Evaluation of equilibrium constants for deprotonation and lactonisation of α-D-isosaccharinic acid

Abstract

A great deal of disagreement exists in the literature regarding the intrinsic deprotonation and lactonisation constants of α-D-isosaccharinic acid (ISA). Based on a combination of nuclear magnetic resonance and interpretations using the specific ion interaction theory (SIT) of extensive experimental Ca(ISA) 2 (cr) solubility data involving α-D-isosaccharinic acid, the reliable value of log 10 K • for [HISA(aq) ISA − + H + ] is −3.27 ± 0.01 and for [HISA(aq) ISL(α-D-isosaccharinate-1,4-lactone)(aq) + H 2 O] is 0.49 ± 0.09. These data also provide log 10 K • of −3.76 ± 0.09 for the reaction [ISL(aq) + H 2 O ISA − + H + ] and −3.88 ± 0.09 for the composite reaction [HISA(aq) + ISL(aq) ISA − + H + ]. Reinterpretation of extensive Ca(ISA) 2 (cr) solubility data using the SIT activity coefficient model provides log 10 K • of −6.40 ± 0.09 for [Ca(ISA) 2 (cr) Ca 2 + + 2(ISA) − ] and of 1.70 ± 0.09 for [Ca 2 + + ISA − CaISA + ] which are consistent with all of the available values.

Complex formation between UO22+and α-isosaccharinic acid: insights on a molecular level

“…Equilibrium constants for deprotonation and lactonization were recently evaluated by Rai and Kitamura. 24 The pK a value of the carboxylic group is 3.27 while the deprotonation of alcohol functionalities is expected to occur above pH 12. 23,25,26 However, the acidity of alcohol functionalities is expected to increase upon their interaction with Lewis acidic metal centers.…”

Developing cellulosic waste products as platform chemicals: protecting group chemistry of α-glucoisosaccharinic acid

“…It should be noted that whilst the gluco-prefix identifies GISAs as being derived from a 1,4glucan such as cellulose , in the early scientific literature and also in current literature describing environmental aspects of GISA's properties [23][24][25][26] these molecules are frequently referred to as isosaccharinic acids (ISA).…”

Complex formation between calcium and hydroxy/oxocarboxylates in neutral and highly alkaline aqueous solutions

“…These results show that the lactonization reaction is very slow compared to simple protonation or deprotonation reactions. From these two kinetic constants, an independent value for the lactonization constant was calculated to be logK = 0.820 (5). [14] These data indicate that the conversion between HIsa and IsaL is relatively slow, while the hydrolysis of the lactone occurs more rapidly.…”

“…On the one hand, both Isaand Glucform sparingly soluble Ca-salts. The solubility products of CaIsa2 and CaGluc2 have been determined to be pKsp = 6.53(2) and 4.19 (5), respectively, at T = (20 ± 1) °C and I = 0 M. [60,131] This means that the relatively large amount of Ca 2+ present in the cement pore water of L/ILW repositories decreases the concentration of the complexant. On the other hand, as the concentration of Ca 2+ may be several orders of magnitude higher than that of the radionuclides, the complexing agents are more likely to form complexes with Ca 2+ than with the radioactive metal ions.…”

“…1. a), a polyhydroxy carboxylate relevant in nuclear waste disposal, the deprotonation constant, pKa was determined to be between 3.27 and 4.46, [2][3][4][5][6][7][8][9][10][11] depending on the temperature, ionic strength and experimental technique applied during the measurements. Table 1 summarizes the values obtained for the reaction HIsa ⇌ Isa -+ H + .…”