Amines from nitrile hydrogenation

Amines from nitriles s. 1, 53 a-Aminoalcohols from cyanohydrins s. 1, 54 Hydrogenation of the isoquinoline ring s. 2, 839 1,2,3 4-T etrahydroquinoxalines Removal of catalyst poisons s. 4, 65 CN —CH2NH2 [Pg.274]

Platinum oxide j hydrogen chloride Prim, amines from nitriles with simultaneous N-debenzylation 1,2-Diamines... 

Prim, and sym. sec. amines from nitriles with replacement of chlorine by hydrogen... 

Mesityl oxide refluxed 16 hrs. in water with a precipitated Ni-catalyst prepared from NiGl2 and Zn-dust in water isobutyl methyl ketone. Y 95%. - These convenient reductions do not require hydrogen. F. e., e.g. prim, amines from nitriles, s. K. Sakai and K. Watanabe, Bull. Chem. Soc. Japan W, 1548 (1967). 

Reductive alkylations and aminations requite pressure-rated reaction vessels and hiUy contained and blanketed support equipment. Nitrile hydrogenations are similar in thein requirements. Arylamine hydrogenations have historically required very high pressure vessel materials of constmction. A nominal breakpoint of 8 MPa (- 1200 psi) requites yet heavier wall constmction and correspondingly more expensive hydrogen pressurization. Heat transfer must be adequate, for the heat of reaction in arylamine ring reduction is - 50 kJ/mol (12 kcal/mol) (59). Solvents employed to maintain catalyst activity and improve heat-transfer efficiency reduce effective hydrogen partial pressures and requite fractionation from product and recycle to prove cost-effective. 

The principal iadustrial production route used to prepare fatty amines is the hydrogenation of nitriles, a route which has been used since the 1940s. Commercial preparation of fatty amines from fatty alcohols is a fairly new process, created around 1970, which utilizes petrochemical technology, Ziegler or Oxo processes, and feedstock. 

The above scheme to account for products of nitrile hydrogenation was proposed sixty years ago (80), and with minor variations 28,45,86] has withstood the test of time, It might be expected from the foregoing that, if a nitrile were reduced in the presence of an amine, unsymmetrical amines would result 48), and indeed the reaction provides an excellent way of preparing these amines 49,74). 

Teter et al. filed a series of patents aimed at the production of organic compounds containing nitrogerf or the production of nitriles and amines from ammonia and olefins by passing mixtures of olefin and NH3 over transition metals, mainly cobalt deposited on various supports at 250-370°C and 100-200 bar [27- 3]. With cobalt on asbestos, a mixture of amine, nitrile, olefin hydrogenation product, polymers, and cracking products is obtained (Eq. 4.1) [31]. 

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. 

The choice of catalyst and variations of the temperature, pressure and concentration of ammonia can control the product mix of amines from hydrogenation of a nitrile. The reaction is shown in Eq. (14.8) ... 

The nitrile is then hydrogenated to a primary amine from which amine derivatives can be made by utilization of a variety of reagents [6, 7]. The example in eqns 6.1.1-6.1.3 shows the conversion of fatty acid to dialkyl secondary amine via catalytic deammoniafication (for this and all subsequent structures n = 80-20 unless otherwise noted) ... 

Catalytic hydrogenation of nitriles has long been used for the preparation of various amines. It is performed over metallic catalysts mostly in the liquid phase. The method is also of industrial importance and has been applied to the commercial production of various amines, for example, various aliphatic amines from fatty acid nitriles, hexa-methylenediamine (1,6-hexanediamine) from adiponitrile, and xylene-a,a -diamines [bis(aminomethyl)benzenes] from the corresponding phthalonitriles. 

Primary amine formation is equally well promoted in alkaline medium, e.g., aqueous ethanolic NaOH solution, that selectively poisons the catalyst for hydrogenolysis reactions. However, saturated NH3/alcohol solutions best afford almost quantitative yields of primary amines from catalytic reduction of nitriles. Ammonia adds to imine 1 to give a 1,1-diamine, which is hydrogenolyzed to the primary amine. In the presence of NHj, finely divided Ni can be used, platinized finely divided Ni for the hydrogenation of hindered nitriles, and rhodium-on-alumina for sensitive compounds. Mild reduction of 3-indoleacetonitrile to tryptamine [equation (c)] is effected at RT over 5% rhodium-on-alumina in 10% ethanolic NH3 with little side reaction , and branched chain amino sugars are conveniently prepared using this selective hydrogenation [equation (d)] . 

When a sufficiently high temperature and a high ammonia/hydrogen ratio are used the selectivity can be shifted from amines to nitriles. For example, reaction of 1-octanol with ammonia over CU/AI2O3 afforded octylaraine as the major product below 220 °C, but the yield of octanenitrile was 96-97 % at 260-280 °C [8]. It was proposed that at low temperatures the reaction was kinetically controlled, whereas above 220 °C the thermodynamic equilibrium favored nitrile formation. 

A large number of oc-amino sulfonic acids have been prepared from the hydrogen sulfite adducts ( -hydroxy sulfonic acids) and ammonia or amines at or slightly above room temperature. 976They are very important intermediates in the Knoevenagel-Bucherer form of the Strecker amino acid synthesis (cf. page 877). In this synthesis the aldehyde-bisulfite compounds are converted by ammonia or amines into a-amino sulfonic acids and thence by alkali cyanide or hydrogen cyanide into oc-amino nitriles, which are then hydrolysed ... 

Copper-chromite type catalysts supported by alumina or graphite and promoted with barium were used for the one step synthesis of tertiary fatty amines (R2NCH3 or RN(CH3)2) from nitrile, methanol and hydrogen. The surface composition of the catalysts was studied by XPS and by adsorption experiments. A correlation was found between the selectivity and the presence of a well-dispersed CUC1O2 phase, stabilized with barium. Moreover the elements influencing the stability of the copper catalysts were also studied and we remarked the effect of the promoter or/and of the support on the variation of the copper surface area in the presence of water or ammonia. These modifications were examined in relation with the change of the catalytic properties with time-on-stream. 

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