Interpreting 1H NMR Spectrum?

📌 CONCEPT: The 1H NMR spectrum provides information about the type of hydrogen atoms and their environment in a molecule.

📐 RULE / FORMULA: The chemical shift (δ) values of hydrogen atoms can be used to determine whether they are aliphatic or aromatic and their environment. The following general guidelines can be applied: aliphatic protons typically appear between δ 0-5, while aromatic protons appear between δ 6-9. The presence of functional groups can also affect the chemical shift values.

💡 WORKED EXAMPLE: In the given 1H NMR spectrum, the signal at δ 1.2 (triplet) is attributed to aliphatic protons that are in the vicinity of a methyl group or an alkyl halide, as they typically appear at low chemical shift values. The signal at δ 2.3 (multiplet) is due to aliphatic protons that are influenced by functional groups such as carbonyl or alkene. The signal at δ 7.5 (singlet) corresponds to aromatic protons that are not affected by any functional group.

⚠️ COMMON MISTAKE: Students often misinterpret the chemical shift values and fail to consider the effect of functional groups on the chemical shift values.