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Title: Lactonization and protonation of gluconic acid: a thermodynamicand kinetic study by potentiometry, nmr and esi-ms

Abstract

In acidic aqueous solutions, gluconate protonation is coupled with lactonization of gluconic acid. With the decrease of pC{sub H}, two lactones ({delta}/{gamma}) are sequentially formed. The {delta}-lactone forms more readily than the {gamma}-lactone. In 0.1 M gluconate solutions, if pC{sub H} is above 2.5, only the {delta}-lactone is generated. When pC{sub H} is decreased below 2.0, the formation of the {gamma}-lactone is observable although the {delta}-lactone predominates. At I = 0.1 M NaClO{sub 4} and room temperature, the deprotonation constant of the carboxylic group, using the NMR technique, was determined to be log K{sub a} = 3.30 {+-} 0.02; the {delta}-lactonization constant, by the batch potentiometric titrations, was obtained to be log K{sub L} = - (0.54 {+-} 0.04). Using ESI-MS, the rate constants of the {delta}-lactonization and the hydrolysis at pC{sub H} {approx} 5.0 were estimated to be k{sub 1} = 3.2 x 10{sup -5} s{sup -1} and k{sup -1} = 1.1 x 10{sup -4} s{sup -1}, respectively.

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
COLLABORATION - Washington StateUniversity
OSTI Identifier:
929316
Report Number(s):
LBNL-62848
Journal ID: ISSN 0095-9782; JSLCAG; TRN: US200813%%184
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solution Chemistry; Journal Volume: 36; Journal Issue: 10; Related Information: Journal Publication Date: 10/2007
Country of Publication:
United States
Language:
English
Subject:
37; AQUEOUS SOLUTIONS; GLUCONIC ACID; HYDROLYSIS; KINETICS; LACTONES; POTENTIOMETRY; THERMODYNAMICS

Citation Formats

Zhang, Z., Gibson, P., Clark, S.B., Tian, G., Zanonato, P., and Rao, L.. Lactonization and protonation of gluconic acid: a thermodynamicand kinetic study by potentiometry, nmr and esi-ms. United States: N. p., 2007. Web. doi:10.1007/s10953-007-9182-x.
Zhang, Z., Gibson, P., Clark, S.B., Tian, G., Zanonato, P., & Rao, L.. Lactonization and protonation of gluconic acid: a thermodynamicand kinetic study by potentiometry, nmr and esi-ms. United States. doi:10.1007/s10953-007-9182-x.
Zhang, Z., Gibson, P., Clark, S.B., Tian, G., Zanonato, P., and Rao, L.. Wed . "Lactonization and protonation of gluconic acid: a thermodynamicand kinetic study by potentiometry, nmr and esi-ms". United States. doi:10.1007/s10953-007-9182-x. https://www.osti.gov/servlets/purl/929316.
@article{osti_929316,
title = {Lactonization and protonation of gluconic acid: a thermodynamicand kinetic study by potentiometry, nmr and esi-ms},
author = {Zhang, Z. and Gibson, P. and Clark, S.B. and Tian, G. and Zanonato, P. and Rao, L.},
abstractNote = {In acidic aqueous solutions, gluconate protonation is coupled with lactonization of gluconic acid. With the decrease of pC{sub H}, two lactones ({delta}/{gamma}) are sequentially formed. The {delta}-lactone forms more readily than the {gamma}-lactone. In 0.1 M gluconate solutions, if pC{sub H} is above 2.5, only the {delta}-lactone is generated. When pC{sub H} is decreased below 2.0, the formation of the {gamma}-lactone is observable although the {delta}-lactone predominates. At I = 0.1 M NaClO{sub 4} and room temperature, the deprotonation constant of the carboxylic group, using the NMR technique, was determined to be log K{sub a} = 3.30 {+-} 0.02; the {delta}-lactonization constant, by the batch potentiometric titrations, was obtained to be log K{sub L} = - (0.54 {+-} 0.04). Using ESI-MS, the rate constants of the {delta}-lactonization and the hydrolysis at pC{sub H} {approx} 5.0 were estimated to be k{sub 1} = 3.2 x 10{sup -5} s{sup -1} and k{sup -1} = 1.1 x 10{sup -4} s{sup -1}, respectively.},
doi = {10.1007/s10953-007-9182-x},
journal = {Journal of Solution Chemistry},
number = 10,
volume = 36,
place = {United States},
year = {Wed Jan 10 00:00:00 EST 2007},
month = {Wed Jan 10 00:00:00 EST 2007}
}
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