有机物解离常数

DISSOCIATION CONSTANTS OF ORGANIC ACIDS AND BASES This table lists the dissociation (ionization) constants of over 1070 organic acids, bases, and amphoteric compounds. All data apply to dilute aqueous solutions and are presented as values of pK a , which is defined as the negative of the logarithm of the equi- librium constant K a for the reaction HA  H+ + A- i.e., K a = [H+][A-]/[HA] where [H+], etc. represent the concentrations of the respective species in mol/L. It follows that pK a = pH + log[HA] – log[A-], so that a solution with 50% dissociation has pH equal to the pK a of the acid. Data for bases are presented as pK a values for the conjugate acid, i.e., for the reaction BH+  H+ + B In older literature, an ionization constant K b was used for the reac- tion B + H 2 O  BH+ + OH- . This is related to K a by pK a + pK b = pK water = 14.00 (at 25°C) Compounds are listed by molecular formula in Hill order. References 1. Perrin, D. D., Dissociation Constants of Organic Bases in Aqueous Solution, Butterworths, London, 1965; Supplement, 1972. 2. Serjeant, E. P., and Dempsey, B., Ionization Constants of Organic Acids in Aqueous Solution, Pergamon, Oxford, 1979. 3. Albert, A., “Ionization Constants of Heterocyclic Substances”, in Katritzky, A. R., Ed., Physical Methods in Heterocyclic Chemistry, Academic Press, New York, 1963. 4. Sober, H.A., Ed., CRC Handbook of Biochemistry, CRC Press, Boca Raton, FL, 1968. 5. Perrin, D. D., Dempsey, B., and Serjeant, E. P., pK a Prediction for Organic Acids and Bases, Chapman and Hall, London, 1981. 6. Albert, A., and Serjeant, E. P., The Determination of Ionization Constants, Third Edition, Chapman and Hall, London, 1984. 7. Budavari, S., Ed., The Merck Index, Twelth Edition, Merck & Co., Whitehouse Station, NJ, 1996. Mol. form. Name Step t/°C pK a CHNO Cyanic acid 25 3.7 CH 2 N 2 Cyanamide 29 1.1 CH 2 O Formaldehyde 25 13.27 CH 2 O 2 Formic acid 25 3.75 CH 3 NO 2 Nitromethane 25 10.21 CH 3 NS 2 Carbamodithioic acid 25 2.95 CH 4 N 2 O Urea 25 0.10 CH 4 N 2 S Thiourea 25 -1 CH 4 O Methanol 25 15.5 CH 4 S Methanethiol 25 10.33 CH 5 N Methylamine 25 10.66 CH 5 NO O-Methylhydroxylamine 12.5 CH 5 N 3 Guanidine 25 13.6 C 2 HCl 3 O Trichloroacetaldehyde 25 10.04 C 2 HCl 3 O 2 Trichloroacetic acid 20 0.66 C 2 HF 3 O 2 Trifluoroacetic acid 25 0.52 C 2 H 