Discussion
Multiplicity of the signal expected in the 1H NMR spectrum of the following compound is :
Answer: D
The CH2 protons give an AB quartet.
The compound is ICH2-CBrClI. The carbon bearing Br, Cl and I (and the CH2I group) has four different substituents, so it is a stereocentre. The two hydrogens of the neighbouring CH2 are then diastereotopic: no symmetry operation exchanges them, so they have different chemical shifts.
With no other protons in the molecule, the two hydrogens couple only to each other (geminal coupling). Two coupled protons with a small shift difference give the four-line AB pattern, with the inner lines taller than the outer ones.
A singlet would require the two protons to be equivalent, which the stereocentre prevents. A doublet or triplet would need coupling to one or two other protons, and there are none.
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