Textbook: Loudon 5th Ed. (2009)

Chapter 15: Dienes, Resonance, and Aromaticity

Practice Problems (No matching mendel sets were found.)

Individual Problems

Problem # 574

Predict the product for each Diels-Alder reaction. Indicate stereochemistry where appropriate.

Problem # 575

Predict the product for each Diels-Alder reaction. Indicate stereochemistry where appropriate.

Problem # 576

Retro Diels-Alder: show a combination of diene and dienophile that would result in each Diels-Alder adduct.

Problem # 528
 

Indicate which of the molecules below are chiral (if any).

Problem # 569

Draw all resonance forms for each species. 

For the anion and cation species, used curved arrows. For the radical species, use hooks.

Problem # 571

Write the structure of the major organic product of each reaction.

Problem # 570

Rank the following dienes in order of decreasing reactivity with a dienophile in a Diels-Alder reaction. (1 = most reactive).

Problem # 577
 

Retro Diels-Alder: show a combination of diene and dienophile that would result in each Diels-Alder adduct.

Problem # 522

Let's work through a 1,2 and 1,4 addition. Draw the structures for each of the species in the six boxes below. Also draw curved arrows to show electron movement. 

Problem # 572
 

Let's work through a conjugate addition problem.

Write out the mechnanism for the formation of the 1,2 and 1,4 products of the reaction below.

Problem # 1281

Allylic and benzylic halides tend to undergo both SN1 and SN2 substitution reactions at a faster rate than their alkyl counterparts.

For example, both allyl chloride and benzyl chloride undergo SN2 reaction at a faster rate than propyl chloride. 

The same holds true for SN1 reactions: a 2° allyl or benzyl halide undergoes SN1 reaction faster than a 2° alkyl halide. Explain.

Problem # 582
 

Rationalize the follwing pKa values. Explain your answer in terms of the stabilites of the conjugates bases of each acid.

Note: the lower the pKa, the stronger the acid.

Problem # 583

Pyrrole is an example of a heteroaromatic compound: it contains a heteroatom (atom that is not carbon or hydrogen, such as N, O, S, etc.), and is aromatic.

Because pyrrole is aromatic, we should be able to draw many resonance forms- usually as many resonance forms as sides (in this case, five sides, so five resonane forms).

Draw all resonance forms for pyrrole. (I've started you off.)

Problem # 584

Imidazole (shown below) has two nitrogen atoms, N-1 and N-3. Which nitrogen is more basic?

To answer this problem, draw the product after each nitrogen protonates, and compare their stabilities. Explain your reasoning.