Question

Question 13.9 Draw the cis and trans structures of hex-2-ene. Which isomer will have higher b.p. and why?

Class XI Hydrocarbons Page 397

Answer 1

CH3-CH2-CH2-CH--CH-CH3

Answer 2

complete structure formula of Hex-2-ene is CH3-CH2-CH2-CH=CH-CH3 , now the structure of cis - and trans- isomers of hex-2-ene is shown in pic.

Cis - form is more polar form than trans form {due to this cis -form has higher dipole moment than trans - form .
we know, the boiling point depends upon dipole - dipole interactions.
The boiling point of cis - isomer is greater than that of trans - isomers, due to greater dipole- dipole interactions in cis - form.