Los Angeles Mission College

CHEM 012A

Exhibit 7-1

CHEM-012A:Organic Chemistry

Practice Test, Chapter 07: Alkenes: Reactions and Synthesis

1)Calculate the degree of unsaturation in each formula below. Show your calculations.

 

Q2. eicosapentaenoic acid, C20H30O2, a constituent of fish oil

 

Q3.         diazepam (Valium), C16H13N2OCl

 

Exhibit 7-2

Dieldrin, C12H8Cl6O, is a pentacyclic compound formerly used as an insecticide.

Q4.         Refer to Exhibit 7-2. Calculate the degree of unsaturation for Dieldrin. Show calculations for credit.

 

Q5.         Refer to Exhibit 7-2. How many double bonds does dieldrin have?

 

Drawing Instructions: Draw structures corresponding to each name below. Either condensed or line structures may be used.

Q6.         Draw: (3E)-3,7-dimethyl-1,3,6-octatriene

 

 

Q7.         Draw: 3,6-dimethyl-1,4-cyclohexadiene

 

 

Q8.         Draw: cis-2-hexene

 

 

Q9.         Draw: trans-4,4-dimethyl-2-pentene

Exhibit 7-3

2-Pentene is an example of a disubstituted alkene. CH3CH=CHCH2CH3

Q10.       Refer to Exhibit 7-3.

1. Draw the cis and trans isomers of 2-pentene and label them.
2. Circle the isomer which is most stable.

 

 

Q11.       The original question was combined with #10. This placeholder question is here to maintain the integrity of the numbering system between the printed copy and ExamView. Therefore, it has been marked "do not use on test" in ExamView's question information dialog. As a result, this placeholder question is automatically prevented from being chosen as a test question.

 

Exhibit 7-4

 

Provide names for each structure below. Be sure to include the cis, trans or E, Z designations where applicable.

 

Q12.       Name:

 

 

 Q13.    Name:

 

 

 

Q14.       Name:

 

 

Q15.    Name:

Exhibit 7-5

Rank each set of substituents using the Cahn-Ingold-Prelog sequence rules by numbering the highest priority substituent 1 and numbering the lowest priority substituent 4. Place the number in the blank below the substituent.

 

 

Q16.

 

 

 

 

 

 

 

 

 

Q17.

 

 

 

 

 

 

 

 

 

Q18.

 

 

 

 

 

 

 

 

 

Q19.

 

 

 

Exhibit 7-6

MATCH each alkene below with the appropriate heat of hydrogenation. Place the letter of the correct answer in the blank

to the left of the alkene.

 

a. 125.9 kJ/mol                  b. 118.4 kJ/mol                  c. 115.5 kJ/mol

 

 

 

Q20.                      

 

 

 

 

 

 

Q21.                     

 

 

 

 

 

 

Q22.                     

 

Q23.       Arrange the following bicyclic alkenes in order of increasing stability (least stable to most stable).

 

 

 

a. III < II < I                          b. I < II < III                          c. I < III < II                          d. II < III < I

 

Exhibit 7-7

 

Assign E or Z configurations to each alkene below.

 

 

 

Q24.

 

 

 

 

 

 

 

 

Q25.

 

 

 

 

 

 

 

 

 

 

Q26.

 

 

Exhibit 7-8

MATCH each definition to the term it describes. Place the letter corresponding to the term in the blank to the left of the definition.

1. Hammond Postulate                      b. Cahn-Ingold-Prelog Rules        c. Markovnikov's Rule

Q27.                      predicts that the more stable carbocation intermediate is formed in electrophilic additions to alkenes.

Q28.                      predicts that the transition state of an exergonic reaction step structurally resembles the reactant.

Q29.                      assigns priorities to the substituent groups on a carbon.

Q30.                      predicts that the transition state of an endergonic reaction step structurally resembles the product.

Q31.                   predicts that in additions of HX to alkenes, the H adds to the less substituted alkene carbon and the X adds to the more substituted alkene carbon.

Q32.       Rank the carbocations below in order of increasing stability (least stable = 1; most stable = 3). Place the number corresponding to the carbocation's relative stability in the blank below the structure.

