Question

QUESTION 3 Which structure gives the TH NMR shown? a. b. C. d. 7 -CO ch الع N- PPM

Answer 1

a A not this compound, because te protons marked 'a' should appear as a singlet for 2H at around 3.3 ppm. Which is not there in the spectrum a В. not this compound, because te protons marked 'a' should appear as a singlet for 2H at around 4.5 ppm. Which is not there in the spectrum a D not this compound, because te protons marked 'a' should appear as a quartet for 2H at around 4.3 ppm. Which is not there in the spectrum So, the spectrum is for this compound. The description is as below

Name: phenyl propionate Chemical Formula: C9H1002 Proposed Structure Exact Mass: 150.0681 a b e a b Η Χ N Degree of Unsaturation=C+1- + 2 2 =9+1-5 = 5 1H NMR #Hydrogen 1 1H Signal H marked a H marked b H marked c H marked d H marked e Chemical Shift (ppm) 7.5 7.4 7.1 2.6 2 2 2 3 Multiplicity triplet doublet doublet quartet triplet 1.2 Multiplicity Rule: The multiplicity of any peak depends on the number of neighboring protons. If a proton contains n number of neighboring protons then the splitting will be n+1. Suppose a proton contains 2 neighboring H then it will give a triplet (2+1). However sometimes the splitting changes due to germinal vicinal etc. coupling in certain cases.