What does the epoxidation of trans-2-pentene produce?

1 Answer
Dec 31, 2014

The epoxidation of trans-pent-2-ene produces a racemic mixture of trans-pent-2-ene epoxide isomers.

The mechanism if the reaction is given here.

The addition is a concerted syn addition.

Groups that were cis in the original alkene remain cis in the product. Groups that were trans remain trans.

Compare the epoxidation of trans-but-2-ene.


If we replace a methyl group with ethyl, we see that the epoxidation of trans-pent-2-ene produces trans-pent-2-ene epoxide.

The product is chiral, so we get a 50:50 mixture of the two enantiomers.

The IUPAC name is (#2S#,#3S#)-3-ethyl-3-methyl-2,3-epoxypentane We also get the (#2R#,#3R#) enantiomer.

Heterocyclic compounds are often named by the Hantzsch-Widman system:

  • The oxygen atom is indicated by the prefix -oxa. It is automatically atom 1 in the ring, and the "a" is omitted before a vowel.
  • The three-membered ring is indicated by the infix -ir (think tri).
  • The saturated ring is indicated by the suffix -ane.

So a third name for this compound is (#2S#,#3S#)-2-ethyl-3-methyloxirane.The lower number is assigned to the substituent that comes first in the name. We also get the #2R#,#3R# enantiomer.