Inspect the following two molecules and consider which compound contains the gre
ID: 599423 • Letter: I
Question
Inspect the following two molecules and consider which compound contains the greater amount of gauche conformation for internal rotation about the central (green) bond. Select the best statement. The oxygen atom of the ether A does not have the hydrogen atoms that the corresponding carbon of butane B does, so there is less steric pressure in A, and hence, A has more of the gauche conformation present. For both compounds, the central atoms have identical substitutents - methyl groups - that experience identical repulsive forces. Therefore, compounds A and B have the same amount of gauche conformation present. The electrons of the oxygen in the ether A take up about as mu Ch space as the hydrogens of the corresponding carbon of 8, and there is very nearly the same amount of steric and electrostatic pressure on the methyl groups of both compounds A and B. Therefore, they have about the same amount of gauche conformation present. The C-O bond is shorter than the C-C bond, so the methyl groups of the ether A are closer together, creating steric strain on the gauche conformation. This phenomenon results in less gauche conformation present for A, and hence more of the gauche conformation for butane B. The C-C bond is shorter than the C-O bond, so the methyl groups of butane 8 are closer together, creating steric strain on the gauche conformation. This phenomenon results in less gauche conformation present for butane B, and hence more of the gauche conformation for the ether A.Explanation / Answer
The C-O ......