9. Alkenes and Alkynes

Predict the major, organic product for the following reaction.

Predict the product of the multistep synthesis

330

Predict the major, organic product for the following reaction.

297

Predict the major, organic product for the following reaction.

325

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

333

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

399

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

391

What are products of the following reactions? b.

455

What are products of the following reactions? a.

404

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

859

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

464

(•••) 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?

331

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

542

(••) 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)

359

(••) 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)

337

(••) 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)

352

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

404

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

371

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

483

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

360

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

322

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

305

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?

342

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

401

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

470

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

434

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

424

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

498

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

477

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

339

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

511

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

633

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

<IMAGE>

(a) H₂ , Pd

266

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

(b) <IMAGE>

270

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>

363

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

260

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.

255

What reagents would you use for the following syntheses?

c. hexane from 3-hexyne

315

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

e. <IMAGE>

308

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>

276

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

f. <IMAGE>

283

What are products of the following reactions?

c. <IMAGE>

d. <IMAGE>

279

Show how you would convert

c. cis-cyclodecene to trans-cyclodecene.

356

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

220

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

235

Predict the product of the following reactions. (b)

402

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

423