 

 

 

 

 

 

 

 

Exhibit 7-9

Consider the following reaction:

 

 

 

Q33.       Refer to Exhibit 7-9. Write the complete stepwise mechanism for this reaction. Show all intermediate structures and show all electron flow using the curved arrow convention.

 

 

 

 

Q34.       Refer to Exhibit 7-9. Draw a qualitative reaction energy diagram for this reaction. Label the positions of all reactants, intermediates and products.

 

 

 

 

 

 

 

 

 

 

Exhibit 7-10

 

Consider the following reaction:

 

Q35.       Refer to Exhibit 7-10. Below are all the chemical structures and intermediates involved in this reaction. On the structures provided, show all electron flow using the arrow formalism for the complete stepwise mechanism for this reaction.

 

 

 

 

 

 

 

 

 

 

 

 

 

Q36.       Refer to Exhibit 7-10. Why does the rearrangement that results in the formation of product B occur?

Q37.       Write the complete stepwise mechanism for the following reaction. Show all intermediate structures and all electron flow with arrows.

 

 

Exhibit 7-11

 

Predict the major organic product for each reaction below.

 

 

 

 

Q38.

 

 

 

 

 

 

 

 

 

 

 

Q39.

 

 

 

 

 

 

 

Q40.

 

 

 

 

 

 

 

 

Q41.

 

 

 

 

 

 

 

Exhibit 7-12

Predict the structure of the alkene you would use to prepare each alkyl halide below.

 

 

 

 

 

 

 

Q43.

 

 

Exhibit 7-13

The reaction of isobutene with HBr in ether gives one of the two products below as the major product. Answer the following question(s) about this reaction.

 

 

 

Q44.       Refer to Exhibit 7-13. Which product would be the major product?

 

Q45.       Refer to Exhibit 7-13. Which product would be formed via a primary carbocation?

 

Q46.       Refer to Exhibit 7-13. Which product would have a higher energy transition state for the formation of the intermediate leading to it?

Q47.       Refer to Exhibit 7-13. According to Hammond's Postulate, which product would have a transition state structure most closely resembling the carbocation intermediate?

 

Q48.       Refer to Exhibit 7-13. Which product would be formed by a carbocation experiencing the greatest degree of hyperconjugative stabilization?

 

Q49.       Refer to Exhibit 7-13. Increasing the temperature at which the reaction is run would lead to an increase in the percentage of which product relative to the other product?

Name the following alkenes and draw their skeletal formulas. Q50.

 

 

 

 

 

Q51.

 

 

Q52.       Cyclohexanol (—OH bonded to cyclohexane) produces cyclohexene when heated to 70 °C in the presence of a sulfuric acid catalyst. Write the equation for the reaction showing only the reactant of interest and the conditions of the reaction

Q53.       Identify the isoprene units in limonene, an essential oil found in oil of lemon and orange.

 

 

 

 

 

Q54.       The following shows the connectivity of atoms only. Atoms other than carbon and hydrogen are labeled.

 

 

 

How many degrees of unsaturation are present in the compound?

a. 1                          b. 2                        c. 3                          d. 4                         e. 5

Q55.       If the following compound were dissolved in ether and treated with HCl, which of the following describes the product(s) of the reaction?

 

 

 

1. 1. 3-bromoheptane
   2. 4-bromoheptane
   3. a mixture of 3-bromoheptane and 4-bromoheptane

Q56.       If the following compound was dissolved in ether and treated with HBr, which of the following describes the major product(s) of the reaction?

 

 

 

 

 

 

 

a.                                                            b.                                            c.

 

 

d. a mixture of and

 

Q57.       Consider the following molecular model.

 

 

 

I

 

Which of the following could be used to synthesize this compound?

 

 

 

a.                                            b.                                            c.

 

 

 

d. Either or

 

 

e. Any of the above

 

 

Q58.       Which of the following does not characterize a more highly substituted carbocation?

1. forms more rapidly than less highly substituted carbocations
2. forms product more rapidly than less highly substituted carbocations
3. has a larger ΔG± than less highly substituted carbocations

4. 

   is more stable than less highly substituted carbocations Q59.           Examine the following reaction.

 

 

 

Which of the following is not indicated by this representation?

 

a. KI is the solvent                                                                           b. Cyclohexene is the reactant of interest.

c. The reaction is carried out at room temperature.          d. The reaction occurs in solution.