1. ALDEHYDES AND KETONES

2. Aldehydes and Ketones

3.   Most Reactive Group –  electrons + polarisation Names al – aldehydes, one - ketones Methanal (formaldehyde) Ethanal (acetaldehyde) Propanal Pentanal

4. Nomenclature of Aldehydes

5. If the aldehyde group is attached to a ring,

6. Nomenclature of Ketones

8. Oxidation

9. An aldehyde has a greater partial positive charge on its carbonyl carbon than does a ketone

10. The carbonyl carbon of an aldehyde is more accessible to the nucleophile Ketones have greater steric crowding in their transition states, so they have less stable transition states Steric factors contribute to the reactivity of an aldehyde

11. 1. Redox reactions Reactions

12. 2. Addition: A N Addition of water Aldehyde hydrate (ketone: ) Addition of bisulfite Bisulfite

13. Addition of NH 3 Aldehyde ammonia (ketone: ) Addition of HCN Cyanohydrine

14. 3. Condensation reactions (addition followed by elimination) Ammonia derivatives Primary amine Schiff base

15. Hydroxylamine Hydrazine Hydrazone Oxime

16. Phenylhydrazine 2,4-dinitrophenylhydrazine 2,4-dinitrophenylhydrazone Phenylhydrazone

17. Aldol condensation Aldol

18. Reaction with alcohol Acetal (condensation!) Hemiacetal (addition!)

19. Keto–Enol Tautomerism

20. Oxidation of a Primary Alcohol

21. Reduction by Addition of a Hydride Ion and a Proton

23. Aldehydes and ketones react with nucleophiles to form addition products: nucleophile addition reactions

25. Water adds to an aldehyde or ketone to form a hydrate

26. Hydration of Aldehydes and Ketones HOH C O HO C O H RR' R R'

27. Alcohols Under Analogous Reaction with Aldehydes and Ketones R"OH C O RR' R"O C O H R R' Product is called a hemiacetal. Product is called a hemiacetal.

28. HCl 2CH 3 CH 2 OH + + H 2 O Benzaldehyde diethyl acetal (66%) Example CHO CH(OCH 2 CH 3 ) 2

29. Reaction with Primary Amines: Imines

30. If the nucleophile that adds to the aldehyde or ketone is an O or an N, a nucleophilic addition–elimination reaction will occur

31. H2NH2NH2NH2N R C O + H a carbinolamine CO HNHNHNHN R N R C + H 2 O (imine) Imine (Schiff's Base) Formation

32. CH 3 NH 2 CHO+ CH=NCH 3 + H 2 O N-Benzylidenemethylamine (70%) Example

33. Reaction with Derivatives of Ammonia H2NH2NH2NH2NG + R2CR2CR2CR2C O R2CR2CR2CR2C NGNGNGNG+ H2OH2OH2OH2O H2NH2NH2NH2NOH R2CR2CR2CR2C NOH hydroxylamineoxime

34. Reaction with Derivatives of Ammonia H2NH2NH2NH2NG + R2CR2CR2CR2C O R2CR2CR2CR2C NGNGNGNG+ H2OH2OH2OH2O H2NH2NH2NH2NOH R2CR2CR2CR2C hydroxylamineoxime H2NH2NH2NH2N NH 2 R2CR2CR2CR2C NNH 2 hydrazinehydrazone etc.

35. + H 2 NNH 2 + H 2 O (73%) ExampleOC NNH 2 C

36. CCH 3 ExampleO + H 2 NNH phenylhydrazine + H 2 O CCH 3 NNH a phenylhydrazone (87-91%)

37. An aldol addition product loses water to form an aldol condensation product

38. 2RCH 2 CH ONaOH RCH 2 CH OH CHCHOR Aldol Condensation

39. Aldol Addition of Acetaldehyde Acetaldol (50%) NaOH, H 2 O 5°C 2CH 3 CH O CH 3 CH OH CH 2 CH O

40. Product is called a hemiacetal. ROH, H + Hemiacetal reacts further in acid to yield an acetal R"O C O H RR' R"O C OR RR' Product is called an acetal. Product is called an acetal.

41. Formaldehyde formaldehyde cannot form an enolate formaldehyde cannot form an enolate formaldehyde is extremely reactive formaldehyde is extremely reactive toward nucleophilic addition toward nucleophilic additionOHCH

42. Acrolein H2CH2CH2CH2C CHCHO

43. H2CH2CH2CH2C CHCHO Acrolein

44. Acrolein H2CH2CH2CH2C CHCHO