Discussion
The major product in the given reaction sequence is Q. The mass spectrum of Q shows
([M] = molecular ion peak)
Answer: B
Q shows [M], [M+2], [M+4] and [M+6] peaks in the ratio 1:3:3:1.
Step 1 is the Kolbe-Schmitt reaction: sodium phenoxide and CO2 give salicylic acid after acidification. In step 2, excess bromine water brominates both positions ortho and para to the strongly activating OH and displaces the carboxyl group (bromodecarboxylation), so Q is 2,4,6-tribromophenol.
Bromine's isotopes 79Br and 81Br are almost equally abundant, so a molecule with three bromines gives a binomial pattern \((1 + 1)^{3}\): peaks at M, M+2, M+4 and M+6 in the ratio 1:3:3:1. One bromine gives 1:1 and two give 1:2:1, the patterns of the other options; 1:1:1:1 matches no isotope distribution.
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development