Supplementary Information for:
Ionization Constants of DL-2-aminobutyric Acid and DL-Norvaline under Hydrothermal conditions by UV-Visible Spectroscopy
Daniel E. Nieto Roca 1 · Carmen M. Romero 1 · Peter R. Tremaine 1
1 Departamento de Química, Facultad de Ciencias, Universidad Nacional de Colombia, Calle 44 # 45-67 Bloque B9, Bogotá, Colombia
2 Department of Chemistry, University of Guelph, Guelph, ON, Canada, N1G 2W1
Fig. S1 Experimental values for the second ionization constant, (Eq. 3), of (a) DL-2-aminobutyric acid and (b) DL-norvaline, plotted as a function of temperature. Solid diamonds correspond to data from the literature [6, 15, 16-19, 22, 23]. Open points show results from this study. Open diamonds, 4-nitrophenol data from Ehlerova et al. [36]. Data for 2-naphthoic acid: open squares, from Xiang and Johnston [28] and open triangles, recalculated from room temperature data (see appendix). Equation 29 fitted with: dashed line, one parameter or continuous line, two calculated parameters
Table S1 Ionization constants (expressed as pK), standard molar Gibbs energies, enthalpies and entropies at 25 °C for the first ionization reaction H2A+(aq) HA±(aq) + H+(aq)
2-Aminobutyric acid / 2.286 a,b / 13.05 a / 1.59 a,b / –38.5 a,b / –100 a,b
Norvaline / 2.318 a / 13.23 a / 1.63 a / –38.9 a / –126 a
Glycine / 2.35 a,b / 13.41 a / 4.1 a / –31.38 a,b / –121 a,b
2-Alanine / 2.348 a,b / 13.4 a / 3.138 a,b / –34.31 a,b / –142.2 a,b
a Ref. [38]
b Ref. [24]
Table S2 Ionization constants (expressed as pK), standard molar Gibbs energies, enthalpies and entropies at 25 °C for the second ionization reaction HA±(aq) A–(aq) + H+(aq)
Amino acid / pKa / DrG° / (kJ·mol–1) / DrH° / (kJ·mol–1) / DrS° / (J·mol–1·K–1) / DrCp° / (J·mol–1·K–1)a,b2-Aminobutyric acid / 9.83 b / 56.11 c / 45.44 b / –36 b / (–80)
Norvaline / 9.808 c / 55.98 c / 45.52 c / –35.15 c / ---
Glycine / 9.77 d / 55.78 d / 44 d / –38.9 e / (–77)
2-Alanine / 9.866 b,c / 56.32 c / 46.19 b,c / –33.5 b,c / (–82)
a Constant value for the temperature range 50 °C £ t £ 125 °C
b Ref. [23]c Ref. [16]
d Ref. [5]
e Ref. [21]
Table S3 Thermodynamic data for the zwitterions of the four amino acids at 25 °C
2-Aminobutyric acid / 224.6 a / 75.51 a / –577.81 b,f
Norvaline / 317.4 c / 91.87 c / –604.59 b,g
Glycine / 37.6 a / 43.26 a / –528.1 b,d
2-Alanine / 141.2 a / 60.47 a / –560.5 b,e
a Ref. [46]
b Ref. [47]
c Ref. [48]
d Ref. [49]
e Ref. [50]
f Value for 4-aminobutyric acid
g Value for 5-aminovaleric acid
Table S4 Predicted values from the SOCW model for and for the first and second ionization reactions of a-amino acids at 10.0 MPa
0.0 / –8.45 / –136.24 / –0.17 / –68.84
12.5 / –7.99 / –73.51 / 0.62 / –93.73
