Determine the Infrared peaks that correspond to each of the following four compounds and explain how these peaks are related to the structure of each compound.



a. Medium peak at 2900 cm^-1, and a strong peak at 1715 cm^-1.
b. Medium peak at 3000cm^-1, a weak peak at 2250 cm^-1, and a weak overtone at 1600 cm^-1
c. Strong, broad 3000 cm^-1, a strong peak at 1690 cm^-1, and a weak peak at 1675 cm^-1
d. Strong, broad 3200 cm^-1, medium peak at 2900 cm^-1, and a weak overtone at 1600 cm^-1

• A. a. The strong peak at 1715cm^-1 hints an alkyne group thus, it is Compound I
  b. The medium peak at 3000cm^-1 hints an —CH₃ group thus, it is Compound III
  c. A strong, broad peak at 3200cm^-1 and a weak peak at 1675^-1 corresponds to an aliphatic chain and a ketonic group respectively, thus it is Compound IV
  d. A strong, broad peak at 3000. cm^-1, and a weak peak at 1675 cm^-1 corresponds to alcohol and α-β unsaturation respectively, thus it is Compound II
• B. a. The strong peak at 1715cm^-1 hints a ketonic group thus, it is Compound IV
  b. A weak peak at 2250 cm^-1 and medium peak at 3000 cm^-1 corresponds to an alkyne group and aromatic ring respectively, thus it is Compound I
  c. A strong, broad peak at 3000. cm^-1, and a weak peak at 1675 cm^-1 corresponds to alcohol and α β unsaturation respectively, thus it is Compound II
  d. A strong, broad peak at 3200 cm^-1, and a weak overtone at 1600 cm^-1 corresponds to an alcohol and an aromatic ring —C—H stretching respectively, thus it is Compound III
• C. a. A strong, broad peak at 3200cm^-1 and a weak peak at 1675^-1 corresponds to an aliphatic chain and a ketonic group respectively, thus it is Compound IV
  b. A strong, broad peak at 3000. cm^-1, and a weak peak at 1675 cm^-1 corresponds to alcohol and α-β unsaturation respectively, thus it is Compound II
  c. The medium peak at 3000cm^-1 hints at an —CH₃ group thus, it is Compound III
  d. The strong peak at 1715cm^-1 hints an alkyne group thus, it is Compound I
• D. a. A strong, broad peak at 3000. cm^-1, and a weak peak at 1675 cm^-1 corresponds to alcohol and α-β unsaturation respectively, thus it is Compound II
  b. A strong, broad peak at 3200cm^-1 and a weak peak at 1675^-1 corresponds to an aliphatic chain and a ketonic group respectively, thus it is Compound IV
  c. The medium peak at 3000cm^-1 hints at an —CH₃ group thus, it is Compound III
  d. The strong peak at 1715cm^-1 hints an alkyne group thus, it is Compound I

Answer: (B)