1 / 18

Chapter 4 Aromatic Hydrocarbons

Chemistry 20. Chapter 4 Aromatic Hydrocarbons. Aromatic Compounds. Unsaturated hydrocarbons. Some of them have pleasant odors. Aromatic compounds. Aromatic Compounds. Aromatic compounds contain benzene ring. Benzene has: 6 C atoms and 6 H atoms. Two possible Lewis structures. C 6 H 6.

emi-whitley
Download Presentation

Chapter 4 Aromatic Hydrocarbons

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. Chemistry 20 Chapter 4 Aromatic Hydrocarbons

  2. Aromatic Compounds Unsaturated hydrocarbons Some of them have pleasant odors. Aromatic compounds

  3. Aromatic Compounds • Aromatic compounds contain benzene ring. • Benzene has: • 6 C atoms and 6 H atoms. • Two possible Lewis structures. C6H6

  4. Aromatic Compounds Arene:A compound containing one or more benzene rings. Aryl group:When we remove a H atom from an arene (Ar-). Phenyl C6H5-

  5. CH2-CH3 Cl CH3 Naming of Aromatic Compounds • Aromatic compounds are named: • With benzene as the parentchain. • Name of substituent comes in front of the “benzene”. • methylbenzene chlorobenzene ethylbenzene

  6. Naming of Aromatic Compounds Some substituted benzenes have common names. CH3 Toluene

  7. Naming of Aromatic Compounds • When two groups are attached to benzene, the ring is numbered to give • the lower numbers to the substituents. • Start numbering from a special name (if we have). • If we do not have, number them to get the smallest set of numbers. • List them by alphabetical order. 3-methyltoluene Ortho Meta Para

  8. Naming of Aromatic Compounds • If we have three or moresubstituents: • Start numbering from a special name (if we have). • If we do not have, number them to get the smallest set of numbers. • List them by alphabetical order.

  9. 1 Naming of Aromatic Compounds Aryl group:When we remove a H atom from an arene (Ar-). Phenyl C6H5-

  10. Chemical properties of benzene Resonance: stable Resonance hybrid: a molecule with two or more Lowis structures. Contributing structure

  11. Halogenation Nitration Sulfonation Chemical properties of benzene No addition reactions (almost unreactive) Aromatic substitution:One of the H atoms is repalecd by some groups.

  12. Chemical properties of benzene 1. Halogenation: Cl and Br react rapidly with benzene in the presence of an iron catalyst.

  13. Chemical properties of benzene 2. Nitration: In presence of concentrated nitric acid and sulfuric acid, one of the H atoms is replaced by a nitro (-NO2) group.

  14. Chemical properties of benzene 3. Sulfonation: In presence of concentrated sulfuric acid and heat, one of the H atoms is replaced by sufonic acid (-SO3H) group. Heat

  15. NO2 Phenol OH • Phenol is the IUPAC name for benzene with a hydroxyl group. Phenol 1 1 2 Cl 3 3 3-Chloro-2-nitrophenol (m-Cresol)

  16. Phenol • Many are used as antiseptics and disinfectants. • Phenols are found widely in nature. • Phenols are weak acids (pKa~10). • Phenols are insoluble in water.

  17. Phenols as antioxidants Autoxidation: foods and other materials that contain C=C are oxidized only in presence of oxygen (no other reactant). R-H group is converted to an R-O-O-H (hydroperoxide) group.

  18. Phenols as antioxidants Phenols are antioxidants and can prevent autoxidation. Vitamin E is a natural antioxidant. The foods are stored in longer period.

More Related