Document Type

Dissertation

Date of Award

1970

Keywords

Cyclohexane, Optical properties, Optical studies, Chiral 1-substituted-2-phenylcyclohexanes

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

First Advisor

Bruce Norcross

Second Advisor

Walter E. Kaskan

Third Advisor

Lawrence Verbit

Series

Science and Mathematics

Abstract

The following 1-substituted-2-phenylcyclohexanes were prepared in racemic and optically-active forms: trans-2-phenylcyclohexanol (I), cis-2-phenylcyclohexanol (II), trans-2-phenylcyclohexylamine (III), cis-2-phenylcyclohexylamine (IV), trans-2-phenylcyclohexanecarboxylic acid (V), trans-2-phenylcyclohexanecarbonyl chloride (VI), and trans-1-hydroxymethyl-2-phenylcyclohexane (VII). The amides from (±)-III and (±)-VI and from (+)-III and (+)-VI were also prepared.

I and II were isolated from a commercial mixture and resolved via the 1-strychnine salts of their hydrogen phthalate esters. III, obtained via hydroboration-amination of 1-phenylcyclohexene, was resolved with d-tartaric acid. IV was prepared by rhodium-catalyzed low-pressure hydrogenation of 2-aminobiphenyl and resolved with d-tartaric acid. V, obtained from the sodium/alcohol reduction of 2-biphenylcarboxylic acid, was resolved with (-)-𝛂-phenylethylamine. VI and VII were prepared from V by treatment with thionyl chloride and reduction with lithium aluminum hydride respectively.

Conformational analysis with NMR, including variable temperature studies on I and II, showed that I-VII exist essentially exclusively in the chair form with the phenyl group equatorial. Infrared spectroscopy was used to monitor the extent of intra- and inter-molecular hydrogen bonding in I, II, and VII. Infrared studies and Corey-Pauling space-filling models indicate that the phenyl group is oriented with its plane approximately perpendicular to the plane of the cyclohexane ring and that rotation about the ∅–C2 bond is probably limited to librational motion at room temperature.

The ORD and CD spectra were examined for possible correlations with assigned absolute configurations and conformations. Solvent studies on II and VII and variable-temperature studies on I and VII were conducted. Absolute configurations, based on reported assignments in the literature, were corroborated by correlations between configurations and optical activity of analogous compounds, and by chemical correlation via asymmetric hydroboration.

A positive background ORD curve and sodium-D-line rotation were found to correspond to a 1S configuration for all of the compounds studied. The Cotton effect at ~220 nm, attributed mainly to the 1La phenyl transition, was positive for compounds I-VI (but not VII) having a 1S configuration. A relation between the sign of this Cotton effect and the helicity of the ∅–C/C–x bonds is suggested. The sign of the CD band observed at ~260 nm (associated with the 1Lb phenyl transition) does not correlate with absolute configurations or the helical arrangements of bonds. The sign of this band may be consistent with an aromatic sector rule but librational freedom of the phenyl group precludes any meaningful correlation with such a rule.

Also described are a study on the low-pressure hydrogenation of 2- and 4-aminobiphenyls over platinum catalysts, the construction and operation of a cell chamber for variable low-temperature optical measurements, and an APL computer program for treatment of ORD, CD, and UV spectral data.

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