Q: Which of the following is the correct formula for calculating specific rotation $$[\alpha]_D$$^{25}$$?

$$[\alpha]_D$$^{25}$$ = \frac{\alpha}{l \times c}$$

Question 1

Which of the following functional groups has the lowest pKa value according to the provided table?

Accepted Answer

Carboxylic acid

Question 2

A pure sample of (R)-2-butanol has a specific rotation of $$-13.5^{\circ}. If a $$mixture of (R)- and (S)-2-butanol has an observed rotation of $$+6.75^{\circ}$$, what is the enantiomeric excess (ee) of the sample?

Accepted Answer

$$50\%$$

Question 3

Given the following reaction energy diagram with three peaks and two valleys between reactant and product, how many transition states and intermediates are present?

Accepted Answer

3 transition states, 2 intermediates

Question 4

Which of the following statements about the relationship between a pair of molecules is correct if they are non-superimposable mirror images?

Accepted Answer

They are enantiomers

Question 5

Gemcitabine is a drug used to treat pancreatic cancer. Which of the following best describes its optical activity?

Accepted Answer

It is optically active because it contains at least one asymmetric carbon

Question 6

Which of the following best describes the relationship between the following two molecules: cis-2-butene and trans-2-butene?

Accepted Answer

They are diastereomers

Question 7

A solution contains $$0.30$$ grams of sucrose dissolved in $$10.0 mL of $$water. The observed rotation is $$1.99^{\circ} in a$$ $$10.0 cm $$cell. What is the specific rotation $$[\alpha]_D$$^{25}$$?

Accepted Answer

$$[\alpha]_D$$^{25}$$ = 66.3$$^{\circ}$$

Question 8

Which of the following cations is most likely to undergo a hydride shift to form a more stable carbocation?

Accepted Answer

A primary carbocation adjacent to a tertiary carbon

Question 9

Which of the following best describes the process of a 'ring flip' in cyclohexane?

Accepted Answer

It converts axial hydrogens to equatorial and vice versa

Question 10

Which of the following is the correct IUPAC name for the compound shown: a cyclobutane ring with two methyl groups at positions 1 and 3?

Accepted Answer

1,3-dimethylcyclobutane

Question 11

Which of the following statements about the stability of carbocations is correct?

Accepted Answer

Benzylic carbocations are stabilized by resonance

Question 12

Which of the following best describes the relationship between the following two molecules: (2R,3S)-2-bromo-3-methylhexane and (2S,3S)-2-bromo-3-methylhexane?

Accepted Answer

They are diastereomers

Question 13

Which of the following is the correct formula for calculating specific rotation $$[\alpha]_D$$^{25}$$?

Accepted Answer

$$[\alpha]_D$$^{25}$$ = \frac{\alpha}{l 	imes c}$$

Question 14

Which of the following best explains why a secondary carbocation is more stable than a primary carbocation?

Accepted Answer

Inductive effects and hyperconjugation from adjacent alkyl groups

Question 15

Which of the following pairs of molecules are diastereomers?

Accepted Answer

cis-1,2-dimethylcyclohexane and trans-1,2-dimethylcyclohexane

Question 16

Which of the following best describes the relationship between the following two molecules: 1-butene and 2-butene?

Accepted Answer

They are constitutional isomers

Question 17

Which of the following is the correct order of acidity (from most acidic to least acidic) for the following functional groups: carboxylic acid, alcohol, alkyne, alkane?

Accepted Answer

Carboxylic acid \u003e alcohol \u003e alkyne \u003e alkane

Question 18

Which of the following best describes the effect of a 'chair flip' on the stability of substituted cyclohexane?

Accepted Answer

The conformation with bulky groups in the equatorial position is more stable

Question 19

Which of the following best describes the relationship between the following two molecules: (E)-2-butene and (Z)-2-butene?

Accepted Answer

They are diastereomers

Question 20

Which of the following is the correct IUPAC name for a compound with a bromine at carbon 2 and a methyl at carbon 3 on a hexane chain, with the 2-bromo group having R configuration and the 3-methyl group having S configuration?

Accepted Answer

(2R,3S)-2-bromo-3-methylhexane

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

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