13C NMR Spectroscopy

Introduction

• 13C NMR in conjunction with 1H NMR offers an important technique for structural elucidation of organic molecules. 13C NMR spectra gives information about the number of non-equivalent carbons and the types of carbon present (methyl, aromatic, carbonyl etc).
• 13C NMR provides direct information about the molecular skeleton which can be used to validate information obtained by 1H NMR.
• The 12C nucleus is not NMR "active". Spin number I = 0. The 13C nucleus has I = 1/2. Natural abundance only 1.08% that of 12C and its sensitivity (magnetogyric ratio) is only about 1.6% that of 1H. Thus the overall sensitivity of 13C NMR compared to 1H NMR is about 1/5700.
• Since …