The following spectra were obtained for an unknown organic compound - HSC - SSCE Chemistry - Question 30 - 2022 - Paper 1

The mass spectrum indicates a parent molecular ion at m/z = 86, consistent with the formula of the named molecule. The base peak at m/z = 43 suggests fragmentation near the carbonyl group (CH3C=O).

The infrared spectrum shows a strong absorption around 1700 cm⁻¹, indicative of a carbonyl group. Additionally, the absence of a broad O-H stretch between 2500-3000 cm⁻¹ eliminates the presence of carboxylic acids.

The carbon-13 NMR spectrum shows five carbons in total, but only four unique chemical environments, as two of the carbons are equivalent. The signal around 22 ppm corresponds to the carbonyl group, while signals between 18-40 ppm correspond to CH and CH3 groups.

The proton NMR spectrum displays three distinct hydrogen environments. The singlet peak (3H) is consistent with a CH group adjacent to two CH3 groups. The septet (1H) indicates a carbon connected to two CH2 groups, while the doublet (6H) corresponds to two methyl groups, each related to a neighboring hydrogen.