Chapter 13, Problem 13.11P

Interpretation Introduction

Interpretation:

The relative signal intensites expected for the ${}^{\text{1}}\text{H NMR}$ and ${}^{\text{13}}\text{C NMR}$ spectra of the given sample $Si{(C{H}_3)}_4$ has to be determined.

Concept Introduction:

The ${}^{1}HNMR$ spectrum of a compound provides some vital information that is required to predict the structure of the compound.  The chemical shift values can predict the groups that are present in the molecule.  The splitting of signals by the $\left(N+1\right)$ rule predicts the number of hydrogens or protons attached to the adjacent carbon in a carbon chain of a compound.  With this information, the structure of the compound can be predicted.

The signals in the ${}^{13}CNMR$ spectrum of a compound is proportional to the number of carbons that are present in the different environment within the molecule.  The carbon which is present in the electron-rich environment shows a signal at a lower frequency and vice-versa.  Therefore, the carbon that is present nearest to the electron-withdrawing groups produces a high-frequency signal.

Tetra methyl silane: The NMR spectrum of any compound is taken with reference to a standard compound called reference compound.  Generally, tetramethylsilane (TMS) is taken as the reference compound.  The methyl protons of TMS are equivalent and produces only one sharp peak at the rightmost end of the scale.