Question

What information does the chemical shift of a peak on HNMR provide about a proton? Use the HNMR of Chlorobutane to illustrate your answer.

Answer 1

Chemical shift value will give the what is the environment of the proton means whether the proton attached to electrnegitive atom or electro +ve atom or whether it is attached to alkene or aromatic ring or aldehyde.

depending up on the value of chemical shift we can easily say

depending up on the area of the peak called integration we can say how many protons are present

depending up on the multiplicity we can say how many protons are there on adjecent carbon means we can derive the alkyl chain

lets consider the example 1-Chlorobutane

Hydrogens which are attached to chlorine attached carbons are more deshielding which will have highest chemical shift values around 3.45 ppm

integration of these protons will be 2 means area under these signal

this protons split in to triplet means adjecent carbon is havibg two hydrogens

the general formula for this splitting is n+1 rulwhere n = adjecent protons.

ChemNMR H Estimation 1.47 3.54 CI 0.94 1.76 PPM