Chapter Questions
Name the following:a. $\operatorname{Br} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{C} \equiv \mathrm{CCH}_{3}$b. c. $\mathrm{CH}_{3} \mathrm{OCH}_{2} \mathrm{C} \equiv \mathrm{CCH}_{2} \mathrm{CH}_{3}$d.
Name the following:
What is the molecular formula for a monocyclic hydrocarbon with 14 carbons and 2 triple bonds?
Draw the condensed and skeletal structures for each of the following:a. 1 -chloro- 3 -hexyneb. cyclooctynec. isopropylacetylened. sec-butylisobutylacetylenee. 4,4 -dimethyl-1-pentynef. dimethylacetylene
Draw the structures and give the common and systematic names for the seven alkynes with molecular formula $\mathrm{C}_{6} \mathrm{H}_{10}$.
Name the following:a. $\mathrm{CH}_{2}=\mathrm{CHCH}_{2} \mathrm{C} \equiv \mathrm{CCH}_{2} \mathrm{CH}_{3}$b. c. d. $\mathrm{HOCH}_{2} \mathrm{CH}_{2} \mathrm{C} \equiv \mathrm{CH}$e. $\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CHCH}=\mathrm{CHCH}=\mathrm{CH}_{2}$f.
What orbitals are used to form the carbon-carbon $\sigma$ bond between the highlighted carbons?a. $\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CHCH}_{3}$b. $\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CHCH}_{3}$c. $\mathrm{CH}_{3} \mathrm{CH}=\mathrm{C}=\mathrm{CH}_{2}$d. $\mathrm{CH}_{3} \mathrm{C} \equiv \mathrm{CCH}_{3}$e. $\mathrm{CH}_{3} \mathrm{C} \equiv \mathrm{CCH}_{3}$f. $\mathrm{CH}_{2}=\mathrm{CHCH}=\mathrm{CH}_{2}$g. $\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CHCH}_{2} \mathrm{CH}_{3}$h. $\mathrm{CH}_{3} \mathrm{C} \equiv \mathrm{CCH}_{2} \mathrm{CH}_{3}$i. $\mathrm{CH}_{2}=\mathrm{CHC} \equiv \mathrm{CH}$
In Table $7.2,$ what is the smallest alkane, the smallest terminal alkene, and the smallest terminal alkyne that are liquids at room temperature, which is generally taken to be $20^{\circ} \mathrm{C}$ to $25^{\circ} \mathrm{C} ?$
Why does cis-2-butene have a higher boiling point than trans-2-butene?
Under what circumstances can you assume that the less stable of two compounds is the more reactive compound?
What is the major product of each of the following reactions?a. $\mathrm{HC} \equiv \mathrm{CCH}_{3} \quad \stackrel{\mathrm{HBr}}{\longrightarrow}$b. c.d. e.f.
Drawing on what you know about the stereochemistry of alkene addition reactions,a. write the mechanism for the reaction of 2 -butyne with one equivalent of $\mathrm{Br}_{2}$.b. predict the configuration of the product of the reaction.
What ketones are formed from the acid-catalyzed hydration of 3 -heptyne?
Which alkyne should be used for the synthesis of each of the following ketones?
Draw all the enol tautomers for each of the ketones in Problem 15.
For each of the following alkynes, draw the products obtained from (1) the acid-catalyzed addition of water (mercuric ion is added for part a) and from (2) hydroboration-oxidation:a. 1 -butyneb. 2-butynec. 2 -pentyne
Only one alkyne forms an aldehyde when it undergoes the mercuric-ion-catalyzed addition of water. Identify the alkyne.
Describe the alkyne you should start with and the reagents you should use if you want to synthesizea. pentane.b. cis-2-butene.c. trans-2-pentene.d. 1 -hexene.
What are products of the following reactions?
Which of the following bases can remove a proton from a terminal alkyne in a reaction that favors products?$$\mathrm{CH}_{3} \mathrm{O}^{-} \quad \mathrm{NH}_{3} \quad \mathrm{CH}_{3} \overline{\mathrm{C}} \mathrm{H}_{2} \quad \mathrm{H}_{2} \mathrm{C}=\overline{\mathrm{C}} \mathrm{H} \quad \mathrm{F}^{-}$$
Explain why an amide ion cannot be used to form a carbanion from an alkane in a reaction that favors products.
Any base whose conjugate acid has a $\mathrm{p} K_{\mathrm{a}}$ greater than _____ can remove a proton from a terminal alkyne to form an acetylide ion (in a reaction that favors products).
