Aldimines aqueous hydrolysis

Formation of an aldimine intermediate is the first step in the catalytic hydrogenation of nitriles. When hydrogenation is carried out in aqueous acidic media, aldehydes may form by hydrolysis of the aldimine. Selective hydrogenation of aromatic nitriles to ben-zaldehydes over finely divided Ni (Raney Ni) is best obtained with an equimolecular amount of H2SO4 in a 10 1 mixture of tetrahydrofuran-water ... 

Antonova and coworkers reported the electroreduction of 4-amino-5-cyano-2-methylpyrimidine to the corresponding amine in acidic aqueous medium. A competitive pathway due to hydrolysis of the intermediate aldimine may occur yielding an aldehyde or an alcohol (Scheme 14). A Ni cathode in HCl solution containing PdCh and substrate at 20 °C and current densities of 2A dm" gave the maximum yield (84%) of the expected amine. It is noteworthy that Pd is electrodeposited on the electrode at the beginning of the... 

Conversion of alditols to aldoses without the need to protect all hydroxy groups has been achieved by monotosylation of one primary hydroxy group, displacement with azide ion and photolysis in methanol to yield the aldimine,which was then hydrolyzed to the aldose. The procedure was illustrated using 3 4-0 isopro ylideno-D-mannitol to produce D-mannose. The synthesis of D-[U- Cjgalactose from methyl <-D-[n- Cjglucopyranoside via aqueous bromine oxidation to the 4.-uloside, reduction by sodium borohydride and hydrolysis has been described, along with the isolation of D-glucuronic acid and methyl o( D-mannopyranoside as by-products. 

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