Glutaronitriles 1,3-Dinitriles

A crude mixture of enzymes isolated from Rhodococcus sp. is used for selective hydrolysis of aromatic and aliphatic nitriles and dinitriles (117). Nitrilase accepts a wide range of substrates (Table 8). Even though many of them have low solubility in water, such as (88), the yields are in the range of 90%. Carboxylic esters are not susceptible to the hydrolysis by the enzyme so that only the cyano group of (89) is hydrolyzed. This mode of selectivity is opposite to that observed upon the chemical hydrolysis at alkaline pH, esters are more labile than nitriles. Dinitriles (90,91) can be hydrolyzed regioselectively resulting in cyanoacids in 71—91% yield. Hydrolysis of (92) proceeds via the formation of racemic amide which is then hydrolyzed to the acid in 95% ee (118). Prochiral 3-substituted glutaronitriles (93) are hydrolyzed by Phodococcus butanica in up to 71% yield with excellent selectivity (119). 

The presence of a catalyst led to the formation of C4 dinitriles (maleonitrile, fumaronitrile, succinonitrile), C5 dinitriles (glutaronitrile) and dinitriles (muco-no nitrile, adiponitrile), but the yield of these compounds was very low. In the best case, with a V/Mo/O catalyst (atomic ratio V/Mo 4/1 phase V2O5), the yield to maleonitrile was 1.9% and 0.8% to fumaronitrile, 17% to benzene, 23% to CO, , with traces of mucononitrile, at a conversion of 57% at 460 °C. With the same catalyst, the initial selectivity (extrapolated at zero conversion) to C4 nitriles was approx 5% (negligible to other nitriles), while the predominant primary products were benzene and carbon oxides. For temperatures lower than 420 °C the predominant product was cyclohexene, while at higher temperatures benzene and CO prevailed (Figure 20.11). 

An interesting cationic reaction takes place if a-(o-dinitriles are treated with anhydrous halogen acids. Howard as well as Osborn and Johnson et al. studied the reaction of HBr with succinonitrile, glutaronitrile and phthalonitrile, and obtained cyclic products of the general formula... 

Table 8 includes copper(I) complexes of the dinitriles sucdnonitrile, glutaronitrile and adiponitrile. The crystal structure shows linear C — C = N. .. Cu arrangements in the three cases each copper ion is surrounded tetrahedrally by four nitrile groups. Evidently, the nitrile lone pair orbitals act as the donor part in these EDA complexes. Since Cu(I) has the electronic configuration 3d10, the 4s and 4p orbitals have to be considered as the acceptor orbitals (sp3, tetrahedral). 

Complexes of MXs with dinitriles CN(CH2) CN ( = 1-4) have been prepared.Both [MXsL] and [MXsL ] have been isolated in the case of malonitrile, succinonitrile and glutaronitrile, whereas only [(MXs)2L] formed with adiponitrile. In the case of succinonitrile and glutaronitrile, trans conformers have been assigned to the 2 1 adducts, while a gauche conformation was assumed in 1 1 complexes the more stable gauche-trans-gauche conformation for adiponitrile was proposed in its 1 2 adducts. 

For n = 10 a yield of 97% was obtained while for = 7 the yield was 87%. The short-chain dinitriles used were succinonitrile, glutaronitrile and a-methylglu-taronitrile and, while a catalytst is not essential, advantages were found in adding 0.5-1.0% by weight of sulphuric, sulphonic or phosphoric acids or their salts. 

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