Hydration of nitriles to amides

Nitrile hydratase (NHase) catalyzes the hydration of nitriles to amides (Figure 1.11) and has been used for production of acrylamide and nicotinamide at large scale. NHases are roughly... 

A variety of methods exist for the hydration of nitriles to amides or to acids (ref. 8). While acidic and basic catalysts have long been employed, the importance of catalytic hydration, especially under neutral conditions, is... 

Hydration of nitriles. The hydration of nitriles to amides is commonly carried out under acid or basic catalysis. The reaction can be carried under neutral conditions by catalysis with a black powder consisting essentially of Cu(0), obtained by reduction of CuS04 with NaBH4 in aqueous NaOH. The method is applicable even to sparingly water-soluble nitriles, and yields range from 50-95% (crude). ... 

Another numerical experiment involved a model active site of Fe-dependent nitrile-hydratase (Nhase), a non-heme Fem enzyme that catalyzes the hydration of nitriles to amides. The mechanism is as yet unknown and computational chemistry may be important to help unraveling it, provided the methods used are adequate, and the idea was that calculating the spectrum is a good check on the computational method. Of the model compound, [Fem(PyPepS)2r (see Figure 3-12) the spectrum in aqueous solution is known. 

Dimethylsulfoxide was found to increase the rate of hydrolysis in esters which were resistant to saponification. Treatment of alkyl toluenesulfonates with sodium naphthalene anion radical in tetrahydrofuran constituted an almost ideal procedure for regenerating the corresponding alcohols. The hydration of nitriles to amides in the presence of nickel catalysts shows an increase in yield with the addition of pyridine. ... 

An excellent example of the application of multiple ENDOR techniques is found in studies of the protein ligation environment of the mononuclear nonheme low-spin Fe " center of nitrile hydratase. This protein catalyzes the hydration of nitriles to amides. Extended X-ray absorption fine structure (EXAFS) studies indicated a mixed N,0/S ligation environment for the Fe. 

Hydration of Nitriles to Amides. By treatment with Mn02, nitriles are readily converted to amides. Mn02 on silica gel is especially efficient to perform this reaction (eqs 36 and 37). ... 

Mn02 - X are generally active cattilysts for oxidation reactions and also active electrode materials for dry cells. Probably due to the high oxidation activity, very few studies have been reported for acid-base properties and catalysis of Mn oxides. Mn02 has been claimed to be efficient for the hydration of nitriles to amides, in which the acidic character of the catalyst seems to play some role. In the case of hydration of acrylonitrile in aqueous solution, a relationship between the equi acid-base point (EABP) of met ll oxides and catalytic function has been suggested. Mn02 (EABP = 3,7) was active and selective for the formation of amide in acidic solution, and MnO (EABP = 11.2) was active in basic solution, but caused more hydration of the C = C bond. 

On the other hand, different heterogeneous ruthenium-based systems able to promote the selective hydration of nitriles to amides have also been developed. 

Garcia-Alvarez R, Diez J, Crochet P, Cadiemo V (2011) Arene-rathenium(ll) complexes containing inexpensive tris(dimethylamino)phosphine Highly efficient catalysts for the selective hydration of nitriles to amides. Organometallics 30 5442... 

Yamaguchi K, Matsushita M, Mizuno N (2004) Efficient hydration of nitriles to amides in water, catalyzed by ruthenium hydroxide supported on alumina. Angew Chem Int Ed 43 1576... 

Polshettiwar V, Varma RS (2009) Nanoparticle-supported and magnetically recoverable ruthenium hydroxide catalyst Efficient hydration of nitriles to amides in aqueous medium. ChemEur J 15 1582... 

Baig RBN, Varma RS (2012) A facile one-pot synthesis of ruthenium hydroxide nanoparticles on magnetic silica Aqueous hydration of nitriles to amides. Chem Commun 48 6220... 

Prakash GKS, Munoz SB, Papp A, Masood K, Bychinskaya I, Mathew T, Olah GA (2012) Nafirai-Ru A sustainable eatalyst for selective hydration of nitriles to amides. Asian J Org Chem 1 146... 

Kumar S, Das P (2013) Solid-supported ruthenium(0) An efficient heterogeneous catalyst for hydration of nitriles to amides under microwave irradiation. New J Chem 37 2987... 

Treatment of aldehydes with cobalt hexaamine bis(tetracarbonyl)cobal-tate gives complexes of structural type [(RCH= NH)Co(NH3)5][Co(CO)4]2. Exposure of the latter to bromine results in nitrile formation in variable yields (Rhee et al, 1970). Hydration of nitriles to amides can be homo-... 

Finally, the coordination and reactivity of nitriles with low-valent late transition-metal complexes is of interest because catalytic hydration of nitriles to amides remains a challenging goal. The development of catalytic reactions that employ transition-metal complexes as catalysts under neutral and mild conditions has been proposed as a particularly important alternative for the nitrile hydration process and considerable efforts have been spent in this direction. 

Kim ES, Kim YM, Kim JN (2010) Facile synthesis of N-Tosyl aza-Baylis-Hilhnan adducts of acrylamide via a Pd-catalyzed hydration of nitrile to amide. Korean Chem Soc 31 700-703... 

Ghaffar T, Parkins AW (2000) The catalytic hydration of nitriles to amides using a homogeneous platinum phosphinito catalyst. J Mol Catal A 160 249—261... 

Cadierno V, Francos J, Gimeno J (2008) Selective ruthenium-catalyzed hydration of nitriles to amides in pure aqueous medium under neutral conditions. Chem Eur J 14 6601-6605... 

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