Soluble cyanide source

Second, the addition of a catalytic amount of second metal salts, especially Cul, to the reaction mixture accelerates the Pd°-catalyzed cyanation.t t f Nitrile solvents are the best reaction media for the Cu+ cocatalyzed processes (Scheme 22). The activating effect of Cu is attributed to the role of vehicle transferring the CN between the poorly soluble cyanide source and the Pd intermediate. The same role exerted by the Pd species is also proposed for the Pd°-catalyzed reaction, CuCN itself is an effective source of cyanide (Scheme 23). ... 

The conversion of co-hydroxyalkanals to the corresponding cyanohydrins in moderate enantioselectivities could also be accomplished by transhydrocyanation with acetone cyanohydrin as the cyanide source. These substrates are considered difficult because of their high solubility in water. Through the employment of an almond meal preparation in a micro-aqueous organic reaction system, the ee-values could be significantly improved [54]. 

One solution to this limitation was the introduction of cyanide sources that are soluble in organic solvents. The initial illustration used diethyl phosphorocyanidate (DEPC)6 for the conversion of 6 to a-aminonitrile 7. This stood in contrast to the classical Strecker reaction conditions which afforded no desired product. 

Although the Pd(PPh3)4-catalyzed cyanation of aryl bromides with KCN or NaCN does not take place under ordinary conditions, Zn(CN)2 as the cyanide source enables the reaction in DMF at 80 °C. The solubility of Zn(CN)2 is lower than that of KCN or NaCN and the covalency of the Zn-CN bond is higher than that of K-CN or Na-CN. Therefore, the concentration of free CN must be a minimum in the reaction solution using Zn(CN)2 as the metal cyanide. Thus, Zn(CN)2 is probably able to maintain the active form of the Pd° catalyst over a longer period of time than KCN or NaCN (Scheme Zn(CN)2 is also an effective cyanide source for the Pd°-catalyzed reac-... 

The original protocol of a one-pot Strecker reaction was performed in water as reaction solvent, but in subsequent procedures, water has been replaced by organic solvents, such as toluene, dichloromethane, and acetonitrile, or nonconventional solvent, such as ionic liquid [68], especially with TMSCN as cyanide source, to improve the solubility of organic reagents. Although there are also examples performed in aqueous media [69], including water-containing DMF [70], polyethylene... 

Facing the requirements of large-scale application of the Strecker reaction, Jacobsen addressed these problems with the revised second-generation catalyst 33 (Table 30.4) [21]. Reactions using the old catalyst generation suffered from the need for cryogenic temperatures (below 0 °C) and used hazardous and expensive cyanide sources (TMSCN/MeOH or HCN). Synthesis of either soluble catalyst 25... 

A similar concept of was pursued by the Ricci group [45], The hydrocyanation of ahphatic N-Boc a-amido sulfones 80 was accompHshed with the cinchona-derived quaternary ammonium salt 82 (Scheme 30.19). Here, acetone cyanohydrin 81 was employed as cyanide source that is cheap, has good solubility in organic solvents, and is available on a large scale. (S)-Configurated primary, secondary, and tertiary aliphatic N-Boc a-amino nitriles 83 were obtained in high yields (85-95%), but enantioselectivities were lower (50-88% ee) in comparison to Ooi s protocol [43, 44]. 

Cyanides are dangerously toxic materials that can cause instantaneous death. They occur in a number of industrial situations but are commonly associated with plating operations, and sludges and baths from such sources. Cyanide is extremely soluble and many cyanide compounds, when mixed with acid, release deadly hydrogen cyanide gas. Cyanide is sometimes formed during the combustion of various nitrile, cyanohydrin, and methacrylate compounds. Cyanides (CN ) are commonly treated by chlorine oxidation to the less toxic cyanate (CNO ) form, then acid hydrolyzed to COj and N. Obviously, care should be taken that the cyanide oxidation is complete prior to acid hydrolysis of the cyanate. 

Influence of the Substituent on the Aromatic Halides on the Rate of Cyanation. The experimental conditions of cyanation, the presence of a solid component slightly soluble (NaCN), or the need of a slow addition of the source of cyanide ion did not allow a rigorous kinetic study of the reaction. However we determined the influence of substituents on the aromatic halides on the rate of cyanation by competitive reactions. The rates relative to chlorobenzene are compared in Table VII. 

Cyanate. Potassium cyanate, [CAS 590-28-3], KCNO, white solid, soluble, formed along with lead metal by reaction of potassium cyanide and lead monoxide solids upon heating. Source of cyanate. 

Cyanide. Potassium cyanide, [CAS 151-50-8], cyanide of potash, KCN, white solid, soluble, very poisonous, formed by reaction of calcium cyanamide and potassium chloride at high temperature. Used as a source of cyanide and for hydrocyanic acid, but usually replaced by the cheaper sodium cyanide. Also used in metallurgy, electroplating,... 

Thiocyanate. Potassium thiocyanate. [CAS 333-20-0]. potassium sulfo-cyauide, potassium sulfocyanate. potassium rhodanate, KCNS, white solid, soluble, mp about 170°C, formed by fusing potassium cyanide and sulfur, and then crystallizing. Used as a source of thiocyanate. 

The thiocyanate ion, S=C=N , also called the rhodanid ion in the early German literature because of the intense red color of its Fe derivative, is obtained by the fusion of alkah metal cyanides with sulfur. It is also the product of the detoxification of the cyanide ion in living systems. Most thiocyanate salts are very soluble in both water and liquid ammonia and are usefiil soluble sources of metal ions in liquid ammonia. Thiocyanogen, N C S , is... 

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