試題詳解

77. Stereoisomers I and II undergo E2 elimination on treatment with sodium ethoxide in ethanol. One isomer reacts 500 times faster than the other. Also, one isomer gives X as the only product, whereas the other gives Y together with some X. Which of the following statements provides the best assignment of I and II?  
(A) II reacts faster and gives both Y and X
(B) II reacts faster and gives only X
(C) I reacts faster and gives both Y and X
(D) I reacts faster and gives only Y
(E) I reacts faster and gives only X