Briefly explain why sulfa drugs such as sulfanilide function as folic acid antagonists. Both have a benzene ring with an NH 2 group para to the polar CO 2 H or sulfonamide group. Both have acidic hydrogens in this same region. Alkenes normally react as nucleophiles, but in this reaction the alkene is an electrophile. Briefly explain why the alkene of CS is electrophilic.
Alkenes normally react as nucleophiles by sharing their p electrons.
The two electron withdrawing nitrile groups make the alkene electron poor, and hence electrophilic. Any of these alternate mechanisms are acceptable as long as they do not violate any chemical common sense. Unwanted quantities of CS gas might be converted to a harmless diamide by hydrolysis. Provide the mechanism for the conversion of a nitrile into an amide as shown below. Although we have no covered this reaction in lecture, use your knowledge of carbonyl chemistry, logical mechanism steps and chemical common sense.