25.0 / –7.77 / –43.00 / 0.90 / –97.35
37.5 / –7.71 / –25.92 / 0.83 / –98.80
50.0 / –7.76 / –15.42 / 0.50 / –100.96
62.5 / –7.90 / –8.71 / –0.03 / –103.16
75.0 / –8.11 / –4.57 / –0.69 / –104.48
87.5 / –8.40 / –2.38 / –1.47 / –104.35
100.0 / –8.76 / –1.85 / –2.33 / –102.55
112.5 / –9.20 / –2.80 / –3.28 / –99.09
125.0 / –9.71 / –5.16 / –4.30 / –94.13
137.5 / –10.32 / –8.89 / –5.40 / –87.85
150.0 / –11.03 / –14.02 / –6.59 / –80.50
162.5 / –11.85 / –20.65 / –7.88 / –72.30
175.0 / –12.82 / –28.91 / –9.29 / –63.52
187.5 / –13.96 / –39.06 / –10.87 / –54.41
200.0 / –15.31 / –51.47 / –12.63 / –45.28
212.5 / –16.94 / –66.71 / –14.66 / –36.54
225.0 / –18.91 / –85.66 / –17.01 / –28.74
237.5 / –21.35 / –109.73 / –19.82 / –22.76
250.0 / –24.43 / –141.23 / –23.24 / –20.10
262.5 / –28.43 / –184.24 / –27.54 / –23.47
275.0 / –33.81 / –246.53 / –33.16 / –38.21
287.5 / –41.42 / –344.48 / –40.88 / –76.03
300.0 / –53.04 / –518.36 / –52.33 / –166.49
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Table S5 Predicted values from the SOCW model for , , and for the first ionization reaction of glycine, 2-alanine, 2-aminobutyric acid and norvaline at 10 MPa
Glycine / 2-Alanine / 2-Aminobutyric acid / Norvaline0.0 / 5.96 / –24.54 / 12.66 / 2.42 / 5.00 / –27.47 / 12.50 / 2.39 / 3.45 / –31.66 / 12.10 / 2.31 / 3.49 / –32.06 / 12.24 / 2.34
12.5 / 4.70 / –29.06 / 13.00 / 2.38 / 3.74 / –31.99 / 12.87 / 2.35 / 2.19 / –36.18 / 12.52 / 2.29 / 2.23 / –36.58 / 12.68 / 2.32
25.0 / 3.99 / –31.49 / 13.38 / 2.34 / 3.03 / –34.42 / 13.29 / 2.33 / 1.48 / –38.61 / 12.99 / 2.28 / 1.52 / –39.01 / 13.15 / 2.30
37.5 / 3.57 / –32.87 / 13.78 / 2.32 / 2.61 / –35.80 / 13.73 / 2.31 / 1.06 / –39.99 / 13.48 / 2.27 / 1.10 / –40.39 / 13.65 / 2.29
50.0 / 3.32 / –33.67 / 14.20 / 2.29 / 2.35 / –36.60 / 14.18 / 2.29 / 0.81 / –40.79 / 13.99 / 2.26 / 0.85 / –41.19 / 14.16 / 2.29
62.5 / 3.17 / –34.12 / 14.62 / 2.28 / 2.21 / –37.05 / 14.64 / 2.28 / 0.66 / –41.24 / 14.50 / 2.26 / 0.70 / –41.64 / 14.68 / 2.28
75.0 / 3.09 / –34.36 / 15.05 / 2.26 / 2.13 / –37.29 / 15.11 / 2.27 / 0.58 / –41.48 / 15.02 / 2.25 / 0.62 / –41.88 / 15.20 / 2.28
87.5 / 3.05 / –34.48 / 15.48 / 2.24 / 2.08 / –37.41 / 15.57 / 2.26 / 0.54 / –41.60 / 15.54 / 2.25 / 0.58 / –42.00 / 15.72 / 2.28
100.0 / 3.02 / –34.55 / 15.91 / 2.23 / 2.06 / –37.48 / 16.04 / 2.25 / 0.51 / –41.67 / 16.06 / 2.25 / 0.55 / –42.07 / 16.25 / 2.27
112.5 / 2.99 / –34.62 / 16.34 / 2.21 / 2.03 / –37.55 / 16.51 / 2.24 / 0.48 / –41.74 / 16.58 / 2.25 / 0.52 / –42.14 / 16.77 / 2.27
125.0 / 2.94 / –34.74 / 16.78 / 2.20 / 1.98 / –37.67 / 16.98 / 2.23 / 0.43 / –41.86 / 17.10 / 2.24 / 0.47 / –42.26 / 17.30 / 2.27
