Organic Acids and Salts

The reaction tool (pH calculator) handles both inorganic and organic compounds. In particular, the extended program version aqion PRO provides more than 100 organic acids and salts listed in the tables below.

The tables contain the molecular formula, the name of the acid or salt, and the acronym under which it appears in the program. The acronym is based on the name of the corresponding anion. In addition, the first table presents the acidity constants for each dissociation step (pKa values at 25°C). Calculated pH values are presented here.

Organic Acids

Formula Name Acronym pK1 pK2 pK3 Ref.
CH2O2 formic acid HFormate 3.75     1
C2H2O3 glyoxilic acid HGlyoxylate 3.18     23
C2H2O4 oxalic acid H2Oxalate 1.27 4.26   4
C2H4O2 acetic acid HAcetate 4.76     12
C2H4O3 glocolic acid HGlycolate 3.83     2
C3H4O2 acrylic acid HAcrylate 4.25     23
C3H4O3 pyruvic acid HPyruvate 2.5     5
C3H4O4 malonic acid H2Maloate 2.83 5.69   523
C3H6O2 propanoic acid HPropanate 4.87     1
C3H6O3 hydroxypropanoic acid HHydroxypropanate 4.51     3
C3H6O3 lactic acid HLactate 3.86     652
C3H6O4 glyceric acid HGlycerate 3.52     23
C4H4O4 fumaric acid H2Fumarate 3.02 4.38   52
C4H4O4 maleic acid H2Maleate 1.93 6.58   5
C4H4O5 oxaloacetic acid H3Oxaloacetate 2.25 4.37 13.03 2
C4H6O2 crotonoic acid HCrotonate 4.62     5
C4H6O3 acetoacetic acid HAcetoacetate 3.58     523
C4H6O3 2-oxobutanoic acid HOxobutanate 2.5     23
C4H6O4 methylmalonic acid H2Methylmaloate 3.07 5.76   23
C4H6O4 succinic acid H2Succinate 4.21 5.64   2
C4H6O5 malic acid H2Malate 3.4 5.2   5
C4H6O6 L-tartaric acid H2L_tartrate 2.98 4.34   23
C4H6O6 DL-tartaric acid H2Dl_tartrate 3.03 4.37   2
C4H6O6 meso-tartaric acid H2Mesotartrate 3.13 4.91   2
C4H6O8 dihydroxytartaric acid HDihydroxytartrate 1.92     23
C4H8O2 butanoic acid HButyrate 4.83     23
C4H8O2 isobutanoic acid HIsobutyrate 4.86     5
C4H8O3 hydroxybutanoic acid HHydroxybutyrate 3.65     5
C5H6O4 itaconic acid H2Itaconate 3.85 5.45   523
C5H6O4 mesaconic acid H2Mesaconate 3.09 4.75   523
C5H6O5 oxoglutaric acid H2Oxoglutarate 2.47 4.68   23
C5H8O4 glutaric acid H2Glutarate 4.32 5.42   523
C5H8O4 methylsuccinic acid H2Methylsuccinate 4.13 5.64   23
C5H10O2 valeric acid HValerate 4.84     123
C5H10O2 isovaleric acid HIsovalerate 4.78     1
C5H10O2 pivalic acid HPivalate 5.03     23
C6H6O phenol HPhenolate 9.99     2
C6H6O6 cis-aconitic acid HCis_aconitate 1.95     23
C6H6O6 trans-aconitic acid H2Trans_aconitate 2.8 4.46   523
C6H8O6 ascorbic acid H2Ascorbate 4.04 11.7   2
C6H8O7 citric acid H3Citrate 3.13 4.76 6.4 1
C6H8O7 isocitric acid H3Isocitrate 3.29 4.71 6.4 23
C6H10O4 adipic acid H2Adipate 4.41 5.41   2
C6H12O2 caproic acid HCaproate 4.85     23
C7H6O2 benzoic acid HBenzoate 4.2     15
C7H6O3 salicylic acid H2Salicylate 3.0 13.4   1
C7H6O4 gentisic acid HGentisate 2.97     23
C7H6O4 protocatechuic acid H3Protocatechuate 4.48 8.83 12.6 23
C7H6O5 gallic acid HGallate 4.41     23
C7H12O2 cyclohexanecarboxylic HCyclohexanecarbox. 4.9     523
C7H12O4 pimelic acid H2Pimelate 4.48 5.42   5
C8H6O4 phthalic acid H2Phthalate 2.95 5.4   1
C8H6O4 isophthalic acid H2Isophthalate 3.46 4.46   5
C8H6O4 terephthalic acid H2Terephthalate 3.51 4.82   53
C8H8O2 phenylacetic acid HPhenylacetate 4.31     2
C8H8O2 toluic acid HToluate 3.91     23
C8H8O2 m-toluic acid HM_toluate 4.27     3
C8H8O2 p-toluic acid HP_toluate 4.37     3
C8H8O3 mandelic acid HMandelate 3.41     5
C8H8O4 homogentistic acid HHomogentisate 4.4     523
C8H14O4 suberic acid H2Suberate 4.52 5.4   5
C8H16O2 octanoic acid HOctanoate 4.89     23
C9H8O2 cinnamic acid HCinnamate 4.44     23
C9H18O2 nonanoic acid HNonanoate 4.96     23

