1 / 18

4.4 Bonding in Alcohols and Alkyl Halides

4.4 Bonding in Alcohols and Alkyl Halides. H. H. H. H. O. C. Cl. C. Dipole Moments. alcohols and alkyl halides are polar. d +. H. d +. d +. d –. d –. H. H. m = 1.9 D. m = 1.7 D. Dipole Moments. alcohols and alkyl halides are polar. m = 1.9 D. m = 1.7 D.

yetta
Download Presentation

4.4 Bonding in Alcohols and Alkyl Halides

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. 4.4Bonding in Alcoholsand Alkyl Halides

  2. H H H H O C Cl C Dipole Moments • alcohols and alkyl halides are polar d+ H d+ d+ d– d– H H m = 1.9 D m = 1.7 D

  3. Dipole Moments • alcohols and alkyl halides are polar m = 1.9 D m = 1.7 D

  4. Dipole-Dipole Attractive Forces d + d – d + d – d + d – d + d – d – d +

  5. Dipole-Dipole Attractive Forces d + d – d + d – d + d – d + d – d – d +

  6. 4.5Physical Properties of Alcohols and Alkyl Halides:Intermolecular Forces • Boiling point • Solubility in water • Density

  7. Effect of Structure on Boiling Point CH3CH2CH3 CH3CH2OH • 44 4846 • -42 -32+78 • 0 1.91.7 CH3CH2F Molecularweight Boilingpoint, °C Dipolemoment, D

  8. Effect of Structure on Boiling Point CH3CH2CH3 • 44 • -42 • 0 Molecularweight Boilingpoint, °C Dipolemoment, D Intermolecular forcesare weak. Only intermolecular forces are induced dipole-induced dipole attractions.

  9. Effect of Structure on Boiling Point CH3CH2F • 48 • -32 • 1.9 A polar molecule;therefore dipole-dipoleand dipole-induceddipole forces contributeto intermolecular attractions. Molecularweight Boilingpoint, °C Dipolemoment, D

  10. Effect of Structure on Boiling Point • 46 • +78 • 1.7 CH3CH2OH Highest boiling point;strongest intermolecularattractive forces. Hydrogen bonding isstronger than other dipole-dipole attractions. Molecularweight Boilingpoint, °C Dipolemoment, D

  11. Figure 4.4 Hydrogen bonding in ethanol d– d+ d+ d–

  12. Figure 4.4 Hydrogen bonding in ethanol

  13. Boiling point increases with increasingnumber of halogens Compound Boiling Point • CH3Cl -24°C • CH2Cl2 40°C • CHCl3 61°C • CCl4 77°C Even though CCl4 is the only compound in this list without a dipole moment, it has the highest boiling point. Induced dipole-induced dipole forces are greatest in CCl4because it has the greatest number of Cl atoms. Cl is more polarizable than H.

  14. But trend is not followed when halogenis fluorine • CH3CH2F -32°C • CH3CHF2 -25°C • CH3CF3 -47°C • CF3CF3 -78°C Compound Boiling Point

  15. But trend is not followed when halogenis fluorine • CH3CH2F -32°C • CH3CHF2 -25°C • CH3CF3 -47°C • CF3CF3 -78°C Compound Boiling Point Fluorine is not very polarizable and induced dipole-induced dipole forces decrease with increasing fluorine substitution.

  16. Solubility in water • Alkyl halides are insoluble in water. • Methanol, ethanol, isopropyl alcohol arecompletely miscible with water. • The solubility of an alcohol in waterdecreases with increasing number of carbons (compound becomesmore hydrocarbon-like).

  17. d+ d– d+ d– d+ d– Figure 4.5 Hydrogen Bonding Between Ethanol and Water

  18. Density • Alkyl fluorides and alkyl chlorides areless dense than water. • Alkyl bromides and alkyl iodides are more dense than water. • All liquid alcohols have densities of about 0.8 g/mL.

More Related