Problem:

Determine the structure of an unknown compound based on the provided proton NMR data.

Step-by-Step Signal Analysis

Signal at 2.44 ppm — Triplet, 2H

• Indicates a –CH₂– group adjacent to another CH₂
• Downfield shift suggests proximity to a carbonyl group

Signal at 2.14 ppm — Singlet, 3H

• –CH₃ group with no neighboring hydrogens
• Deshielded due to attachment to a carbonyl carbon → methyl ketone

Signal at 1.50 ppm — Quintet, 2H

• –CH₂– group flanked by two other CH₂ groups

Signal at 1.30 ppm — Multiplet, 4H

• Two –CH₂– groups within a chain
• Surrounded by multiple non-equivalent neighbors

Signal at 0.90 ppm — Triplet, 3H

• –CH₃ group adjacent to a CH₂ → terminal methyl group

Structural Deduction

Combining all signals, the structure corresponds to a linear ketone with seven carbon atoms:

CH₃–CO–CH₂–CH₂–CH₂–CH₂–CH₃

This is a methyl ketone with a straight alkyl chain — specifically:

✅ Final Answer

Heptan-2-one

NMR Summary Table