A circular dichroism study of the following phenylcyclohexane derivatives has been carried out: (lS,-2R)-( +)-truns-2-phenylcyclohexanol, (1S,2R)-( +)-trans-2-phenylcyclohexylamine, (1S,2S)-( +)-trms-2-phenylcyclohexanecarboxylic acid, (1S,2S)-(+)-trms-2-phenylcyclohexanecarbonyl chloride, (lS,2S)-(+)-rrans-l-hydroxymethyl-2-phenylcyclohexane, (1R,2R)-( -)-cis-2-phenylcyclohexanol, and (1R,2R)-( -)-cis-2-phenylcyclohexyl-amine. The absolute configuration of (+)-trans-2-phenylcyclohexanecarboxylic acid was determined by its oxidation cleavage to (1S,2S)-( +)-truns-l,2-cyclohexanedicarboxylic acid. Variable temperature nmr measurements indicate that the compounds exist almost exclusively in the conformation having the phenyl group equatorial. Infrared hydrogen-bonding studies are reported for the alcohols in the series. The Cotton effects appearing in the 210-220-nm region are considered to be primarily associated with the IL, transition of the aromatic ring. It is proposed that CD Cotton effects due to this transition in appropriate phenyl-containing compounds may be characterized by typical widths at half-height of 10-20 nm. A quadrant rule is formulated for the sign of the 'La Cotton effect in monosubstituted benzene derivatives. hiroptical methods, as Prelog3 terms optical ro-
nated during the Morgan-Elson reaction, and any mechanism proposed for this reaction should take this into account. Because the colored products of the Morgan-Elson reaction are unstable and disappear in a few hours, I have not attempted to identify the colored compounds bound to solid supports. These experiments represent one example of an approach to elucidating reaction mechanisms. In cases where the product may be removed from the solid support and its structure identified, this method will lead to useful models of reaction mechanisms.
An experiment for the integrated organic and physical laboratoryThe division of matter into solids, liquids, and gases is not an absolute classification; many substances of intermediate properties are known. One
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