The stability of sucrose monolaurate: Rate of formation of lauric acid

Anderson, Ronald D.; Polack, Alan E.

doi:10.1111/j.2042-7158.1968.tb09755.x

Cited by 7 publications

(7 citation statements)

References 11 publications

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“…The second-order rate constants for hydrolysis of the three sucrose esters, plotted in this way, are shown in Figure 2. This figure also includes second-order rate constants derived from results of a previous study of sucrose laurate hydrolysis at pH 9.3, in a NaOH/NaBO 3 buffer of 0.2 ionic strength at temperatures of 298, 319, and 344 K and initial concentrations below the cmc (8). The Arrhenius plots are linear, and there is fairly good agreement between data from this study and those previously determined.…”

Section: Resultssupporting

confidence: 75%

“…Hydrolysis rates of sucrose laurate, sucrose α-sulfonyl laurate, and sucrose α-ethyl laurate were determined in a NaOH/NaHCO 3 buffer solution with pH 11 at several temperatures between 300 and 350 K (27 and 77°C). Micelles in solution can reduce the rate of base-catalyzed sucrose ester hydrolysis (8). For this reason, the initial concentrations of the esters were chosen to be below (or in the region of) the critical micelle concentration (cmc).…”

Section: Resultsmentioning

confidence: 99%

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Sugar fatty acid ester surfactants: Base‐catalyzed hydrolysis

Baker

Furlong

Grieser

et al. 2000

J Surfact & Detergents

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Rate constants for the base-catalyzed hydrolysis of sucrose laurate, sucrose α-sulfonyl laurate, and sucrose α-ethyl laurate were measured at several temperatures in pH 11 buffer. Activation energies and Arrhenius factors for the hydrolysis reactions were determined. At 27°C, sucrose laurate hydrolyzed fastest and sucrose α-ethyl laurate slowest. Activation energies and Arrhenius factors showed that both steric and electronic factors affect the rates of ester hydrolysis. Other work has shown that bacterial hydrolysis of sugar fatty acid esters is inhibited in the presence of either α-sulfonyl or α-alkyl groups. A kinetic study of base-catalyzed ester hydrolysis has revealed reasons for the inhibition of bacterial hydrolysis and provided information regarding ester stability at elevated pH.Biodegradation of sugar fatty acid esters by initial hydrolysis was found to be inhibited by the presence of α-alkyl or α-sulfonyl substituents adjacent to the ester bond (1,2). Lipases catalyze bacterial hydrolysis by a nucleophilic process involving a negatively charged tetrahedral intermediate (3-6). The essence of this enzymatic process is similar to the base-catalyzed hydrolysis of esters by hydroxide. This occurs almost universally by a bimolecular nucleophilic mechanism that also involves the formation of a negatively charged tetrahedral intermediate. Both processes are therefore expected to be subject to some of the same steric and electronic influences.Although there is a negatively charged residue in the active site of lipases, it is unlikely that electrostatic repulsion with sulfonyl groups inhibits hydrolysis since this is not observed in the case of other negatively charged substrates (6). On the other hand, the presence of alkyl groups adjacent to the carbonyl carbon of esters is known to reduce the rate of hydrolysis considerably (7). By determining the importance of steric and electronic factors in controlling the kinetics of base-catalyzed hydrolysis of sucrose esters, deductions can be made regarding factors affecting the corresponding enzymatic process.In addition, many cleaning formulations in which these surfactants may be applied have an elevated pH. However, stability of sugar esters to hydrolysis under these conditions is not well understood. It is therefore useful to investigate the factors influencing base hydrolysis of sugar esters from the point of view of formulation stability.In the current study, high-performance liquid chromatography (HPLC) was used to measure base hydrolysis rates of three key sugar esters: sucrose laurate, sucrose α-ethyl laurate, and sucrose α-sulfonyl laurate. The general structure of these surfactants is shown in Scheme 1; R=H in the case of sucrose laurate, SO 3 − Na + in the case of sucrose α-sulfonyl laurate, and CH 2 CH 3 in the case of sucrose α-ethyl laurate. Second-order rate constants for hydrolysis at elevated pH were determined at several different temperatures. This allowed energies of activation and Arrhenius factors to be determined in each case. The relative inf...

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Section: Resultssupporting

confidence: 75%

Section: Resultsmentioning

confidence: 99%

Sugar fatty acid ester surfactants: Base‐catalyzed hydrolysis

Baker

Furlong

Grieser

et al. 2000

J Surfact & Detergents

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“…We maintain the concentration of sucrose monolaurate at 10 mM which is well above its critical micelle concentration as reported in the literature. 47 At this particular concentration, sucrose monolaurate aggregates as micelles, and the average diameter of the micellar aggregates lies in the range of ∼5 nm. Interestingly, in the DLS histogram of the sucrose monolaurate micelle, there is an intense peak that appears in the larger diameter region, the reason of which is discussed in the latter section.…”

Section: Resultsmentioning

confidence: 93%

Effect of Vitamin E and a Long-Chain Alcohol n-Octanol on the Carbohydrate-Based Nonionic Amphiphile Sucrose Monolaurate—Formulation of Newly Developed Niosomes and Application in Cell Imaging

et al. 2017

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We have introduced new niosome formulations using sucrose monolaurate, vitamin E and n-octanol as independent additives. Detailed characterization techniques including turbidity, dynamic light scattering, transmission electron microscopy, ξ potential, and proton nuclear magnetic resonance measurements have been introduced to monitor the morphological transition of the carbohydrate-based micellar assembly into niosomal aggregates. Moreover, microheterogeneity of these niosomal aggregates has been investigated through different fluorescence spectroscopic techniques using a hydrophobic probe molecule coumarin 153 (C153). Further, it has been observed that vitamin E and octanol have an opposing effect on the rotational motion of C153 in the respective niosome assemblies. The time-resolved anisotropy studies suggest that incorporation of vitamin E and octanol into the surfactant aggregates results in slower and faster rotational motion of C153, respectively, compared to the micellar assemblies. Moreover, the ability to entrap a probe molecule by these niosomes is utilized to encapsulate and deliver the anticancer drug doxorubicin inside the mammalian cells which is monitored through fluorescence microscopic images. Interestingly, the niosome composed of vitamin E demonstrated better cytocompatibility toward primary chondrocyte cell lines compared to the octanol-forming niosome.

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“…This is probably because under such extremely harsh conditions monoesters are quickly hydrolyzed to monosaccharide esters and then further hydrolyzed at the ester bond to yield a fatty acid. Anderson et al also reported that an unknown faint spot at an Rf value similar to that of sucrose diester was found in the thin-layer chromatography analysis 16 . We assume that this faint spot corresponds to a monosaccharide ester.…”

Section: Hydrolysis Behavior Under Acidic Conditionsmentioning

confidence: 99%