Stereochemistry of cis-2-hydroxy-2-phenyl-cyclohexanecarboxylic acid (cicloxilic acid)

The configuration of cis-2-hydroxy-2-phenyl-cyclohexanecarboxilic acid (cicloxilic acid) was deduced by comparing its NMR and IR spectra with those of its diastereoisomer and of their respective analogs, the 1-hydroxy(bicyclohexyl)-2-carboxylic acids. The diastereoisomer was prepared by converting cicloxilic acid to the corresponding 2-chloro-2-phenyl-cyclohexanecarboxylic acid and subsequent hydrolysis of the latter with aqueous solvents in the presence of wet silver oxide, or by simple solvolysis. The pair of 1-hydroxy(bicyclohexyl)-2-carboxylic acid was prepared from the respective phenylic terms by catalytic hydrogenation. Comparison of the NMR spectra revealed the spatial arrangement of the -H and -COOH groups on the carbon-alpha atom and the study of the interaction between the substitutents -OH and -COOH by IR spectrography revealed the position of the -OH group with respect to the -COOH group, as a result of which the configuration and conformation of the compounds under study were established. Cicloxilic acid is thus represented by the steric formula 4.