Question

Show how you might prepare 1-penten-3-one from 3-pentanone.

Short answer

The compound 3-pentanone undergoes α-bromination with acetic acid and forms α-bromo ketone. Then the α-bromo ketone undergoes dehydration by pyridine and gives 1-penten-3-one.

Step-by-step solution

Sunthesis of 1-Penten-3-one

The compound 3-pentanone undergoes α-bromination with acetic acid and forms α-bromo ketone. Then the α-bromo ketone undergoes dehydration by pyridine and gives 1-penten-3-one.

Explanation of α-bromination

Reaction of halogen (such as bromine) in acetic acid with aldehyde and ketone is called α-bromination because in this reaction the α-hydrogen gets eliminate and the bromine takes its place.

Mechanism of the reaction

The mechanism of preparation of 1-Penten-3-one from 3-pentanone is