2 Cl 2 O 2 Dichloroacetic acid 25 1.35 C 2 H 2 O 3 Glyoxylic acid 25 3.18 C 2 H 2 O 4 Oxalic acid 1 25 1.25 2 25 3.81 C 2 H 3 BrO 2 Bromoacetic acid 25 2.90 C 2 H 3 ClO 2 Chloroacetic acid 25 2.87 C 2 H 3 Cl 3 O 2,2,2-Trichloroethanol 25 12.24 C 2 H 3 FO 2 Fluoroacetic acid 25 2.59 C 2 H 3 F 3 O 2,2,2-Trifluoroethanol 25 12.37 C 2 H 3 IO 2 Iodoacetic acid 25 3.18 C 2 H 3 NO 4 Nitroacetic acid 24 1.48 C 2 H 3 N 3 1H-1,2,3-Triazole 20 1.17 C 2 H 3 N 3 1H-1,2,4-Triazole 20 2.27 C 2 H 4 N 2 Aminoacetonitrile 25 5.34 C 2 H 4 O Acetaldehyde 25 13.57 C 2 H 4 OS Thioacetic acid 25 3.33 C 2 H 4 O 2 Acetic acid 25 4.756 C 2 H 4 O 2 S Thioglycolic acid 25 3.68 C 2 H 4 O 3 Glycolic acid 25 3.83 C 2 H 5 N Ethyleneimine 25 8.04 Mol. form. Name Step t/°C pK a C 2 H 5 NO Acetamide 25 15.1 C 2 H 5 NO 2 Acetohydroxamic acid 8.70 C 2 H 5 NO 2 Nitroethane 25 8.46 C 2 H 5 NO 2 Glycine 1 25 2.35 2 25 9.78 C 2 H 6 N 2 Ethanimidamide 25 12.1 C 2 H 6 O Ethanol 25 15.5 C 2 H 6 OS 2-Mercaptoethanol 25 9.72 C 2 H 6 O 2 Ethyleneglycol 25 15.1 C 2 H 7 AsO 2 Dimethylarsinic acid 1 25 1.57 2 25 6.27 C 2 H 7 N Ethylamine 25 10.65 C 2 H 7 N Dimethylamine 25 10.73 C 2 H 7 NO Ethanolamine 25 9.50 C 2 H 7 NO 3 S 2-Aminoethanesulfonic acid 1 25 1.5 2 25 9.06 C 2 H 7 NS Cysteamine 1 25 8.27 2 25 10.53 C 2 H 7 N 5 Biguanide 1 11.52 2 2.93 C 2 H 8 N 2 1,2-Ethanediamine 1 25 9.92 2 25 6.86 C 2 H 8 O 7 P 2 1-Hydroxy-1,1- diphosphonoethane 1 1.35 2 2.87 3 7.03 4 11.3 C 3 H 2 O 2 2-Propynoic acid 25 1.84 C 3 H 3 NO Oxazole 33 0.8 C 3 H 3 NO Isoxazole 25 -2.0 C 3 H 3 NO 2 Cyanoacetic acid 25 2.47 C 3 H 3 NS Thiazole 25 2.52 C 3 H 3 N 3 O 3 Cyanuric acid 1 6.88 2 11.40 3 13.5 C 3 H 4 N 2 1H-Pyrazole 25 2.49 C 3 H 4 N 2 Imidazole 25 6.99 8-42 Section 8.indb 42 4/30/05 8:46:46 AM Mol. form. Name Step t/°C pK a C 3 H 4 N 2 S 2-Thiazolamine 20 5.36 C 3 H 4 O Propargyl alcohol 25 13.6 C 3 H 4 O 2 Acrylic acid 25 4.25 C 3 H 4 O 3 Pyruvic acid 25 2.39 C 3 H 4 O 4 Malonic acid 1 25 2.85 2 25 5.70 C 3 H 4 O 5 Hydroxypropanedioic acid 1 2.42 2 4.54 C 3 H 5 BrO 2 3-Bromopropanoic acid 25 4.00 C 3 H 5 ClO 2 2-Chloropropanoic acid 25 2.83 C 3 H 5 ClO 2 3-Chloropropanoic acid 25 3.98 C 3 H 6 N 2 3-Aminopropanenitrile 20 7.80 C 3 H 6 N 6 1,3,5-Triazine-2,4,6- triamine 25 5.00 C 3 H 6 O Allyl alcohol 25 15.5 C 3 H 6 O 2 Propanoic acid 25 4.87 C 3 H 