4-r-butylcyclohexanol

Fig. 3.8. Approximate energy diagram for acetylation of cis- and fronj-4-r-butylcyclohexanol.

The tmns cis ratio at equilibrium for 4-r-butylcyclohexanol has been established for several solvents near 80°C ... 

Further examples Decan-l-ol Cyclohexylmethanol Heptan-2-ol 4-r-Butylcyclohexanol (15) -> (16)... 

Fig. 2 Proposed transition-states for the formation of cis-4-r-butylcyclohexanol (left) and trans-4-t-butylcyclohexanol (right).

In the Oppenauer oxidation of an equimolar mixture of cis- and trans-4-r-butylcyclohexanol, the cis-alcohol is converted selectively over both Ti-beta and Al-beta (Table 2), which is probably due to the same spatial restriction on the transition-states as for the reduction depicted in Fig. 2. In this way, the MPVO reduction and oxidation are in harmony as to the high transition-state selectivity. 

Liquid-phase Oppenauer oxidation of 4-r-butylcyclohexanol (1 1 cis/trans mixture) with butanone as the oxidant. 

The trans xis ratio of equilibrium for 4-r-butylcyclohexanol has been determined in several solvents near 80° C. From the data, calculate the conformational free energy, —AG, for the hydroxy group in each solvent. What correlation do find between the observed conformational equilibria and properties of the solvent ... 

The importance of coplanarity of the eliminating fragments is emphasised by the large difference in the Arrhenius activation energies for elimination from cw-4-r-butylcyclohexanol (E (cis) = 21 kcal.mole" ) and rra/iJ-4-r-butylcyclo-hexanol (Epitrans) = 38 kcal.mole ) . In the trans isomer, elimination must occur from a diequatorial syn-clinal conformation, or a diaxial conformation with the bulky r-butyl substituent in an unfavourable axial conformation, or an initial epimerisation to the cis isomer, or via a boat conformation, all possibilities which involve much higher energy intermediates than the diaxial elimination from the cis isomer. The products of elimination from the four stereoisomers of 1-decalol are also consistent with anti stereospecificity ... 

With unhindered ketones, steric repulsions between the substrate and a small reagent become less important, and other considerations come into play. The reduction of 4-r-butylcyclohexanone with sodium borohydride or lithium aluminum hydride gives predominantly the product of axial hydride transfer, the equatorial alcohol /ra s-4-r-butylcyclohexanol... 

In chromic acid oxidation of isomeric cyclohexanols it is usually found that axial hydroxyl groups react more rapidly than equatorial groups. For example, rra/i5-4-r-butylcyclohexanol is less reactive (by a factor of 3 2) than the cis isomer. An even larger difference is noted with cis- and trans-3,3,5-trimQthyU cyclohexanol. The trans alcohol is more than 35 times more reactive than the cis. Are these data compatible with the mechanism given on page 482 What additional detail do these data provide about the reaction mechanism Explain. 

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