Fructose selective

Catalyst Glucose conversion (%) Fructose selectivity (%) Cation leaching (%) Glucose disappearance rate (x 104 s-1)... 

Draffin, S.P. Duggan, P.J. Duggan, S.A.M. Highly fructose selective transport promoted by boronic acids based on a pentaerjrihritiol eore. Org. Lett. 2001. 3 (6). 917-920. 

The D-fructose selective monoboronic acid-based sensor 5 was enhanced by James in 1995 with the introduction of a... 

Lakowicz has also examined the quenching and recovery of a sulfonated poly-(phenylene ethynylene) by a bisboronic acid viologen (81) on addition of saccharides [150]. The system is D-fructose selective and produces up to 70 fold fluorescence enhancement on addition of saccharides. 

Wang has recently shown that alizarin red S and phenyl boronic acid (PBA) could be used in competitive assays for saccharides [151, 152]. The system is D-fructose selective, which is the expected selectivity for a monoboronic acid system [12]. It takes advantage of the known interaction of alizarin red S with boronic acids [153]. Observed stability constants (X pp) for the PBA alizarin red S assay were 160 for D-fructose and 4.6 M for D-glucose in water at pH 7.4 (phosphate buffer). 

Duggan has developed a highly lipophilic boronic acids 231 and 232, which are able to transport fructose with very high selectivity. " Duggan has achieved unprecedented fructose selectivity by using a rigid five cavitand rim-appended with boronic acid receptor groups. ... 

The selective separation range of P-6/S-200 was determined with Blue Dextran (Vexdi exclusion limit) and fructose (V,o total permeation limit). Molecular weight (degree of polymerization) calibration (Fig. 16.22) was established with dextran standards and low dp pullulans (dp 3, 6, 9, 12, 15, 18) formed by the controlled hydrolysis of high dp pullulan. 

Table 3. Selection of Products Derived from Fructose 1,6-Bisphosphatc Aldolase Catalyzed Additions of Dihydroxyacetonc Phosphate to Respective Aldehydes...

Bacillus licheniformis produces a water-insoluble levan that has potential application as a selective plugging agent in MEOR. The microorganisms grow on sucrose, glucose, and fructose but produce levan only on sucrose. Thus plugging may be selectively controlled in the reservoir by substrate manipulation. Oil reservoirs that have a temperature of less than 55° C, a pH between 6 and 9, a pressure less than 500 atm, and a salt concentration of 4% or less are potentially suitable [1480]. 

Sucrase-type (non-Leloir-type) enzymes that operate both regio- and stereo-selectively, using sucrose as a cheap substrate, or, in some cases (such as cyclodextrin (CD) transferases) starch these enzymes are, however, limited to the transfer of only glucose or fructose... 

The ultraviolet absorption spectra of compounds II from D-glucose and XI from D-fructose show an absorption band at 250 m/j, in accordance with their furan character.9 The product of periodate oxidation (V) and the dimethyl ester of the derived dicarboxylic acid (III) absorb at 285 and 262 m/i, respectively. The anhydrides of the condensates, XXXIV, do not exhibit selective absorption in the ultraviolet region, but the product of their oxidation (XXXVI) with periodic acid shows8 a band at about 270 m/i. 

The endo-spiro-OZT could be prepared through a reaction sequence similar to that applied for the exo-epimer, with spiro-aziridine intermediates replacing the key spiro-epoxides (Scheme 18). Cyanohydrin formation from ketones was tried under kinetic or thermodynamic conditions, and only reaction with the d-gluco derived keto sugar offered efficient stereoselectivity, while no selectivity was observed for reaction with the keto sugar obtained from protected D-fructose. The (R) -cyanohydrin was prepared in excellent yield under kinetic conditions (KCN, NaHC03, 0 °C, 10 min) a modified thermodynamic procedure was applied to produce the (S)-epimer in 85% yield (Scheme 18). 

Ketoses should react under a similar scheme. Indeed they do but an important problem in the chemistry of ketoses consists on the lack of selectivity due to (1) the complexity of their tautomeric equilibria and (2) their tendency to form tertiary oxocarbenium ions under acidic conditions. Thus, mixtures of open-chain, cyclic and dehydrated products are frequently obtained.7 The discussion about OZT structures obtained from D-fructose as proposed by Zemplen, Wickstrom and more recently by Grouiller et al. continues today. In fact, the first authors claimed the fusion of OZT on a pyran form of D-fructose, while Grouiller suggested the formation of a mixture of fused OZTs with /1-pyran (major) and p-furan (minor) forms (Scheme 22).18... 

In the continuation of this work, a broad range of OZTs was prepared from selectively protected derivatives of D-fructose and L-sorbose (Scheme 26).47... 

The convenient method to obtain sucrose based polymers was proposed by Barros s group.82 The preparation of a monomer is depicted in Fig. 61. Selective protection of the 6 -OH (fructose part) followed by benzylation of the remaining seven hydroxyl groups and regeneration of the 6 -OH afforded the monoalcohol. Reaction of this derivative with crotoyl chloride (and others) provided the monomer 191 ready for polymerization (Fig. 61). 

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