Why is N-ethylsaccharin more stable?

Question

In the reaction between sodium saccharin and iodoethane (a nucleophilic substitution reaction) two products are formed, O-ethylsaccharin and N-ethylsaccharin. My textbook states that N-ethylsaccharin is more stable, but doesn't say why. Does anyone know why?

Answer 1

Sodium saccharin is a sulfimide. The Sodium is ionically bound to the Nitrogen in the compound. It will dissociate in water, leaving the Nitrogen with a negative charge.

For the N-ethylsaccharin, the Ethyl group is bound to the Nirtogen giving the same spacial configuration for the five membered ring (which is flat or planar). The carbonyl carbon is sp2 and flat. This has little ring strain and is stable.

For the O-ethylsaccharin, the Ethyl group is attached to the Oxygen (what was the carbonyl Oxygen), giving the Carbon an sp3 configuration (joined to two other carbons, the Oxygen with the Ethyl group and a Hydrogen). This put strain on the ring, and therefore is less stable.