6 O 2 S (Methylthio)acetic acid 25 3.66 C 3 H 6 O 3 Lactic acid 25 3.86 C 3 H 6 O 3 3-Hydroxypropanoic acid 25 4.51 C 3 H 6 O 4 Glyceric acid 25 3.52 C 3 H 7 N Allylamine 25 9.49 C 3 H 7 N Azetidine 25 11.29 C 3 H 7 NO 2-Propanone oxime 25 12.42 C 3 H 7 NO 2 L-Alanine 1 25 2.34 2 25 9.87 C 3 H 7 NO 2 β-Alanine 1 25 3.55 2 25 10.24 C 3 H 7 NO 2 Sarcosine 1 25 2.21 2 25 10.1 C 3 H 7 NO 2 S L-Cysteine 1 25 1.5 2 25 8.7 3 25 10.2 C 3 H 7 NO 3 L-Serine 1 25 2.19 2 25 9.21 C 3 H 7 NO 5 S DL-Cysteic acid 1 25 1.3 2 25 1.9 3 25 8.70 C 3 H 7 N 3 O 2 Glycocyamine 25 2.82 C 3 H 8 O 2 Ethylene glycol monomethyl ether 25 14.8 C 3 H 8 O 3 Glycerol 25 14.15 C 3 H 9 N Propylamine 25 10.54 C 3 H 9 N Isopropylamine 25 10.63 C 3 H 9 N Trimethylamine 25 9.80 C 3 H 9 NO 2-Methoxyethylamine 25 9.40 C 3 H 9 NO Trimethylamine oxide 20 4.65 C 3 H 10 N 2 1,2-Propanediamine, (±) 1 25 9.82 2 25 6.61 C 3 H 10 N 2 1,3-Propanediamine 1 25 10.55 2 25 8.88 C 3 H 10 N 2 O 1,3-Diamino-2-propanol 1 20 9.69 2 20 7.93 C 3 H 11 N 3 1,2,3-Triaminopropane 1 20 9.59 2 20 7.95 C 4 H 4 FN 3 O Flucytosine 3.26 C 4 H 4 N 2 Pyrazine 20 0.65 C 4 H 4 N 2 Pyrimidine 20 1.23 C 4 H 4 N 2 Pyridazine 20 2.24 C 4 H 4 N 2 O 2 Uracil 25 9.45 C 4 H 4 N 2 O 3 Barbituric acid 25 4.01 C 4 H 4 N 2 O 5 Alloxanic acid 25 6.64 Mol. form. Name Step t/°C pK a C 4 H 4 N 4 O 2 5-Nitropyrimidinamine 20 0.35 C 4 H 4 O 2 2-Butynoic acid 25 2.62 C 4 H 4 O 4 Maleic acid 1 25 1.92 2 25 6.23 C 4 H 4 O 4 Fumaric acid 1 25 3.02 2 25 4.38 C 4 H 4 O 5 Oxaloacetic acid 1 25 2.55 2 25 4.37 3 25 13.03 C 4 H 5 N Pyrrole 25 -3.8 C 4 H 5 NO 2 Succinimide 25 9.62 C 4 H 5 N 3 2-Pyrimidinamine 20 3.45 C 4 H 5 N 3 4-Pyrimidinamine 20 5.71 C 4 H 5 N 3 O Cytosine 1 4.60 2 12.16 C 4 H 5 N 3 O 2 6-Methyl-1,2,4-triazine- 3,5(2H,4H)-dione 7.6 C 4 H 6 N 2 1-Methylimidazol 25 6.95 C 4 H 6 N 4 O 3 Allantoin 25 8.96 C 4 H 6 N 4 O 3 S 2 Acetazolamide 7.2 C 4 H 6 O 2 trans-Crotonic acid 25 4.69 C 4 H 6 O 2 3-Butenoic acid 25 4.34 C 4 H 6 O 2 Cyclopropanecarboxylic acid 25 4.83 C 4 H 6 O 3 2-Oxobutanoic acid 25 2.50 C 4 H 6 O 3 Acetoacetic acid 25 3.6 C 4 H 6 O 4 Succinic acid 1 25 4.21 2 25 5.64 C 4 H 6 O 4 Methylmalonic acid 1 25 3.07 2 25 5.76 C 4 H 6 O 5 Malic acid 1 25 3.40 2 25 5.11 C 4 H 6 O 6 DL-Tartaric acid 1 25 3.03 2 25 4.37 C 4 H 6 O 6 meso-Tartaric acid 1 25 3.17 2 25 4.91 