Tert-butylcyclohexane exists practically (> 99.99%) in a single conformational form. Represent in cavalier perspective the chair conformation of the most stable tert-butylcyclohexane and explain why the other chair conformation is very disadvantaged.

Following is a planar hexagon representation of L-fucose, a sugar component of the determinants of the A, B, O blood group typing. For more on this system of blood typing, see Chemical Connections: A, B, AB, and O Blood Group Substances in Chapter 25. (a) Draw the alternative chair conformations of L-fucose. (b) Which of them is more stable? Explain.

Ketones react with alcohols to yield products called acetals. Why does the all-cis isomer of 4-tert-butyl-1,3-cyclohexanediol react readily with acetone and an acid catalyst to form an acetal, but other stereoisomers do not react? In formulating your answer, draw the more stable chair conformations of all four stereoisomers and the product acetal for each one.

Gibbs free energy differences between axial-substituted and equatorial-substituted chair conformations of cyclohexane were given in Table 2.4. (a) Calculate the ratio of equatorial to axial tert-butylcyclohexane at 25C. (b) Explain why the conformational equilibria for methyl, ethyl, and isopropyl substituents are comparable but the conformational equilibrium for tert-butylcyclohexane lies considerably farther toward the equatorial conformation.

Following are the alternative chair conformations for trans-1,2-dimethylcyclohexane.(a) Estimate the difference in free energy between these two conformations.(b) Given your value in (a), calculate the percent of each chair present in anequilibrium mixture of the two at 25°C.

Why is this chair conformation the most stable trans-1-chloro-3-flurocyclohexane? Wouldn't the conformation with Cl & F in equatorial positions be the most stable conformation?

Tert-butylcyclohexane exists practically (> 99.99%) in a single conformational form. Represent in perspective the most stable conformer of trans-4 isopropylcyclohexan-1-ol.

[Referenca cis-2,5-dimethyl-1,3-dioxane The structure of cis-2,5-dimethyl-1,3-dioxane is shown above, without stereochemistry. In the most stable chair conformation, predict the orientation of the two methyl group both equat 1 axial and In the sketchpad, draw the structure of cis-2,5-dimethyl-1,3-dioxane. both axial • Draw your ring as a flat hexagon with wedge/dash bonds to indicate stereochemistry. If a group is achiral, do not use wedged or hashed bonds on it. • In cases where there is more than one answer, just draw one.

Write the two chair conformations of each of the following and in each part designate whichconformation would be the more stable: (a) cis-1-tert-butyl-3-methylcyclohexane, (b) trans-1-tert-butyl-3-methylcyclohexane, (c) trans-1-tert-butyl-4-methylcyclohexane, ( d) cis-1-tert-butyl-4-methylcyclohexane.

trans-1,4-Di-tert-butylcyclohexane exists in a normal chair conformation. cis-1,4-Di-tertbutylcyclohexane, however, adopts a twist-boat conformation. Draw both isomers and explain why the cis isomer is more stable in a twist-boat conformation.