9. Alkenes and Alkynes

Predict the major, organic product for the following reaction.

Predict the product of the multistep synthesis

325

Predict the major, organic product for the following reaction.

294

Predict the major, organic product for the following reaction.

323

Which reaction would be best suited to make the following target molecule?

328

Answer Problem 39 , parts a–h, using 2-butyne as the starting material instead of propyne. h. H2/Lindlar catalyst

391

Answer Problem 39 , parts a–h, using 2-butyne as the starting material instead of propyne. g. excess H2, Pd/C

380

What are products of the following reactions? b.

449

What are products of the following reactions? a.

390

What stereoisomers are obtained from the following reactions? b. CH3CH2C☰CCH2CH3→1.H2/Lindlar catalyst 2. D2, Pd/C

848

What stereoisomers are obtained from the following reactions? a. CH3CH2C☰CCH2CH3→1.Na, NH3(liq), −78°C 2. D2, Pd/C

458

(•••) LOOKING AHEAD CHAPTER 10 The following reaction was recently reported to have been performed electrochemically.

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(a) Identify the reagent and a solvent that could have been used if this reaction was done traditionally. (b) What safety and environmental hazards are improved or worsened when doing this reaction electrochemically?

325

Show how you would convert a. oct-3-yne to cis-oct-3-ene. b. pent-2-yne to trans-pent-2-ene.

536

(••) For the alkynes shows here, show the product(s) expected to form when treated under the following conditions: (i) H₂ , Pd/C; If you expect two products, show both. (c)

355

(••) For the alkynes shows here, show the product(s) expected to form when treated under the following conditions: (ii) H₂, Pd/C, Pb(OAc)₂ , CaCO₃ (Lindlar's catalyst); (If you expect two products, show both. (c)

332

(••) For the alkynes shows here, show the product(s) expected to form when treated under the following conditions: (iii) Na⁰ , NH₃ (liquid), ―33°C . If you expect two products, show both. (c)

346

Predict the product of the following alkyne reductions. (a)

396

Predict the product of the following alkyne reductions. (b)

365

Predict the product of the following alkyne reductions. (c)

471

Suggest alkynes that might be used to make the following trans-alkenes. (a)

357

Suggest alkynes that might be used to make the following trans-alkenes. (a)

317

Suggest alkynes that might be used to make the following trans-alkenes. (a)

300

When sodium generates electrons in the presence of ammonia, these electrons persist in solution, giving the blue color. However, electrons do not persist when sodium is added to water. Why?

337

Predict the product of the following hydrogenation reactions run with a poisoned catalyst. (a)

389

Predict the product of the following hydrogenation reactions run with a poisoned catalyst. (a)

460

Predict the product of the following hydrogenation reactions run with a poisoned catalyst. (a)

426

Hydrogenation of which alkynes would produce the following cis-alkenes? (c)

420

Predict the product of the following hydrogenation reactions. (a)

494

Predict the product of the following hydrogenation reactions. (c) Note: D is an isotope of H and behaves similarly.

473

The following deprotonation step occurs during the trans reduction of an alkyne. Calculate K_eq for this reaction. <IMAGE>

329

Sodium amide, the base we use to deprotonate terminal alkynes, is synthesized by reducing ammonia via a mechanism similar to the reduction of alkynes in Figure 10.21. Suggest a mechanism for this reaction. <IMAGE>

2NH₃ 2Na⁰NH₂ + H₂

503

Reduction of an alkyne using the Lindlar catalyst, a reaction presented in Section 10.6.2, produces only the cis-alkene. Why?

622

Identify the product when each of the following reactions is performed on the triglyceride of linoleic acid (linoleate).

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(a) H₂ , Pd

259

Hydrogenation of which alkynes would produce the following cis-alkenes?

(b) <IMAGE>

265

Long, polarized bonds are also reducible in the same way that the C―C π bond of an alkyne is. Show a mechanism by which a C―Br bond might be reduced by sodium metal. <IMAGE>

330

What is the major product of the reaction of 1 mol of propyne with each of the following reagents?

g. excess H2, Pd/C

h. H2/Lindlar catalyst

249

Describe the alkyne you should start with and the reagents you should use if you want to synthesize

c. trans-2-pentene.

d. 1-hexene.

251

What reagents would you use for the following syntheses?

c. hexane from 3-hexyne

304

How can the following compounds be prepared using ethyne as the starting material?

e. <IMAGE>

301

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:

f. <IMAGE>

269

How can the following compounds be prepared using ethyne as the starting material?

f. <IMAGE>

281

What are products of the following reactions?

c. <IMAGE>

d. <IMAGE>

272

Show how you would convert

c. cis-cyclodecene to trans-cyclodecene.

346

What reaction would acetylene likely undergo if it were kept at 1500 °C for too long?

216

Hydration of alkynes (via oxymercuration) gives good yields of single compounds only with symmetrical or terminal alkynes. Show what the products would be from hydration of each compound.

(d) cyclodecyne

229

Predict the product of the following reactions. (b)

397

Describe the alkyne you should start with and the reagents you should use if you want to synthesize b. cis-2-butene.

415