took place, the maximum number of ligands added to the cation was three and this only occurred for the reactions of ammonia with [Cu2(CN)]+, [Cu3(CN)2]+, [Ag3(CN)2]+, and [ Ag4(CN)3]+. Most of the ions reacted sequentially with two molecules of the donor with the order of reactivity being Cu > Ag and NH3 > H2S > CO. 

Due to the sensitivity of acyl cyanides towards excess cyanide ions it is in general advisable not to use alkali metal cyanides as reagents unless special conditions are secured. Therefore, in most cases cyanides of heavy metals (low concentration of free cyanide) have been applied. These transformations require rather drastic conditions, which restricts the application mainly to the preparation of aromatic acyl cyanides. The latter can be obtained in good yield if copper(I) cyanide is heated with acid chlorides in aromatic solvents for several hours at temperatures of 160 More recent developments are based on the same strategy, but allow the application of milder conditions. In most cases acid chlorides are converted to acyl cyanides. Some reagents and the reaction conditions for their application according to equation (42) are collected in Table 12. 

A typical reaction condition for the alkaline chlorination of 1 kg (2.2 lb) of cyanide to cyanate requires 6 kg (13.2 lb) each of sodium hydroxide and chlorine. The reaction is carried out at pH 10, and at least 15 min contact time is required to drive the reaction to completion. If metal cyanide complexes are present, extended chlorination for longer periods may be necessary. Complete destruction of cyanate requires a second oxidation stage with approx 45 min retention at a pH below 8.5. The theoretical reagent requirement for this second stage is 4.1 kg (9.0 lb) of chlorine and 1.1 kg (2.4 lb) of caustic per kg (2.2 lb) of cyanide. 

Use Solvent for polymerization and cyanide reactions analytical reagent spinning polyacrylonitrile and other synthetic fibers industrial cleaners, pesticides, paint stripping hydraulic fluids preservation of cells at low temperatures diffusion of drugs, etc., into blood stream by topical application medicine (antiinflammatory) veterinary medicine plant pathology and nutrition pharmaceutical products metal-complexing agent. 

The exceptional strength of the metal-cyanide linkage makes it challenging to develop catalytic processes that involve excess CN" as reagent. The Pd-catalyzed cyanation of aryl halides discussed in Chapter 19 to form aryl nitriles initially suffered from the formation of catalytically inactive cyanide complexes containing multiple CN" ligands the reaction has been improved by the use of ZnfCN) or Kj[Fe(CN)J as the CN" source. ... 

The method is based on insertion of aqueous cyanide solutions into a SPR-packed column. The eluent containing the analyte as a metal-cyanide complex, as a reaction product of solid reagent and cyanide, was measured by flame atomic absorption spectrometry (FAAS). 

Dehalogenation of monochlorotoluenes can be readily effected with hydrogen and noble metal catalysts (34). Conversion of -chlorotoluene to Ncyanotoluene is accompHshed by reaction with tetraethyl ammonium cyanide and zero-valent Group (VIII) metal complexes, such as those of nickel or palladium (35). The reaction proceeds by initial oxidative addition of the aryl haHde to the zerovalent metal complex, followed by attack of cyanide ion on the metal and reductive elimination of the aryl cyanide. Methylstyrene is prepared from -chlorotoluene by a vinylation reaction using ethylene as the reagent and a catalyst derived from zinc, a triarylphosphine, and a nickel salt (36). 

Heterocyclic structures analogous to the intermediate complex result from azinium derivatives and amines, hydroxide or alkoxides, or Grignard reagents from quinazoline and orgahometallics, cyanide, bisulfite, etc. from various heterocycles with amide ion, metal hydrides,or lithium alkyls from A-acylazinium compounds and cyanide ion (Reissert compounds) many other examples are known. Factors favorable to nucleophilic addition rather than substitution reactions have been discussed by Albert, who has studied examples of easy covalent hydration of heterocycles. 

Vinylic copper reagents react with CICN to give vinyl cyanides, though BrCN and ICN give the vinylic halide instead." Vinylic cyanides have also been prepared by the reaction between vinylic lithium compounds and phenyl cyanate PhOCN." Alkyl cyanides (RCN) have been prepared, in varying yields, by treatment of sodium trialkylcyanoborates with NaCN and lead tetraacetate." Vinyl bromides reacted with KCN, in the presence of a nickel complex and zinc metal to give the vinyl nitrile. Vinyl triflates react with LiCN, in the presence of a palladium catalyst, to give the vinyl nitrile." ... 

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