Conformational analysis. LVI. Chlorocyclohexane and 1-chloro-1-methylcyclohexane

Abstract

From studies on chlorocyclohexane, 1-chloro-1-methylcyclohexane, cisand trans-4-t-butyl-1-chlorocyclchexane, cisand trans-4-t-butyl-l-chloro-l-methylcyclohexane1 and l-chloro-1,4,4-trimethylcyclohexane, the conformational energy of chlorine was determined by a study of the molar absorbance of the C-C1 stretching frequency in the infrared, supplemented by variable-temperature infrared spectroscopy and equilibrium measurements, to be 0.4 kcal/mole, favoring the equatorial conformation when the chlorine was secondary, and it was found that, when the chlorine and methyl were geminal, the conformational energy was 1.1 kcallmole, favoring the chlorine axial and methyl equatorial.

Conformation analysis. XXVI. Conformational equilibriums in 5,5-disubstituted 1,3-dioxanes

“…d Equilibration of 4-fer/-butyl-substituted compounds. 6 Proton nmr using 4-ierr-butyl-substituted models. / Using 3.1 kcal/mol for ACc,h5°; cf.…”

“…The AG°values for the 5monosubstituted 1,3-dioxanes are those indicated in Table IV -0.04 ± 0.01 " Concentration 0.2 M in each solvent studied. 6 For dielectric constants, see footnote a, Table III. c 1,2-Dimethoxyethane.…”

Sodium Diisopropylamide-Mediated Dehydrohalogenations: Influence of Primary- and Secondary-Shell Solvation

“…Conformationally constrained cyclohexyl halides offer a pedagogically convenient means to underscore the importance of antiperiplanar (trans-diaxial) alignments in dehydrohalogenations . Ironically, we know of only one example of the elimination of a 4- tert -butylcyclohexane derivative with adequate isotopic labeling to demonstrate trans-diaxial elimination, and it was not a trivial analysis . Unexpectedly, NaDA/THF-mediated eliminations of both cis - 17 and trans - 17 afford 4- tert -butylcyclohexene ( 18 , eq ) in excellent yields with similar facilities ( k ax/cis / k eq/trans = 10 in neat THF at −35 °C)…”

Silacyclohexanes, Sila(hetero)cyclohexanes and Related Compounds: Structure and Conformational Analysis

“…In the Me ax Ph eq conformer, both Ph-'orthogonal' and Ph-'horizontal' rotamers are destabilized by repulsive interactions of ortho-protons with either the Me group or α-CH eq protons, while in the Ph-'horizontal' rotamer of the Me eq Ph ax conformer the latter destabilization is avoided. For the sake of fairness, it should be noted that there are examples of additivity of conformational effects in cyclohexanes [27,28], but in general, the conclusion about the absence of additivity of the A values in geminally disubstituted cyclohexanes made ten years ago [18] is undoubtedly true.…”