lecture 21.3

lecture 21.3 - 21-21-1Organic Organic...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 21-21-1Organic Organic ChemistryChemistryWilliam H. BrownWilliam H. BrownChristopher S. FooteChristopher S. FooteBrent L. IversonBrent L. Iverson21-21-2Benzene andBenzene andand the Concept ofand the Concept ofAromaticityAromaticityChapter 21Chapter 2121-21-3Acidity of PhenolsAcidity of Phenolsthe greater acidity of phenols compared with alcohols is due to the greater stability of the phenoxide ion relative to an alkoxide ionThese 2 Kekulstructures areequivalentHHOOOOHOThese three contributing structuresdelocalize the negative chargeonto carbon atoms of the ringHOOOOHO21-21-4Acidity of PhenolsAcidity of PhenolsAlkyl and halogen substituents effect acidities by inductive effectsalkyl groups are electron-releasinghalogens are electron-withdrawingp-ChororophenolpKa 9.18m-ChlorophenolpKa 8.85PhenolpKa 9.95m-CresolpKa 10.01p-CresolpKa 10.17OHOHOHOHOHCH3CH3ClCl21-21-5Acidity of PhenolsAcidity of Phenolsnitro groups increase the acidity of phenols by both an electron-withdrawing inductive effect and a resonance effectOHNO2OHOHNO2PhenolpKa 9.95p-NitrophenolpKa 7.15m-NitrophenolpKa 8.2821-21-6Acidity of PhenolsAcidity of Phenolspart of the acid-strengthening effect of -NO2is due to its electron-withdrawing inductive effectin addition, -NO2substituents in the ortho and para positions help to delocalize the negative charge++delocalization of negativecharge onto oxygen furtherincreases the resonancestabilization of phenoxide ionOOONOONO21-21-7Acidity of PhenolsAcidity of PhenolsPhenols are weak acids and react with strong bases to form water-soluble saltswater-insoluble phenols dissolve in NaOH(aq)OHNaOHO- Na...
View Full Document

This note was uploaded on 03/30/2008 for the course CHEM 262 taught by Professor Forbes during the Spring '08 term at UNC.

Page1 / 25

lecture 21.3 - 21-21-1Organic Organic...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online