Organic chemistry for medicine and biology students Chem

Organic chemistry for medicine and biology students Chem 2311 Chapter 9 Aldehydes and Ketones By Prof. Dr. Adel M. Awadallah Islamic University of Gaza 1

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Nomenclature of Aldehydes and Ketones Common aldehydes 4

Common Ketones 5

Nomenclature of aldehydes and ketones (al) aldehyde, (one) ketone alkanes < alkenes < OH < ketone < aldehyde < acid < ester Examples 6

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Acyl groups 8

Common aldehydes and ketones 9

Synthesis of aldehydes and Ketones 1) 2) 3) Oxidation of Alcohols primary gives aldehydes using PCC secondery gives ketones Friedel-Crafts From Alkynes 10

Naturally occuring aldehydes and Ketones 11

The carbonyl group 12

Reactions of the carbonyl group 13

A. Hydration and Hemiacetal Formation • • • Water adds rapidly to the carbonyl function of aldehydes and ketones. In most cases the resulting hydrate (a geminal-diol) is unstable relative to the reactants and cannot be isolated. Exceptions to this rule exist, one being formaldehyde (a gas in its pure monomeric state). Thus, a solution of formaldehyde in water (formalin) is almost exclusively the hydrate, or polymers of the hydrate. Another is chloral hydrate 14

Addition of Alcohols 15

Examples 16

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Addition of hydrogen cyanide to aldehydes and ketones 18

Reducing Agents The reduction of an aldehyde You get exactly the same organic product whether you use lithium tetrahydridoaluminate or sodium tetrahydridoborate. For example, with ethanal you get ethanol: 19

The reduction of a ketone • Again the product is the same whichever of the two reducing agents you use. • For example, with propanone you get propan-2 -ol: • Reduction of a ketone leads to a secondary alcohol. 20

REACTION OF ALDEHYDES AND KETONES WITH GRIGNARD REAGENTS 21

The reaction between Grignard reagents and methanal The reaction between Grignard reagents and other aldehydes The reaction between Grignard reagents and ketones 22

OXIDATION OF ALDEHYDES AND KETONES 23

ADDITION-ELIMINATION REACTIONS OF ALDEHYDES AND KETONES 24

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with hydroxylamine The product is an "oxime" - for example, ethanal oxime. 26

Formation of Imines and Related Compounds The reaction of aldehydes and ketones with ammonia or 1ºamines forms imine derivatives, also known as Schiff bases, (compounds having a C=N function). 27