The structure for the compound having molecular formula C 8 H 10 O is to be proposed based on the distinct signals in its 1 H NMR spectrum. Concept introduction: In 1 H NMR spectroscopy, protons in different environments within a molecule have different chemical shifts, that is, they experience different degrees of shielding. In addition to chemical shift, a 1 H NMR spectrum provides structural information based on the number of signals, which tells how many different kinds of protons are there; integrated areas, which tells the ratios of the various kinds of protons; and splitting pattern, which gives information about the number of protons that are within two or three bonds of the one giving the signal. Spin-spin splitting of NMR signals results from the coupling of the nuclear spins that are separated by two bonds (geminal coupling) or three bonds (vicinal coupling). In these cases, the number of peaks into which a signal is split is equal to (n+1) , where n is the number of protons to which the proton in question is coupled. Protons that have the same chemical shift do not split each other’s signals. Complicated splitting patterns can result when a proton is unequally coupled to two or more protons that are different from one another. The ideal range for alkane protons is δ 0.9 - δ 1.4 ; for alcohol, it is δ 2 - δ 5.0 , and for aromatic protons, it is δ 6.5 - δ 8.5 . The chemical shift of a signal prompts about the aromatic rings, double bonds, or nearby electronegative atoms. The integration of each signal suggests the number of protons responsible for that signal. The splitting pattern of a signal indicates the number of neighboring protons that are distinct from the protons responsible for that signal. To deduce the structure of an unknown compound, the first step is to find the index of hydrogen deficiency if the molecular formula is given. Based on the data given in the 1 H NMR, molecular fragments with multiple carbon atoms can be built.

Question

Are there signals that you can assign to specific protons in the molecule (labeled a-k)? Complete this column of the table. It may not be possible to assign each signal to a specific proton.

Answer 1

Question

Chapter 16, Problem 16.32P

Interpretation Introduction

Interpretation:

The structure for the compound having molecular formula C8H10O is to be proposed based on the distinct signals in its 1H NMR spectrum.

Concept introduction:

In ^1HNMR spectroscopy, protons in different environments within a molecule have different chemical shifts, that is, they experience different degrees of shielding.

In addition to chemical shift, a 1H NMR spectrum provides structural information based on the number of signals, which tells how many different kinds of protons are there; integrated areas, which tells the ratios of the various kinds of protons; and splitting pattern, which gives information about the number of protons that are within two or three bonds of the one giving the signal. Spin-spin splitting of NMR signals results from the coupling of the nuclear spins that are separated by two bonds (geminal coupling) or three bonds (vicinal coupling). In these cases, the number of peaks into which a signal is split is equal to (n+1), where n is the number of protons to which the proton in question is coupled. Protons that have the same chemical shift do not split each other’s signals.

Complicated splitting patterns can result when a proton is unequally coupled to two or more protons that are different from one another.

The ideal range for alkane protons is δ 0.9- δ 1.4; for alcohol, it is δ 2- δ 5.0, and for aromatic protons, it is δ 6.5- δ 8.5.

The chemical shift of a signal prompts about the aromatic rings, double bonds, or nearby electronegative atoms. The integration of each signal suggests the number of protons responsible for that signal. The splitting pattern of a signal indicates the number of neighboring protons that are distinct from the protons responsible for that signal. To deduce the structure of an unknown compound, the first step is to find the index of hydrogen deficiency if the molecular formula is given. Based on the data given in the 1H NMR, molecular fragments with multiple carbon atoms can be built.

Expert Solution & Answer

Trending nowThis is a popular solution!

See solution

Check out sample textbook solution

Students have asked these similar questions

Are there signals that you can assign to specific protons in the molecule (labeled a-k)? Complete this column of the table. It may not be possible to assign each signal to a specific proton.

What is the molecular formula structure and its proton environment of these two spectrum?

Based on the spectra you located, does your molecule have a carbonyl? If so, what functional group is it a part of (carboxylic acid, ketone, aldehyde, ester, amide) and what is the frequency (in wavenumbers) of the absorption peak? If not, what is the approximate frequency range for a carbonyl? Does your molecule have either an –O-H or –N-H bond? If so, what functional group is it a part of (carboxylic acid, alcohol, amine, amide) and what is the frequency (in wavenumbers) of the absorption peak? If not, what are the approximate frequency ranges for an –O-H and an –N-H bond? Does your molecule have either an alkyne or nitrile functional group? If so, which functional group is it and what is the frequency (in wavenumbers) of the absorption peak? If not, what is the approximate frequency range for a triple bond?