Chapter 2 Aldehydes and Ketones Introduction 1.Aldehydes 2.Nomenclature of Aldehydes 3.Physical Properties of Aldehydes 4.Chemical Properties of Aldehydes 5.Preparation of Aldehydes 6.Some Important Aldehydes 7.Ketones Table of Contents

Chapter 2 8.Nomenclature of Ketones 9.Physical Properties of Ketones 10.Chemical Properties of Ketones 11.Preparation of Ketones 12.Acetone Table of Contents Aldehydes and Ketones

Chapter 2 What are the simple C-H-O compounds besides alcohols? What do you think about why aldehydes and ketones are studied together? Can you list down some name of solvents that you learn so far? Warm Up Aldehydes and Ketones

Chapter 2 Introduction The group C=O is known as carbonyl group. This group is found in aldehydes, ketones, carboxylic acids, esters and acid derivatives. In this group carbon atom makes sp 2 hybridization. Therefore there are one pi and three sigma bonds in carbonyl group. Oxygen is more electronegative than carbon in the carbonyl group.

Chapter 2 1. Aldehydes Compounds in which one hydrogen atom and one carbon atom are bonded to the carbon atom in the carbonyl group are called aldehydes. R may be alkyl or aryl group. C n H 2n O is general formula of aliphatic aldehydes. The simplest member is formaldehyde, HCOH. is representation of aldehydes.

Chapter 2 2. Nomenclature of Aldehydes Longest chain of carbon atoms containing the aldehyde group is selected. Number 1 is the carbonyl carbon. Change –e ending in alkane names with –al. Methanal Formaldehyde Ethanal Acetaldehyde 2-methyl propanal

Chapter 2 Example 2 Name the following compounds 2-ethyl-3-methyl pentanal 3-bromo-2-nitro butanal 3-hydroxyl butanal 3-phenyl propanal 2. Nomenclature of Aldehydes A. B. C. D.

Chapter 2 Example 3 Draw the structures of following aldehydes. A.2-chloropentanal B.2,3-dihydroxylpropanal C.2, 2-dibromohexanal D.3-cyclopropyl-2-methyl-pentanal 2. Nomenclature of Aldehydes

Chapter 2 3. Physical Properties of Aldehydes They are polar molecules. They do not have hydrogen bonds between their molecules; therefore they have lower boiling points than corresponding alcohols but higher boiling points than ethers. Formaldehyde is a gas at room temperature. The C 2 to C 11 are liquids. Higher than C 11 are solids at room temperature. Lower members are soluble in water. As the molar mass increases solubility decreases.

Chapter 2 4. Chemical Properties of Aldehydes 1. Oxidation Reactions K 2 Cr 2 O 7, KMnO 4 or K 2 CrO 4 can be used in the presence of acids.

Chapter 2 Reaction with KMnO 4 Aldehydes are oxidized with KMnO 4 to carboxylic acids. 4. Chemical Properties of Aldehydes

Chapter 2 In the addition reactions pi bond in the carbonyl group, C=O, is broken. 2. Addition Reactions Addition of Hydrogen Aldehydes are reduced to alcohols in the presence of Ni and Pt catalyst under certain conditions. 4. Chemical Properties of Aldehydes

Chapter 2 5. Preparation of Aldehydes 1. Oxidation of Primary Alcohols

Chapter 2 5. Preparation of Aldehydes 2. Dehydrogenation of Primary Alcohols

Chapter 2 6. Some Important Aldehydes 1. Formaldehyde Colorless gas with pungent odor, soluble in water. Simplest aldehyde, discovered by the Russian Chemist A. Butlerov in Widely used in the manufacture of building materials and household products. It hardens proteins and prevents them decaying. % 40 solution of formaldehyde is called formalin, used to store biological products.

Chapter 2 6. Some Important Aldehydes 1. Formaldehyde It is produced from methanol by dehydrogenation with a catalyst of Cu and silver, and it is called Hoffman Method.

Chapter 2 6. Some Important Aldehydes 2. Acetaldehyde Colorless, volatile and poisonous liquid, soluble in water. Used to obtain many organic compounds, such as acetic acid, ethyl alcohol, synthetic rubber. It has carcinogen effect.

Chapter 2 7. Ketones The compounds in which the two alkyl or aryl groups attached to the carbonyl carbon are called ketones. is representation of ketones. R may be alkyl or aryl group. C n H 2n O is general formula of ketones. Ketones might be either symmetrical or unsymmetrical with respect to alkyl groups.

Chapter 2 8. Nomenclature of Ketones For the simple ketones names of alkyl or aryl groups followed by the word “ketone” are used. Dimethyl ketone acetone Methyl propyl ketone Ethyl phenyl ketone isopropyl methyl ketone

Chapter 2 8. Nomenclature of Ketones For the complex ketones IUPAC names are used. Longest chain of carbon atoms containing the ketone group is selected. Number 1 to the carbon atom starting nearer to the carbonyl carbon. Change –e ending in alkane names with –one. 3-methyl-2-butanone 3-bromo-2-pentanone

Chapter 2 8. Nomenclature of Ketones Example 7 Name the following aldehydes 4-chloro-2-pentanone A. 2-ethyl cyclohexanone B. 1-phenyl-3-pentanone C. 4-pentene-2-one D.

Chapter 2 8. Nomenclature of Ketones Example 8 Write the structural formulae of the following compounds. A.2-pentanone B.5-bromo-3-methyl-2-hexanone C.Methyl phenyl ketone D.Isopropyl methyl ketone E.3-methyl cyclopentanone

Chapter 2 9. Physical Properties of Ketones Lower molecular weight ketones are liquids. More than C 11 atoms are solids. Soluble in water by forming hydrogen bonds. Liquid ketones are used as solvents in the preparation of paint chemicals. Solubility decreases with increasing size of the molecule. They are polar molecules but there is no hydrogen bonding between the molecules.

Chapter Chemical Properties of Ketones 1.Addition Reactions Addition of Hydrogen

Chapter Preparation of Ketones 1.Oxidation of Secondary Alcohols

Chapter Preparation of Ketones 2. Dehydrogenation of Secondary Alcohols

Chapter Acetone Smallest ketone Colorless, volatile liquid with pleasant odor. It is soluble in water, alcohol and ether. It is a perfect organic solvent used for varnishes, lacquers, resins, plastics, paints, oils and their derivatives. It burns with a blue dull flame. It is very difficult to oxidize.

End of the chapter 2