Question

how to distinguish between but-1-ene and but-2-ene chemically

Answer 1

Hey dear,

● But-1-ene and but-2-ene -
- Basic difference in two compounds is position of double bond.
- But-1-ene structure
CH3-CH2-CH=CH2
- But-2-ene structure
CH3-CH=CH-CH3

● Chemical test for differention -
This basically involves two steps -
- Ozonolysis
- Iodoform test

# But-1-ene -
But-1-ene on ozonolysis gives propionaldehyde and formaldehyde. CH3-CH2-CH=CH2 + 2[O] ---> CH3-CH2-CHO + HCHO

These aldehydes are unreactive to iodoform test and dont give any colour.

# But-2-ene -
But-2-ene on ozonolysis gives 2 molecules of acetaldehyde. CH3-CH2=CH-CH2 + 2[O] ---> 2CH3-CHO

Acetaldehyde on iodoform test gives yellow colour.


Hope this helps you...