C 4 H 6 O 6 L-Tartaric acid 1 25 2.98 2 25 4.34 C 4 H 6 O 8 Dihydroxytartaric acid 25 1.92 C 4 H 7 ClO 2 2-Chlorobutanoic acid 2.86 C 4 H 7 ClO 2 3-Chlorobutanoic acid 4.05 C 4 H 7 ClO 2 4-Chlorobutanoic acid 4.52 C 4 H 7 NO 2 4-Cyanobutanoic acid 25 2.42 C 4 H 7 NO 3 N-Acetylglycine 25 3.67 C 4 H 7 NO 4 Iminodiacetic acid 1 2.98 2 9.89 C 4 H 7 NO 4 L-Aspartic acid 1 25 1.99 2 25 3.90 3 25 9.90 C 4 H 7 N 3 O Creatinine 1 25 4.8 2 9.2 C 4 H 7 N 5 2,4,6-Pyrimidinetriamine 20 6.84 C 4 H 8 N 2 O 3 L-Asparagine 1 20 2.1 2 20 8.80 C 4 H 8 N 2 O 3 N-Glycylglycine 1 25 3.14 2 8.17 C 4 H 8 O 2 Butanoic acid 25 4.83 C 4 H 8 O 2 2-Methylpropanoic acid 20 4.84 C 4 H 8 O 3 3-Hydroxybutanoic acid, (±) 25 4.70 C 4 H 8 O 3 4-Hydroxybutanoic acid 25 4.72 C 4 H 8 O 3 Ethoxyacetic acid 18 3.65 C 4 H 9 N Pyrrolidine 25 11.31 Dissociation Constants of Organic Acids and Bases 8-43 Section 8.indb 43 4/30/05 8:46:48 AM Mol. form. Name Step t/°C pK a C 4 H 9 NO Morpholine 25 8.50 C 4 H 9 NO 2 2-Methylalanine 1 25 2.36 2 25 10.21 C 4 H 9 NO 2 N,N-Dimethylglycine 25 9.89 C 4 H 9 NO 2 DL-2-Aminobutanoic acid 1 25 2.29 2 25 9.83 C 4 H 9 NO 2 4-Aminobutanoic acid 1 25 4.031 2 25 10.556 C 4 H 9 NO 2 S DL-Homocysteine 1 25 2.22 2 25 8.87 3 25 10.86 C 4 H 9 NO 3 L-Threonine 1 25 2.09 2 25 9.10 C 4 H 9 NO 3 L-Homoserine 1 25 2.71 2 25 9.62 C 4 H 9 N 3 O 2 Creatine 1 25 2.63 2 25 14.3 C 4 H 10 N 2 Piperazine 1 25 9.73 2 25 5.33 C 4 H 10 N 2 O 2 2,4-Diaminobutanoic acid 1 25 1.85 2 25 8.24 3 25 10.44 C 4 H 10 O 4 1,2,3,4-Butanetetrol 13.9 C 4 H 11 N Butylamine 25 10.60 C 4 H 11 N sec-Butylamine 25 10.56 C 4 H 11 N tert-Butylamine 25 10.68 C 4 H 11 N Diethylamine 25 10.84 C 4 H 11 NO 3 Tris(hydroxymethyl) methylamine 20 8.3 C 4 H 12 N 2 1,4-Butanediamine 1 25 10.80 2 25 9.63 C 5 H 4 BrN 3-Bromopyridine 25 2.84 C 5 H 4 ClN 2-Chloropyridine 25 0.49 C 5 H 4 ClN 3-Chloropyridine 25 2.81 C 5 H 4 ClN 4-Chloropyridine 25 3.83 C 5 H 4 FN 2-Fluoropyridine 25 -0.44 C 5 H 4 N 2 O 2 4-Nitropyridine 25 1.61 C 5 H 4 N 4 1H-Purine 1 20 2.30 2 20 8.96 C 5 H 4 N 4 O Hypoxanthine 25 8.7 C 5 H 4 N 4 O Allopurinol 10.2 C 5 H 4 N 4 O 3 Uric acid 12 3.89 C 5 H 4 N 4 S 1,7-Dihydro-6H- purine-6-thione 1 7.77 2 11.17 C 5 H 4 O 2 S 2-Thiophenecarboxylic acid 25 3.49 C 5 H 4 O 2 S 3-Thiophenecarboxylic acid 25 4.1 C 5 H 4 O 3 2-Furancarboxylic acid 