Final answer:
The principle organic product when ethyl trans 2 butenoate reacts with CN- in ethanol is ethyl β-cyano-2-butenoate, through a Michael addition mechanism.
Step-by-step explanation:
The principle organic product expected when ethyl trans 2 butenoate reacts with CN- in ethanol is a cyanoethylated product resulting from the nucleophilic addition of the cyanide ion to the β-carbon of the α,β-unsaturated ester (ethyl trans 2 butenoate). The reaction likely proceeds through a Michael addition mechanism, where the cyanide ion, being a good nucleophile, attacks the electrophilic β-carbon, forming a new carbon-carbon bond.
This would result in the formation of ethyl β-cyano-2-butenoate as the main product. This type of nucleophilic addition reaction is a common transformation in organic synthetic chemistry where a nucleophile adds to the α,β-unsaturated carbonyl compound.