Chapter 15.10, Problem 25ATS

Interpretation Introduction

Interpretation:

The structure of PMPEA has to be deduced from given ${}^{\text{1}}\text{H}$ NMR spectral data.

Concept Introduction:

NMR spectroscopy:

It is the study of the interaction between electromagnetic radiation and the nuclei of atoms and the variety of nuclei studied includes ${}^{\text{1}}\text{H,}{}^{\text{13}}\text{C,}{}^{\text{15}}\text{N,}{}^{\text{19}}\text{F}\text{and}{}^{\text{31}}\text{P}$

Chemical shift: The frequency of the proton signal in the spectrum with reference to the standard compound  which may be TMS(Tetramethylsilane) shows signal at 0 ppm(parts per million).

Chemical shift values for protons in different electronic environment

Types of protons	Chemical shift
Methyl	$\text{~0}\text{.9}$
methylene	$\text{~1}\text{.2}$
Methine	$\text{~1}\text{.7}$
Allylic	$\text{~2}$
Alkynyl	$\text{~2}\text{.5}$
Aromatic methyl	$\text{~2-5}$
Alkyl halide	$\text{~2-4}$

Alcohol	$~2-5$
Vinyl	$~4.5-6.5$

Aryl	$~6.5-8$
Aldehyde	$~10$
carboxylic	$~12$

HDI (Index of hydrogen deficiency): HDI values gives information on the level of unsaturation (means a double bond or a ring) on the structure of the compound.

  $\text{HDI= }\frac{\left(\text{ 2C+2+N-H-X}\right)}{\text{2}}$

  $\begin{array}{l}\text{C }\text{indicates}\text{number}\text{of}\text{carbon}\\ \text{N }\text{indicates}\text{number}\text{of}\text{nitrogen}\\ \text{H }\text{indicates}\text{number}\text{of}\text{hydrogen}\\ \text{X }\text{indicates}\text{number}\text{of}\text{halogen}\end{array}$