25 3.16 C 5 H 4 O 3 3-Furancarboxylic acid 25 3.9 C 5 H 5 N Pyridine 25 5.23 C 5 H 5 NO 2-Pyridinol 1 20 0.75 2 20 11.65 C 5 H 5 NO 3-Pyridinol 1 20 4.79 2 20 8.75 C 5 H 5 NO 4-Pyridinol 1 20 3.20 2 20 11.12 C 5 H 5 NO 2(1H)-Pyridinone 1 20 0.75 2 20 11.65 C 5 H 5 NO Pyridine-1-oxide 24 0.79 C 5 H 5 NO 2 1H-Pyrrole-2-carboxylic acid 20 4.45 Mol. form. Name Step t/°C pK a C 5 H 5 NO 2 1H-Pyrrole-3-carboxylic acid 20 5.00 C 5 H 5 N 3 O Pyrazinecarboxamide 0.5 C 5 H 5 N 5 Adenine 1 4.3 2 9.83 C 5 H 5 N 5 O Guanine 40 9.92 C 5 H 6 N 2 2-Pyridinamine 20 6.82 C 5 H 6 N 2 3-Pyridinamine 25 6.04 C 5 H 6 N 2 4-Pyridinamine 25 9.11 C 5 H 6 N 2 2-Methylpyrazine 27 1.45 C 5 H 6 N 2 O 2 Thymine 25 9.94 C 5 H 6 O 4 1,1-Cyclopropanedi- carboxylic acid 1 25 1.82 2 25 7.43 C 5 H 6 O 4 trans-1-Propene-1,2- dicarboxylic acid 1 25 3.09 2 25 4.75 C 5 H 6 O 4 1-Propene-2,3- dicarboxylic acid 1 25 3.85 2 25 5.45 C 5 H 6 O 5 2-Oxoglutaric acid 1 25 2.47 2 25 4.68 C 5 H 7 NO 3 5,5-Dimethyl-2,4- oxazolidinedione 37 6.13 C 5 H 7 NO 3 L-Pyroglutamic acid 25 3.32 C 5 H 7 N 3 2,5-Pyridinediamine 20 6.48 C 5 H 7 N 3 Methylaminopyrazine 25 3.39 C 5 H 7 N 3 O 4 Azaserine 8.55 C 5 H 8 N 2 2,4-Dimethylimidazole 25 8.36 C 5 H 8 N 4 O 3 S 2 Methazolamide 7.30 C 5 H 8 O 2 trans-3-Pentenoic acid 25 4.51 C 5 H 8 O 4 Dimethylmalonic acid 25 3.15 C 5 H 8 O 4 Glutaric acid 1 18 4.32 2 25 5.42 C 5 H 8 O 4 Methylsuccinic acid 1 25 4.13 2 25 5.64 C 5 H 9 NO 2 L-Proline 1 25 1.95 2 25 10.64 C 5 H 9 NO 3 5-Amino-4-oxopentanoic acid 1 25 4.05 2 25 8.90 C 5 H 9 NO 3 trans-4-Hydroxyproline 1 25 1.82 2 25 9.66 C 5 H 9 NO 4 L-Glutamic acid 1 25 2.13 2 25 4.31 3 9.67 C 5 H 9 N 3 Histamine 1 25 6.04 2 25 9.75 C 5 H 10 N 2 O 3 Glycylalanine 25 3.15 C 5 H 10 N 2 O 3 L-Glutamine 1 25 2.17 2 25 9.13 C 5 H 10 N 2 O 4 Glycylserine 1 25 2.98 2 25 8.38 C 5 H 10 O 2 Pentanoic acid 20 4.83 C 5 H 10 O 2 2-Methylbutanoic acid 25 4.80 C 5 H 10 O 2 3-Methylbutanoic acid 25 4.77 C 5 H 10 O 2 2,2-Dimethylpropanoic acid 20 5.03 C 5 H 10 O 4 D-2-Deoxyribose 25 12.61 C 5 H 10 O 5 L-Ribose 25 12.22 C 5 H 10 O 5 D-Xylose 18 12.14 C 5 H 11 N Piperidine 25 11.123 C 5 H 11 N N-Methylpyrrolidine 25 10.46 C 5 H 11 NO 4-Methylmorpholine 25 7.38 C 5 H 11 NO 2 L-Valine 1 25 2.29 2 25 9.74 8-44 Dissociation Constants of Organic Acids and Bases Section 8.indb 44 4/30/05 