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.

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.

LIGHT ABSORPTION STUDIES: PART XIV. THE ULTRAVIOLET ABSORPTION SPECTRA OF PHENOLS

1959 ◽  
Vol 37 (8) ◽  
pp. 1294-1304 ◽  
Author(s):  
J. C. Dearden ◽  
W. F. Forbes
Keyword(s):  
Hydrogen Bonding ◽  
Spectral Analysis ◽  
Absorption Spectra ◽  
Excited States ◽  
Light Absorption ◽  
Steric Effects ◽  
Benzene Derivatives ◽  
Substituted Phenols ◽  
Absorption Bands ◽  
Absorption Studies

A spectral analysis of benzene derivatives is extended to substituted phenols. The discussion emphasizes hydrogen bonding and steric effects which occur in phenols. Some of the phenolic absorption bands are ascribed to locally excited states.

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 XVI. THE ULTRAVIOLET ABSORPTION SPECTRA OF FLUOROBENZENES

1959 ◽  
Vol 37 (12) ◽  
pp. 1977-1985 ◽  
Author(s):  
W. F. Forbes
Keyword(s):  
Absorption Spectra ◽  
Light Absorption ◽  
Fluorine Atom ◽  
Ultraviolet Absorption ◽  
Mesomeric Effect ◽  
First Approximation ◽  
Absorption Studies

The ultraviolet absorption spectra of a series of fluorobenzenes are determined. It is found that as a first approximation a fluoro substituent does not appreciably affect the benzenoid absorption. The spectra are discussed on the assumption that the mesomeric effect of the fluorine atom is small.

LIGHT ABSORPTION STUDIES: PART XVII. THE ULTRAVIOLET ABSORPTION SPECTRA OF CHLOROBENZENES

1960 ◽  
Vol 38 (7) ◽  
pp. 1104-1112 ◽  
Author(s):  
W. F. Forbes
Keyword(s):  
Absorption Spectra ◽  
Chlorine Atom ◽  
Light Absorption ◽  
Fluorine Atom ◽  
Ultraviolet Absorption ◽  
Electronic Interaction ◽  
Mesomeric Effect ◽  
Spectral Changes ◽  
Absorption Studies ◽  
Solute Interactions

The ultraviolet absorption spectra of a series of chlorobenzenes are determined. The spectral data suggest that the apparent mesomeric effect of the chlorine atom is greater than that of the fluorine atom, that solvent–solute interactions are generally less important in chlorobenzenes than in fluorobenzenes, and that, as expected, the effective interference radius of the chlorine atom is large. Moreover, spectral changes in o-substituted chlorobenzenes are consistent with the assumption that maximum electronic interaction requires the chlorine atom to be in the same plane as the benzene ring. The conformations of o-chloroacetophenone and o-chlorophenol are briefly discussed.

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