Tables of Spectral Data for Structure Determination of Organic Compounds

Abstract

This book, a revised translation of a successful German work, is a compilation of data for the spectroscopic methods most widely used for the structural elucidation of organic molecules, viz. 'H NMR, 13C NMR, IR and UV/visible spectroscopy and mass spectrometry. It updates and extends the information provided by such standard works as those of Bellamy on IR group frequencies and of Jackman and Sternhell on ' H NMR, and assembles in a single volume data which have hitherto been available mostly in separate specialised texts.The book is divided into six sections of comparable length, within which data are presented in well organized tables or annotated structural diagrams. Further information is provided by appended comments and short notes.The first section summarizes the structural information which may be derived from the presence of signals in particular spectral regions, while a series of combination tables collates all spectroscopic data according to compound type and gives references to the remaining five sections, in which in-depth coverage is given to each technique in turn.The ' H and 13C N M R sections list chemical shifts and coupling constants (lH-lH, 'H-13C and couplings of 'H and 13C with common heteronuclei) for compounds ranging from simple alkanes to condensed heteroaromatics. Rules for the prediction of these parameters are described and spectra of common NMR solvents are shown. The W/visible section includes a table of A, , and em, values for a wide range of simple chromophores and illustrates the use of the Woodward and Scott rules for Am= prediction. Also provided is a useful catalogue of reference spectra for common chemical structures. A comprehensive table of group frequencies arranged by chemical structure forms the basis of the IR section; the associated comments are particularly informative. A short discussion of interferences in IR spectra is given and spectra of common IR solvents and suspension media are shown. Mass spectrometry coverage, confined to 70 eV EI spectra, includes a table of assignments and parent molecules for ions of up to 167 mass units. Other information includes isotope patterns for all natural elements, spectra of common solvents and contaminants and a short discussion of metastable peaks.While not replacing the established spectroscopic texts, this book provides a wealth of information at a comparatively modest price and will appeal to the more committed student. It will also be a valuable reference work for any laboratory combining spectroscopic methods for the determination of chemical structure. As a consequence of its integrated approach, the specialist reader is exposed to the advantages of other techniques and, in this respect, the re-emphasis on the somewhat neglected structural uses of UV/visible spectroscopy is particularly appropriate. The absence of any discussion on the newer ionization methods for mass spectrometry is unfortunate, and it is to be hoped that this omission will be rectified in subsequent editions.The text is logically organized and we...

DSC-FTIR microspectroscopy used to investigate the heat-induced intramolecular cyclic anhydride formation between Eudragit E and PVA copolymer

“…Several characteristic IR absorption bands and their assignments at the initial temperature (30 1C) are shown: 1730 cm À1 (C¼O stretching of ester), 1456 cm À1 (C-H bending of methyl), 1271 and 1246 cm À1 (C-O stretching of ester) and 1153 cm À1 (C-N stretching of aliphatic amine and/or C-O stretching of ester). 17,18 As shown in Figures 1a and c, the wavenumber and peak intensity of the IR spectra changed significantly with the increase of temperature. Once the Eudragit E film was heated beyond 180 1C, the intensities of three specific peaks at 1801, 1763 and 1010 cm À1 began to increase with temperature, which is consistent with our previous report.…”

“…13 The new peaks at 1801 and 1763 cm À1 were assigned to the symmetric and asymmetric C¼O stretching vibrations in the anhydride, implying that anhydride formation occurred in the Eudragit E film during the heating process. [17][18][19] In addition, the intensity of a new peak at 1010 cm À1 due to the asymmetric stretching mode of C-O-C also increased beyond 180 1C, strongly supporting the cyclic anhydride formation via ester condensation in the Eudragit E film. This result is consistent with the report by Pretsch et al, 18 in which the carbonyl stretching vibration of six-membered cyclic anhydrides exhibited unique peaks at 1800 and 1760 cm À1 , rather than at 1850 and 1775 cm À1 as was shown by five-membered cyclic anhydrides.…”

“…[17][18][19] In addition, the intensity of a new peak at 1010 cm À1 due to the asymmetric stretching mode of C-O-C also increased beyond 180 1C, strongly supporting the cyclic anhydride formation via ester condensation in the Eudragit E film. This result is consistent with the report by Pretsch et al, 18 in which the carbonyl stretching vibration of six-membered cyclic anhydrides exhibited unique peaks at 1800 and 1760 cm À1 , rather than at 1850 and 1775 cm À1 as was shown by five-membered cyclic anhydrides. This result confirms the formation of six-membered cyclic anhydrides in the Eudragit E film during the heating process.…”

“…The observation of the peaks at both 1799 and 1759 cm À1 in the IR spectrum of the PVA copolymer also confirmed the formation of six-membered cyclic anhydrides. 18 The proposed process of thermally induced anhydride formation for PVA copolymers via ester condensation is depicted in Scheme 1. The sharp peak at 1140 cm À1 almost disappeared from the IR spectrum of the 320 1C-heated PVA copolymer, which indicates that the thermally induced ester condensation also altered the crystallinity of the PVA in the PVA copolymer.…”

Communiols E−H: New Polyketide Metabolites from the Coprophilous Fungus Podospora communis

“…NMR spectra were recorded using CDCl3 solvent, and chemical shifts were referenced to the residual solvent signals (δH 7.24/δC 77.0). 1 H NMR data were recorded at 300 MHz (Bruker AC-300) or 600 MHz (Bruker AMX-600), 13 C NMR data were recorded at 75 MHz (AC-300), and selective INEPT data were recorded at 90 MHz (Bruker WM-360). All 2D NMR data were recorded at 600 MHz ( 1 H dimension).…”