H2O
AN
DCE
GP
Figure from:
Acidities of strong neutral
Brønsted acids in different media
pKa
30
250.1 (341.1)
20
http://dx.doi.org/10.1002/poc.2946
CH3COOH
H3C
244.9 (334.0)
240.5 (328.1)
J. Phys. Org. Chem. 2012
OH
251.0 (342.3)
SO2NH2
HCl
19.6
238.2 (324.9)
29.1
237.5 (324.0)
F3C
26.87
15.6
CF3
OH
CF3
O
15.5
233.4 (318.3)
23.90
23.51
11.08
10
10.21
10.1
10.00
9.5
2.3
1.8
0
0.4
F
F
21.10
20.55
18.88
16.66
16.13
14.57
10.3
9.2
7.6
6.0
229.8 (313.5)
229.0 (312.4)
F
F
F
HI
COOEt
H
CN
F
FF
F
226.7 (309.2)
226.2 (308.6)
NH
S
O
O
F
F
F
F
OH
CN
NO2
5.5
11.61
0.3
11.0
0.0
F
F3 C
4.7
3.8
F
F
221.5 (302.1)
220.4 (300.6)
-3.7
-4.9
-5.1
~-7
-9
~-9
~-9.5
5.5
5.1
4.48
2.8
CN
-6.4
F
F
F
219.6 (299.5)
219.2 (299.0)
CN
O2N
CN
OH
8.19
CF3
F
F
8.9
<-2
F
FF
F
NO2
-0.4
<-1
-2.0
-10
231.6 (315.9)
F
17.75
5.89
5.4
4.76
4.4
4.09
12.5
HBr
NO2
O2N
CN
H
216.1 (294.8) CN
NC
214.8 (293.0)
213.4 (291.1)
-6.5
-7.7
NO2
CF3SO2OH
O2N
SO2NHSO2
NO2
OH
0.7
-0.1
-11.4
-12.3
-12
208.4 (284.2)
208.0 (283.7)
C2F5SO2
C2F5SO2
-2.8
SO2CF3
F3CO2S
SO2CF3
NH
-15.3
-20
NC
195.9 (267.2)
NC
CN
CN
H
CN
Figure 1. Trends of acidity changes on transfer between water, acetonitrile, 1,2-dichloroethane and the gas
phase of a set of acids of different molecular structure.
The values are presented on a relative scale taking the pKa value picric acid as zero in all media. The GA values (given
in brackets) have been converted to the corresponding pKa values (see eq 2 in text) in order to make the spans of the
values in different media directly comparable. Colors: red – OH acids, blue – NH acids, black – CH acids, green –
hydrohalogenic acids.