Hydrogenation to Primary Amines

Besson et al. studied the hydrogenation of valeronitrile over Raney Ni, prepared from chromium- and molybdenum-doped Ni2Al3 alloys, in cyclohexane at 90°C and 1.6 MPa H2.30 Chromium was found to be an effective promoter for initial activity and for the selectivity to primary amine (83-85%, compared to 79.2% with unpromoted catalyst), whereas the addition of molybdenum was not effective. 

An aliphatic dinitrile sebaconitrile has been converted to 1,10-decanediamine in 79-80% yields with addition of an 8 molar ratio of ammonia to the nitrile (7.20).34 In this hydrogenation, the presence of ammonia at least in 5 molar ratio to the nitrile was claimed to be necessary to minimize the formation of secondary amine. The hydrogenation of a number of dinitriles, including industrially important adiponitrile and m- 

There have been many known cases where high yields of primary amines were obtained over cobalt catalysts in the hydrogenation of nitriles. Hydrogenation of 3,4- 

Excellent yields (93-97%) of 1,6-hexanediamine were obtained in the hydrogenation of adiponitrile over Raney Co (eq. 7.24), Co-A1203 (Raney type), and Co-kieselguhr as catalysts with addition of ammonia.22 The yields decreased from 97.2 to 93.1% in the absence of ammonia and from 93 to 77% with nickel catalyst in place of cobalt catalyst. 

The byproducts of the hydrogenation of adiponitrile are small amounts of hexahydroazepine, 1,2-diaminocyclohexane and 2-(aminomethyl)cyclopentylamine, besides acyclic secondary products. In an example of a continuous process, a 1 12.5 molar ratio of adiponitrile and ammonia that was mixed with 10-fold amount of a hydrogenated reaction mixture from a prior run to give a 1 44 adiponitrile-ammonia mixture 

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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). 

Aromatic nitriles hydrogenate to primary amine over palladium-on-carbon in ethanol-HCl or acetic acid" finely divided Ni (Raney Ni) in ethanol/NH3 [equation (f)]. Rhodium hydroxide and (7 3) rhodium-platinum oxide inhibited by LiOH convert ben-zonitrile to benzylamine, and isophthalonitrile or terephthalonitrile to the corresponding diamines [equation (g)]. ... 

Nitrils are reduced by nascent hydrogen to primary amines methyl cyanide yields ethylamine —... 

Nitro groups are readily reduced to primary amines by a variety of methods Cat alytic hydrogenation over platinum palladium or nickel is often used as is reduction by iron or tin m hydrochloric acid The ease with which nitro groups are reduced is especially useful m the preparation of arylamines where the sequence ArH ArN02 ArNH2 IS the standard route to these compounds... 

A class of nitrogen containing compounds that was omitted from the section just dis cussed includes mines and their derivatives Immes are formed by the reaction of aide hydes and ketones with ammonia Immes can be reduced to primary amines by catalytic hydrogenation... 

Reduction of nitriles (Section 22.9) Nitriles are reduced to primary amines by lithium aluminum hydride or by catalytic hydrogenation. 

Hydrogenation of oximes to primary amines usually can be made to proceed smoothly despite the potential complications cited earlier. Many of the same considerations applicable to control of nitrile reductions hold for oxime reductions as well. Oximes, unlike nitriles, can be reduced to hydroxylamines. 

Supported Co, Ni, Ru, Rh, Pd and Pt as well as Raney Ni and Co catalysts were used for the hydrogenation of dodecanenitrile to amines in stirred SS autoclaves both in cyclohexane and without a solvent. The reaction temperature and the hydrogen pressure were varied between 90-140 °C and 10-80 bar, respectively. Over Ni catalysts NH3 and/or a base modifier suppressed the formation of secondary amine. High selectivity (93-98 %) to primary amine was obtained on Raney nickel, Ni/Al203 and Ru/A1203 catalysts at complete nitrile conversion. With respect to the effect of metal supported on alumina the selectivity of dodecylamine decreased in the order Co Ni Ru>Rh>Pd>Pt. The difference between Group VIII metals in selectivity can be explained by the electronic properties of d-band of metals. High selectivity to primary amine was achieved on base modified Raney Ni even in the absence of NH3. 

While the desired product of the hydrogenation of nitriles is often the primary amines, the proportion of primaiy/secondary/tertiary amines in the product is strongly affected by the nature of metal. In the hydrogenation of nitriles on Group VIII metals, the selectivity of primary amine decreases in the order Co>Ni>Ru>Rh>Pd>Pt [1], The difference between Group VIII metals in selectivity to primary amine is explained by the difference in the electronic... 

PPI dendrimers are synthesized via the reaction sequence as shown in Fig. 2. This repetitive reaction sequence involves a Michael addition of two equivalents of acrylonitrile to a primary amine, followed by hydrogenation of the nitrile groups to primary amines. Commercially available PPI dendrimers are usually terminated with amine groups. 

In the reduction of imines and enamines with hydrogen telluride and sodium hydrogen telluride, hydrolysis leading to primary amines and carbonyl compounds is frequently competitive with the reduction. This undesired side reaction is minimized by the addition of triethylamine, in the case of hydrogen telluride. ... 

Te catalyst) reduces tertiary amine iV-oxides to the corresponding amines.Azides are reduced to primary amines by sodium hydrogen telluride. ... 

Hydrazo compounds were hydrogenolyzed to primary amines by catalytic hydrogenation over palladium [740]. Since hydrazo compounds are intermediates in the reductive cleavage of azo compounds to amines it is very likely that all the reducing agents converting azo compounds to amines cleave also the hydrazo compounds (p. 96). 

Manufacturing processes and equipment are similar to those employed for alcohol ethoxylate preparation. In the absence of steric hindrance, ethylene oxide reacts with both hydrogens of primary amines at relatively low temperatures (90—120°C) without added catalysts (105). When the nitrogen atom is hindered, as it is in the Triton RW products, only one of the amino hydrogens reacts with ethylene oxide. Once this reaction is complete, a basic catalyst is added and ethoxylation proceeds in the manner of the alcohol-based nonionics. In IV-alkyl-l,3-propanediamine, all three amino hydrogens are available for reaction with ethylene oxide. N-Alkyl-1,3-propanediamines are prepared from fatty monoamines and acrylonitrile, followed by reduction of the resulting 3-cyanoethylalkyl amine. 

Alkenes can be aminated172 in the allylic position by treatment with solutions of imido selenium compounds R—N=Se=N—R.173 The reaction, which is similar to the allylic oxidation of alkenes with Se02 (see 4-4), has been performed with R = f-Bu and R = Ts. The imido sulfur compound TsN=S=NTs has also been used.174 In another reaction, compounds containing an active hydrogen can be converted to primary amines in moderate yields by treatment with 0-(2,4-dinitrophenyl)hydroxylamine.175... 

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