Charcoal block reduction

Charcoal block reductions (a) Heat a little of the substance (3-4 mg) in a small cavity scooped in a charcoal block in a blowpipe flame (Table V.4). 

Table VI.3 Charcoal block reductions in the presence of soda...

Azomethines (Schiff bases) have been prepared in order to block the amino group, using different carbonyl compounds as reagents. Aqueous formaldehyde condenses with amino acids in the presence of palladised charcoal in a hydrogen atmosphere with the production of a dimethylamino group (the reduction time is 3—12 h at 20°C). The free carboxyl group is esterified with diazomethane [260]. The general application of this procedure is limited, however, and the N,N-dimethylaminomethyl esters produced are very volatile so that mere evaporation of the ethereal solution of diazomethane at room temperature results in losses and low yields of the derivatives of Ala, Gly, Val and Leu. 

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