LIGHT ABSORPTION STUDIES: PART VI. THE EFFECTIVE INTERFERENCE VALUES OF NON-BONDED ATOMS IN SOLUTION. PART I. SOME PRELIMINARY OBSERVATIONS

1956 ◽  
Vol 34 (11) ◽  
pp. 1542-1552 ◽  
Author(s):  
W. F. Forbes ◽  
W. A. Mueller
Keyword(s):  
Potential Energy ◽  
Light Absorption ◽  
Interatomic Distance ◽  
Neutral Solution ◽  
Absorption Data ◽  
Absorption Studies ◽  
Minimum Interference

The application of light absorption data to determine minimum interference radii of various atoms in solution is examined. Three separate methods are suggested and the relation between potential energy and interatomic distance of two non-bonded atoms is discussed. The values obtained in neutral solution are as follows: H, 0.95 ± 0.1 Å; O (in C=O), 1.0 ± 0.15 Å; and CH3, 1.7 ± 0.2 Å.

LIGHT ABSORPTION STUDIES: PART V. THE RELATION OF MESOMERIC EFFECTS AND ULTRAVIOLET LIGHT ABSORPTION SPECTRA

1956 ◽  
Vol 34 (10) ◽  
pp. 1447-1456 ◽  
Author(s):  
W. F. Forbes ◽  
Audrey S. Ralph
Keyword(s):  
Absorption Spectra ◽  
Ultraviolet Light ◽  
Light Absorption ◽  
Absorption Data ◽  
Absorption Studies

A method for the determination of mesomeric effects from ultraviolet light absorption data is critically discussed. For halogen-substituted compounds, the method gives an order of mesomeric effects different from that which is usually accepted for the halogens.

LIGHT ABSORPTION STUDIES: PART I. ULTRAVIOLET ABSORPTION SPECTRA OF SUBSTITUTED ACETOPHENONES

1955 ◽  
Vol 33 (6) ◽  
pp. 1145-1154 ◽  
Author(s):  
W. F. Forbes ◽  
W. A. Mueller
Keyword(s):  
Absorption Spectra ◽  
Ultraviolet Light ◽  
Steric Hindrance ◽  
Light Absorption ◽  
Reaction Rates ◽  
Steric Effects ◽  
Absorption Data ◽  
Absorption Studies ◽  
Anomalous Reaction ◽  
Electronic And Steric Effects

The steric hindrance postulated by Arnold and co-workers to account for anomalous reaction rates of some substituted acetophenones has been verified by means of ultraviolet light absorption data. The spectra of a number of other substituted acetophenones have been discussed in terms of the electronic and steric effects of substituents.

Oxidation of GR-S Vulcanizates

1946 ◽  
Vol 19 (3) ◽  
pp. 696-711
Author(s):  
J. Reid Shelton ◽  
Hugh Winn
Keyword(s):  
General Nature ◽  
Oxygen Absorption ◽  
Specimen Thickness ◽  
Absorption Data ◽  
First Order ◽  
Rapid Absorption ◽  
Constant Rate ◽  
Absorption Studies ◽  
Three Stages ◽  
Useful Life

Abstract Oxygen absorption studies on a tread type GR-S vulcanizate show: 1. There are three stages involved in the oxidation: (1) an initial rapid absorption, of apparent first order at constant pressure, which is of short duration and appears to involve a limited number of especially reactive centers in the vulcanizate ; (2) a constant-rate reaction, of apparent zero order at constant oxygen pressure, which would extend over most of the useful life of the vulcanizate in service ; (3) an autocatalytic reaction, beginning after a given stock has absorbed a definite amount of oxygen that is independent of the temperature at which the absorption takes place. 2. The rate of oxygen absorption increases with temperature. The temperature coefficient for the constant rate reaction is 2.6 for a 10° C change in temperature over the range 80° to 120° C. 3. Diffusion is not rate controlling, provided the specimen thickness does not exceed 0.080 inch at 100° C or 0.040 inch at 120° C. 4. The effect of cure on the rate of oxygen absorption by GR-S vulcanizates is slight, and consequently, the technique is particularly useful for studying the effect of changes in compounding upon aging resistance. 5. Oxygen absorption data can be satisfactorily correlated with changes in physical properties during aging. While the fundamental nature of the mechanism of the oxidation of GR-S is still unknown, considerable information has been obtained with respect to some of the factors involved, and the general nature of the reaction has been established. This information, together with the work still in progress, should be of value in pointing the way toward possible methods of improving the resistance of GR-S to aging.

