1. Chapter 4 Ketones and Aldehydes

2. Chapter 182 4.1 Carbonyl Structure Carbon is sp 2 hybridized. C=O bond is shorter, stronger, and more polar than C=C bond in alkenes. =>

3. Chapter 183 4.2 Carbonyl Compounds =>

4. Chapter 184 4.3 Naming Aldehydes IUPAC: Replace -e with -al. The aldehyde carbon is number 1. If -CHO is attached to a ring, use the suffix -carbaldehyde. There are no cycloaldehydes =>

5. Chapter 185 Examples 3-methylpentanal 2-cyclopentenealdehyde => benzaldehyde - aromatic =>

6. Chapter 186 Small unbranched aldehyde common names Use the common name of the acid. Drop -ic acid and add -aldehyde.  1 C: formic acid, formaldehyde  2 C’s: acetic acid, acetaldehyde  3 C’s: propionic acid, propionaldehyde  4 C’s: butyric acid, butyraldehyde. =>

7. Chapter 187 4.4 IUPAC Names for Ketones Replace -e with -one. Indicate the position of the carbonyl with a number. Number the chain so that carbonyl carbon has the lowest number. For cyclic ketones the carbonyl carbon is assigned the number 1. =>

8. Chapter 188 Examples 3-methyl-2-butanone 3-bromocyclohexanone 4-hydroxy-3-methyl-2-butanone =>

9. Chapter 189 Common Names for Simple Ketones Named as alkyl attachments to -C=O. methyl isopropyl ketone ethyl isopropyl ketone => CH 3 CH2H2 C O CH CH 3 CH 3

10. Chapter 1810 Historical Common Names acetone acetophenone benzophenone =>

11. Chapter 1811 Name as Substituent On a molecule with a higher priority functional group, C=O is oxo- and -CHO is formyl. Aldehyde priority is higher than ketone. 3-methyl-4-oxopentanal 3-formylbenzoic acid =>

12. Chapter 1812 4.5 Isomerism in aldehydes and ketones Aldehydes and ketones are constitutional isomers Aldehydes and ketones can have skeletal and positional isomers if there are enough carbons. Stereoisomers are also possible if there is a ring or C=C in the molecule

13. Chapter 1813 4.6 Selected Common aldehydes and ketones Formaldehyde Acetone Vanillin Benzaldehyde Cinnamaldehyde Butanedione

14. Chapter 1814 Formaldehyde Gas at room temperature. Formalin is a 40% aqueous solution. trioxane, m.p. 62  C formaldehyde, b.p. -21  C formalin =>

15. Chapter 1815 Industrial Importance Acetone and methyl ethyl ketone are important solvents. Formaldehyde used in polymers like Bakelite . Flavorings and additives like vanilla, cinnamon, artificial butter. =>

16. Chapter 1816 Formaldehyde -formalin Acetone – solvent and metabolic product Vanillin - vanilla flavoring Benzaldehyde - almond flavor Cinnamaldehyde - cinnamon Butanedione - butter

17. Chapter 1817 4.7 Physical properties Boiling points – page 121 Solubility – water solubility page 123

18. Chapter 1818 Boiling Points More polar, so higher boiling point than comparable alkane or ether. Cannot H-bond to each other, so lower boiling point than comparable alcohol. =>

19. Chapter 1819 Solubility Good solvent for alcohols. Lone pair of electrons on oxygen of carbonyl can accept a hydrogen bond from O-H or N-H. Acetone and acetaldehyde are miscible in water. =>

20. Chapter 1820 4.8 Preparation of Aldehydes and Ketones Oxidation  2  alcohol + Na 2 Cr 2 O 7  ketone  1  alcohol  aldehyde

21. Chapter 1821 4.9 Oxidation and reduction of Aldehydes and ketones

22. Chapter 1822 =>

23. Chapter 1823 Tollens Test Add ammonia solution to AgNO 3 solution until precipitate dissolves. Aldehyde reaction forms a silver mirror. =>

24. Chapter 1824 Oxidation of ketones Ketones  no reaction

25. Chapter 1825 Reduction – Catalytic Hydrogenation Ketones give secondary alcohols Aldehydes give primary alcohols H 2 / Ni CH 3 CHOCH 3 CH 2 OH O H 2 / Ni OH H

26. Chapter 1826 Reduction: aldehyde + hydrogen --> pri. Alcohol Form of addition reaction.

27. Chapter 1827 Reduction: aldehyde + hydrogen Break hydrogen bond

28. Chapter 1828 Reduction: aldehyde + hydrogen Break double bond and use electrons to bond with hydrogen.

29. Chapter 1829 Reduction: aldehyde + hydrogen Brief Method

30. Chapter 1830 4.10 Addition of Alcohol Hemiacetal and Acetal Functional Groups

31. Chapter 1831 Hemiacetal and Acetal Functional Groups Hemiacetal: alcohol and ether on same carbon Acetal: Two ethers on same carbon

32. Chapter 1832 Mechanism Must be acid-catalyzed. Adding H + to carbonyl makes it more reactive with weak nucleophile, ROH. Hemiacetal forms first, then acid- catalyzed loss of water, then addition of second molecule of ROH forms acetal. All steps are reversible. =>

33. Chapter 1833 Hemiacetal Synthesis: aldehyde + alcohol Alcohol + aldehyde --> hemiacetal Ethanal + methanol Alcohol oxygen becomes an ether Carbon double bond oxygen becomes an alcohol

34. Chapter 1834 Mechanism for Hemiacetal =>

35. Chapter 1835 Aldehyde and Ketone Reactions

36. Chapter 1836 Synthesis of Acetal Functional Group Acetal: alcohol plus hemiacetal (ether synthesis) Acetal: Two ethers on same carbon

37. Chapter 1837 =>

38. Chapter 1838 Aldehyde and Ketone Reactions

39. Chapter 1839 Mechanism Hemiacetal to Acetal =>

40. Chapter 1840 Cyclic Acetals Addition of a diol produces a cyclic acetal. Sugars commonly exist as acetals or hemiacetals. =>

41. Chapter 1841 SKIP 4.11 AND 4.12 THE END