Rank the following from strongest base to weakest base:a. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}=\overline{\mathrm{C}} \mathrm{H} \quad \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{C} \equiv \overline{\mathrm{C}} \quad \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \overline{\mathrm{C}} \mathrm{H}_{2}$b. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{O}^{-} \quad \mathrm{F}^{-} \quad \mathrm{CH}_{3} \mathrm{C} \equiv \mathrm{C}^{-} \quad ^{-}\mathrm{NH}_{2}$
Which carbocation is more stable?$$\mathrm{CH}_{3} \mathrm{CH}_{2} \text { or } \mathrm{H}_{2} \mathrm{C}=\mathrm{CH}$$
Which carbocation is more stable?a. $\mathrm{H}_{2} \mathrm{C}=\mathrm{CH} \quad$ or $\quad \mathrm{HC} \equiv \mathrm{C}^{+}$b. $\mathrm{HC} \equiv \mathrm{C}^{+}$ or $\mathrm{CH}_{3}^{+} \mathrm{CH}_{2}$
A chemist wants to synthesize 3 -heptyne but cannot find any 1 -pentyne, the starting material used in the synthesis just described. How else can 3-heptyne be synthesized?
How could the following compounds be synthesized from acetylene?a. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{C} \equiv \mathrm{CH}$b.c. $\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CH}_{2}$d.e.f.
What is the major product obtained from the reaction of each of the following compounds with excess HCI?a. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{C} \equiv \mathrm{CH}$ b. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{C} \equiv \mathrm{CCH}_{2} \mathrm{CH}_{3}$ c. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{C} \equiv \mathrm{CCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}$
Draw a condensed structure for each of the following:a. 2 -hexyneb. 5 -ethyl- 3 -octynec. methylacetylened. vinylacetylenee. methoxyethynef. sec-butyl-tert-butylacetyleneg. 1 -bromo-l-pentyneh. 5 -methyl- 2 -cyclohexenoli. diethylacetylenej. di-tert-butylacetylenek. cyclopentylacetylenel. 5,6 -dimethyl- 2 -heptyne
A student was given the structural formulas of several compounds and was asked to give them systematic names. How many did she name correctly? Correct those that are misnamed.a. 4 -ethyl- 2 -pentyneb. 1 -bromo- 4 -heptynec. 2 -methyl- 3 -hexyned. 3 -pentyne
Identify the electrophile and the nucleophile in each of the following reaction steps. Then draw curved arrows to illustrate the bond-making and bond-breaking processes.- Each arrow represents the movement of two electrons from a nucleophile to an electrophile.- The tail of the arrow is positioned where the electrons are in the reactant.- The tail of the arrow always stars at a lone pair or a bond.The head of the arrow points to where these electrons will end up.- The head of the arrow always points at an atom or at a bond.
What is each compound's systematic name?
What reagents should be used to carry out the following syntheses?
a. Draw the structures and give the common and systematic names for alkynes with molecular formula $\mathrm{C}_{7} \mathrm{H}_{12} .$ Ignore stereosiomers. (Hint: There are 14.)b. How many would there be if stereoisomers are included?
Draw the mechanism for the following reaction:
How can the following compounds be synthesized, starting with a hydrocarbon that has the same number of carbons as the desired product?a.b. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}$c.
What reagents would you use for the following syntheses?a. $(Z)-3$ -hexene from 3 -hexyneb. $(E)-3$ -hexene from 3 -hexynec. hexane from 3 -hexyne
What is the major product of the reaction of 1 mol of propyne with each of the following reagents?a. HBr (1 mol)b. HBr (2 mol)c. $\mathrm{Br}_{2}(1 \mathrm{mol}) / \mathrm{CH}_{2} \mathrm{Cl}_{2}$d. $\mathrm{Br}_{2}(2 \mathrm{mol}) / \mathrm{CH}_{2} \mathrm{Cl}_{2}$e. aqueous $\mathrm{H}_{2} \mathrm{SO}_{4}, \mathrm{HgSO}_{4}$f. $\mathrm{R}_{2} \mathrm{BH}$ in $\mathrm{THF}$ followed by $\mathrm{H}_{2} \mathrm{O}_{2} / \mathrm{HO}^{-} / \mathrm{H}_{2} \mathrm{O}$g. excess $\mathrm{H}_{2}, \mathrm{Pd} / \mathrm{C}$h. $\mathrm{H}_{2} /$ Lindlar catalysti. sodium amidej. the product of part i followed by 1-chloropropane
Answer Problem 37 , parts a-h using 2 -butyne as the starting material instead of propyne.What will be the major product of the reaction of 1 mol of propyne with each of the following reagents?a. HBr (1 mol)b. HBr (2 mol)c. Br $2(1 \mathrm{mol}) / \mathrm{CH} 2 \mathrm{Cl} 2$d. Br $2(2 \mathrm{mol}) / \mathrm{CH} 2 \mathrm{C} 12$e. aqueous $\mathrm{H} 2 \mathrm{SO} 4, \mathrm{HgSO}$f. $\mathrm{R} 2 \mathrm{BH}$ in THF followed by $\mathrm{H} 2 \mathrm{O} 2 / \mathrm{HO}-/ \mathrm{H} 2 \mathrm{O}$g. excess $\mathrm{H} 2, \mathrm{Pd} / \mathrm{C}$h. H2/Lindlar catalysti. sodium amideJ. the product of part i followed by 1 -chloropropane
What is each compound's systematic name?a. $\mathrm{CH}_{3} \mathrm{C}=\mathrm{CCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}=\mathrm{CH}_{2}$b.c. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{C} \equiv \mathrm{CCH}_{2} \mathrm{CH}_{2} \mathrm{C} \equiv \mathrm{CH}$d.e.f.
