Butadiene chlorination process

An improved process for the continuous chlorination in vapor phase of butadiene to a mixture of dichlorobutenes, the process comprising the following steps:

• 1. premixing chlorine with a portion of the total butadiene, the mole ratio of butadiene to chlorine in the mixture being at least 3:1 but no more than 30:1, and the temperature of the mixture being at least 90.degree. C. but no more than 200.degree. C.;
• 2. continuously introducing the chlorine-butadiene mixture at one end of a tubular reactor maintained above 90.degree. C., while introducing the remainder of butadiene into the reactor at at least one point downstream from the injection point of the chlorine-butadiene mixture, the temperature of butadiene at each injection point being lower than the temperature of the reacting mixture at that point, both the temperature and the volume of this additional butadiene being adequate to prevent the internal temperature in the reactor from exceeding about 250.degree. C. or falling downstream from any butadiene injection point below about 130.degree. C.;
• and
• 3. recovering dichlorobutenes from the reactor effluent.