8:46:49 AM Mol. form. Name Step t/°C pK a C 5 H 11 NO 2 DL-Norvaline 1 2.36 2 9.72 C 5 H 11 NO 2 L-Norvaline 1 25 2.32 2 25 9.81 C 5 H 11 NO 2 N-Propylglycine 1 25 2.35 2 25 10.19 C 5 H 11 NO 2 5-Aminopentanoic acid 1 25 4.27 2 25 10.77 C 5 H 11 NO 2 Betaine 0 1.83 C 5 H 11 NO 2 S L-Methionine 1 25 2.13 2 25 9.27 C 5 H 12 N 2 O Tetramethylurea 2 C 5 H 12 N 2 O 2 L-Ornithine 1 25 1.71 2 25 8.69 3 25 10.76 C 5 H 13 N Pentylamine 25 10.63 C 5 H 13 N 3-Pentanamine 17 10.59 C 5 H 13 N 3-Methyl-1-butanamine 25 10.60 C 5 H 13 N 2-Methyl-2-butanamine 19 10.85 C 5 H 13 N 2,2-Dimethylpropylamine 25 10.15 C 5 H 13 N Diethylmethylamine 25 10.35 C 5 H 14 NO Choline 25 13.9 C 5 H 14 N 2 1,5-Pentanediamine 1 25 10.05 2 25 10.93 C 6 H 3 Cl 3 N 2 O 2 4-Amino-3,5,6-trichloro- 2-pyridinecarboxlic acid 3.6 C 6 H 3 N 3 O 7 2,4,6-Trinitrophenol 24 0.42 C 6 H 4 Cl 2 O 2,3-Dichlorophenol 25 7.44 C 6 H 4 N 2 O 5 2,4-Dinitrophenol 25 4.07 C 6 H 4 N 2 O 5 2,5-Dinitrophenol 15 5.15 C 6 H 4 N 4 Pteridine 20 4.05 C 6 H 5 BrO 2-Bromophenol 25 8.45 C 6 H 5 BrO 3-Bromophenol 25 9.03 C 6 H 5 BrO 4-Bromophenol 25 9.37 C 6 H 5 Br 2 N 3,5-Dibromoaniline 25 2.34 C 6 H 5 ClO 2-Chlorophenol 25 8.56 C 6 H 5 ClO 3-Chlorophenol 25 9.12 C 6 H 5 ClO 4-Chlorophenol 25 9.41 C 6 H 5 Cl 2 N 2,4-Dichloroaniline 22 2.05 C 6 H 5 FO 2-Fluorophenol 25 8.73 C 6 H 5 FO 3-Fluorophenol 25 9.29 C 6 H 5 FO 4-Fluorophenol 25 9.89 C 6 H 5 IO 2-Iodophenol 25 8.51 C 6 H 5 IO 3-Iodophenol 25 9.03 C 6 H 5 IO 4-Iodophenol 25 9.33 C 6 H 5 NO 2-Pyridinecarboxaldehyde 25 12.68 C 6 H 5 NO 4-Pyridinecarboxaldehyde 30 12.05 C 6 H 5 NO 2 Nitrobenzene 0 3.98 C 6 H 5 NO 2 2-Pyridinecarboxylic acid 1 20 0.99 2 20 5.39 C 6 H 5 NO 2 3-Pyridinecarboxylic acid 1 25 2.00 2 25 4.82 C 6 H 5 NO 2 4-Pyridinecarboxylic acid 1 25 1.77 2 25 4.84 C 6 H 5 NO 3 2-Nitrophenol 25 7.23 C 6 H 5 NO 3 3-Nitrophenol 25 8.36 C 6 H 5 NO 3 4-Nitrophenol 25 7.15 C 6 H 5 N 3 1H-Benzotriazole 20 1.6 C 6 H 5 N 5 O 2-Amino-4- hydroxypteridine 1 20 2.27 2 20 7.96 C 6 H 5 N 5 O 2 Xanthopterin 2 20 6.59 Mol. form. Name Step t/°C pK a 3 20 9.31 C 6 H 6 BrN 2-Bromoaniline 25 2.53 C 6 H 6 BrN 3-Bromoaniline 25 3.53 C 6 H 6 BrN 4-Bromoaniline 25 3.89 C 6 H 6 ClN 2-Chloroaniline 25 2.66 C 6 H 6 ClN 3-Chloroaniline 25 3.52 C 6 H 6 ClN 4-Chloroaniline 25 3.98 C 6 H 6 FN 2-Fluoroaniline 25 3.20 C 6 H 6 FN 