CHM 25500 Lecture Notes - Lecture 18: Substituent, Potential Energy, Activation Energy
Document Summary
Chm 255 - lecture 18 - alkenes and alkynes: reactions and the e-z system. A different system must be used to distinguish between cis and trans isomers for alkenes because more branches are possible. E-z system solves problems of cis-trans system when applied to alkenes. E = entgagen (german), means opposite sides. Z = zusammmen (german), means same side. E-z system uses the same priority rules as the r-s system. The molecule is split in half across the double bond and each substituent in each pair on either side of the double bond is prioritized as higher or lower priority. If the two higher priority groups are on the same side of the double bond the molecule is z. If the two higher priority groups are on opposite sides of the double bond the molecule is e. Reactions are sometimes analyzed in terms of the energy absorbed and released during the process of the reaction.