and methanol at about 60 u00b0 to 80 u00b0 c for about three to eight hours in another method of reduction the compound of formula iv is reduced with an excess of a mixture of calcium chloride zinc dust and activated charcoal in aqueous ethanol at about 20 u00b0 to 30 u00b0 c for about 30 minutes to two hours the amino compound of formula v is converted to the corresponding diazonium salt of formula vi in which n is as defined herein and x sup u2296 is cl sup u2296 or bf 4 sup u2296 for this conversion a solution of the compound of formula v is treated with an excess of sodium nitrite in 15 to 20 hydrochloric acid at about 10 u00b0 to 0 u00b0 c to obtain the corresponding diazonium salt of formula vi in which x is cl sup u2296 if an excess of fluoboric acid is added to the latter reaction mixture the corresponding diazonium salt of formula vi in which x is bf 4 sup u2296 readily precipitates from the reaction solution the diazonium salt of formula vi is useful for preparing a number of compounds of formula vii if desired the diazonium salt of formula vi in which x sup u2296 is bf 4 sup u2296 can be reacted with an excess of a solution of potassium cyanide and copper i.