Photochemical reactions of carbohydrates

Binkley, Roger W.; Binkley, Wendell W.

doi:10.1016/s0008-6215(00)88034-9

Cited by 9 publications

(3 citation statements)

References 13 publications

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“…This result was attributed to a competition reaction between the generated amine radical with monomer or TTMSS (See Scheme 1). It was reported that some carbon-centered radicals can abstract a hydrogen atom from TTMSS, and the rate constants were about (1.4–3.8) × 10 5 M −1 s −1 [60]. Because the addition rate constant is very close to the hydrogen abstraction rate constant, part of the amine radicals can react with TTMSS and generate silyl radicals (Scheme 1), which then react with monomers and produce the macroradicals.…”

Section: Discussionmentioning

confidence: 98%

Tris(trimethylsilyl)silane as a co-initiator for dental adhesive: Photo-polymerization kinetics and dynamic mechanical property

Song

et al. 2016

Dental Materials

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Objectives The purpose of this study was to evaluate the polymerization behavior of a model dentin adhesive with tris(trimethylsilyl)silane (TTMSS) as a co-initiator, and to investigate the polymerization kinetics and mechanical properties of copolymers in dry and wet conditions. Methods A co-monomer mixture based on HEMA/BisGMA (45/55, w/w) was used as a model dentin adhesive. The photoinitiator system included camphorquinone (CQ) as the photosensitizer and the co-initiator was ethyl-4-(dimethylamino) benzoate (EDMAB) or TTMSS. Iodonium salt, diphenyliodonium hexafluorophosphate (DPIHP) serving as a catalyst, was selectively added into the adhesive formulations. The control and the experimental formulations were characterized with regard to the degree of conversion (DC) and dynamic mechanical properties under dry and wet conditions. Results In two-component photoinitiator system (CQ/TTMSS), with an increase of TTMSS concentration, the polymerization rate and DC of C═C double bond increased, and showed a dependence on the irradiation time and curing light intensity. The copolymers that contained the three-component photoinitiator system (CQ/TTMSS/DPIHP) showed similar dynamic mechanical properties, under both dry and wet conditions, to the EDMAB-containing system. Significance The DC of formulations using TTMSS as co-initiator showed a strong dependence on irradiation time. With the addition of TTMSS, the maximum polymerization rate can be adjusted and the network structure became more homogenous. The results indicated that the TTMSS could be used as a substitute for amine-type co-initiator in visible-light induced free radical polymerization of methacrylate-based dentin adhesives.

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Section: Discussionmentioning

confidence: 98%

Tris(trimethylsilyl)silane as a co-initiator for dental adhesive: Photo-polymerization kinetics and dynamic mechanical property

Song

et al. 2016

Dental Materials

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“…For synthetic applications, Bernd Giese's group also made carbohydrate radicals available for the formation of carbon-carbon bonds under mild conditions [10]. Due to steric interactions, carbohydrates provide high stereoselectivities [11,12], and the importance of such reactions has been reviewed many times [13][14][15][16][17][18]. Furthermore, under appropriate conditions, 2-deoxy sugars can be synthesized from bromo sugars in only one step [19].…”

Section: Introductionmentioning

confidence: 99%

Addition of Heteroatom Radicals to endo-Glycals †

Linker

2020

Chemistry

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Radical reactions have found many applications in carbohydrate chemistry, especially in the construction of carbon–carbon bonds. The formation of carbon–heteroatom bonds has been less intensively studied. This mini-review will summarize the efforts to add heteroatom radicals to unsaturated carbohydrates like endo-glycals. Starting from early examples, developed more than 50 years ago, the importance of such reactions for carbohydrate chemistry and recent applications will be discussed. After a short introduction, the mini-review is divided in sub-chapters according to the heteroatoms halogen, nitrogen, phosphorus, and sulfur. The mechanisms of radical generation by chemical or photochemical processes and the subsequent reactions of the radicals at the 1-position will be discussed. This mini-review cannot cover all aspects of heteroatom-centered radicals in carbohydrate chemistry, but should provide an overview of the various strategies and future perspectives.

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“…of hexopyranosides are readily converted to C-6 aldehyde carbohydrates by photolysis(92)(93)(94)(95)(96)(97)e Irradiation of 6-deoxy-6-iodo-l,2:3,4-di-0j-isopropy 1 idene-^_-D-galactopyranose with added base gives 6-deoxy-l,2:3,4-di-Oj-isopropy 1 idene-^_-D-galactopyranose(98)e Galactose azine is converted to a mixture of lyxose and galactose when subjected to uv light(99). Decarboxylation of 2-deoxy-(2 ?,4?-dinitroaniline) -JD-gluconic acid by irradiation has been reported (100).Binkley and Binkley(101) studied the photolysis of D-galactose oxime and found the major product to be an unstable nitrogen-containing compound, which spontaneously decomposed to _D-lyxose. Deoxy sugars have also been prepared by photodecomposition of dimethyl thiocarbamate derivatives(102).…”

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confidence: 99%

Photolysis of some carbohydrate dithiobis(thioformates)

Stout¹,

Doane²,

Russell³

et al. 1975

J. Org. Chem.

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The photolysis of several oxidatively coupled xanthates of model sugar compounds has been investigated. The photolysis of bis (1,2: 3,4-di-Oj-isopropylidene-Q'-'D-galactopyranos-G-yl) dithiobis-(thioformate) (XXXIII) gave the xanthate ester, bis(6-deoxy-l,2:3,4di-Oj-isopropylidene-^-D-galactopyranos-6-y 1) 6-jO, 6 f-^Sj-dithiocarbonate (LXX) in 78% yield. In concentrated solutions, bis(1,2:3,4-di-0isopropylidene-^j-D-galactopyranos-6-y1) tetrathiobis (thioformate) (LXIX) was produced along with LXX. The photolysis of bis (1,2:5,6di-0_-isopropylidene-G^-D-glucofurano.s-3-yl) dithiobis (thioformate) (XIV) gave bis(3-deoxy-l,2:5,6-di-0^isopropylidene-a^-D-glucofuranos-3-yl) 3-jO, 3 8-Sr-dithiocarbonate (LXXVl), in which an oxygen atom on the sugar ring has been replaced with sulfur with retention of configuration. A cyclic mechanism in which either the excited thiocarbonyl sulfur or a sulfur of the disulfide linkage attacks the carbon giving a front side displacement of oxygen has been proposed to account for the observed results.

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Photochemical reactions of carbohydrates

Cited by 9 publications

References 13 publications

Tris(trimethylsilyl)silane as a co-initiator for dental adhesive: Photo-polymerization kinetics and dynamic mechanical property

Tris(trimethylsilyl)silane as a co-initiator for dental adhesive: Photo-polymerization kinetics and dynamic mechanical property

Addition of Heteroatom Radicals to endo-Glycals †

Photolysis of some carbohydrate dithiobis(thioformates)

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