Phenols - PowerPoint PPT Presentation

1 / 15
About This Presentation
Title:

Phenols

Description:

Picric acid (2,4,6-trinitrophenol) 2,4,6-trinitrophenol is so acidic that it is called picric acid; it has a Ka = 10-1 (pKa =1) ... – PowerPoint PPT presentation

Number of Views:47
Avg rating:3.0/5.0
Slides: 16
Provided by: UNC9151
Category:
Tags: acid | phenols | picric

less

Transcript and Presenter's Notes

Title: Phenols


1
Phenols
2
Phenol
  • The antiseptic property
    of phenol was discovered
    in 1865 by Joseph Lister,
    a physician in Scotland.
  • Listerine, named after him, contains phenol as
    the active ingredient.
  • Today, over two million tons of phenol are made
    each year in the US alone.
  • Phenol is used for resins, glue to make plywood,
    plastics, and pharmaceuticals.

3
Examples of Phenols
4
More phenols
5
Slight Acidity of Phenol
  • Phenol has a Ka 10-10 (pKa 10)
  • Alcohols have a Ka 10-16 (pKa 16)
  • The reason phenol is more acidic than an alcohol
    is resonance stabilization of the phenolate anion
    (next slide)

6
Resonance of Phenolate ion
Substituents that stabilize an anion enhance the
acidity of phenol. Phenol has a pKa 10
p-nitrophenol has a pKa 7.1
7
Picric acid (2,4,6-trinitrophenol)
  • 2,4,6-trinitrophenol is so acidic that it is
    called picric acid it has a Ka 10-1 (pKa 1)
  • The enhanced acidity compared to phenol itself
    (Ka 10-10) is due to the increased resonance
    stabilization of the conjugate base (phenolate
    anion) by the nitro groups

8
IR spectrum of phenol
O-H
C-O
CC
9
IR spectrum of cyclohexanol
O-H
C-O
10
IR spectrum of 1-butanol
C-O
O-H
C-O
O-H
11
(No Transcript)
12
H
H
H
13
(No Transcript)
14
(No Transcript)
15
Summary of Spectral Features
  • IR O-H stretch, 3600-3000 cm-1, broad
  • (alcohols and phenols)
  • C-O stretch, 1250 to 1050 cm-1, (higher
  • for phenols than for alcohols)
  • 13C-NMR C-O, 60-65 d (alcohols)
  • 160 d (phenols)
  • 1H-NMR -CH2-O, 3.5 d
Write a Comment
User Comments (0)
About PowerShow.com