72-03-7Relevant articles and documents
Fluorescent monitoring of the reaction kinetics of nonfluorescent molecules enabled by a fluorescent receptor
Bai, Lin-Ming,Zhou, Hang,Liu, Wei-Er,Chai, Hongxin,Yang, Liu-Pan,Yan, Wei,Zhang, Wen,Yang, Hong-Hui,Jiang, Wei
supporting information, p. 3128 - 3131 (2019/04/02)
A facile fluorescent method was developed to quantitatively monitor the hydrolysis kinetics of nonfluorescent esters by using a fluorecent endo-functionalized molecular tube and its recognition ability towards small polar molecules in water. It is possible to determine the apparent rate constants and study the structure-activity relationship.
Nitrous Oxide as a Hydrogen Acceptor for the Dehydrogenative Coupling of Alcohols
Gianetti, Thomas L.,Annen, Samuel P.,Santiso-Quinones, Gustavo,Reiher, Markus,Driess, Matthias,Grützmacher, Hansj?rg
supporting information, p. 1854 - 1858 (2016/02/03)
The oxidation of alcohols with N2O as the hydrogen acceptor was achieved with low catalyst loadings of a rhodium complex that features a cooperative bis(olefin)amido ligand under mild conditions. Two different methods enable the formation of either the corresponding carboxylic acid or the ester. N2 and water are the only by-products. Mechanistic studies supported by DFT calculations suggest that the oxygen atom of N2O is transferred to the metal center by insertion into the Rh-H bond of a rhodium amino hydride species, generating a rhodium hydroxy complex as a key intermediate.
Modelling of the periodic anaerobic baffled reactor (PABR) based on the retaining factor concept
Skiadas,Gavala,Lyberatos
, p. 3725 - 3736 (2007/10/03)
The fact that the active biomass is continuously removed from the continuously stirred anaerobic digesters, leading to long retention times, has been overcome in a number of high rate systems based on immobilization of the active biomass, such as the Upflow Anaerobic Sludge Blanket Reactor (UASBR) and the Anaerobic Baffled Reactor (ABR). A kinetic model of glucose consumption, which was developed based on a batch kinetic experiment, was used for the development of a dynamic model for the prediction of the behaviour of the recently developed flexible reactor called the Periodic Anaerobic Baffled Reactor (PABR). The PABR may be operated as a UASBR, an ABR or at an intermediate mode. The key assumption of the model is that the hydraulic behaviour of a PABR is equivalent with the behaviour of CSTRs in series as concerning the dissolved matter, whereas the biomass is allowed to be retained in the PABR through a retention factor accounting for precipitation. The model adequately predicted the experimental behaviour of a glucose fed PABR. The model was subsequently used to examine the behaviour of the PABR as a function of operating conditions, both for constant and varying loading rates. It was shown that for different cases, the reactor should best be operated as a UASBR or as an ABR. The fact that the active biomass is continuously removed from the continuously stirred anaerobic digesters, leading to long retention times, has been overcome in a number of high rate systems based on immobilisation of the active biomass, such as the Upflow Anaerobic Sludge Blanket Reactor (UASBR) and the Anaerobic Baffled Reactor (ABR). A kinetic model of glucose consumption, which was developed based on a batch kinetic experiment, was used for the development of a dynamic model for the prediction of the behaviour of the recently developed flexible reactor called the Periodic Anaerobic Baffled Reactor (PABR) [(1998) Wat. Sci. Technol. 38(8-9), 401- 408]. The PABR may be operated as a UASBR, an ABR or at an intermediate mode. The key assumption of the model is that the hydraulic behaviour of a PABR is equivalent with the behaviour of CSTRs in series as concerning the dissolved matter, whereas the biomass is allowed to be retained in the PABR through a retention factor accounting for precipitation. The model adequately predicted the experimental behaviour of a glucose fed PABR. The model was subsequently used to examine the behaviour of the PABR as a function of operating conditions, both for constant and varying loading rates. It was shown that for different cases, the reactor should best be operated as a UASBR or as an ABR. (C) 2000 Elsevier Science Ltd.
Formation of interim by-products in methanogenic degradation of butyrate
Fang, Herbert H. P.,Jia, Xiao-Shan
, p. 1791 - 1798 (2007/10/03)
The formation of interim by-products during the methanogenic degradation of butyrate was monitored and analyzed in this study. Two series of experiments were conducted at various butyrate concentrations and under the influence of increased partial pressur
The Kinetics of Basic Cleavage of Nitrophenyl Alkanoate Esters by 'Hydroxypropyl-β-cyclodextrin' in Aqueous Solution
Gadosy, Timothy A.,Tee, Oswald S.
, p. 715 - 722 (2007/10/02)
The kinetics of cleavage of m- and p-nitrophenyl alakanoates by 'hydroxypropyl-β-cyclodextrin' (Hp-β-CD) in basic aqueous solution vary significantly with the chain length of the esters (C2 to C10).For both series of esters with short chains (C2 to C6) simple saturation kinetics are observed, indicative of 1:1 (ester:CD) binding and reaction of one molecule of ester with one molecule of Hp-β-CD.For longer chains, there is also a cleavage process involving two molecules of Hp-β-CD.This type of behaviour was not found previously for the same esters reacting with α-CD and with β-CD but it has been observed for some carboxynitrophenyl alkanoates.With the longest esters there is also evidence of productive 1:2 (ester:CD) binding.For the 1:1 binding, there is a linear dependence of the strength on acyl chain length and the close similarity of the dissociation constants for the two series of esters implicate inclusion of the alkyl chains of the esters acyl groups.Transition-state binding is more complex: for the meta-nitro isomers aryl-group inclusion appears dominant whereas for the para isomers there seems to be a switch from aryl-group inclusion to acyl-group inclusion, occurring at a chain length of C6-C7.
