CH ENGR 104C Lecture Notes - Lecture 13: Chemical Polarity, Bond Energy, Boiling Point

• School: UCLA
• Department: Chemical Engineering
• Course: CH ENGR 104C
• Professor: Dr.Patrick Wen

Document Summary

Both sides of an alkene undergo nucleophilic or electrophilic attack. The lack of a polar bond results in alkenes having a lower boiling point than carbonyls that are about the same size. (fig. 1) Due to polarity, double bond can be an h-bond acceptor. Carbonyls undergo regioselective attack by nucleophile or electrophile. Due to polar character (& for some carbonyls, the ability to form h-bonds) of the carbonyl group, carbonyls have higher boiling points. (fig. 1) Relative boiling points3: (higher bp) amide > carboxylic acid > nitrile. >> ester ~ acyl chloride ~ aldehyde ~ ketone (lower bp) C=c bond has a bond energy of ~146 kcal/mole. Higher bond energy of the c=o bond of carbonyls suggests that they are thermodynamically unfavorable. The polarity of the carbonyl group and its higher basicity than alkenes lower the transition state energy of activation and therefore result in a faster rate.