This video looks at the reaction of ethanol with thionyl chloride (SOCl2). Thiony chloride is an excellent chlorinating agent, substituting the OH group of the ethanol with a Cl atom, to form chloroethane (an alkyl halide). It is a dangerous chemical to work with, producing both acidic fumes of HCl and highly poisonous sulfur dioxide in its reaction with water vapour and other OH bearing molecules such as alcohols and carboxylic acids. There are accompanying videos that look at the reactions of alcohols and carboxylic acids with phosphorus pentachloride and thionyl chloride (SOCl2).