Lactones. 2. Enthalpies of hydrolysis, reduction, and formation of the C4-C13 monocyclic lactones. Strain energies and conformations
Wiberg, Kenneth B.,Waldron, Roy F.
, p. 7697 - 7705 (2007/10/02)
The enthalpies of hydrolysis of the monocyclic lactones from γ-butyrolactone to tridecanolactone were determined calorimetrically, and the acyclic ethyl having the number of atoms were studied in the fashion. The enthalpies of reduction of the lactones to the corresponding α,ω-alkanediols with lithium triethylborohydride also were determined. The enthalpies of formation of the lactones and the ethyl esters were derived from these data. They were converted to values for the gas phase by measuring the enthalpies of vaporization of ethyl esters and of lactones. In the of γ-butyrolactone and δ-valerolactone, the enthalpies of formation were in good accord with the previously reported values determined via combustion calorimetry. The strain energies of the lactones were obtained via isodesmic reactions. Valerolactone had a strain energy of 11 kcal/mol, and the largest strain energy was found with octanolactone (13 kcal/mol). The conformations of γ-butyrolactone and δ-valerolactone were studied via MP2/6-31G* geometry optimizations, and the conformations of the other lactones were studied with use of the molecular mechanics program MM3. The energies of the lactones estimated via molecular mechanics were compared with the experimental results.
Kinetics and Mechanism of Aquation of Propionatopentaamminerhodium(III) Ion in Acidic Media
Chatterjee, C.,Bali, A. S.
, p. 439 - 441 (2007/10/02)
The kinetics of aquation of propionatopentaamminerhodium(III) complex have been studied in aqueous perchloric acid media (0.02-0.1 mol dm-3) over a temperature range of 60-80 deg C and ionic strength = 0.1 mol dm-3 (sodium perchlorate).The observed dependence of the aquation rate on suggests the operation of two concurrent paths: kobs = k0 + kH(+), where k0 and kH(+) are the rate constants for uncatalysed and acid-catalysed pathways respectively.The values of the rate constants and activation parameters have been evaluated and the results discussed with reference to the reported data for other carboxylatopentaamminerhodium(III) complexes.Analysis of rate data suggests Rh-O bond cleavage in the transition state for both the paths.
Electrochemical Reduction of Carbon Dioxide Using Iron-Sulfur Clusters as Catalyst Precursors
Nakazawa, Makoto,Mizobe, Yasushi,Matsumoto, Yoichi,Uchida, Yasuzo,Tezuka, Meguru,Hidai, Masanobu
, p. 809 - 814 (2007/10/02)
The potential-current relationships of DMF solutions of a series of iron-sulfur compounds have revealed that in the presence of clusters 2- (R=PhCH2 or But) and 3- (M=Mo or W) the electroreduction of CO2 proceeds at the potential shifted by about 0.7 and 0.5 V, respectively, to the positive direction compared to the potential at which CO2 is reduced without any catalyst.When controlled potential electrolysis of a DMF solution containing 2- was carried out under CO2 at -2.0 V vs.SCE, phenylacetate and formate were formed as the products resulting from CO2 reduction.The cubane structure of this cluster collapsed rapidly under these conditions.However, when excess amount of PhCH2SH was added to the catholyte, the cluster structure was preserved during a relatively long period of electrolysis, and the yield of phenylacetate increased but that of formate decreased compared with the reaction in the absence of free PhCH2SH.
Tin Oxide Surfaces. Part 11.-Infrared Study of the Chemisorption of Ketones on Tin(IV) Oxide
Harrison, Phillip G.,Maunders, Barry M.
, p. 1329 - 1340 (2007/10/02)
Infrared spectroscopy has been employed to study the chemisorption of a number of unsymmetrical ketones, RCOMe, onto tin(IV) oxide.In every case, the final product was the surface carboxylate, RCO2-(ads).The data suggested a mechanism involving initial coordination of the ketone to a surface tin site, followed by nucleophilic attack of a neighbouring hydroxyl group at the carbonyl carbon atom.
KINETICS AND MECHANISM OF THE RUTHENIUM (III) CATALYSED OXIDATION OF SOME ALIPHATIC AND CYCLIC KETONES BY PERIODATE ION IN AQUEOUS ALKALINE MEDIUM: A NOVEL BEHAVIOUR OF RUTHENIUM (III)
Pati, Subas C.,Panda, Markandeswar
, p. 271 - 282 (2007/10/02)
Kinetics of ruthenium(III) chloride catalysed oxidation of acetone, ethylmethyl ketone, isobutylmethyl ketone, pentan-2-one, cyclopentanone and cyclohexanone by sodium metaperiodate in aqueous alkaline medium at constant ionic strength is reported.The order with respect to (IO4)(1-) is found to be zero.The order with respect to (substrate) is unity for acetone, ethylmethyl ketone, isobutylmethyl ketone and cyclopentanone, whereas, pentan-2-one and cyclohexanone exhibit fractional dependence on substrate, in the entire range of substrate concentration studied.Strikingly, the order with respect to is fractional in case of the ketones where substrate dependence is unity and unity where the substrate dependence is fractional.The reaction rate increases linearly following a nearly unit dependence on (OH)(1-) at lower concentration of alkali and levels off after a particular (OH)(1-).The activation parameters have been evaluated.A suitable mechanism has been postulated and rate laws have been deduced.
