Aldol condensation

By Priyanka kalamkar

1. Saraswathi Vidya Bhavan’s College of Pharmacy ALDOL CONDENSATION By Mrs. Priyanka Kalamkar Asst Professor

2. ALDOL CONDENSATION Key points to remember

3. What is ALPHA HYDROGEN ?

4. What is aldol condensation? Aldehyde or ketone which has alpha hydrogen reacts with any strong bases such as NaOH to give aldol ( β – Hydroxy aldehyde or ketone) as the product. Reaction doubles the number of carbon atoms of initial aldehyde or ketone.

5. Acetaldehyde β - Hydroxyacetaldehyde (ALDOL) -H 2 O α , β –unsaturated aldehyde Aldol Reaction

6. Mechanism of ALDOL CONDENSATION

7. STEP 1 : Abstraction of α – Hydrogen and formation of Carbanion Carbanion (Nucleophile is generated) Acetaldehyde

8. STEP 2 : Attack of Nucleophile on carbonyl C of another molecule of Aldehyde and ketone Alkoxide ion – Intermediate

9. STEP 3 : Protonation of Alkoxide ion β - Hydroxyacetaldehyde (ALDOL)

10. STEP 4 : Dehydration of Aldol β - Hydroxyacetaldehyde (ALDOL) α , β –unsaturated aldehyde

11. α , β – unsaturatedaldehyde ALDOL Carbanion Acetaldehyde Another molecule of Acetaldehyde MECHANISM OF ALDOL CONDENSATION

12. Which of the following will undergo Aldol condensation and why ? (a) Formaldehyde (c) Benzaldehyde (b) Propanal (d) Acetone

13. Answer ……..

14. A] B] C] D] No α Carbon so no α -hydrogen α Carbon is there but no α –hydrogen

15. Animated video of mechanism by Dr. Anwar Shaikh

16. CLASS WORK Acetone NaOH Predict the product of the following reaction with structure and IUPAC Name(1M). Explain in detail with mechanism (2M).

17. Answer…… α Carbon β Carbon 2 + H 2 O

18. References 1] Morrison and Boyd, organic chemistry, seventh edition, (2011) 2] https://www.youtube.com/watch?v=Hfx3ln8KgsI 3] https://www.chemistryscl.com/reactions/aldol-condensation/main.html