1H and 13C NMR spectroscopy are very helpful in identifying aromatic compounds. Typically, aromatic hydrogens are highly deshielded by the aromatic ring current. As a result, they exhibit characteristic 1H NMR absorptions in the range of 6.5–8 ppm. For instance, aromatic hydrogens of benzene absorb at 7.3 ppm. However, aromatic hydrogens of large rings absorb farther upfield or downfield. Consider [18]annulene. It has 12 hydrogens outside the ring, which are highly deshielded by the aromatic ring current. The 6 hydrogens inside the ring are highly shielded. Consequently, the outside hydrogens absorb downfield at a high frequency. The inside hydrogens absorb upfield at a low frequency. Aromatic carbons exhibit 13C NMR absorptions in the range of 110–150 ppm. For instance, aromatic carbons of benzene absorb at 128 ppm.