Chapter 13: Problem 264
Explain why \(\left(\mathrm{CH}_{3}\right)_{4} \mathrm{~N}^{+}\) is neither a nucleophile nor an electrophile.
Chapter 13: Problem 264
Explain why \(\left(\mathrm{CH}_{3}\right)_{4} \mathrm{~N}^{+}\) is neither a nucleophile nor an electrophile.
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Get started for freeUnder \(\mathrm{S}_{\mathrm{N}} 1\) conditions, 2 -bromo octane, of specific rotation \(-20.8^{\circ}\), was found to yield 2 -octanol of specific rotation \(+3.96^{\circ}\). If optically pure 2-bromooctane has a specific rotation of \(-34.6^{\circ}\) and optically pure 2-octanol has a specific rotation of \(-9.9^{\circ}\) calculate: (a) the optical purity of reactant and product; (b) the percentage of racemization and of inversion accompanying the reaction; (c) the percentage of front side and of back side attack on the carbonium ion.
Outline all steps in a possible laboratory synthesis of each of the following, using benzene, toluene, and any needed aliphatic or inorganic reagents. (a) p-bromobenzyl chloride (b) triphenylchloromethane (c) allyl iodide (d) benzal bromide (e) \(\mathrm{m}\) -nitrobenzotrichloride (f) 1,2 -dichloro-1- phenylethane (g) phenylacetylene (h) phenylcyclopropane
Each of the following cations is capable of rearranging to a more stable cation. Limiting yourself to a single 1,1 -shift, suggest a structure for the rearranged cation. (a) \(\mathrm{CH}_{3} \mathrm{CHCH}_{3} \mathrm{C}^{+} \mathrm{HCH}_{3}\) (b) \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}^{+} \mathrm{CHCH}_{3}\) (c) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{C}^{+} \mathrm{HCH}\left(\mathrm{CH}_{3}\right) \mathrm{C}\left(\mathrm{CH}_{3}\right)_{3}\) (d) \(\mathrm{CH}_{2}=\mathrm{CHCH}_{2} \mathrm{C}^{+} \mathrm{HCH}_{2} \mathrm{CH}_{3}\) (e) \(\mathrm{CH}_{3} \mathrm{OCH}_{2} \mathrm{C}^{+} \mathrm{HC}\left(\mathrm{CH}_{3}\right)_{3}\)
Ethyl chloride \((0.1 \mathrm{M})\) reacts with potassium iodide \((0.1 \mathrm{M})\) in acetone solution at \(60^{\circ}\) to give ethyl iodide and potassium chloride at a rate of \(5.44 \times 10^{-7}\) mole/liter/sec (a) If the reaction proceeded by an \(\mathrm{S}_{\mathrm{N}} 2\) mechanism, what would the rate of the reaction be at \(0.01 \mathrm{M}\) concentrations of both reactants? Show your method of calculation. (b) Suppose the rate were proportional to the square of the potassium iodide concentration and the first power of the ethyl chloride \(\left(\mathrm{S}_{\mathrm{N}} 3\right)\). What would the rate be with \(0.01 \mathrm{M}\) reactants? (c) If one starts with solutions initially \(0.1 \mathrm{M}\) in both reactants, the rate of formation of ethyl iodide is initially \(5.44 \times 10^{-7}\) mole/liter/sec but falls as the reaction proceeds and the reactants are used up. Make plots of the rate of formation of ethyl iodide against the concentration of ethyl chloride as the reaction proceeds (remembering that one molecule of ethyl chloride consumes one molecule of potassium iodide) on the assumption that the rate of reaction is proportional to the first power of the ethyl chloride concentration; and to (1) the zeroth power, (2) the first power, and (3) the second power of the potassium iodide concentration. (d) What kind of experimental data would one need to tell whether the rate of the reaction of ethyl chloride with potassium iodide is first order in each reactant or first order in ethyl chloride and zero order in potassium iodide?
Benzyl bromide reacts with \(\mathrm{H}_{2} \mathrm{O}\) in formic acid solution to yield benzyl alcohol? the rate is independent of \(\left[\mathrm{H}_{2} \mathrm{O}\right]\). Under the same conditions \(\mathrm{p}\) -methylbenzyl bromide reacts 58 times as fast. Benzyl bromide reacts with ethoxide ion in dry alcohol to yield benzyl ethyl ether \(\left(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}_{2} \mathrm{OC}_{2} \mathrm{H}_{5}\right) ;\) the rate depends upon both \([\mathrm{RBr}]\) and \(\left[\mathrm{OC}_{2} \mathrm{H}_{5}^{-}\right]\). Under the same conditions \(\mathrm{p}\) -methylbenzyl bromide reacts \(1.5\) times as fast. Interpret these results. What do they illustrate concerning the effect of: (a) polarity of solvent, (b) nucleophilic power of the reagent, and (c) electron release by substituents?
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