Structure Determination By Spectroscopic Methods

A Practical Approach

Raul SanMartin, Maria Teresa Herrero

• Publisher: CRC Press
• Year: 2020
• Print ISBN: 9780367510169
• eBook ISBN: 9781351032483
• Topic: Physical Sciences
• Subtopic: Biology

The authors travel with the reader through the challenging maze of structure determination, showing how to distinguish between valuable and deceiving data from IR, NMR and MS spectra, extracting structural conclusions and putting all the pieces together to solve the structure elucidation puzzle. Indeed, human reasoning is key to combining the information contained in those bands, signals and peaks by a rationale that enables the makeup of a chemical structure. A number of increasingly more complex problems will act as trip segments and, in addition to the spectra themselves, each chapter is supplemented with figures and tables that decipher the above data and serve as maps for the journey.

PROBLEMS

Problem 1

A colorless liquid was isolated as the main product from the halogenation of a mixture of alkanes. Determine its structure from the following spectra and spectral data.

EI-MS (70 eV)

Figure 1.1 EI-MS unknown compound 1.

IR SPECTRUM (Thin film)

Figure 1.2 IR spectrum of unknown compound 1.

¹H NMR SPECTRUM (300 MHz, CDCl₃)

Figure 1.3 ¹H NMR spectrum of unknown compound 1.

¹³C{ ¹H} NMR AND DEPT-135 SPECTRA (75.5 MHz, CDCl₃)

Figure 1.4 ¹³C{¹H} NMR and DEPT spectra of unknown compound 1.

Problem 2

Catalytic hydrogenation of a sample of coal tar provided, after chromatographic separation, a yellowish white powder. Draw a structure for this compound that is consistent with all the spectra and spectral data presented below.

HRMS: (M⁺) found 180.0939

EI-MS (70 eV)

Figure 2.1 EI-MS of unknown compound 2.

...

TABLE 2.1 Main peaks found in the EI-MS spectrum of unknown compound 2.

m/z	Abundance (%)	m/z	Abundance (%)	m/z	Abundance (%)
75.10	6.0	139.10	6.0	176.10	29.0
76.10	16.0	150.10	9.0	177.20	18.0
82.60	5.0	151.10

Table of contents

• Cover
• Title Page
• Copyright Page
• Preface
• Acknowledgements
• Contents
• Bibliography
• Instrumentation
• Spectral Data
• Problem-Solving Strategies
• Summary Tables of Some Useful Spectroscopic Data
• Abbreviations
• Problems
• Solutions to Problems
• References
• Index