Unsaturated nitriles, hydrogenation

The hydrogenation of 3 butene nitrile B3N and 2 butene nitrile B2N is reported in figure 1 and table 3. Initial rates are calculated on the basis of product formation. When comparing the influence of Pd content on catalytic hydrogenation of B3N, an increase in the rate of reaction with the Pd content is observed. On the other hand, the rate of hydrogenation of B2N is lower than that of B3N on the same (Pd-1) catalyst. The preliminary results of the C4 unsaturated nitriles hydrogenation confirm several trends already observed on Raney nickel (14). 

The presence of ammonia during hydrogenation suppresses formation of secondary amines and inhibits hydrogenation of double bonds in unsaturated nitriles. Eatty amines are used as corrosion inhibitors, flotation agents, quaternary salts for sanitizing agents and textile fabric softeners, and surface-active agents. 

Hydroxy-20-cyanohydrins can be oxidized to 3-ketones in good yield with chromic acid, and the osmate ester of the unsaturated nitrile is also stable to this oxidant. " After hydrolysis of the osmate ester, the new 17-hydroxy-20-cyanohydrin which is presumably formed cannot be isolated, but loses hydrogen cyanide during the hydrolysis, and only the 17a-hydroxy-20-ketone is obtained. 

In 1989, Isayama and Mukaiyama reported a related Co-catalyzed coupling reaction that employs a,b-unsaturated nitriles, amides, and esters with PhSiLb as a hydrogen source [9]. Cobalt-bis(diketonato) complex, Co(II)(dpm)2 [dpm = bis(dipivaloylmethanato)] (5mol%), exhibited high catalytic activity at 20 °C in the coupling of excess acrylonitrile and ben-zaldehyde to provide b-hydroxy nitrile 4 in 93% yield (syn anti = 50 50) (Scheme 5). N,N-Dimethylacrylamide and methyl cinnamate both reacted... 

A new water soluble palladium(O) complex was also prepared. This compound and a previously reported related species were examined as catalysts in the hydrogenation of unsaturated nitriles in water. It was found that the pH of the solvent plays a crucial role in determining both yield and reaction course.869... 

The selectivity of RNH2 on M/A1203 and Raney catalysts decreased in the order Co Ni Ru>Rh>Pd>Pt. This order corresponds to the opposite sequence of reducibility of metal-oxides [8] and standard reduction potentials of metalions [9], The difference between Group VIII metals in selectivity to amines can probably been explained by the difference in the electronic properties of d-bands of metals [3], It is interacting to note that the formation of secondary amine, i.e. the nucleophilic addition of primary amine on the intermediate imine can also take place on the Group VIII metal itself. Therefore, the properties of the metal d-band could affect the reactivity of the imine and its interaction with the amine. One could expect that an electron enrichment of the metal d-band will decrease the electron donation from the unsaturated -C=NH system, and the nucleophilic attack at the C atom by the amine [3], Correlation between selectivity of metals in nitrile hydrogenation and their electronic properties will be published elsewhere. 

Preparative routes to 5/7-dibenz[6,e]azepine-6,11 -diones (morphanthridinediones) are based mainly on the cyclization of 2-aminobenzophenone-2 -carboxylic acids and their derivatives (55LA(594)89). Studies on a-aminodiphenyImethane-2 -carboxylic acid reveal that cyclization to 5,11 -dibenz[6,e ]azepinone (188) is much slower at room temperature than the cyclizations of the analogous 2-aminobiphenyl-2 -carboxylic acid and the 2 -aminobiphenylacetic acid (189), which at room temperature cyclize spontaneously to phenanthridone and dibenz[f>,d]azepin-6-one (190) respectively (61JOC1329). The hydrogen bromide-induced cyclization of dinitriles (Scheme 16) is adaptable to the synthesis of 2-amino-7-bromo-3//-azepines and 5H-dibenz[c,e]azepin-7-ones (67JOC3325). Apparently, for unsymmetrical dinitriles cyclization is such as always to give the azepine with the bromo substituent attached to the carbon of the a,j8-unsaturated nitrile as exemplified in Scheme 16. 

Wabnitz, T.C., Rizzo, S., Gotte, C., Buschauer, A., Benincorid, T. and Reiser, O. Enantioselective Hydrogenation of Diaryl-substituted ot, -Unsaturated Nitriles. Tetrahedron Lett, 2006, 47, 3733-3736. 

Other c,/3-unsaturated nitriles (Eq. 68) converted into the corresponding epoxides by hydrogen peroxide oxidation under controlled pH include a-phenykiimamomtrile, a-oyano-/3-methylcrotorKH)itril and ethyl a-cyano- -methylcrotonftte.mj-1817... 

The reaction of alkaline hydrogen peroxide with ogg-unsaturated nitriles was first explored by Murray and Cloke,120 who found that certain of these compounds (Eq. fld), when subjected to the JRadzis-icwBki amidation procedure, yielded a, -epoxyamides instead of the anticipated a t-unB turated amides. 

Coupling of a, -unsaturated nitriles, amides, or esters with RCHO.3 This coupling can be effected with Co(acac)2 as catalyst and C6H5SiH3 as the hydrogen source. Thus the reaction of benzaldehyde with acrylonitrile in 1,2-dichloroethane with C6H5SiH3 (2 equiv.) and a catalytic amount of Co(acac)2 at 70° provides the (3-silyloxy nitrile as the major product (equation I). 

Sanui and co-workers [67] carried out hydroformylation of polypentenamer (PPA). They converted hydroformyl group of the modified PPA to the aldoxime and subsequently to nitrile derivatives (Scheme 4.5). Then they carried out hydrogenation to convert the amorphous, unsaturated nitrile derivative to the crystalline saturated polymer. 

Reaction of a four-carbon unit with sulfur sources such as hydrogen sulfide, carbon disulfide, and elemental sulfur is one of the traditional thiophene syntheses that belong to this category (Equation 18). A wide variety of hydrocarbons, for example, alkanes, alkenes, dienes, alkynes, and diynes, serve as four-carbon units. Another practical method is the sulfuration of 1,4-dicarbonyl compounds (Paal synthesis). The method has become very popular with development of sulfuration reagents such as Lawesson s reagent. The reaction of a,/3-unsaturated nitriles with elemental sulfur in basic media, Gewald synthesis, is also useful for the preparation of 2-aminothiophenes which are important compounds in dyestuff and pharmaceutical industries. 

Homogeneous hydrogenation of nitriles, Saturated nitriles are hydrogenated to primary amines in 67-100% yield with 1 as catalyst in THF. The catalytic activity of 1 for aromatic nitriles is not so high as for hydrogenation of aliphatic nitriles. The C=C bond of unsaturated nitriles is reduced more readily than the C=N bond. This catalyst is also eflective for dehydrogenation of amines (benzylamine — benzonitrile, 27% yield). 

Unsaturated nitriles are converted smoothly to the saturated compounds by selective hydrogenation over palladinized charcoal or by chemical reduction. " The reaction is of special value in the preparation of a variety of substituted cyano compounds from the olefinic nitriles obtained in cyanoacetic ester condensations (method 387). 

Cationic Rh complexes [RhL(C0)(PPh3)2]C104 (L = unsaturated nitrile) show catalytic activities for the hydrogenation of a,3-unsaturated nitriles under mild conditions (30 °C). Selective reduction of the carbon-carbon double bonds of a,3-unsaturated carbonyls also occurs in high yield with [ Rh( 1,5-hexa-diene)Cl 2] and a phase transfer catalyst in aqueous media. ... 

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