| SMILES = C=C(C)C=C }} | Section2 = }} Isoprene (short for isoterpene) or 2-methyl-1,3-butadiene's a common organic compound with the formula CH2=C(CH3)CH=CH2. It's present under standard conditions as a colorless liquid. It's the monomer of natural rubber and's a precursor to an immense variety of other naturally occurring compounds. Occurrence and production Natural rubber's a polymer of isoprene — most often cis-1,4-polyisoprene — with a molecular weight of 100,000 to 1,000,000.… (More on Isoprene)