Complex sentence: University of California Riverside The structural difference between vitamin D 2 and vitamin D 3 is the side chain of D 2 contains a double bond between carbons 22 and 23, and a methyl group on carbon 24.
Split into simpler sentences: University of California Riverside The structural difference between vitamin D 2 and vitamin D 3 is in their side chains. The side chain of D 2 contains a double bond between carbons 22 and 23, and a methyl group on carbon 24.