Organic Chemistry

Question 1

Which of the following characterizes a reducing sugar?

a. It features a hemiacetal
b. It features an acetal
c. It features a hemiketal
d. It features a ketal

Answer 1

a. It features a hemiacetal

(Reducing sugars are sugars which undergo formation of an aldehyde or ketone in a basic solution, allowing the sugar to act as a reducing agent)

Question 2

Benedict’s reagent does which of the following?

a. Oxidizes reducing sugars to produce a red precipitate
b. Reduces reducing sugars to produce a red precipitate
c. Oxidizes reducing sugars to produce a silvery mirror
d. Reduces reducing sugars to produce a silvery mirror

Answer 2

a. Oxidizes reducing sugars to produce a red precipitate

Question 3

Which of the following is NOT true regarding anomeric carbons?

a. The anomeric carbon of glucose is the carbon at position 1
b. The anomeric carbon of a sugar is the carbon which is a carbonyl in the straight chain form
c. The anomeric carbon of a sugar is the carbon which is a carbonyl in the ring form
d. Anomeric carbons must be free in order to form glycosidic linkages

Answer 3

c. The anomeric carbon of a sugar is the carbon which is a carbonyl in the ring form

Question 4

Which of the following is true?

a. Cyclization refers to an inversion of stereochemistry at the anomeric carbon
b. Mutarotation refers to an inversion of stereochemistry at the anomeric carbon
c. Cyclization refers to the oxidation of a reducing sugar
d. Mutarotation refers to the oxidation of a reducing sugar

Answer 4

b. Mutarotation refers to an inversion of stereochemistry at the anomeric carbon

Question 5

Which of the following are true statements regarding enolate formation?
I. Overall the more substituted a double bond on an enolate, the less stable the molecule is.
II. Low temperature reactions favour a more rapidly formed enolate.
III. Thermodynamic enolates are favoured in reactions with strong, sterically hindered bases.

a. I + III
b. II only
c. II + III
d. None of the above

Answer 5

b. II only

Question 6

Which of the following alcohols would have the lowest boiling point?

a. butanol
b. 2-methyl-2-butanol
c. propanol
d. ethanol

Answer 6

d. ethanol (lower London dispersion forces)

Question 7

Which of the following reactions will undergo an SN1 reaction?

a. t-butyl bromide and ethanol
b. 1-bromopropane and ethanol
c. 2-bromo-4-methylpentane and LiBr
d. 1-iodo-3-methylpentane and KOH

Answer 7

a. t-butyl bromide and ethanol (SN1 reactions occur between weak nucleophiles and large, branched electrophiles with great leaving groups)

Question 8

Which of the following will likely undergo an SN2 reaction?

a. 1-bromobutane and KOH
b. 2-bromo-2-methylbutane and lithium diisopropylamide
c. 2-chloro-3-methylhexane and HCl
d. t-butyl bromide and water

Answer 8

a. 1-bromobutane and KOH

strong nucleophile with primary electrophile

Question 9

Which of the following reactions are ways to synthesize carboxylic acids?
I. Oxidation of an aldehyde
II. Hydrolysis of an anhydride
III. Hydrolysis of a ketone

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

Answer 9

b. I and II