Q4 · CSIR-NET Chemistry, June 2014
Paper: CSIR-NET June 2014 · Subject: Organic Chemistry · Chapter: Photochemical Reactions · Topic: Photocycloaddition · Marks: 2 · Difficulty: Medium
The major product formed in the following photochemical reaction is 
(a)
(b)
(c)
(d)
Answer
Answer: A ✓ checked by 4AB · confidence medium
Explanation
1,2,4-Tri-tert-butylbenzene relieves its ortho strain by photochemical valence isomerisation to the Dewar benzene in which one t-Bu sits at a bridgehead and the other two on separate double bonds, with the cis bridgehead H (a).
Study loop for Photochemical Reactions