3-Fluoroaniline 25 3.59 C 6 H 6 FN 4-Fluoroaniline 25 4.65 C 6 H 6 IN 2-Iodoaniline 25 2.54 C 6 H 6 IN 3-Iodoaniline 25 3.58 C 6 H 6 IN 4-Iodoaniline 25 3.81 C 6 H 6 N 2 O 3-Pyridinecarboxamide 20 3.3 C 6 H 6 N 2 O 2-Pyridinecarbox- aldehyde oxime 1 20 3.59 2 20 10.18 C 6 H 6 N 2 O 2 2-Nitroaniline 25 -0.25 C 6 H 6 N 2 O 2 3-Nitroaniline 25 2.46 C 6 H 6 N 2 O 2 4-Nitroaniline 25 1.02 C 6 H 6 O Phenol 25 9.99 C 6 H 6 O 2 p-Hydroquinone 1 25 9.85 2 25 11.4 C 6 H 6 O 2 Pyrocatechol 1 25 9.34 2 25 12.6 C 6 H 6 O 2 Resorcinol 1 25 9.32 2 25 11.1 C 6 H 6 O 2 S Benzenesulfinic acid 20 1.3 C 6 H 6 O 3 S Benzenesulfonic acid 25 0.70 C 6 H 6 O 4 5-Hydroxy-2-(hydroxy- methyl)-4H-pyran-4-one 7.9 C 6 H 6 O 4 S 3-Hydroxybenzene- sulfonic acid 25 9.07 C 6 H 6 O 4 S 4-Hydroxybenzene- sulfonic acid 25 9.11 C 6 H 6 O 6 cis-1-Propene-1,2,3- tricarboxylic acid 25 1.95 C 6 H 6 O 6 trans-1-Propene-1,2,3- tricarboxylic acid 1 25 2.80 2 25 4.46 C 6 H 6 S Benzenethiol 25 6.62 C 6 H 7 BO 2 Benzeneboronic acid 8.83 C 6 H 7 N Aniline 25 4.87 C 6 H 7 N 2-Methylpyridine 25 6.00 C 6 H 7 N 3-Methylpyridine 25 5.70 C 6 H 7 N 4-Methylpyridine 25 5.99 C 6 H 7 NO 2-Aminophenol 1 20 4.78 2 20 9.97 C 6 H 7 NO 3-Aminophenol 1 20 4.37 2 20 9.82 C 6 H 7 NO 4-Aminophenol 1 25 5.48 2 25 10.30 C 6 H 7 NO 2-Methoxypyridine 20 3.28 C 6 H 7 NO 3-Methoxypyridine 25 4.78 C 6 H 7 NO 4-Methoxypyridine 25 6.58 C 6 H 7 NO 3 S 2-Aminobenzenesulfonic acid 25 2.46 C 6 H 7 NO 3 S 3-Aminobenzenesulfonic acid 25 3.74 C 6 H 7 NO 3 S 4-Aminobenzenesulfonic acid 25 3.23 C 6 H 8 N 2 N-Methylpyridinamine 20 9.65 C 6 H 8 N 2 o-Phenylenediamine 1 20 4.57 Dissociation Constants of Organic Acids and Bases 8-45 Section 8.indb 45 4/30/05 8:46:51 AM Mol. form. Name Step t/°C pK a 2 20 0.80 C 6 H 8 N 2 m-Phenylenediamine 1 20 5.11 2 20 2.50 C 6 H 8 N 2 p-Phenylenediamine 1 20 6.31 2 20 2.97 C 6 H 8 N 2 Phenylhydrazine 15 8.79 C 6 H 8 O 2 2,4-Hexadienoic acid 25 4.76 C 6 H 8 O 2 1,3-Cyclohexanedione 25 5.26 C 6 H 8 O 4 2,2-Dimethyl-1,3- dioxane-4,6-dione 5.1 C 6 H 8 O 6 L-Ascorbic acid 1 25 4.04 2 16 11.7 C 6 H 8 O 7 Citric acid 1 25 3.13 2 25 4.76 3 25 6.40 C 6 H 8 O 7 Isocitric acid 1 25 3.29 2 25 4.71 3 25 6.40 C 6 H 9 NO 6 Nitrilotriacetic acid 1 20 3.03 2 20 3.07 3 20 10.70 C 6 H 9 NO 6 L-γ-Carboxyglutamic acid 1 25 1.7 2 25 3.2 3 25 4.75 4 25 9.9 C 6 H 