Protons on aliphatic (alkyl) groups are highly shielded and typically appear in the range of 0.7 to 1.5 ppm in ^1H NMR spectroscopy. The degree of shielding depends on the substitution pattern of the carbon to which the proton is attached: the fewer the substituents, the more shielded the proton. Each additional alkyl group tends to deshield the proton by approximately 0.2–0.4 ppm, shifting the signal downfield. In the case of 2,2-dimethylbutane, the protons on the terminal methyl groups (CH₃) are highly shielded and appear upfield, while the protons on the methylene group (CH₂) are slightly deshielded due to the adjacent quaternary carbon. The unique symmetry of 2,2-dimethylbutane results in a simplified ^1H NMR spectrum, with distinct signals corresponding to the different proton environments. Below are the 1H NMR and 13C NMR for 2,2-dimethylbutane, illustrating these features.
In ^13C NMR spectroscopy, the carbon atoms in 2,2-dimethylbutane exhibit distinct chemical shifts based on their local environments. The quaternary carbon (C-2) at the center of the molecule, bonded to two methyl groups and two methylene groups, typically appears highly shielded, often in the range of 30–40 ppm. The methylene carbon (C-3) is slightly more deshielded due to its attachment to the quaternary carbon and usually resonates around 20–30 ppm. The terminal methyl carbons (C-1 and C-4) are the most shielded and typically appear in the range of 10–20 ppm. The symmetry of 2,2-dimethylbutane simplifies the 13C NMR spectrum, resulting in fewer distinct signals corresponding to the unique carbon environments. Below are the 13C NMR spectra for 2,2-dimethylbutane, illustrating these features.