Tetrachloroethylene synthesis occurs at which temperature and pressure?

• A. 100 C at 1 atm
• B. 200 C at 50 atm
• C. 300 C at 200 atm
• D. 400 C at 1 atm

Answer: (C)

Synthesis of tetrachloroethylene relies on driving the chlorination reaction to full substitution, which needs enough energy to overcome barriers and a high concentration of chlorine to push the reaction toward complete chlorination. At about 300 C, the reaction proceeds quickly enough to favor rapid chlorination, and at about 200 atm the chlorine gas is held at high pressure, increasing its effective concentration and steering the process toward forming the fully chlorinated product rather than partially chlorinated or side products.

Lower temperatures or pressures tend to give slower reactions and more partial chlorination or unwanted byproducts, while too high a temperature can cause decomposition or less selective reactions. The 300 C, 200 atm conditions strike a balance that maximizes yield of tetrachloroethylene.