Question 1

Which of the following statements best describes the stereochemical outcome when (S)-1-bromo-1-phenylethane undergoes an $$S_N1$$ reaction with $$CH_3SH$$?

Accepted Answer

The product will be a mixture of R and S enantiomers, with slightly more S than R.

Question 2

Which of the following carbocations is most likely to undergo rearrangement?

Accepted Answer

A primary carbocation adjacent to a tertiary carbon

Question 3

Which of the following correctly describes intermediates and/or transition states?

Accepted Answer

Transition states have partially formed bonds, whereas intermediates have fully formed bonds.

Question 4

Which of the following is an isolated diene?

Accepted Answer

A diene with two double bonds separated by more than one single bond.

Question 5

What product is formed when (R)-2-chloropentane reacts with hydroxide ion in an $$S_N2$$ reaction?

Accepted Answer

(S)-2-pentanol

Question 6

Which of the following best describes the carbon-chlorine bond of an alkyl chloride?

Accepted Answer

Polar, $$\delta^+ at $$carbon and $$\delta^- at $$chlorine

Question 7

Which of the following is NOT normally considered to be a nucleophile?

Accepted Answer

$$CH_3CH_2^+$$

Question 8

Which halide reacts most rapidly via an $$S_N2$$ mechanism?

Accepted Answer

Methyl iodide ($$CH_3I)$$

Question 9

Which of the following factors has NO effect on the rate of an $$S_N1$$ reaction?

Accepted Answer

The concentration of the nucleophile

Question 10

What is the nucleophile in the reaction where $$H_2O$$ reacts with $$CH_3I$$?

Accepted Answer

$$H_2O$$

Question 11

Which of the following are the elimination products of the reaction $$CH_3CH_2Br + OH^- \rightarrow$$ ?

Accepted Answer

$$CH_2$$=$$CH_2 + Br^- + H_2O$

Question 12

Which of the following is the most stable alkene product in an E2 elimination of 2-bromo-3-methylpentane?

Accepted Answer

The most substituted (tetra-substituted) alkene

Question 13

How many distinct alkene products are possible when 2-iodopentane undergoes E2 elimination?

Accepted Answer

3

Question 14

Which of the following bases will favor the formation of the least substituted alkene (Hofmann product) in an E2 elimination?

Accepted Answer

tert-butoxide ion

Question 15

Calculate the degree of unsaturation for a compound with molecular formula $$C_{23}H$$_{38}$$. What is the value?

Accepted Answer

5

Question 16

Which of the following statements about $$S_N2$$ reactions is correct?

Accepted Answer

$$S_N2$$ reactions proceed with complete inversion at the chiral carbon.

Question 17

Which of the following best explains why $$S_N1$$ reactions often give a mixture of stereoisomers?

Accepted Answer

The nucleophile attacks from either side of the planar carbocation intermediate.

Question 18

Which of the following is the correct IUPAC name for the compound with the structure: $$(Z)-6-$$chloro-1-methylcyclohexene?

Accepted Answer

$$(Z)-6-$$chloro-1-methylcyclohexene

Question 19

Rank the following alkenes in order from most stable to least stable: (i) most substituted, (ii) trans, (iii) cis, (iv) constrained ring.

Accepted Answer

most substituted \u003e trans \u003e cis \u003e constrained ring

Organic Chemistry Practice Exam 3 – Step-by-Step Study Guidance

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