ORGANIC CHEMISTRY GGC>CUSTOM<-TEXT
ORGANIC CHEMISTRY GGC>CUSTOM<-TEXT
2nd Edition
ISBN: 9781119288510
Author: Klein
Publisher: WILEY
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Chapter 16.5, Problem 8ATS
Interpretation Introduction

Interpretation: The compound that gives a signal between 6 and 7ppm in the 1H NMR spectrum is to be predicted.

Concept Introduction:

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). The frequency of absorption of protons from the reference proton which depends on the various factors like inductive effect, anisotropic effect, diamagnetic effect etc...

Chemicalshift=signalfrequency-referencefrequencyfrequencyofspectrometer(106)

Inductive effect: Generally, an electronegative atom pulls the electron density from its neighbor atoms causing the less electron cloud around those atoms is known as inductive effect and those atoms experience the strong external magnetic field; the resonance (energy) gap between spin states increases which absorbs the higher radio frequency and gets shift in order to the reference proton.

Anisotropic effect: The chemical shift of protons affected by the motion of nearby π-electrons which characterized by the external magnetic field. The motion of nearby π-electrons generates an induced magnetic field that affects the chemical shift value of subjected protons.

Bench mark values: The chemical shift values to remember for the protons below

Methyl 0.9 (chemical shift)
Methylene 1.2 (chemical shift)
Methine 1.7 (chemical shift)

Inductive effect: The presence of functional groups at the alpha position has impact on the protons

FUNCTIONAL GROUP EFFECT ON THE ALPHA PROTONS EFFECT ON THE BETA PROTONS
Oxygen of an alcohol or ether +2.5 +0.5
Oxygen of ester +3.0 +0.6
Carbonyl groups +1.0 +0.2

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Chapter 16 Solutions

ORGANIC CHEMISTRY GGC>CUSTOM<-TEXT

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