pyridine; thionyl chloride in dichloromethane T=0°C; 1.5 h; Yield given. Yields of byproduct given;

pyridine; thionyl chloride 1.) CH2Cl2, 0 deg C, 1.5 h; 2.) 295 deg C, without solvent, 4 h; Yield given. Multistep reaction. Yields of byproduct given;