Benzonitrile hydration

Die Reduktion von Nitrilen zu prim. Aminen mit Natrium- oder Kaliumboranat wird durch Obergangsmetall-Salze katalysiert2-4. Zur Reduktion wird allerdings sehr viel Hydrid verbraucht. Aus Benzonitril erhalt man z.B. in Gegenwart von Kobalt(II)-chlo-rid-Hexakis-hydrat 72°/o d. Th. Benzylamin5. 

Scheme 22 Hydration of benzonitrile catalyzed by cationic porphyrin 59a...

We also found that iridium hydrido(hydroxo) complexes like [ lrH(diphos-phine) 2( x-OH)2( x-Cl)]Cl (43) and the precursor diphosphine complexes 42 can also catalyze the hydration of nitriles. In the presence of catalyhc amounts of these complexes, heating acetonitrile and benzonitrile with excess water at 120°C gave the corresponding amides [47, 50]. 

MeCH=CH, Ph) in the presence of Na2C03 (Eq. 6.41). The methanolysis of benzonitrile also proceeded to give the imino ether in the presence of [Cp Ir(T -CH2CHCHPh)(NCPh)]OTf and Na2C03 (Eq. 6.42). The methanolysis of benzonitrile proceeded much more rapidly than the hydration. Based on the isolated or detected intermediate complexes, plausible reaction mechanisms are suggested. 

For the hydration reaction of benzonitrile, the arranged order, expressed in terms of either total activity per gram or activity per acidic site, is the following ... 

When the reaction is carried out in boiling DMSO, no significant gain in the yield of benzamide (30%) is observed. Since under these conditions the primary dehydration of aldoximes is evident, the formation of benzamide is most likely to result from hydration of the intermediate benzonitrile rather than by the Beckmann rearrangement scheme. 

Hydrogen atoms and hydroxyl radicals react with aliphatic compounds mainly by H-abstraction from the chain, although reactions with certain substituents are also important. With hydrated electrons the functioned group is the only site of reaction and its nature determines the reactivity. The reactions of hydrated electrons are by definition electron transfer reactions. The rate of reaction of a certain substrate will depend on its ability to accommodate an additional electron. For example, in an unsaturated compound the rate may depend on the presence of a site with a partial positive charge. Thus acrylonitrile and benzonitrile are three orders of magnitude more reactive toward e q than are ethylene and benzene. On the other hand, this large difference does not exist in the case of addition of H and OH. 

The kinetics of nitrile hydration by H4Ru4(n4-0)(n3-0H)(n2-0H)(PCy3)4 (CO)4 has been examined the nitrile-containing tetranuclear cluster 44 was reported to have four times the catalytic activity of its precursor in the hydration of benzonitrile.34... 

Raney nickel hydrogenation of nitriles is aqueous acetic acid or in aqueous acetic acid-pyridine in the presence of sodium hypophosphite (NaH PO-i), which becomes oxidized to the phosphate, converts the nitriles into the corresponding aldehydes. The reaction takes place at room temperature and pressure. Yields are in the range 50-90%. Thus a solution of 1 g. of benzonitrile and 2 g. of hydrated sodium hypo-phosphite in 29 ml. of a 1 1 2 water-acetic acid-pyridine mixture was stirred with 0.3-0.4 g. of Raney nickel at 40-45° for 1 hr. benzaldehyde was isolated as the 2,4-dinitrophenylhydrazone. 

A review has highlighted the photocycloaddition reactions of alkenes with aromatic esters and nitriles. Cycloadditions occur by a (3+2)-mode and provides a path to medium size ring systems. When the cinnamic acid derivative (9) is irradiated at 359 nm in ethanol with added Ti02 the product (10) is formed in 30% yield. Analogous products are formed from other straight chain alcohols such as (11) from propan-l-ol. Benzonitrile can be photochemically hydrated in the presence of oxophosphorus porphyrins. " ... 

The hydrations were carried out either at low substrate concentrations with slow feeding of the substrate (for example benzonitrile, 2,6-difluorobenzonitrile and 3-indoleacetonitrile) or, in the case of less toxic substrates, by direct incubation at high substrate concentrations (for example 3-indolylacetonitrile and 2-cyanopyr-azine[2, 76]). 

