Two propylene glycols, C3H302, are known, viz.
Thus ethane gives H3C CH2 CH3, propane; ethylene gives H 2 C:CH CH 3, propylene; and acetylene gives HC: C CH 3, allylene.
In comparison with the isomeric propylene, CH 3 HC:CH 2, it is remarkably inert, being only very slowly attacked by bromine, which readily combines with propylene.
Propylene is liberated during the reaction, and the phosphoric acid ester of meta-cresol which is formed is then fused with potash.
Propylene, C 3 H 6, may be obtained by passing the vapour of trimethylene through a heated tube (S.