Two propylene glycols, C3H302, are known, viz.
It may also be obtained by oxidizing allylene and propylene with cold potassium permanganate solution, by the hydrolysis of barbituric acid (malonyl urea) with alkalis (A.
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.
Strecker, Ann., 1850, 75, p. 27); by the oxidation of propylene glycol (A.