LIGHT ABSORPTION STUDIES: PART XV. THE ULTRAVIOLET ABSORPTION SPECTRA OF ANISOLES

1959 ◽  
Vol 37 (8) ◽  
pp. 1305-1314 ◽  
Author(s):  
J. C. Dearden ◽  
W. F. Forbes
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Atom ◽  
Absorption Spectra ◽  
Hydroxy Group ◽  
Light Absorption ◽  
Spectral Properties ◽  
Ultraviolet Absorption ◽  
Steric Interactions ◽  
Absorption Studies ◽  
Methoxy Groups

Anisoles, compared with phenols, possess similar spectral properties, except that properties determined mainly by the hydrogen atom of the hydroxy group are modified. In this way, comparison of the ultraviolet absorption spectra of phenols and anisoles permits, for example, the study of the spectral effects of hydrogen bonding and the study of steric interactions involving the hydroxy and methoxy groups.

LIGHT ABSORPTION STUDIES: PART II. ULTRAVIOLET ABSORPTION SPECTRA OF SUBSTITUTED BENZOIC ACIDS AND PHENYL BENZOATES

1955 ◽  
Vol 33 (12) ◽  
pp. 1829-1839 ◽  
Author(s):  
W. F. Forbes ◽  
M. B. Sheratte
Keyword(s):  
Absorption Spectra ◽  
Light Absorption ◽  
Ultraviolet Absorption ◽  
Steric Effects ◽  
Benzoic Acids ◽  
Absorption Studies ◽  
Substituted Benzoic Acids ◽  
Electronic And Steric Effects

The spectra of a number of substituted benzoic acids, acetanilides, and phenyl benzoates are discussed in terms of the electronic and steric effects of substituents.

LIGHT ABSORPTION STUDIES: PART XII. ULTRAVIOLET ABSORPTION SPECTRA OF BENZALDEHYDES

1958 ◽  
Vol 36 (10) ◽  
pp. 1362-1370 ◽  
Author(s):  
J. C. Dearden ◽  
W. F. Forbes
Keyword(s):  
Absorption Spectra ◽  
Light Absorption ◽  
Electronic Spectra ◽  
Spectral Properties ◽  
Ultraviolet Absorption ◽  
Benzene Derivatives ◽  
Formyl Group ◽  
Steric Interactions ◽  
Absorption Studies ◽  
Acetyl Group

The electronic spectra of benzaldehydes in the region 220–360 mμ are recorded and discussed in terms of previously stated hypotheses. The formyl group is shown to endow benzene derivatives with spectral properties similar to those of the acetyl group in acetophenones, except that steric interactions are slightly modified.

LIGHT ABSORPTION STUDIES: PART XI ELECTRONIC ABSORPTION SPECTRA OF NITROBENZENES

1958 ◽  
Vol 36 (10) ◽  
pp. 1350-1361 ◽  
Author(s):  
W. F. Forbes
Keyword(s):  
Absorption Spectra ◽  
Electronic Absorption ◽  
Light Absorption ◽  
Electronic Absorption Spectra ◽  
Ultraviolet Absorption ◽  
Electronic Interactions ◽  
Absorption Studies

The spectra of nitrobenzenes are discussed in terms of previously proposed hypotheses relating electronic interactions and ultraviolet absorption spectra.

LIGHT ABSORPTION STUDIES: PART XVIII. THE ULTRAVIOLET ABSORPTION SPECTRA OF BROMOBENZENES

1961 ◽  
Vol 39 (5) ◽  
pp. 1131-1142 ◽  
Author(s):  
W. F. Forbes
Keyword(s):  
Spectral Data ◽  
Absorption Spectra ◽  
Light Absorption ◽  
Bromine Atom ◽  
Ultraviolet Absorption ◽  
Steric Effects ◽  
Benzene Derivative ◽  
Previous Part ◽  
Absorption Studies ◽  
Band Spectra

The ultraviolet absorption spectra of bromobenzene in various solvents, and the spectra of a series of substituted bromobenzenes in cyclohexane solution, are reported. The B-band spectral data confirm the hypotheses postulated for the B-band spectra of chlorobenzenes in the previous part of this series of papers. That is, the bromine atom usually gives rise to greater steric effects than the chlorine atom and the apparent mesomeric interaction as judged from these spectra increases with the size of the halogen substituent.Both bromobenzene and chlorobenzene C-band intensities are unusually small, and this is assumed to account for the frequent C-band similarity between the spectrum of a mono-substituted benzene derivative PhX, where X = OH, OCH3, NH2, and the spectrum of the corresponding chloro- or bromo-substituted PhX derivative.

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