Question

Condensation Reactions Homework (Chapter 19) NAME 1. Explain why aldehyde A is more reactive to nucleophilic addition reactions than ketone B. В 2. Give the curved arrow mechanism for each aldol reaction. O Он NaOH a. Н.о Н Н ОН NaOH Н.о NaOH, H2O heat Н NaOH, H2O d. heat н"

Answer 1

1. Aldehyde A is more reactive than ketone B to nucleophilic addition reaction . There are two reasons :

a. Steric reason : Aldehyde is sterically less hindered than ketone so nucleophile approach easily .

b. electronic reason : Due to + I effect in ketone carbonyl carbon has less concentration of positive charge compare to Aldehyde which lacks + I effect from one side .

These two reasons favour the aldehyde in nucleophilic addition reaction.

2.

OH (2) (a) NaOH I I H0H Mechanism :-) stepl: Abstraction of acidic H 1 HO Step 2: Attack on another aldehyde 0:00 10: He Step 3: Protonation : 01 OH (Product.) (6) Mechanism in case & of a . analogous to o so proceed as NaOH,40 heat Step: Deprotonation Step2: Attack on other aldehyde Step 3: Protonatio OM 0: 9: H Step 4: -04 Removal of water oh 0 0 H Н " (d) Mechanism is some of c.