9 N 3 4,6-Dimethylpyrimi- dinamine 20 4.82 C 6 H 9 N 3 O 2 L-Histidine 1 25 1.80 2 25 6.04 3 25 9.33 C 6 H 10 O 2 Cyclopentanecarboxylic acid 25 4.99 C 6 H 10 O 3 Ethyl acetoacetate 25 10.68 C 6 H 10 O 4 3-Methylglutaric acid 25 4.24 C 6 H 10 O 4 Adipic acid 1 18 4.41 2 18 5.41 C 6 H 11 NO 2 2-Piperidinecarboxylic acid 1 25 2.28 2 25 10.72 C 6 H 11 NO 3 Adipamic acid 25 4.63 C 6 H 11 NO 4 2-Aminoadipic acid 1 25 2.14 2 25 4.21 3 25 9.77 C 6 H 11 N 3 O 4 N-(N-Glycylglycyl)glycine 1 25 3.225 2 25 8.09 C 6 H 11 N 3 O 4 Glycylasparagine 1 25 2.942 2 18 8.44 C 6 H 12 N 2 Triethylenediamine 1 3.0 2 8.7 C 6 H 12 N 2 O 4 S 2 L-Cystine 1 1 2 2.1 3 8.02 4 8.71 C 6 H 12 O 2 Hexanoic acid 25 4.85 C 6 H 12 O 2 4-Methylpentanoic acid 18 4.84 C 6 H 12 O 6 β-D-Fructose 25 12.27 C 6 H 12 O 6 α-D-Glucose 25 12.46 C 6 H 12 O 6 D-Mannose 25 12.08 C 6 H 13 N Cyclohexylamine 25 10.64 C 6 H 13 N 1-Methylpiperidine 25 10.38 C 6 H 13 N 1,2-Dimethylpyrrolidine 26 10.20 C 6 H 13 NO N-Ethylmorpholine 25 7.67 Mol. form. Name Step t/°C pK a C 6 H 13 NO 2 L-Leucine 1 25 2.33 2 25 9.74 C 6 H 13 NO 2 L-Isoleucine 1 25 2.32 2 25 9.76 C 6 H 13 NO 2 L-Norleucine 1 25 2.34 2 25 9.83 C 6 H 13 NO 2 6-Aminohexanoic acid 1 25 4.37 2 25 10.80 C 6 H 13 NO 4 N,N-Bis(2-hydroxy- ethyl)glycine 2 20 8.35 C 6 H 13 N 3 O 3 Citrulline 1 25 2.43 2 25 9.69 C 6 H 14 N 2 cis-1,2-Cyclohexane- diamine 1 20 9.93 2 20 6.13 C 6 H 14 N 2 trans-1,2-Cyclohexane- diamine 1 20 9.94 2 20 6.47 C 6 H 14 N 2 cis-2,5-Dimethyl- piperazine 1 25 9.66 2 25 5.20 C 6 H 14 N 2 O 2 L-Lysine 1 25 2.16 2 25 9.06 3 25 10.54 C 6 H 14 N 4 O 2 L-Arginine 1 25 1.82 2 25 8.99 3 25 12.5 C 6 H 14 O 6 D-Mannitol 18 13.5 C 6 H 15 N Hexylamine 25 10.56 C 6 H 15 N Diisopropylamine 25 11.05 C 6 H 15 N Triethylamine 25 10.75 C 6 H 15 NO 3 Triethanolamine 25 7.76 C 6 H 16 N 2 1,6-Hexanediamine 1 0 11.86 2 0 10.76 C 6 H 16 N 2 N,N,N’,N’-Tetramethyl- 1,2-ethanediamine 1 25 10.40 2 25 8.26 C 6 H 19 NSi 2 Hexamethyldisilazane 7.55 C 7 HF 5 O 2 Pentafluorobenzoic acid 25 1.75 C 7 H 3 Br 2 NO 3,5-Dibromo-4- hydroxybenzonitrile 4.06 C 7 H 3 N 3 O 8 2,4,6-Trinitrobenzoic acid 25 0.65 C 7 H 4 Cl 3 NO 3 Triclopyr 2.68 C 7 H 4 N 2 O 6 2,4-Dinitrobenzoic acid 25 1.43 C 7 H 5 BrO 2 2-Bromobenzoic acid 25 2.85 C 7 H 5 BrO 2 3-Bromobenzoic acid 25 3.81 C 7 H 5 BrO 2 4-Bromobenzoic acid 25 3.96 C