Some Salts of Organic Acids

Formula Name Acronym in aqion
(NH4)2C6H6O7 diammonium hydrogen citrate (NH4)2HCitrate
(NH4)3C6H5O7 triammonium citrate (NH4)3Citrate
Ca(CH3COO)2 calcium acetate CaAcetate2
Ca(HCOO)2 calcium formate CaFormate2
CaHC6H5O7 calcium hydrogen citrate CaHCitrate
Ca(C3H5O3)2 calcium lactate CaLactate2
Fe(HCOO)2 iron(II) formate FeFormate2
K2HC6H5O7 dipotassium hydrogen citrate K2HCitrate
K3C6H5O7 tripotassium citrate K3HCitrate
KCH3COO potassium acetate KAcetate
KHCOO potassium formate KFormate
KH2C6H5O7 potassium dihydrogen citrate KH2Citrate
KC3H5O3 potassium lactate KLactate
Mg(CH3COO)2 magnesium acetate MgAcetate2
Mg(HCOO)2 magnesium formate MgFormate2
MgHC6H5O7 magnesium hydrogen citrate MgHCitrate
Mg(C3H5O3)2 magnesium lactate MgLactate2
Na2HC6H5O7 disodium hydrogen citrate Na2HCitrate
Na3C6H5O7 trisodium citrate Na3Citrate
NaCH3COO sodium acetate NaAcetate
NaHCOO sodium formate NaFormate
NaH2C6H5O7 sodium dihydrogen citrate NaH2Citrate
NaHC6H6O6 sodium ascorbate NaHAscorbate
NaC3H5O3 sodium lactate NaLactate
NH4CH3COO ammonium acetate NH4Acetate
NH4HCOO ammonium formate NH4Formate
NH4C6H7O7 ammonium dihydrogen citrate NH4H2Citrate
NH4C6H7O6 ammonium ascorbate NH4Ascorbate
NH4C3H5O3 ammonium lactate NH4Lactate

Calculated pH values for 1, 10, 100, and 1000 mM are presented here.

References

  1. Database minteq.dat: J.D. Allison, D.S. Brown, K.J. Novo-Gradac: MINTEQA2/PRODEFA2, A Geochemical Assessment Model for Environmental Systems, Version 3.0, User’s Manual, EPA/600/3-91/021, March 1991

  2. Dissociation Constants Of Organic Acids and Bases (1070 compounds), http://de.scribd.com/doc/123136012/Tabela-pKa-organicos

  3. Dissociation Constants Of Organic Acids and Bases (600 compounds), http://zirchrom.com/organic.htm

  4. Database EQ3/6.dat: T.J. Wolery: EQ3/6, A Software Package for Geochemical Modeling of Aqueous Systems: Package Overview and Installation Guide (Version 7.0), Lawrence Livermore National Laboratory UCRL-MA-110662 PT I, Sep 1992

  5. pKa Data Compiled by R. Williams, http://research.chem.psu.edu/brpgroup/pKa_compilation.pdf

  6. Database llnl.dat: ‘thermo.com.V8.R6.230’ prepared by Jim Johnson at Lawrence Livermore National Laboratory, in Geochemist’s Workbench format. Converted to Phreeqc format by Greg Anderson with help from David Parkhurst (llnl.dat 4023 2010-02-09 21:02:42Z dlpark)

[last modified: 2015-11-24]