137.5 / 2.86 / –34.96 / 17.21 / 2.19 / 1.90 / –37.89 / 17.45 / 2.22 / 0.35 / –42.08 / 17.63 / 2.24 / 0.39 / –42.48 / 17.83 / 2.27
150.0 / 2.72 / –35.29 / 17.65 / 2.18 / 1.75 / –38.22 / 17.93 / 2.21 / 0.21 / –42.41 / 18.15 / 2.24 / 0.25 / –42.81 / 18.36 / 2.27
162.5 / 2.50 / –35.80 / 18.10 / 2.17 / 1.54 / –38.73 / 18.41 / 2.21 / –0.01 / –42.92 / 18.69 / 2.24 / 0.03 / –43.32 / 18.90 / 2.27
175.0 / 2.19 / –36.49 / 18.55 / 2.16 / 1.23 / –39.42 / 18.90 / 2.20 / –0.32 / –43.61 / 19.23 / 2.24 / –0.28 / –44.01 / 19.45 / 2.27
187.5 / 1.77 / –37.42 / 19.01 / 2.16 / 0.81 / –40.35 / 19.40 / 2.20 / –0.74 / –44.54 / 19.78 / 2.24 / –0.70 / –44.94 / 20.00 / 2.27
200.0 / 1.21 / –38.63 / 19.48 / 2.15 / 0.25 / –41.56 / 19.91 / 2.20 / –1.30 / –45.75 / 20.34 / 2.25 / –1.26 / –46.15 / 20.57 / 2.27
212.5 / 0.47 / –40.16 / 19.98 / 2.15 / –0.49 / –43.09 / 20.44 / 2.20 / –2.04 / –47.28 / 20.92 / 2.25 / –2.00 / –47.68 / 21.16 / 2.28
225.0 / –0.48 / –42.09 / 20.49 / 2.15 / –1.44 / –45.02 / 20.99 / 2.20 / –2.99 / –49.21 / 21.53 / 2.26 / –2.95 / –49.61 / 21.77 / 2.28
237.5 / –1.69 / –44.49 / 21.03 / 2.15 / –2.65 / –47.42 / 21.56 / 2.21 / –4.20 / –51.61 / 22.16 / 2.27 / –4.16 / –52.01 / 22.40 / 2.29
250.0 / –3.25 / –47.51 / 21.60 / 2.16 / –4.21 / –50.44 / 22.18 / 2.21 / –5.76 / –54.63 / 22.82 / 2.28 / –5.72 / –55.03 / 23.07 / 2.30
262.5 / –5.27 / –51.32 / 22.22 / 2.17 / –6.23 / –54.25 / 22.83 / 2.23 / –7.78 / –58.44 / 23.53 / 2.29 / –7.74 / –58.84 / 23.78 / 2.32
275.0 / –7.93 / –56.24 / 22.89 / 2.18 / –8.90 / –59.17 / 23.54 / 2.24 / –10.44 / –63.36 / 24.29 / 2.31 / –10.40 / –63.76 / 24.54 / 2.34
287.5 / –11.58 / –62.80 / 23.63 / 2.20 / –12.54 / –65.73 / 24.31 / 2.27 / –14.09 / –69.92 / 25.12 / 2.34 / –14.05 / –70.32 / 25.38 / 2.36
300.0 / –16.85 / –72.11 / 24.47 / 2.23 / –17.82 / –75.04 / 25.19 / 2.30 / –19.36 / –79.23 / 26.04 / 2.37 / –19.32 / –79.63 / 26.31 / 2.40
Table S6 Predicted values from the SOCW model for , , and for the second ionization reaction of glycine, 2-alanine, 2-aminobutyric acid and norvaline at 10 MPa
0.0 / 46.26 / –31.03 / 54.74 / 10.47 / 48.45 / –25.63 / 55.45 / 10.60 / 47.70 / –28.13 / 55.39 / 10.59 / 47.78 / –27.28 / 55.23 / 10.56
12.5 / 45.20 / –34.82 / 55.15 / 10.08 / 47.39 / –29.42 / 55.80 / 10.20 / 46.64 / –31.92 / 55.76 / 10.20 / 46.72 / –31.07 / 55.60 / 10.17
25.0 / 44.00 / –38.94 / 55.61 / 9.74 / 46.19 / –33.54 / 56.19 / 9.84 / 45.44 / –36.04 / 56.18 / 9.84 / 45.52 / –35.19 / 56.01 / 9.81
37.5 / 42.77 / –42.97 / 56.12 / 9.44 / 44.96 / –37.57 / 56.63 / 9.52 / 44.21 / –40.07 / 56.66 / 9.53 / 44.29 / –39.22 / 56.48 / 9.50
50.0 / 41.53 / –46.90 / 56.68 / 9.16 / 43.72 / –41.50 / 57.13 / 9.23 / 42.97 / –44.00 / 57.19 / 9.24 / 43.05 / –43.15 / 56.99 / 9.21
