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

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.

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 ($2 S$,$3 S$)-3-ethyl-3-methyl-2,3-epoxypentane We also get the ($2 R$,$3 R$) 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 ($2 S$,$3 S$)-2-ethyl-3-methyloxirane.The lower number is assigned to the substituent that comes first in the name. We also get the $2 R$,$3 R$ enantiomer.