Hydrolysis of D-glucono-.delta.-lactone. I. General acid-base catalysis, solvent deuterium isotope effects, and transition state characterization

Abstract

Polarimetric and spectrophotometric methods have been used to study the hydrolysis of D-gluCOn0-&lactone over a wide range of pH values at 25.0'. The reaction has been found to exhibit both general acid and general base catalysis. Catalytic coefficients for hydronium ion and malonic, formic, and acetic acids conform to the Bronsted relation with an exponent a = 0.42 i 0.02. General acid catalysis by dihydrogen phosphate monoanion is ca. 50-fold larger than that ascribable to it from the pK, of HzP04-. Catalytic coefficients for water, malonate monoanion, formate, acetate, imidazole, monohydrogen phosphate, and Tris conform to the Brgnsted relation with an exponent /3 = 0.45 i 0.02. Hydroxide ion shows a positive deviation of ca. two log units from this line. In the water-catalyzed hydrolysis, the solvent isotope effect k B ,~/ k~z~ has a value of 3.9. The solvent deuterium isotope effects associated with a number of general acids and bases are also shown to be quite similar to those observed in the hydration of acetaldehyde and in the mutarotation of glucose. Further transition state characterization follows from the absence of oxygen exchange during the hydrolysis of Dglucono-&lactone.he Mactone of D-gluconic acid occupies a central T position in biological systems. For example, its 6-phosphate derivative is the immediate oxidation product of glucose 6-phosphate in the hexose monophosphate shunt. Besides its importance in biological systems, the lactone has several diverse functions, including its use as a sequestering agent. Moreover, its hydrolysis to D-gluconic acid (eq 1) is of much OH OH COOH (1)

Intramolecular Lactonization of Poly(α-hydroxyacrylic acid): Kinetics and Reaction Mechanism

“…In the present work, no strong pH dependency of reaction rates was seen but the rates measured are in good accordance with previous studies based on similar cyclic lactone structures of gluconic acid or its derivatives, thus supporting the addition-elimination approach [12,24]. Furthermore, the formation of a transient tetrahedral intermediate, resulting from an analogous rate-limiting nucleophilic attack of hydroxide, has been discussed in the context of another related compound D-glucuno--lactone [25].…”

A microrheological study of hydrogel kinetics and micro-heterogeneity

“…The selected masses of GdL are 5.34 mg, 4.01 mg and 2.67 mg; equivalent to 10 mM, 7.5 mM and 5 mM GdL, respectively. The sample is then mixed, by shaking vigorously for 20 s. The resulting hydrolysis of GdL leads to the formation of gluconic acid via a series of intermediate steps [37]. Hence, the pH decreases gradually and gelation occurs over time.…”

Acaricidal Activity of DHEMH, Derived from Patchouli Oil, against House Dust Mite, Dermatophagoides farinae

“…Pogostone is a ketone containing lactone and therefore unstable in alkaline and acidic conditions. [30][31][32][33][34] An openring hydrolysis reaction resulted in the formation of DHEMH from pogostone during the extraction and separation (Fig. 2).…”