Arylmethyl-benzaldazine allgemeine Arbeitsvorschrifl3 1 g 2-Arylmethyl-benzonitril, 0.5 g Raney-Nik-kel, 10 ml 85%ige Hydrazin-Hydrat und 50 ml Athanol werden bis zur Ammoniak-Entwicklung auf 50-55° er-hitzt. Man filtriert vom Nickel ab, engt das Filtrat bis zur Ausfallung des Azins ein und kristallisiert a us einem Benzol-Athanol-Gemisch um Ausbeute —90% d.Th. 

Chlorosulfonic acid added with stirring at 20° to a soln. of chloral hydrate in CC14, benzonitrile added after 10 min., followed by more chlorosulfonic acid, the exothermic reaction checked by external cooling, and worked up after 1 hr. —> N,N -dibenzoyl-l,l-diamino-2,2,2-trichloroethane. Y 85%. (L. Haskelberg and D. Lavie, J. Org. Chem. 14, 498 (1949).)... 

Hydration of nitriles Formation of 1 benzonitriles in one step is shown. 

Benzonitrile added to Urushibara nickel-zinc catalyst (s. Synth. Meth. 12, 93) in water, and refluxed ca. 8hrs. until the oil drops of benzonitrile on the water have disappeared benzamide. Y 78%. — Water as solvent suppresses the activity of the catalyst for hydrogenation but promotes the activity for hydration. F. e. s. K. Watanabe, Bull. Ghem. Soc. Japan 37, 1325 (1964). 

Benzaldehyde or propionaldehyde refluxed with excess 70%-hydrazine hydrate and KCN in alcohol until NHg-evolution ceases -> benzonitrile or propionitrile. Y 70-90%. W. Kohler, Z. Chem. 11, 343 (1971). 

Honda M, Kuno S, Sonehara S, Fnijimoto K, Suzuki K, Nakagawa Y, Tomishige K (2011) Tandem carboxylation-hydration reaction system from methanol, CO2 and benzonitrile to dimethyl carbonate and benzamide catalyzed by Ce02. ChemCatChem 3(2) 365-370... 

RuCl2N2C,2Hi8, Ruthenium(II), bis(acetonitrile)dicbloro(i -l,5> cyclooctadiene)-, 26 69 RuQ2N2C22H22, Ruthenium(II), bis(benzonitrile)dichloro(if -l,S-cyclooctadiene)-, 26 70 RuCl2 606C3oH3c 6H20, Rutbenium(ll), tris-(2,2 -bipyridineK dkhloride, hcxa-hydrate, 28 338... 

The reaction profile showed that benzonitrile, benzaldehyde and benzoic acid could be formed during the transformation. The amorphous Mn02 showed high activities for the amidation of benzaldehyde with urea to form benzonitrile under oxidation conditions. Furthermore, amorphous Mn02 also showed high activities for the hydration of benzonitrile to benzamide. However, benzoic acid could not be converted into benzamide under this system. 

Since the primary dehydration of aldoximes in these conditions has been proved, the conclusion is made [7] that benzamide is generated not via the Beckmann rearrangement, but owing to hydration of the benzonitrile formed (Scheme 1.181). 

SCHEME 1.181 Hydration of the benzonitrile to benzamide in the KOH/DMSO system. 

Nitrile complexes [Cp Ir(77 -CH2CHCHPh)(NCMe)]OTf (Cp = CjMej- and OTf = -OSO2CF3) and [Cp Ir(77 -CH2CHCHPh)(NCCH = CHMe)]OTf catalyzed the hydration of the nitriles (acetonitrile, crotononitrile, benzonitrile) in the presence of Na2C03 to produce amides. Plausible mechanism for these catalytic reactions involved the amido-ether complex formation [44], Also, unsaturated nitriles were treated under these catalytic conditions [45] (Scheme 25). 

Nickel catalyzed O-H additions to imsaturated systems are limited to the hydration reactions of nitriles for the synthesis of amides. These reactions have been widely studied by Prof. J. J. Garcia and his research group and their results recently reviewed [60]. They reported the isolation and characterization of Ni(0) complexes of type [(dippe)Ni(ri -NCR], R = aryl, heteroaryl or alkyl, derived from the reductive interaction of [(dippe)NiH]2 with organic cyanides. The catalytic and synthetic utility of these complexes was demonstrated first in the catalytic hydration of benzonitrile and acetonitrile [61] and then extended to dicyanobenzenes [62], to mono- and dicyanoalkanes [63] and finally to cyanopyridines [64]. 

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