The chemical shifts of the methyl groups of three related molecules,pinnae, a-pinane, and B-pinene, follow. CH CH, CH CH3 CH3 CH 1.27 ppm CH CH3 CH2 1.23 1.17 1.63 0.99 Ppm Ppm ppm ppm 0.72 ppm 1.01 ppm 0.85 ppm B-Pinene Pinane a-Pinene Build models of these three compounds, and then explain why the two circled methyl groups have such small chemical shifts.