What is the molecular formula of a hydrocarbon that has 1 triple bond, 2 double bonds, 1 ring, and 32 carbons?
a. Starting with 3-methyl-1-butyne, how can you prepare the following alcohols?1. 2-methyl-2-butanol2. 3-methyl-1-butanolb. In each case, a second alcohol would also be obtained. What alcohol would it be?
Which of the following names are correct? Correct those that are not correct.a. 4 -heptyneb. 2 -ethyl- 3 -hexynec. 4 -chloro- 2 -pentyned. 2,3 -dimethyl- 5 -octynee. 4,4 -dimethyl- 2 -pentynef. 2,5 -dimethyl- 3 -hexyne
Which of the following pairs are keto-enol tautomers?
How can the following compounds be prepared using ethyne as the starting material?
Do the equilibria of the following acid-base reactions lie to the right or the left? (The $\left.\mathrm{p} K_{\mathrm{a}} \text { of } \mathrm{H}_{2} \mathrm{O}_{2} \text { is } 11.6 .\right)$$$\begin{aligned}\mathrm{HOOH}+\mathrm{HO}^{-} & \rightleftharpoons \mathrm{HOO}^{-}+\mathrm{H}_{2} \mathrm{O} \\ \mathrm{RC} \equiv \mathrm{CH}+\mathrm{HOO}^{-} & \rightleftharpoons \mathrm{RC} \equiv \mathrm{C}^{-}+\mathrm{HOOH} \end{aligned}$$
What stereoisomers are obtained when 2 -butyne undergoes each of the following reaction sequences?a. $1 . \mathrm{H}_{2} /$ Lindlar catalyst $2 . \mathrm{Br}_{2} / \mathrm{CH}_{2} \mathrm{Cl}_{2}$b. $1 . \mathrm{Na} / \mathrm{NH}_{3}(\mathrm{liq}),-78^{\circ} \mathrm{C} 2 . \mathrm{Br}_{2} / \mathrm{CH}_{2} \mathrm{Cl}_{2}$c. $1 . \mathrm{Cl}_{2} / \mathrm{CH}_{2} \mathrm{Cl}_{2}$ 2. $\mathrm{Br}_{2} / \mathrm{CH}_{2} \mathrm{Cl}_{2}$
Show how the following compounds can be synthesized starting with ethyne:a. cis- 2 -octeneb. trans-3-heptene
Draw the keto tautomer for each of the following:
Show how each of the following compounds can be prepared using the given starting material, any needed inorganic reagents, and any organic compound that has no more than four carbons:
A chemist is planning to synthesize 3 -octyne by adding 1 -bromobutane to the product obtained from the reaction of 1-butyne with sodium amide. Unfortunately, however, he forgot to order 1-butyne. How else can he prepare 3-octyne?
a. Explain why a single pure product is obtained from hydroboration-oxidation of 2 -butyne, whereas two products are obtained from hydroborationoxidation of 2 -pentyne.b. Name two other internal alkynes that yield only one product upon hydroboration-oxidation.
What stereoisomers are obtained from the following reactions?a. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{C} \equiv \mathrm{CCH}_{2} \mathrm{CH}_{3}$1. $\mathrm{Na}, \mathrm{NH}_{3}(\text { liq }),-78^{\circ} \mathrm{C}$2. $\mathrm{D}_{2}, \mathrm{Pd} / \mathrm{C}$b. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{C} \equiv \mathrm{CCH}_{2} \mathrm{CH}_{3}$1. $\mathrm{H}_{2} /$ Lindlar catalyst2. $\mathrm{D}_{2}, \mathrm{Pd} / \mathrm{C}$
Explain why, in hydroboration-oxidation, $\mathrm{HO}^{-}$ and $\mathrm{HOOH}$ cannot be added until after the hydroboration reaction is over.
Starting with ethyne, describe how the following compounds can be synthesized:a. $(3 S, 4 R)$-4-bromo-3-hexanol and $(3 R, 4 S)$-4-bromo-3-hexanolb. $(3 R, 4 R)$-4-bromo-3-hexanol and $(3 S, 4 S)$-4-bromo-3-hexanol
$\alpha$ -Farnesene is a dodecatetraene found in the waxy coating of apple skins. What is its systematic name? Include $E$ and $Z$ where necessary to indicate the configuration of the double bonds.
Show how the following compound can be prepared from the given starting material. Draw the structure of the compound that is formed in each step of the synthesis.
What are the products of the following reactions?