Question

3. Indicate how many different 1H-NMR signals are expected for the following molecules and describe their multiplicity (splitting) BrCHCHBr CICH,CHI CI

Answer 1

no of peaks The noig parks shocon by a compoand depends On the peesence of magnetically non-equivalent protons in the compound 80 to predict NMR spectra (proton NMR), we have to Count plotos with different magnetic environment · profons with different linkage give different NMR Signals [ In aliphatic compounds pistons attached to Same carbon ace completely equivalent and therefore give single NMR signal] y C-C-4 all six peotons ace equivalent # . 80 one peak . C 1 Sigural) CH₂ - CH₂ - CH₂ a peaks. а нь (terminal methyl geoceps are equivalent and Labelled as 'a' and the other one '6²) • Magnetically non- equivalent pidfons give different NMR Signals. 3 peaks bna Ceciel

Splitting of peaks: In NMR peak will be split where Na no. of hydrogens on atoms.at into N+1 peaks the adjacent of there are no hydrogens on the adjacent atoms, then the resonance will remain a single peak, a singlet of there is one hecleopen them N+1 = 1+1=2 split into a peaks of equal size. a doublet. $ N=2 ; N4S - 2+1=3 = triplet (split Punto there peaks with the eatio of 1:281. and 80 on ..

- Br CH2 CH2 Br 1 peak. N=0 Singlet Since all protons are in the same enviconment by symmetry > cl Ch CH, I a peaks. N+1=3: both peaks into 3 il: Priplet . will split

3 peaks (a, b, c) LC сус for afb N=1 ; Ntiza · doublet. for a N. za ; n+1=3 A Teiplet CH be - CH2 - Br a 2 peaks. Nooo for both peakse 2. Binglet X Br