isomers
Which of the following best describes constitutional isomers?
A) Same molecular formula, same connectivity
B) Same molecular formula, different connectivity
C) Different molecular formulas, same connectivity
D) Mirror images of each other
B) Same molecular formula, different connectivity
Which of the following carbons is chiral?
A) CH₃CH₂CH₃
B) CH₃CHBrCH₃
C) CH₃CH₂Cl
D) CHBrClF
D) CHBrClF
Which statement correctly describes alcohol classification?
A) A primary alcohol has the –OH on a tertiary carbon.
B) A tertiary alcohol has –OH on a carbon bound to three other carbons.
C) A secondary alcohol has the –OH on a methyl carbon.
D) All alcohols contain a carbonyl group.
B) A tertiary alcohol has –OH on a carbon bound to three other carbons.
What is the trend with polarizability and boiling point and molecular mass?
Boiling point ↑ with polarizability and molecular mass
Why do alcohols generally have much higher boiling points than comparable alkyl halides?
Because alcohols form hydrogen bonds; alkyl halides only have dipole-dipole and dispersion forces.
Which of the following molecules can exhibit cis–trans isomerism?
A) CH₃CH=CHCH₃
B) CH₂=CH₂
C) CH₃CH₂CH₂CH₃
D) CH₃CH₂OH
A) CH₃CH=CHCH₃
What is the maximum number of stereoisomers possible for a compound with three asymmetric centers?
A) 4
B) 6
C) 8
D) 16
8
Which of the following is the correct name for (CH₃)₂CHCH₂OH?
A) 1-propanol B) 2-butanol C) 1-butanol D) 2-methyl-1-propanol
D) 2-methyl-1-propanol
Order the following by increasing boiling point: CH₃Cl, CH₃Br, CH₃I, CH₃F
CH₃F < CH₃Cl < CH₃Br < CH₃I
Which of the following is a tertiary alkyl halide?
A) 1-chloropropane
B) 2-bromobutane
C) 2-chloro-2-methylpropane
D) 1-iodobutane
C) 2-chloro-2-methylpropane
What causes restricted rotation leading to cis–trans isomerism?
A) σ bonds
B) pi bonds
C) sp³ hybridization
D) Single bonds
B) pi bonds
Which of the following statements about enantiomers is FALSE?
A) They have identical melting points and boiling points.
B) They rotate plane-polarized light in opposite directions.
C) They react identically with achiral reagents.
D) They can be superimposed.
D) They can be superimposed.
Write the general reaction converting an alcohol to an alkyl halide using HX.
R–OH+HX→R–X+H2O
As branching in an alcohol increases, what happens to its boiling point and solubility in water?
Boiling point ↓ (weaker dispersion forces); solubility ↓ (less surface for H-bonding).
Amine inversion prevents separation of enantiomers for which type of molecules?
A) Quaternary ammonium salts
B) Tertiary amines
C) Primary amines
D) Amides
B) Tertiary amines
A chiral molecule and its mirror image are called:
A) Constitutional isomers
B) Enantiomers
C) Diastereomers
D) Meso compounds
enantiomers
Which of the following pairs are diastereomers?
A) (2R,3R) and (2S,3S)
B) (2R,3S) and (2S,3R)
C) (2R,3R) and (2R,3S)
D) (2S,3S) and (2S,3S)
C) (2R,3R) and (2R,3S)
What is the rate-determining step in the SN1 reaction of a tertiary alcohol with HCl?
Slow step --> Dissociation of the protonated alcohol (H₂O loss) to form a carbocation.
Define polarizability and describe its periodic trend.
Ability of e⁻ cloud to distort; ↑ down a group (larger atoms), ↓ across a period (smaller, tightly bound e⁻).
Predict whether (R)-(−)-carvone and (S)-(+)-carvone will have the same smell.
→ Explain using the relationship between chirality and biological activity.
Different smells. Spearmint ( R) and Caraway (S) are enantiomers of each other and interact differently.
A meso compound must have:
A) No asymmetric centers
B) A plane of symmetry
C) Optical activity
D) Two identical enantiomers
a plane of symmetry
Identify which of the following compounds are optically active:
a) 2-bromobutane
b) 1-bromobutane
c) cis-1,2-dichlorocyclohexane
d) trans-1,2-dichlorocyclohexane
(2 answers)
a) 2-bromobutane
d) trans-1,2-dichlorocyclohexane
Describe the mechanism reaction name of tertiary alcohol conversion to an alkyl halide with HBr and list the 3 steps.
SN1 mechanism:
1️⃣ Protonation of –OH → better leaving group (H₂O)
2️⃣ Loss of water → carbocation
3️⃣ Nucleophilic attack by Br⁻ → alkyl bromide
Which alcohol type would not undergo SN1 substitution under normal acid-catalyzed conditions?
Primary alcohol (carbocation too unstable).
Cholesterol has an observed rotation of −0.78° for 0.3 g in 15 mL of chloroform using a 10-cm tube.
→ Calculate the specific rotation [α].
[α] =a obs / l*c
= -0.78° / 1.0 x (0.3/15)
=-0.78° / 0.02 = −39°