Question 1

Which of the following statements best describes the stereochemistry of (S)-serine?

Accepted Answer

It rotates plane-polarized light in a counterclockwise direction.

Question 2

In the reaction of $$Cl_2$$ with ethane under UV light, which of the following events is a chain termination step?

Accepted Answer

Cl• + Cl• → Cl$$_2$$

Question 3

Which of the following statements correctly describes the contribution of entropy ($$	riangle S) to $$Gibbs free energy ($$	riangle G$$)?

Accepted Answer

The entropy term makes a greater contribution to $$	riangle G at $$high temperatures.

Question 4

Which of the following compounds has the highest boiling point?

Accepted Answer

n-butyl chloride

Question 5

Which of the following statements correctly describes SN2 reactions of alkyl halides (RX) with base?

Accepted Answer

Rate = k[RX][base], occurs with inversion, rearrangements are never seen.

Question 6

Given the bond dissociation energies below (in kcal/mol), estimate the $$	riangle H$$ for the propagation step: $$CH_3CH_2Cl + Cl_2$ ightarrow CH_3CH_2Cl + Cl•.

$$Bond dissociation energies:
$$CH_3CH_2-H$$: 98
$$Cl-Cl$$: 58
$$H-Cl$$: 103
$$CH_3CH_2-Cl$$: 80

Accepted Answer

$$-22$$ kcal/mol

Question 7

Which of the following compounds is the least reactive in an SN1 reaction?

Accepted Answer

CH$$_3CH$_2Cl$$

Question 8

Which of the following is the best solvent for an SN2 reaction?

Accepted Answer

DMSO

Question 9

Which of the following is a carbene?

Accepted Answer

:CCl$$_2$$

Question 10

If the equilibrium constant ($$K_{eq}) of a $$reaction is $$0.5$$, which of the following must be true?

Accepted Answer

Gibbs free energy ($$	riangle G) is $$positive.

Question 11

How many enantiomers are there of the molecule shown below (with four different substituents on each of two chiral centers)?

Accepted Answer

4

Question 12

Which of the following pairs of stereoisomers are diastereomers?

Accepted Answer

Molecules that are non-mirror image stereoisomers.

Question 13

Which of the following alkyl halides would undergo an SN2 reaction most readily?

Accepted Answer

CH$$_3CH$_2CH$_2Cl$$

Question 14

Which of the following statements about meso compounds is correct?

Accepted Answer

Meso compounds have chiral centers but are achiral overall.

Question 15

A mixture of $$(-)-2-$$butanol has a specific rotation of $$-10.07^	ext{o}$$, while pure $$(-)-2-$$butanol has a specific rotation of $$-13.5^	ext{o}. $$What is the percentage of each enantiomer in the mixture?

Accepted Answer

74.6% $$(-)-$$enantiomer, 25.4% $$(+)-$$enantiomer

Question 16

Which of the following reagents would most likely cause a rearrangement in the reaction of a secondary alkyl bromide?

Accepted Answer

CH$$_3OH$$

Question 17

Which of the following is the correct IUPAC name for the compound shown below?

$$\begin{array}{c}
	ext{CH}_3	ext{CH}_2	ext{CH}(Br)	ext{CH}_3
\end{array}$$

Accepted Answer

2-bromobutane

Question 18

Which of the following best describes the product of the reaction: $$CH_3CH_2Br + NaCN \xrightarrow{DMF}$$ ?

Accepted Answer

CH$$_3CH$_2CN$$

Question 19

Which of the following statements about the energy diagram of an exothermic reaction is correct?

Accepted Answer

The products are lower in energy than the reactants.

Organic Chemistry Exam Study Guide: Stereochemistry, Reaction Mechanisms, and Physical Properties

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