in diethyl ether; ethanol byproducts: NaNO3; pptn. on mixing Zn-salt soln. (dry EtOH) with Na-salt soln. (dry ether),NaNO3 ppt. filtration off, filtrate washing (dry benzene), dissoln. in isooctane, dry EtOH addn., powder oxalic acid addn., mixt. stirring for 1 h; ppt. sepn. (centrifugation), washing (MeOH/CHCl3 1:1, acetone/MeOH 1:1),drying;