LIGHT ABSORPTION STUDIES: PART XXI. THE ULTRAVIOLET AND INFRARED ABSORPTION OF o-ALKYL- AND o,o′-DIALKYL-SUBSTITUTED ANISOLES

1965 ◽  
Vol 43 (9) ◽  
pp. 2603-2609 ◽  
Author(s):  
A. Balasubramanian ◽  
J. C. Dearden ◽  
W. F. Forbes ◽  
N. F. Cheetham
Keyword(s):  
Dipole Moment ◽  
Spectral Data ◽  
Vapor Phase ◽  
Infrared Absorption ◽  
Light Absorption ◽  
Steric Effects ◽  
Absorption Studies

Steric effects, previously reported by other workers in o- and o,o′-alkyl-substituted anisoles, were reinvestigated using compounds carefully purified by vapor phase chromatography. The ultraviolet spectral data indicate that the o-alkyl-substituted anisoles exist in one conformation, whereas the investigated o,o′-dialkyl-substituted anisoles exist in a different conformation. The conformations appear to be almost independent of the size of the substituent groups. Infrared, dipole moment, and other data are consistent with this interpretation.

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 IV. THE EFFECTS OF STERICALLY HINDERED CONFORMATIONS ON THE ELECTRONIC SPECTRA (B-BANDS) OF CONJUGATED SYSTEMS

1956 ◽  
Vol 34 (9) ◽  
pp. 1347-1355 ◽  
Author(s):  
W. F. Forbes ◽  
W. A. Mueller
Keyword(s):  
Spectral Data ◽  
Light Absorption ◽  
Electronic Spectra ◽  
Steric Effects ◽  
Type I ◽  
Conjugated Systems ◽  
Absorption Studies ◽  
Sterically Hindered

The equation ε/ε0 = cos2(θ1 − θ2) recently proposed by Braude and co-workers is developed to account more rigorously for the spectra of unsymmetrical molecules. The results obtained from the revised equation, [Formula: see text] support the interference value of hydrogen obtained independently from spectral data, and suggest a re-examination of the reported theories accounting for the spectra of alicyclic enones and dienones, and for steric effects of type I.

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 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 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 III. STRUCTURE AND LIGHT ABSORPTION OF TRISUBSTITUTED BENZENE DERIVATIVES

1956 ◽  
Vol 34 (9) ◽  
pp. 1340-1346 ◽  
Author(s):  
W. F. Forbes ◽  
W. A. Mueller
Keyword(s):  
Absorption Spectra ◽  
Light Absorption ◽  
Steric Effects ◽  
Benzene Derivatives ◽  
Absorption Studies ◽  
Electronic And Steric Effects

The spectra of a number of trisubstituted benzene derivatives which have recently been described by Doub and Vandenbelt are discussed in terms of the electronic and steric effects. The assumption of Doub and Vandenbelt, that the steric effects are usually small in absorption spectra, is criticized.

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