Doc Brown's Chemistry  Molecular structure deduction

3 problems to solve, mainly based on spectra data

INDEX of all ir, mass, 1H and 13C NMR spectroscopy pages * [SEARCH]

NMR problem solving with associated molecular data

These questions illustrate how you can unite various sources of data-information to deduce the structure of a molecule

You will need tables of nmr chemical shifts and

characteristic infrared absorption frequencies (as wavenumber cm^-1)

Atomic masses: C = 12, H = 1, O =16  *  Answers to NMR problems

NMR PROBLEM 1 with associated infrared spectrum, molecular ion and % element by mass data

	% mass element analysis: 82.76% C and 17.24% H
	Infrared spectrum: Peaks in 2850-2950 cm-1 region NO suggestion of any specific functional group absorption
	Molecular ion peak from mass spectrometry: 58

NMR PROBLEM 2 with associated infrared spectrum, molecular ion and % element by mass data 

	% mass element analysis: 54.55% C, 9.09% H and 36.36% O
	Infrared spectrum: sharp strong absorption at 1735-1750 cm-1 NO broad absorption band from ~2500-3200 cm-1
	Molecular ion peak from mass spectrometry: 88

NMR PROBLEM 3 with associated infrared spectrum, molecular ion and % element by mass data

	% mass element analysis: 62.07% C, 10.34% H and 27.59% O
	Infrared spectrum: strong sharp absorption at 1700-1725 cm-1 moderate, broad absorption at ~2450-3150 cm-1
	Molecular ion peak from mass spectrometry: 116