This question does not contain the structures of the molecules. The structures in Daylight SMILES format are:
I. C1=CC=CC=C1C(=O)C
II. C1=CC=CC=C1CC=O
III. C1=CC(C)=CC=C1C=O
IV. C1=CC=CC=C1CCC
V. C1=CC=CC=C1C(C)C
The structures are also attached
Answer:
The structure of compound IV is consistent with the information obtained analysis
Proposed structures for the ions with m/z values of 120, 105,77 and 43 are (also attached):
C1=CC=CC=C1C(=[OH0+])C |^1:7|
C1C([CH0+]=O)=CC=CC=1
C1[CH0+]=CC=CC=1
C(#[OH0+])C
respectively
Explanation:
The IR peak at 1687 cm⁻¹ is indicative of an α unsaturated carbonyl carbon. While the 1H NMR singlet is of the methyl group next to carbonyl and the multiplet near 7.1 ppm is a characteristic peak of benzene. This data shows points towards structure I.
Mass spectrum peak at 120 m/z is of molecular ion peak. In the case of carbonyl-containing molecule, this peak is observable. The signal at 105 shows the loss of a methyl group next to the carbonyl. m/z value of 77 is the characteristic cationic peak of benzene, while the peak at 43 infers the formation of acylium ion (RCO+) due to α-cleavage. All this data agrees with the structure of acetophenone (Structure 1)