62.5 / 40.25 / –50.78 / 57.29 / 8.92 / 42.44 / –45.38 / 57.67 / 8.97 / 41.69 / –47.88 / 57.76 / 8.99 / 41.77 / –47.03 / 57.55 / 8.96
75.0 / 38.95 / –54.58 / 57.95 / 8.69 / 41.14 / –49.18 / 58.26 / 8.74 / 40.39 / –51.68 / 58.38 / 8.76 / 40.47 / –50.83 / 58.17 / 8.73
87.5 / 37.64 / –58.27 / 58.66 / 8.50 / 39.83 / –52.87 / 58.90 / 8.53 / 39.08 / –55.37 / 59.05 / 8.55 / 39.16 / –54.52 / 58.82 / 8.52
100.0 / 36.35 / –61.80 / 59.41 / 8.32 / 38.54 / –56.40 / 59.58 / 8.34 / 37.79 / –58.90 / 59.77 / 8.37 / 37.87 / –58.05 / 59.53 / 8.33
112.5 / 35.09 / –65.12 / 60.20 / 8.15 / 37.28 / –59.72 / 60.31 / 8.17 / 36.53 / –62.22 / 60.52 / 8.20 / 36.61 / –61.37 / 60.28 / 8.16
125.0 / 33.88 / –68.21 / 61.03 / 8.01 / 36.07 / –62.81 / 61.07 / 8.01 / 35.32 / –65.31 / 61.32 / 8.04 / 35.40 / –64.46 / 61.06 / 8.01
137.5 / 32.74 / –71.02 / 61.91 / 7.87 / 34.93 / –65.62 / 61.88 / 7.87 / 34.18 / –68.12 / 62.15 / 7.91 / 34.26 / –67.27 / 61.89 / 7.87
150.0 / 31.69 / –73.55 / 62.81 / 7.75 / 33.88 / –68.15 / 62.71 / 7.74 / 33.13 / –70.65 / 63.02 / 7.78 / 33.21 / –69.80 / 62.74 / 7.74
162.5 / 30.73 / –75.78 / 63.74 / 7.64 / 32.92 / –70.38 / 63.58 / 7.62 / 32.17 / –72.88 / 63.92 / 7.66 / 32.25 / –72.03 / 63.63 / 7.63
175.0 / 29.88 / –77.70 / 64.70 / 7.54 / 32.07 / –72.30 / 64.47 / 7.51 / 31.32 / –74.80 / 64.84 / 7.56 / 31.40 / –73.95 / 64.54 / 7.52
187.5 / 29.14 / –79.32 / 65.68 / 7.45 / 31.33 / –73.92 / 65.39 / 7.41 / 30.58 / –76.42 / 65.79 / 7.46 / 30.66 / –75.57 / 65.48 / 7.42
200.0 / 28.52 / –80.66 / 66.68 / 7.36 / 30.71 / –75.26 / 66.32 / 7.32 / 29.96 / –77.76 / 66.75 / 7.37 / 30.04 / –76.91 / 66.43 / 7.33
212.5 / 28.01 / –81.72 / 67.70 / 7.28 / 30.20 / –76.32 / 67.27 / 7.23 / 29.45 / –78.82 / 67.73 / 7.28 / 29.53 / –77.97 / 67.40 / 7.25
225.0 / 27.60 / –82.55 / 68.73 / 7.21 / 29.79 / –77.15 / 68.23 / 7.15 / 29.04 / –79.65 / 68.72 / 7.21 / 29.12 / –78.80 / 68.38 / 7.17
237.5 / 27.28 / –83.19 / 69.76 / 7.14 / 29.47 / –77.79 / 69.20 / 7.08 / 28.72 / –80.29 / 69.72 / 7.13 / 28.80 / –79.44 / 69.37 / 7.10
250.0 / 27.02 / –83.70 / 70.81 / 7.07 / 29.21 / –78.30 / 70.17 / 7.01 / 28.46 / –80.80 / 70.73 / 7.06 / 28.54 / –79.95 / 70.36 / 7.03
262.5 / 26.76 / –84.19 / 71.85 / 7.01 / 28.95 / –78.79 / 71.15 / 6.94 / 28.20 / –81.29 / 71.74 / 7.00 / 28.28 / –80.44 / 71.37 / 6.96
275.0 / 26.39 / –84.87 / 72.91 / 6.95 / 28.58 / –79.47 / 72.14 / 6.87 / 27.83 / –81.97 / 72.76 / 6.93 / 27.91 / –81.12 / 72.38 / 6.90
287.5 / 25.71 / –86.10 / 73.98 / 6.89 / 27.90 / –80.70 / 73.14 / 6.81 / 27.15 / –83.20 / 73.79 / 6.88 / 27.23 / –82.35 / 73.40 / 6.84
300.0 / 24.27 / –88.62 / 75.07 / 6.84 / 26.46 / –83.22 / 74.16 / 6.76 / 25.71 / –85.72 / 74.85 / 6.82 / 25.79 / –84.87 / 74.44 / 6.78
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