Stephen E. Wiberley

Flow Properties of Lithium Stearate-Oil Model Greases as Functions of Soap Concentration and Temperature

Lithium stearate-oil greases having 4, 8, and 12% soap were prepared and flow properties of the greases were investigated, at 0, 25, and 37.8 C. Flow data were obtained with a cone and plate viscometer equipped with automatic programming and recording of shear stress versus rate of shear, and of shear stress versus time at selected shear rates. Flow curves, shear stress versus shear rate, were obtained for an initial and a repeat 300-sec cycle of shear with maxima of 1520 sec−1 and of 15,200 sec−1, Flow curves were measured for highly worked samples, previously sheared at 19,000 sec−1 for 1000 sec. The rate of change of shearing stress required to maintain a constant rate of shear was measured at nine shear rates in the interval from 190 sec−1 to 19,000 sec−1. Similar flow measurements were made on greases containing stearic acid additives. Initial flow resistance, ascribed to soap structural elements, showed temperature and concentration dependence differing from that of the sheared soap, and was destroy...

THE VIBRATIONAL ORIGIN OF GROUP FREQUENCIES

Publisher Summary This chapter discusses the vibrational origin of group frequencies with an emphasis on mechanical effects. A characteristic of a group frequency vibration is that the mechanical interaction effects that control the form of the vibration are relatively constant from molecule to molecule, making the frequency readily predictable. Mechanical interaction effects only occur between vibrations belonging to the same symmetry species. In a molecule with a plane of symmetry such as vinyl chloride, in-plane vibrations do not interact with out-of-plane vibration. The chapter focuses on the infrared frequencies that are absorbed by certain chemical functional groups of atoms, such as carbonyls. It further reviews the vibration of a diatomic molecule and a complex module consisting of a number of bonded atoms. X—H stretching frequencies are higher than Y—X stretching frequencies where Y is a nonhydrogen atom directly attached to X. It means that hydrogen stretching vibrations are more or less mechanically independent of the rest of the molecule and tend to make good group frequencies. The chapter presents a list of the approximate X—H stretching frequencies and the force constants for various X—H groups arranged according to the periodic table.

The infrared and Raman spectrum and thermodynamic functions of cyclopropyl cyanide

Abstract Cyclopropane is the only molecule containing the cyclopropane ring which has been thoroughly investigated from a spectroscopic viewpoint. The infrared spectrum of cyclopropyl cyanide in the liquid and vapor phase has been measured from 2 to 25 microns using lithium fluoride, sodium chloride, and cesium bromide prisms. The Raman spectrum of the liquid and qualitative polarization data have been obtained. A normal coordinate analysis was done on the skeletal molecule assuming a Cs point group. Using the calculated values and data on related molecules a complete vibrational assignment of the experimentally determined frequencies has been made. The moments of inertia and the thermodynamic functions have been calculated.

Infrared Spectra of Polynuclear Aromatic Compounds in the C-H Stretching and Out-of-Plane Bending Regions

A study has been made of the infrared spectra of 33 poly-nuclear aromatic compounds including some known carcinogens. In most cases, the number of fused rings may be determined by measuring the frequency of the characteristic aromatic (C-H) stretching vibration with a LiF prism. For unsubstituted fused rings, the (C-H) stretching vibration shifts to lower frequencies as the number of fused rings increases. In addition, the position of the fused rings can be established from data obtained from the out-of-plane (C-H) bending vibrations in the range of 700 to 900 cm−1.

CHAPTER 9 – CARBONYL COMPOUNDS

Publisher Summary Carbonyl compounds give rise to a strong band at 1900–1550 cm−1 caused by the stretching of the C=O bond. This chapter illustrates some carbonyl vibrations and some general spectral features for a selection of carbonyl compounds, which show some bands from the attached groups. It further presents a summarization of the carbonyl spectral regions. The factors that cause shifts in the carbonyl frequencies are also discussed in the chapter. Ketones are characterized by the strong C=O stretching frequency absorption near 1715 cm−1. Ketones with a chlorine on the α-carbon absorb at higher frequencies when the chlorine is rotated near the oxygen than when the chlorine is not near the oxygen due to a field effect.

CHAPTER 8 – AROMATIC AND HETEROAROMATIC RINGS

Publisher Summary This chapter focuses on aromatic and heteroaromatic rings. All the modes of vibration of a monosubstituted benzene ring are illustrated in the chapter. The chapter reviews the general appearance of monosubstituted benzenes and ortho, meta, and para substituted benzenes in the infrared spectrum. It further illustrates the ring modes of benzene1-10 and the modes for mono, ortho, meta, and para substitued benzenes in the 1600 and 1500 cm−1 regions. The chapter presents the characteristic bands for substituted naphthalenes and pyridine compounds. Five-membered ring heteroaromatic compounds with two double bonds in the ring show three ring stretching bands near 1590, 1490, and 1400 cm−1. The chapter reviews the metal complexes of the cyclopentadienyl ring with a large number of different metals and illustrates the bands for the cyclopentadienyl ring.

