Question

29. The mass spectrum of the compound shown below has significant fragmentation peaks at m/z 85, 58, 57, 43, and 42. which two of these peaks are due to α-cleavage, and which one of therm is due to a McLafferty rearrangement? 30. Draw the expected 'H NMR spectrum for PhC02CH(CH3)2. Show correct shifts, multiplicities, and # of H-atoms. Finally, indicate which diagnostic IR absorptions you would expect to see for this compound. 6 4 2 0 PPM IR absorbances:

Answer 1

4-methylpentan-2-one Chemical Formula: C6H120 Molecular Weight: 100 16 Molecular Weight: 100 16 Chemical Formula: C4Hg Exact Mass: 57 07 Chemical Formula: C3H7 Exact Mass: 43 05 Chemical Formula: C5Hgo Exact Mass: 85 07 Peaks at m/z 85 and 57 are due to a-cleavage McLafferty rearrangement Molecular Weight: 58 08 p clevage Peaks at m/z 58 is due to

In the IR spectrum of isopropyl benzoate, a characteristic peak at around 1700 cm^-1 is due to the C=O stretching frequency peak.

804 O13 8.04 5 24 7.55 doublet 1.30 7.07 161 166 8.04 7.55 6 h triplet 1H septet 1H PPM

A peak at around 3050 cm^-1 is due to the Aromatic C-H stretching frequency peak. Peaks at around 2950, 2900 cm^-1 are due to the C-H stretching frequency peaks of CH₃ or CH group.

4 Peaks between 1400-1600 cm^-1 are due to the C=C stretching frequency peaks of aromatics.

A peak at around 1250 cm^-1 is due to the Aromatic C-O stretching frequency peak.