Sodium borohydride, 0.1 mol, was added in portions over the course of 1 h to a solution of 0.1 mol of 4-formyl-1, 3, 5-trimethylpyrazole and 1.2 g of benzyltriethylammonium chloride in 50 ml of water, cooled with ice water. In doing so, one must take care that the temperature of the reaction mixture is no higher than 10oC. The mixture was first stirred with cooling with ice water and then at room temperature for 3 h, after which it was acidified with HCl, ...
