B forms in the reaction of A with a strong, non nucleophilic base. B reacts with bromine to form rac — Analytical Chemistry Chemistry Question
Cyclohexanes
B forms in the reaction of A with a strong, non nucleophilic base. B reacts with bromine to form racemic C. The final products D (major) and E (minor) form by the reaction of C with a strong, non nucleophilic base.
[VISUAL]
Draw a 3-D structure of A in its most stable conformation. Circle the atoms that are possibly involved in the reaction to B.
Model Answer
The chair is the most stable conformation of a cyclohexane ring. Large substituents prefer the equatorial position. In an elimination reaction of an E2 type, the groups that are eliminated must have antiperiplanar positions. This is only possible in a chair conformation if both groups are in axial positions.
[VISUAL]
Draw the structure of B.
Model Answer
[VISUAL]
Draw a 3-D structure of C (only one enantiomer needs to be drawn) in its most stable conformation. Circle the atoms that are possibly involved in the reaction of C to D and E.
Model Answer
[VISUAL]
Draw the structures of D and E.
Model Answer
Because of the electron-attracting effect of bromine, the proton of a carbon that is bound to a bromine substituent, becomes more acidic. This proton is therefore removed more easily by a base and D becomes the major product.
[VISUAL]