Chapter 11

For each of the following reactions determine the oxidation state of the carbons in the reactants and products and decide whether the overall changes involve oxidation, reduction, or neither. a. \(\mathrm{CH}_{4}+\mathrm{Cl}_{2} \rightarrow \mathrm{CH}_{3} \mathrm{Cl}+\mathrm{HCl}\) b. \(\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CH}_{2}+\mathrm{HCl} \rightarrow \mathrm{CH}_{3} \mathrm{CH}(\mathrm{Cl}) \mathrm{CH}_{3}\) c. \(\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CH}_{2}+\mathrm{HOCl} \rightarrow \mathrm{CH}_{3} \mathrm{CH}(\mathrm{OH}) \mathrm{CH}_{2} \mathrm{Cl}\) d. \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{C}=\mathrm{CH}_{2}+\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CH} \rightarrow\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CHCH}_{2} \mathrm{C}\left(\mathrm{CH}_{3}\right)_{3}\) e. \(n\left(\mathrm{CH}_{2}=\mathrm{CHCN}\right) \rightarrow-\left(\mathrm{CH}_{2} \mathrm{CH}(\mathrm{CN})\right)_{n}-\) f. \(\mathrm{CH}_{3} \mathrm{OH} \rightarrow \mathrm{CH}_{2}=\mathrm{O}+\mathrm{H}_{2}\)

Balance each of the following equations. You may need to add \(\mathrm{H}_{2} \mathrm{O}\) to one side or the other of the equations. a. \(\stackrel{\oplus}{\mathrm{K}}^{\ominus} \mathrm{M} \mathrm{O}_{4}+\mathrm{RCH}=\mathrm{CH}_{2} \rightarrow \mathrm{RCO}_{2} \stackrel{\oplus}{\mathrm{K}}+\mathrm{CH}_{2}=\mathrm{O}+\mathrm{MnO}_{2}\) b. \(\mathrm{CrO}_{3}+\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}_{2} \mathrm{CH}_{3} \rightarrow \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{H}+\mathrm{Cr}^{3 \oplus}\)

Draw structures for the products expected from the following reactions. Show configurations where significant. a. b. cis-2-butene \(\frac{\mathrm{D}_{2}, \mathrm{Pt}}{25^{\circ}}\) c. \(\mathrm{CH}_{2}=\mathrm{CHCOCH}_{3} \stackrel{\mathrm{H}_{2}, \mathrm{Pt}}{{ }_{25^{\circ}}}\) d. 1 -penten-3-yne \(\stackrel{\mathrm{H}_{2}, \mathrm{Pd}-\mathrm{Pb}}{\longrightarrow}\) e. \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{C} \equiv \mathrm{CC}_{6} \mathrm{H}_{5} \stackrel{\mathrm{H}_{2}, \mathrm{Pd}-\mathrm{Pb}}{\longrightarrow}\) f. 1,3 -dimethylcyclopentene \(\stackrel{\mathrm{H}_{2}, \mathrm{Pt}}{25^{\circ}}\)

a. Would you expect a carbon-nitrogen triple bond to be hydrogenated more, or less, easily than a carbon-carbon triple bond? b. Why is it difficult to hydrogenate a tetrasubstituted alkene such as 2,3 -dimethyl-2-butene?

Consider that it is necessary to synthesize pure samples of \(D, L\) -hexane- \(3,4-\mathrm{D}_{2}\) and meso-hexane- \(3,4-\mathrm{D}_{2} .\) Show how this might be done both with diimide and catalytic-type reductions, assuming that any necessary deuterium-labeled reagents and six-carbon organic compounds are available.

What products would you expect from hydroboration of the following alkenes with a dialkylborane, \(\mathrm{R}_{2} \mathrm{BH}\), followed by isomerization at \(160^{\circ} ?\) a. \(\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CHCH}_{3}\)

a. Draw the structure and configuration of the product expected of the reaction between 1-bromo-1-hexyne and diethylborane, \(\left(\mathrm{C}_{2} \mathrm{H}_{5}\right)_{2} \mathrm{BH}\). b. When the product is treated with sodium methoxide, \(\mathrm{NaOCH}_{3}\), then with propanoic acid, trans-3-octene is formed. Show the steps involved in forming this trans-alkene.

A hydrocarbon of formula \(\mathrm{C}_{11} \mathrm{H}_{18}\) on reaction with ozone in dichloromethane gave, after the addition of water and finely divided zinc, three products in equimolar amounts that were identified as 2 -butanone \(\left(\mathrm{CH}_{3} \mathrm{COCH}_{2} \mathrm{CH}_{3}\right)\), methanal \(\left(\mathrm{CH}_{2} \mathrm{O}\right)\), and cyclohexane-1,4-dione \(\mathrm{Draw}\) the structure of the hydrocarbon \(\mathrm{C}_{11} \mathrm{H}_{18} .\)

Starting with cyclohexene, show how you could prepare each of the following compounds: a. the epoxide of cyclohexene b. cis-cyclohexane-1,2-diol c. trans-cyclohexane- 1,2 -diol

Suppose you were given four unlabeled bottles, each of which is known to contain one of the following compounds: pentane, 1 -pentene, 2 -pentyne, or 1 -pentyne. Explain how you could use simple chemical tests (preferably testtube reactions) to identify the contents of each bottle. (Notice that all four compounds are low-boiling liquids.)

