Question 1

Which of the following statements correctly describes the difference between $$S_N1$$ and $$S_N2$$ mechanisms?

Accepted Answer

$$S_N1$$ reactions proceed via a carbocation intermediate and can result in a mixture of inversion and retention of configuration, while $$S_N2$$ reactions proceed via a concerted mechanism and result in complete inversion.

Question 2

Given the substrate $$CH_3Br ($$methyl bromide), which reaction mechanism is most likely to occur with a strong nucleophile?

Accepted Answer

$$S_N2$$ mechanism, because methyl halides are unhindered.

Question 3

Which of the following best explains why $$sp^2$$ hybridized carbon-carbon bonds are shorter than $$sp^3$$ hybridized carbon-carbon bonds?

Accepted Answer

Because $$sp^2$$ hybrid orbitals have more s-character, resulting in greater electron density between the nuclei.

Question 4

How many elements of unsaturation are present in $$C_5H_8$$?

Accepted Answer

2

Question 5

Which of the following is the correct IUPAC name for the compound $$CH_2=$$CHCH_2CH_3$$?

Accepted Answer

1-butene

Question 6

According to the Ingold-Prelog rules, which of the following statements is true when assigning E/Z stereochemistry to alkenes?

Accepted Answer

The isomer is Z if the highest priority groups are on the same side of the double bond.

Question 7

Which of the following statements about stereoisomers of alkenes is correct?

Accepted Answer

Alkenes with double bonds inside rings cannot show E/Z isomerism.

Question 8

A tertiary alkyl halide ($$R_3CX) is $$treated with a weak nucleophile in a polar solvent. Which reaction mechanism is most likely?

Accepted Answer

$$S_N1$$

Question 9

Which of the following bases would most likely favor the formation of the Hofmann product in an E2 elimination?

Accepted Answer

Potassium tert-butoxide ($$KOtBu)$$

Question 10

Which of the following statements about the dehydration of alcohols is correct?

Accepted Answer

The reaction uses a concentrated acid and heat, and rearrangements are common.

Question 11

In the addition of $$HX to an $$alkene, which product is favored according to Markovnikov’s rule?

Accepted Answer

The halide adds to the more substituted carbon.

Question 12

Which of the following is the major product when 2-methylbutan-2-ol is dehydrated with concentrated $$H_2SO_4$$?

Accepted Answer

2-methylbut-2-ene

Question 13

Which of the following statements about E2 eliminations is correct?

Accepted Answer

E2 eliminations are favored by strong bases and occur in a single concerted step.

Question 14

Which conformation of cyclohexane is required for an E2 elimination to occur?

Accepted Answer

Both the leaving group and the hydrogen must be in axial positions.

Question 15

Which of the following is the correct formula to calculate the number of elements of unsaturation in a hydrocarbon?

Accepted Answer

$$\frac{2C+2-H}{2}$$

Question 16

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

Accepted Answer

$$S_N2$$ reactions result in complete inversion of configuration at the reaction center.

Question 17

Which of the following is the correct IUPAC name for the compound $$CH_3CH=CHCH_2CH_3$$?

Accepted Answer

pent-2-ene

Question 18

Which of the following statements about the addition of water to alkenes is correct?

Accepted Answer

The reaction forms an alcohol and follows Markovnikov’s rule.

Question 19

Which of the following is true regarding the stability of carbocations formed during $$S_N1$$ reactions?

Accepted Answer

Tertiary carbocations are more stable due to hyperconjugation and inductive effects.

Organic Chemistry I: Alkenes, Alkyl Halides, and Stereochemistry Study Notes

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