91Ó°ÊÓ

Write the structure of the products that you expect from the reaction of 1 -methylcyclohexanol with (a) concentrated \(\mathrm{HCl}\) and (b) concentrated \(\mathrm{H}_{2} \mathrm{SO}_{4}\). Compare and contrast the mechanisms of the two processes. (Hint: Compare the relative nucleophilicity of \(\mathrm{Cl}^{-}\) and \(\mathrm{HSO}_{4}^{-}\). Caution: When writing mechanisms, use "arrow pushing" to depict electron flow; write out every step separately; formulate complete structures, including charges and relevant electron pairs; and draw explicit reaction arrows to connect starting materials or intermediates with their respective products. Don't use shortcuts, and don't be sloppy!)

2-Methylcyclohexanol, on treatment with HBr, gives 1-bromo-1-methylcyclohexane. Explain by a mechanism.

Give detailed mechanisms and final products for the reaction of 3-methyl-2-pentanol with each of the reagents that follow. (a) \(\mathrm{NaH}\) (b) Concentrated \(\mathrm{HBr}\) (c) \(\mathrm{PBr}_{3}\) (d) \(\mathrm{SOCl}_{2}\) (e) Concentrated \(\mathrm{H}_{2} \mathrm{SO}_{4}\) at \(130^{\circ} \mathrm{C}\) (f) Dilute \(\mathrm{H}_{2} \mathrm{SO}_{4}\) in \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{COH}\)

Give the expected product(s) of the reaction of 1 -pentanol with each of the following reagents. (a) \(\mathrm{K}^{+-} \mathrm{OC}\left(\mathrm{CH}_{3}\right)_{3}\) (b) Sodium metal (c) \(\mathrm{CH}_{3} \mathrm{Li}\) (d) Concentrated HI (e) Concentrated \(\mathrm{HCl}\) (f) \(\mathrm{FSO}_{3} \mathrm{H}\) (g) Concentrated \(\mathrm{H}_{2} \mathrm{SO}_{4}\) at \(130^{\circ} \mathrm{C}\) (h) Concentrated \(\mathrm{H}_{2} \mathrm{SO}_{4}\) at \(180^{\circ} \mathrm{C}\) (i) \(\mathrm{CH}_{3} \mathrm{SO}_{2} \mathrm{Cl},\left(\mathrm{CH}_{3} \mathrm{CH}_{2}\right)_{3} \mathrm{~N}\) (j) \(\mathrm{PBr}_{3}\) (k) \(\mathrm{SOCl}_{2}\) (l) \(\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}+\mathrm{H}_{2} \mathrm{SO}_{4}+\mathrm{H}_{2} \mathrm{O}\) (m) \(\mathrm{PCC}\), \(\mathrm{CH}_{2} \mathrm{Cl}_{2}\) (n) \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{COH}+\mathrm{H}_{2} \mathrm{SO}_{4}\) (as catalyst)

Propose efficient syntheses for each of the following ethers, using haloalkanes or alcohols as starting materials.