Show how the (Delta \(\mathrm{H}\) ) values of the following processes can be combined to calculate the heat of solution $$ \begin{array}{ll} \text { of } \mathrm{Na}^{\oplus}(g)+\mathrm{Cl}^{\ominus}(g) \text { at } 298^{\circ} \mathrm{K} \\ \mathrm{Na}(s)+\frac{1}{2} \mathrm{Cl}_{2}(g) \rightarrow \mathrm{Na}^{\oplus}(a q)+\mathrm{Cl}^{\ominus}(a q) & \Delta H^{0}=-97 \mathrm{kcal} \\ \mathrm{Na}(g) \rightarrow \mathrm{Na}^{\oplus}(g)+\mathrm{e}^{-} & \Delta H^{0}=+118 \mathrm{kcal} \\ \mathrm{Cl}^{\ominus}(g) \rightarrow \mathrm{Cl} \cdot(g)+\mathrm{e}^{-} & \Delta H^{0}=+83 \mathrm{kcal} \\ \frac{1}{2} \mathrm{Cl}_{2}(g) \rightarrow \mathrm{Cl} \cdot(g) & \Delta H^{0}=+2929 \\ \mathrm{Na}(s) \rightarrow \mathrm{Na}(g) & \Delta H^{0}=+26 \mathrm{kcal} \end{array} $$

A serious contamination in butenyne made by dimerization of ethyne with cuprous ion is 1,5-hexadien-3-yne. Show how this substance can be formed.

When 5 -decyne is heated with diborane at \(160^{\circ}\) and the product is oxidized with hydrogen peroxide in basic solution, 1,10 -decanediol is obtained. Write equations to show the several reactions involved in these transformations. You need not show detailed mechanisms.

Show the structures of the products expected in each step of the following sequences. Be sure to indicate the stereochemistry of reactions where this is important. Remember that \(\mathrm{D}\) is the hydrogen isotope of mass \(2 .\) a. cis-2-butene \(\stackrel{\mathrm{C}_{2} \mathrm{NND}_{2}}{\longrightarrow}\) b. 1 -methylcyclohexene \(\stackrel{\mathrm{BH}_{3}}{\longrightarrow} \stackrel{160^{\circ}}{\longrightarrow} \stackrel{\mathrm{H}_{2} \mathrm{O}_{2}, \ominus}{\longrightarrow} \mathrm{OH}\) CC1=CC2CCC1C2 \(\mathrm{BH}_{3}, \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{D}\) C. d. propyne \(\stackrel{\mathrm{RBD}}{\longrightarrow} \stackrel{\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{H}}{\longrightarrow} \stackrel{\mathrm{O}_{3}}{\longrightarrow} \stackrel{\mathrm{H}_{2} \mathrm{O}, \mathrm{Zn}}{\longrightarrow}\) e. 2 -butyne \(\stackrel{\mathrm{R}_{2} \mathrm{~B} \mathrm{H}}{\longrightarrow} \mathrm{H}_{2} \mathrm{O}_{2},{ }^{\ominus} \mathrm{OH}\) f. \(\mathrm{CH}_{3} \mathrm{C} \equiv \mathrm{CH} \stackrel{\mathrm{R}_{2} \mathrm{BD}}{\longrightarrow} \stackrel{\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{D}}{\longrightarrow}\) g. 3-methylcyclopentene \(\stackrel{\mathrm{BH}_{3}}{\longrightarrow} \stackrel{160^{\circ}}{\longrightarrow} \stackrel{\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{T} \mathrm{CH}=\mathrm{CH}_{2}}{\longrightarrow}\) (as trapping agent) h. 1-pentene \(\stackrel{\mathrm{HBr}, \mathrm{ROOR} \mathrm{CH}_{3} \mathrm{C}=\mathrm{CNa} \mathrm{H}_{2}, \mathrm{Pd}-\mathrm{Pb}}{\longrightarrow} \stackrel{\mathrm{O}_{3}}{\longrightarrow} \stackrel{\mathrm{Na}_{2} \mathrm{SO}_{3}}{\longrightarrow}\) i. 1 -pentene \(\stackrel{\mathrm{BH}_{3}}{\longrightarrow} \stackrel{\mathrm{H}_{2} \mathrm{~N}-\mathrm{OSO}_{3} \mathrm{H}}{\longrightarrow}\)

Two stable compounds of formula \(\mathrm{C}_{6} \mathrm{H}_{6}\) react with bromine and with \(\mathrm{KMnO}_{4} .\) On hydrogenation with a platinum catalyst at \(25^{\circ}\), both absorb two moles of hydrogen and form cyclohexane. Write possible structures for these substances and explain how electronic spectra may be used to tell which compound is which.

How would you distinguish between the components in each of the following pairs using chemical methods (preferably test-tube reactions)? a. \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{C} \equiv \mathrm{CH}\) and \(\mathrm{CH}_{3} \mathrm{C} \equiv \mathrm{CCH}_{3}\) b. \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{C} \equiv \mathrm{CH}\) and \(\mathrm{CH}_{2}=\mathrm{CH}-\mathrm{CH}=\mathrm{CH}_{2}\) c. \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{C} \equiv \mathrm{CC}_{6} \mathrm{H}_{5}\) and \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{C}_{6} \mathrm{H}_{5}\)