F. F. Bentley

Infrared spectra of inorganic ions in the cesium bromide region (700–300 cm−1)

Abstract The infrared spectra from 300–880 cm−1 of 208 inorganic substances are reported. Nearly all are salts containing polyatomic ions. Spectral curves are presented for 140 of the compounds, and a list of characteristic frequencies is given for twenty ions. Among other matters discussed are: (a) the non-reproducibility of some of the spectra, and reasons for this, (b) absorption due to the torsional oscillation of water molecules, and (c) some vibrational assignments for MnO4−1 and CrO42−1.

Characteristic group frequencies of bromo and iodoalkanes in the cesium bromide region

Abstract The infrared spectra of 74 normal and branched bromo and iodoalkanes have been recorded and studied in the range of 667-286 cm−1. It was found that the number and position of the frequencies characteristic of the CX stretching vibration are dependent on the rotational isomers present as well as the structure of the alkyl substituents in the vicintiy of the CX group. Conformational structures and representative spectra are presented along with correlation charts which list the CX stretching vibration for various primary, secondary and tertiary bromo and iodoalkanes.

Infrared‐Absorption Spectra of Chloro‐, Bromo‐, and Iodoalkanes in the 400‐to‐100‐cm−1 Region

The infrared‐absorption spectra of 18 haloalkanes have been studied and the carbon—halogen bending vibration assigned for each molecule. The effect of rotational isomerism on this vibration was determined. The low‐frequency torsional modes have also been assigned. Solid‐state studies contributed to the support of the assignments and made it possible to determine rotational effects.

Vibrational Spectra of Benzene Derivatives. II. Frequency Assignments in the CsBr Region

Frequency assignments in the CsBr spectral region (65 0 to 28 5 cm−1) have been made from the spectra of 279 benzene derivatives The Raman spectra of 119 of these compounds were also used as aids in making the assignments. The assigned frequencies include several benzene-like ring-deformations and some vibrations that are either internal vibrations of the substituent group or involve the ring-substituent bond. A variation in frequency with symmetry or substitution type (ortho, meta, para, etc.) was found for the ring-deformations. Within a given substitution type certain of the ring-deformation vibrations were found to be sensitive to substituent effects The assigned frequencies involving the substituent group can be classified as characteristic frequencies of benzene compounds with a particular substituent

New spectra-structure correlations of ketones in the 700–750 cm−1 region

Abstract The spectra of forty-two ketones of varying structure have been recorded and analyzed in the range of 700–350 cm −1 . It has been found that structural configurations adjacent to the carbonyl group shift the typical ketone absorption in a specific manner. It is therefore possible to differentiate several classes of ketones by means of their infrared spectra in this region. Evidence is presented for the reversal of a previous assignment of two skeletal frequencies of acetone.

Analytical applications of far infrared spectra—II: Spectra-structure correlations for aliphatic and aromatic hydrocarbons in the cesium bromide region

Abstract The infrared absorption spectra of some 400 aliphatic and aromatic hydrocarbons have been investigated from 15 to 35 μ and the characteristic absorption frequencies incorporated into spectra-structure correlation charts. The classes of compounds studied were alkanes, alkenes, cyclopropanes, cyclopentanes, cyclohexanes, substituted benzenes, naphthalenes and biphenyls. The skeletal bending frequencies of the alkanes and alkenes and the non-planar bending frequencies of the aromatic hydrocarbons are the most useful for qualitative analysis in this region. The wavelength and intensity of the out-of-plane ring frequencies of aromatic molecules give some indication of the nature of the substituents. Typical infrared spectra of the hydrocarbons are presented.

The infrared spectra of some aliphatic monocarboxylic acids in the 700-350 cm−1 region

Abstract The infrared spectra of 28 aliphatic monocarboxylic acids of varying structure are recorded in the 700-350 cm −1 region. It is shown that the structural configuration adjacent to the carbonyl group affects the spectra in a specific manner. It is therefore possible to differentiate α-alkyl branched acids from straight-chain acids. Striking differences in the spectra of liquid and solid forms of the straight-chain acids were observed. The spectra of the solids below about 510 cm −1 are quite characteristic of the individual acids and may be used for differentiation of these compounds.

Carbon–Fluorine Bond Stretchings in Some Acyclic Organic Molecules

The purpose of this paper is to call attention to the existing discrepancy between qualitative and quantitative interpretations of certain carbon–fluorine stretching modes in fluorine substituted compounds.

Far-Infrared Group Frequencies. I. Aliphatic Alcohols

The far-infrared spectra of a number of aliphatic alcohols have been recorded as dilute solutions in cyclohexane. A characteristic band is present at 210±5 cm−1 and is assigned to the hydroxyl torsion on the basis of the deuterium shifts. The position of the band is not sensitive to steric effects but is very sensitive to proximity of electron rich systems. The hydroxyl torsion shifts to ∼300 cm−1 in benzene. Uses of this group frequency for spectra structure correlations are discussed.

The Far Infrared Spectra of Monosubstituted Pyridines

Infrared spectra in the cesium bromide region are presented for 43 monosubstituted pyridines. Two- and 3-substituted pyridines are characterized in this region by two relatively intense bands near 600 and 400 cm−1. No strong characteristic bands are found for 4-substituted pyridines. The vapor-phase contours of the far infrared bands of 2-fluoro- and 2-chloropyridine indicate that the 600 and 400 cm−1 bands arise, respectively, from an in-plane and an out-of-plane vibration. The pyridine spectra are compared with the spectra of some substituted benzenes