The 1 H NMR spectra for methanol at room temperature and -40 0 C should be sketched. Concept introduction: Hydroxyl group in methanol involves in H bonding. But at high temperatures, these hydrogen bonding is weakened and its signal is shielded due to the increase in the rate of intermolecular proton exchange. So at room temperature the two types of H are undetectable in NMR. But at low temperatures, formation of H bonding is encouraged and lowers the rate of proton exchange. So, at low temperatures two types of H are detectable hence, spin-spin coupling can be observed.

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Principles of Instrumental Analysis

7th Edition
Douglas A. Skoog + 2 others
Publisher: Cengage Learning
ISBN: 9781305577213
BuyFind

Principles of Instrumental Analysis

7th Edition
Douglas A. Skoog + 2 others
Publisher: Cengage Learning
ISBN: 9781305577213

Solutions

Chapter 19, Problem 19.19QAP
Interpretation Introduction

Interpretation:

The 1H NMR spectra for methanol at room temperature and -400C should be sketched.

Concept introduction:

Hydroxyl group in methanol involves in H bonding. But at high temperatures, these hydrogen bonding is weakened and its signal is shielded due to the increase in the rate of intermolecular proton exchange. So at room temperature the two types of H are undetectable in NMR. But at low temperatures, formation of H bonding is encouraged and lowers the rate of proton exchange. So, at low temperatures two types of H are detectable hence, spin-spin coupling can be observed.

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