1 / 27

Chapter 17 Aldehydes and Ketones

Chapter 17 Aldehydes and Ketones. 17.1 Nomenclature. O. O. H. H. O. O. HCCHCH. Nomenclature of Aldehydes. 4,4-dimethylpent anal. 5-hex enal. 2-phenylprop anedial. O. C. H. Nomenclature of Aldehydes. when named as a suffix. when named as a substituent. formyl group.

floyd
Download Presentation

Chapter 17 Aldehydes and Ketones

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 17Aldehydes and Ketones

  2. 17.1Nomenclature

  3. O O H H O O HCCHCH Nomenclature of Aldehydes 4,4-dimethylpentanal 5-hexenal 2-phenylpropanedial

  4. O C H Nomenclature of Aldehydes when named as a suffix when named as a substituent formyl group carbaldehyde carboxaldehyde

  5. O O CH3CH2CCH2CH2CH3 CH3CHCH2CCH3 CH3 H3C O Substitutive Nomenclature of Ketones 3-hexanone 4-methyl-2-pentanone 4-methylcyclohexanone

  6. O O CH3CH2CCH2CH2CH3 CH2CCH2CH3 O H2C CH CHC CH2 Functional Class Nomenclature of Ketones ethylpropyl ketone benzylethyl ketone divinyl ketone

  7. 17.2Structure and Bonding:The Carbonyl Group

  8. Structure of Formaldehyde planar bond angles: close to 120° C=O bond distance: 122 pm

  9. The Carbonyl Group very polar double bond O 1-butene propanal dipole moment = 2.5D dipole moment = 0.3D

  10. O H O Carbonyl group of a ketone is morestable than that of an aldehyde Alkyl groups stabilize carbonyl groups the sameway they stabilize carbon-carbon double bonds,carbocations, and free radicals. heat of combustion 2475 kJ/mol 2442 kJ/mol

  11. O H O Spread is greater foraldehydes andketones than for alkenes Heats of combustion ofC4H8 isomeric alkenes CH3CH2CH=CH2 2717 kJ/mol cis-CH3CH=CHCH3 2710 kJ/mol trans-CH3CH=CHCH3 2707 kJ/mol (CH3)2C=CH2 2700 kJ/mol 2475 kJ/mol 2442 kJ/mol

  12. •• – •• O O •• •• •• C C + Resonance Description ofCarbonyl Group nucleophiles attack carbon; electrophiles attack oxygen

  13. Bonding in Formaldehyde Carbon and oxygen are sp2 hybridized

  14. Bonding in Formaldehyde The half-filledp orbitals oncarbon andoxygen overlapto form a p bond

  15. 17.3Physical Properties

  16. O OH Aldehydes and ketones have higher boilingthan alkenes, but lower boiling points than alcohols. boiling point More polar than alkenes, but cannot form intermolecular hydrogen bonds to other carbonyl groups –6°C 49°C 97°C

  17. 17.4Sources of Aldehydes and Ketones

  18. O Many aldehydes and ketones occur naturally 2-heptanone(component of alarm pheromone of bees)

  19. Many aldehydes and ketones occur naturally O H trans-2-hexenal (alarm pheromone of myrmicine ant)

  20. Many aldehydes and ketones occur naturally O H citral (from lemon grass oil)

  21. Synthesis of Aldehydes and Ketones from alkenes ozonolysis from alkynes hydration (via enol) from arenes Friedel-Crafts acylation from alcohols oxidation A number of reactions alreadystudied provideefficient syntheticroutes to aldehydes and ketones.

  22. O O C C R H R OH What about..? aldehydes from carboxylic acids

  23. O O C C R H R OH What about..? aldehydes from carboxylic acids 1. LiAlH4 PDC, CH2Cl2 2. H2O RCH2OH

  24. O O COH CH CH2OH Example benzaldehyde from benzoic acid 1. LiAlH4 PDCCH2Cl2 2. H2O (83%) (81%)

  25. O O C C R R' R H What about..? ketones from aldehydes

  26. O O C C R R' R H What about..? ketones from aldehydes 1. R'MgX OH PDC, CH2Cl2 2. H3O+ RCHR'

  27. O CH3CH2C(CH2)3 CH3 OH CH3CH2CH(CH2)3 CH3 Example 3-heptanone from propanal O C CH3CH2 H (57%) 1. CH3(CH2)3MgX H2CrO4 2. H3O+

More Related