Evans pKa Table - pKa H₂O(DMSO) and Substrate Values

Sep 17, 2026

Evans pKa tables compile experimentally based and extrapolated pKa values across multiple chemical classes, reporting both aqueous (H₂O) and DMSO solvent conditions. The tables organize inorganic acids, carboxylic acids, alcohols, and numerous protonated species, then extend to nitrogen acids/related protonated nitrogen derivatives and additional groups such as amines, amides, and hydrocarbons/carbonyl compounds. Notes clarify that negative values in H₂O/DMSO and high values for water/DMSO were extrapolated by several methods, and that earlier literature numbers can be erroneous.

LanguageEnglish

CategoryResearch & Report

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Pages6

Reading Time15 min

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pKa H₂O(DMSO)

Inorganic acids and protonated species

Substrate pKa for nitrogen acids

pKa of C–H bonds and carbonyl compounds

pKa H₂O(DMSO) H₂O(DMSO) pKa pKa H₂O(DMSO) Substrate Substrate pKa H2O(DMSO) Substrate Substrate | INORGANIC ACIDS | CARBOXYLIC ACIDS | ALCOHOLS | PROTONATED SPECIES | | --- | --- | --- | --- | | 14.0
H₂O
(32)
0.0
H₃O+
H₂S
7.00
HBr
-9.00(0.9)
HCI
(1.8)
-8.0
HF
(15)
3.17
7.5
HOCI
HCIO₄
-10
(12.9)
9.4
HCN
HN₃
4.72 (7.9)
4.00
HSCN
1.9,7.21
H₂SO₃
H₂SO₄
-3.0,1.99
2.12,7.21,
H₃PO₄
12.32
-1.3
HNO₃
3.29
HNO₂
-0.98,6.50
H₂CrO₄
-2.6 (1.6)
CH₃SO₃H
CF₃SO₃H
-14 (0.3)
NH₄Cl
9.24
9.23
B(OH)₃
11.6
HOOH | 4.76(12.3)
CH₂NO₂
1.68
CH₂F
2.66
CH₂Cl
2.86
2.86
CH₂I
3.12
CHCl₂
1.29
CCl₃
0.65
CF₃
-0.25
H
3.77
3.6,10.3
HO
4.2(11.1)
C₆H₅
2.17
o-O₂NC₆H₄
m-O₂NC₆H₄
2.45
p-O₂NC₆H₄
3.44
o-CIC₆H₄
2.94
m-CIC₆H₄
3.83
p-CIC₆H₄
3.99
o-(CH₃)₃N+C₆H₄1.37
p-(CH₃)₃N+C₆H₄3.43
p-OMeC₆H₄
4.47
4.25
R=H
3.02,4.38
trans-CO₂H
cis-CO₂H
1.92,6.23 | (31.2)
14.0
HOH
MeOH
(27.9)
15.5
i-PrOH
(29.3)
16.5
(29.4)
t-BuOH
17.0
c-hex₃COH
24.0
CF₃CH₂OH
12.5 (23.5)
(CF₃)₂CHOH
(18.2)
9.3
(18.0)
C₆H₅OH
9.95
m-O₂NC₆H₄OH
8.4
(10.8)
p-O₂NC₆H₄OH
7.1
p-OMeC₆H₄OH
10.2
(19.1)
(17.1)
2-napthol
OXIMES&HYDROXAMIC ACIDS
11.3(20.1)
8.88(13.7)
(NH)
(18.5)
PEROXIDES
11.5
MeOOH
8.2
CH₃CO₃H | -12.4
-7.8
-6.2
-6.5
-3.8
-2.05
-2.2
-1.8
0.79 (+1.6
(+5.5
SULFINIC&SULFONIC ACIDS | | | | | -2.6
2.1 | 3) 5) *Values<0 for H₂O and DMSO,and values>14 for water and>35 for DMSO were extrapolated using various methods. The pka of water and H₃O+have been experimentally determined to be 14.0 and 0.0,respectively.Earlier values of 15.7 and -1.74,respectively are erroneous numbers proposed by scientists who made some errors in the calculated “"rational"values.See:1)Helv.Chim.Acta 2014,97,1.and 2)J.Chem.Educ.2017,94,690. | D.H.Ripin,D.A. | Evans | | | pKa's of N | itrogen Acids | | | --- | --- | --- | --- | --- | --- | --- | | Substrate | pKa H₂O | (DMSO | Substrate pka H₂O(DMSO)
)Substrate
pka H₂O(DMSO)
Substrate pka H₂O (DMSO) | | | | | PROTONATED NITROGEN | | | AMINES | | IMIDES | HYDROXAMIC ACID&AMIDINES | | N+H₄
EtN+H₃
i-Pr₂N+H₂
Et₃N+H | 9.2
10.6
11.05
10.75 | (10.5)
(9.00) | HN₃
4.7(7.9)
NH₃
38 (41)
i-Pr₂NH
(36 THF))
26(THF)(30)
TMS₂NH
PhNH₂(30.6) | | (14.7)
Ac₂NH
(17.9) | R=Me (
Ph | | PhN+H₃ | 4.6 | (3.6) | | | SULFONAMIDE | | | PhN+(Me)₂H | 5.20 | (2.50) | | | | HETEROCYCLES | | Ph₂N+H₂
2-napthal-N+H₃ | 0.78
4.16 | | (37) | | | | | | 8.12 | | (26.5) | | GUANIDINIUM,
HYRDAZONES,-IDES,&-INES
(21.6)
(17.2)
PhSO₂NHNH₂
PhNHNHPh
(26.1) | | | | 5.96
11.0 | (9.80) | AMIDES&CARBAMATES | | | | | | | | | | | | | | | | | | | | | N-Me morpholin | e
7.38
-9.3
2.97, | 8.82 | (17.2) | | | | | | | | | (26.9)
OEt
(24.8) | | | | | | | (20.5) | | PROTONATED HETEROCYCLES
) | | | | | | | | | | | (2.97,8.93)
6.90,9.95 | | | | | 6.95 | (165) | | -9.0,12.0
(-,7.50) | | | | | R R=
5.21(3.4)
4.95(0.90)
6.75(4.46) | | | PhCN+H | -10 | | | | 0.72 | | | *Values<0 for H₂O and DMSO,and values>14 for water and>35 for DMS

FAQs

What do the tables report for each substrate or species?

They present pKa values under two solvent conditions, including H₂O and H₂O(DMSO), along with related substrate and protonated-species entries.

Are all pKa values measured experimentally?

The notes indicate that values below 0 for H₂O and DMSO, and values above 14 for water and above 35 for DMSO, were extrapolated using various methods.

Do the tables address potential errors in earlier literature pKa values?

Yes. The text states that earlier reported pKa values for water and H₃O+ can be erroneous and cites specific references where those numbers were proposed.

Sep 17, 2026

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