Neighboring Carbon and Hydrogen. XIX. t-Butylcyclohexyl Derivatives. Quantitative Conformational Analysis

Abstract

The layers were separated, and the aqueous portion extracted several times with 5-ml. portions of methylene chloride. The combined methylene chloride extracts were washed with water, dried over magnesium sulfate and concentrated. The residual 2-chloro-2,3,3-trimethyIbutane was purified by sublimation under reduced pressure. The recovery was 0.60 g.The following procedures were used to convert the chloride samples to silver chloride for radioactive assay. A portion of the aqueous hydrochloric acid solution containing about 1-2 millimoles of chloride ion was diluted to 5 ml. with water containing 1 ml. of 6 IV nitric acid. The solution was warmed to about 50°and 10 ml. of 10% silver nitrate solution added rapidly with stirring. The precipitate of silver chloride was collected on a sintered-glass funnel, rinsed several times with acetone and dried in an evacuated desiccator over phosphorus pentoxide. The organic chloride (about 0.1-0.2 g.) was dissolved in 5 ml. of ethanol, warmed to 50-60°and a warm solution of 10 ml. of 10% silver nitrate containing 1 ml. of 6 At nitric acid was added with stirring. The precipitated silver chloride was collected and dried as above.The samples for counting were prepared by weighing out identical amounts of silver chloride on copper dishes previously checked for radioactive contamination. The samples were counted in a methane-filled proportional counter ("Nucleometer," Radiation Counter Laboratories).Trials indicated that the manner of spreading of the samples in the sample dish was not critical provided the samples were spread reasonably evenly. In the experiment described above, the measured activities for 29.0-mg. samples of silver chloride corrected for background with standard deviations were 1309 ± 44 and 15 ± 10 counts per minute for the silver chloride from the original aqueous solution and the organic chloride from the reaction mixture, respectively.In this experiment, the initial reaction mixture contained 98.5 millimoles of hydrochloric acid and 7.4 millimoles of organic chloride. If complete equilibration had occurred, the activity of the organic chloride would be (98.5/106) X 1310 ± 44 = 1220 ± 41 counts per minute. The extent of exchange was thus (15 ± 10/1220) X 100 or 1.2 ± 0.8%. Further experimental results regarding the exchanges are presented in Table II.Cambridge 39, Mass.

Microbial Oxidation of Cyclic Alcohols to the Corresponding Ketones

“…6), because the steric hindrance of the tert-butyl group is so large that it is known to be fixed in the equatorial position. 8 ) When the commercially available mixture of cis-and trans-4-t-Bu-C 6 -OL (33 : 67) was subjected to microbial oxidation (300 mg/50 ml medium, 30°C, 5 days) by C. equi, the cis/trans ratio of recovered alcohol (total 72%) changed to 11 : 89. These results strongly suggested that trans-4-t-Bu-C 6 -OL was not or little, if any, affected by the bacterium.…”

“…Strikingly, the reactivity of cyclooctanol was very low. While both smaller and larger ring-sized alcohols such as cyclopentanol, cyclohexanol, were oxidized smoothly, medium ring-sized alcohols (n = 7,8) were…”

“…Thus, it is necessary to use other substrates to evaluate was 2.97 at 25°C. 8 ) Clearly, the stereoselectivity of the enzymatic reaction is higher, and it is expected that it can be applied to further useful transformation of cycloalkanols.…”

A neutron diffraction study of trans-4-t-butylcyclohexyl toluene-p-sulphonate, C17H26SO3

“…A widely accepted method of locking the mobile cyclohexane system into one of two chair conformations has been the use of the t-butyl group (Winstein & Holness, 1955). Any comparison of data on cyclohexane systems locked into two different conformations relies on assumptions that the cyclohexane ring is unaltered by the different substitutions.…”

Syntheses and eliminations of cyclopentyl derivatives

“…It was thought that the bulky tertiarybutyl group would cause a large puckering of the cyclopentane ring and the ring would be "locked" in an envelope or half-chair conformation, analogous to the ^-butylcyclohexyl compounds studied (92,93). A compar ison of this system with the unsubstituted cyclopentyl compounds and the previously studied phenyl-, methyl-and jL-propylcyclopentyl compounds should give a good indication of the steric requirements of a _t-butyl group and its effect on the conformation of the five-membered ring.…”