ORGANIC LAB Midterm Exam

Question 1

Do N—H or O—H protons typically split?

Answer 1

No

Terminal neighbors to the N—H or O—H group (e.g. —CH₃) will display a singlet splitting pattern.

Question 2

Splitting Pattern: J_X = J_Y

Answer 2

One-Level Splitting

Question 3

Splitting Pattern: J_X ≠ J_Y

Answer 3

Two-Level Splitting

Question 4

Does long-range coupling/splitting occur outside of the aromatic system?

Answer 4

No

Question 5

Downfield

Deshielded

Answer 5

Greater Chemical Shift

The proton has less electron density due to nearby electronegative elements/groups.

Question 6

Upfield

Shielded

Answer 6

Smaller Chemical Shift

The proton has greater electron density due to there being few/no nearby electronegative elements/groups.

Question 7

R_f Value: Ketone vs. Alcohol

Thin-Layer Chromatography

Answer 7

• The ketone will have the greater R_f value because it is a hydrogen-bond acceptor ONLY.
• The alcohol will have the smaller R_f value because it is a hydrogen-bond acceptor AND hydrogen-bond donor.

Since the alcohol group can donate hydrogen-bonds and accept hydrogen bonds, it will interact more will the silica stationary phase (and travel a smaller vertical distance on the TLC plate).

Question 8

R_f Value: Ether vs. Alcohol

Thin-Layer Chromatography

Answer 8

• The ether will have the greater R_f value because it is a hydrogen-bond acceptor ONLY.
• The alcohol will have the smaller R_f value because it is a hydrogen-bond acceptor AND hydrogen-bond donor.

Since the alcohol group can donate hydrogen-bonds and accept hydrogen bonds, it will interact more will the silica stationary phase (and travel a smaller vertical distance on the TLC plate).

Question 9

R_f Value: Ether vs. Ketone

Thin-Layer Chromatography

Answer 9

The ether and ketone will have similar R_f values because they are both hydrogen-bond acceptors ONLY.

Question 10

Separation: Ionic Compound

Extraction Scheme

Answer 10

Water + Ether

The ionic compound will separate into the acqueous layer.

Question 11

Separation: Proton-Donating Compound

Extraction Scheme

Answer 11

Base (e.g. NaOH)

The proton-donating compound will separate into the acqueous layer.

Question 12

Separation: Proton-Accepting Compound

Extraction Scheme

Answer 12

Acid (e.g. HCl)

The proton-accepting compound will separate into the acqueous layer.

Question 13

Separation: Nonpolar Compound

Extraction Scheme

Answer 13

The nonpolar compound will remain in the organic phase/layer at the end of the extraction scheme.

Question 14

(Non-Ionic) Proton-Donating Groups

Extraction Scheme

Answer 14

• Alcohols (—OH)
• Carboxylic Acids (—COOH)

Question 15

(Non-Ionic) Proton-Accepting Compounds

Extraction Scheme

Answer 15

• Amines (—NH₂)