COMPOUNDS CONTAINING BORON, SILICON, PHOSPHORUS, SULFUR, OR HALOGEN

Publisher Summary This chapter discusses the spectra of various chemical groups such as boron, silicon, phosphorus, sulfur, and halogen under the functional group categories. It presents a list of the spectral for boron compounds. The compounds containing the B—O linkage—such as borates, boronates boronites, boronic anhydrides, borinic acids, and boronic acids—are characterized by intense absorption at 1380–1310 cm−1, involving the stretching of the B—O bond. The high frequency and intensity is due to the fact that the B—O has some polar double bond character. The OH groups in boronic acids and boric acid in the solid state absorb near 3300–3200 cm−1 due to the bonded OH stretch. The compounds having a B—N linkage—such as borazines and amino boranes—have strong absorption at 1465–1330 cm−1 involving the stretching of the B—N bond. This bond has some polar double bond character as the B—O bond. Normal BH and BH2 groups absorb at 2640–2350 cm−1 due to the BH stretch. The chapter further presents a summarization of the more common silicon correlations and a list of correlations for phosphorus groups.

VIBRATIONAL AND ROTATIONAL SPECTRA

Publisher Summary The energy of a molecule consists partly of translational energy, rotational energy, vibrational energy, and electronic energy. Electronic energy transitions give rise to the absorption or emission in the ultraviolet and the visible regions of the electromagnetic spectrum. Pure rotation gives rise to the absorption in the microwave region or the far infrared. Molecular vibrations give rise to the absorption bands throughout most of the infrared region of the spectrum. This chapter focuses on vibrational and rotational spectra and discusses how molecular vibrations and rotations interact with radiation to create the infrared and Raman spectra. The vibrational and the rotational frequencies of molecules can be studied by Raman spectroscopy and by infrared spectroscopy. While they are related to each other, the two types of spectra are not exact duplicates and each has its individual strong points. In Raman spectroscopy, only the wave number is used. Infrared and Raman spectrum both involve vibrational and rotational energy levels; they are not duplicates of each other but rather complement each other. This is because the intensity of the spectral band depends on how effectively the photon energy is transferred to the molecule.

METHYL AND METHYLENE GROUPS

Publisher Summary This chapter discusses the spectra–structure correlations. These correlations are infrared correlations unless they are specifically labeled as Raman correlations. Molecular vibrational frequencies are the same in infrared and Raman spectra and for groups such as O—H, C—H, C≡N, C=0, and C=C frequency, correlations will be the same for both techniques. The chapter focuses on the vibrations of methyl and methylene groups. The vibrations of the CH3 group are illustrated in the chapter. There are three CH bonds in a methyl group; therefore, there are three CH stretching vibrations. In the symmetric, in-phase stretching vibration, the whole CH3 group stretches in-phase. The two out-of-phase stretching vibration is characterized as a “half-methyl” stretch. The chapter further illustrates the vibrations of the CH2 group and presents a list for the CH2 spectral regions.

Infrared absorption of branched-chain fatty acids and derivatives in the carbon-hydrogen stretching region

SummaryAn investigation of the lithium fluoride region makes it possible to characterize a number of structural isomers of branched-chain fatty acids. For example, 2-methyl, 3-methyl, and 5-methyl hexanoic acids may be distinguished. Similarly a number of isomers of octanoic acid may be identified ; 2-n-propyl and 2-isopropyl hexanoic acid may be differentiated. The isomers of 2-n-butyl hexanoic acid may also be identified.Absorption bands at 2960 cm−1 and 2930 cm−1 have been assigned, respectively, to asymmetrical methyl stretching modes and in-phase vibrations of the methylene group. Absorption at 2870 cm−1 is associated with symmetrical stretching modes of the methyl group. The absorption at 2860 cm−1 has been assigned to the out-of-phase vibrations of the methylene group. These assignments correspond to those of Fox and Martin and of Pozefsky and Coggeshall.The absorption bands at 2930 cm−1 and 2860 cm−1 are stronger than those at 2960 cm−1 and 2870 cm−1 when the ratio of methylene groups to methyl groups equals or exceeds three to one. The one exception to this rule is the case of 2-methyl hexanoic acid and the corresponding silver salt and di-soap. An interaction between the methyl group in the two-position and the acid group has been proposed as an explanation for this case.As the spectra of the fatty acids and their silver salt and aluminum di-soap derivatives are identical in the carbon-hydrogen region, it is obvious that other derivatives of these acids may be identified by reference to the spectra reported.