Vinyl Chloride
Vinyl chloride is a gas, mainly used as a precursor for Polyvinyl Chloride, or PVC. Its chemical formulae is C2H3Cl.
In situ Production
Vinyl Chloride on Mars could be produced from the the hydrochlorination of acetylene. The reactive is hydrogen chloride (HCl) in solution in water, known as hydrochloric acid.
HCl + C2H2 -> C2H3Cl
Hydrogen chloride is produced from the direct reaction of Chlorine and Hydrogen:
Cl2 + H2 → 2 HCl
Acetylene can be obtained as a side reaction of ethylene production through steam reforming.
Chlorine gas is the byproduct of the production of caustic soda, or Sodium Hydroxide (NaOH). Caustic soda is produced by the electrolysis of sodium chloride(NaCl-table salt) using the Chloralkali process.
Hydrogen can be obtained by electrolysis of water.