Page 181 - Principles of Catalyst Development

CATALYST CHARACTERIZATION 169
TABLE 7.12. Hammett Indicators Used in Acidity Measurement

Equivalent
Indicator Acid color Base color pK" % H 2SO 4

Brom thymol blue Yellow Blue +6.8
p-Ethoxychrysoidin Red Yellow +5.0
4-Phenylazo-1-
naphthalamine Red Yellow +4.0
Aminoazoxylene Red Yellow +3.5
Benzene-azo-
dimethylaniline Red Orange +3.2
2-Amino-5-azotoluene Red Yellow +2.0
Benzeneazo-
diphenylamine Purple Yellow +1.5 0.02
p- N itrobenzeneazo
diphenylamine Violet Orange 0.43
p- Nitrodiphenylamine Red-Orange Orange -2.1 40
Dicinnamalacetone Red Yellow -3.0 48
Benzalacetophenoue Yellow Colorless -5.6 71
Anthraquinone Yellow Colorless -8.2 91

N
'E
"
(f)
UJ
...J
:::>
u 5.0
UJ
...J
0
~ ::,
4.0
::?
0
3.0
)(
a:
IJJ
I- 2.0
f:
UJ
z
;; 1.0
«
...J
>-
I-
:::>
CD 0 +4 +2 0 -2 -4 -6 -8
c:: I
ACID STRENGTH, pK.
Figure 7.28. Results with Hammett indicators.