Name_____________________
Aquinas College, CY 212, Spring 2015
Exam 2, March 24 th , 2015
Write how many pi electrons are present in the cyclic system of each of the following molecules.
1) 2)
The lone pair on the nitrogen in pyrrole is in a p orbital while the lone pair on the nitrogen in pyridine is in an sp 2 hybridized orbital because its p-orbital is already occupied.
3) 4)
Circle whether the following molecules are aromatic, nonaromatic or antiaromatic. Unless otherwise indicated, assume each molecule is planar.
5) 6)
Both furan and oxazole are planar with a continuous cycle of p orbitals. Also both furan and oxazole have 6 pi electron in the cyclic system of p orbitals.
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Name_____________________
11)
7) 8)
10)
Provide the name of each of the following benzene derivatives.
9)
Aquinas College, CY 212, Spring 2015
2

Name_____________________
Aquinas College, CY 212, Spring 2015
Provide the product of each of the following Diels-Alder reactions accounting for the correct
stereochemistry as necessary.
12)
13)
The key observation here is that the hydrogens are trans to each other in the dienophile.
Consequently, they should be trans to each other in the product.
14)
To get the stereochemistry correct on this question you must correctly apply the (out-endo-cis) rule.
Provide the reactants of each of the following Diels-Alder reactions accounting for the correct
stereochemistry as necessary.
3

Name_____________________
15)
Aquinas College, CY 212, Spring 2015
16)
For the following pairs of dienes, circle which will react more quickly in a Diels-Alder reaction.
17)
The diene on the left is locked in an s-cis conformation while the diene on the right is locked in an strans conformation.
18)
The diene on the left has more steric hindrance between the two methyl groups when in the s-cis conformation than the one on the right.
4

Name_____________________
Aquinas College, CY 212, Spring 2015
22)
23)
21)
Provide the major organic product(s) for the following reactions. For the purpose of this exam, assume that a reaction occurs even for deactivated substrates. For any Friedel-Crafts acylations of monosubstituted benzene derivatives assume that steric factors prevent ortho substitution.
19)
20)
5

Name_____________________
27)
26)
25)
24)
Aquinas College, CY 212, Spring 2015
6

Name_____________________
Aquinas College, CY 212, Spring 2015
30)
29)
28)
This reaction is a nucleophilic aromatic substitution (elimination-addition) reaction. An additionelimination mechanism is unlikely because there are no strong EWGs ortho or para to the leaving group (Cl).
This reaction is a nucleophilic aromatic substitution (addition-elimination) reaction. The presence of the strong electron withdrawing groups (NO
2
) that are ortho and para to the leaving group (F) indicate that it will be addition-elimination instead of elimination-addition.
7

Name_____________________
Aquinas College, CY 212, Spring 2015
Provide the mechanism for the following reaction. Draw all curved arrows and lone pairs. If the mechanism involves a sigma complex, show all resonance forms.
31)
8

Name_____________________
Aquinas College, CY 212, Spring 2015
32) Complete the mechanism for the following reaction for one of the two products. Show all curved arrows, lone pairs, and correct formal charges.
9

Name_____________________
Aquinas College, CY 212, Spring 2015
Grading Rubric (105 points)
Questions 1-4 (pi electrons) (8 points)
2 points each
Questions 5-8 (aromatic) (12 points)
3 points each
0 points if more than one answer circled
Questions 9-11 (Nomenclature) (6 points)
2 points each
Wrong base name (-1 point)
Errors involving commas or hyphens or parenthesis (-1/2 point each)
Wrong numbering (-1 point)
Wrong alphabetizing (-1 point)
Wrong substituent name (-1 point)
Z vs. E (-1 point)
Note: If the wrong base chain was chosen, apply the last five penalty conditions according to the new base chain.
Questions 12-14 (Diels-Alder Products) (9 points)
3 points each
(-3 points for incorrect connectivity)
(-1 point for incorrect stereochemistry)
(-2 for errors with pi bonds or carbons with too few/many hydrogens)
Questions 15-16 (Diels-Alder Reactants) (8 points)
2 points for Diene
(-2 points for incorrect connectivity)
(-1 point for incorrect stereochemistry)
2 points for Dienophile
(-2 points for incorrect connectivity)
(-1 point for incorrect stereochemistry)
Questions 17-18 (Relative Diene Reactivity) (4 points)
2 points each
Questions 19-30 (36 points)
3 points each
2 points for correct group added
1 point for correct regiochemistry
Minor errors e.g. # of hydrogens (-1 point)
Notes Related to Steric Factors
Question 25 (Though minor, the product with the nitro group ortho to both methyl groups will be accepted as long as the first product is also shown)
Question 26 and 29: Will be accepted without ortho product as one might make steric arguments based on the acyl group.
Question 27 (Though minor, the product with the nitro group ortho to the methoxy and bromine will be accepted if other two products are also shown)
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Name_____________________
Aquinas College, CY 212, Spring 2015
Question 31 (EAS Mechanism) (10 points)
1 point per arrow (5 points)
2 points for the electrophile (2 points)
Incorrect formal charge (-1 point per structure)
Incorrect lone pairs (-1 point per structure)
1 point for each sigma complex (3 points)
Incorrect formal charge (-1/2 point per structure)
Incorrect lone pairs (-1/2 point per structure)
Question 32 (Benzyne Mechanism) (12 points)
1 point per arrow (8 points)
Note: A concerted E2 elimination with 3 arrows is acceptable and will count as 4 points for 4 arrows.
Benzyne Intermediate (2 points)
Anion intermediate in the addition half of the reaction (2 points)
Incorrect formal charge (-1 point per structure)
Incorrect lone pairs (-1 point per structure)
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