Enzyme-Catalyzed Transetherification of Alkoxysilanes

Abbate, Vincenzo; Brandstadt, Kurt F.; Taylor, Peter G.; Bassindale, Alan R.

doi:10.3390/catal3010027

Cited by 11 publications

(13 citation statements)

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“…Indeed, powerful directed evolution strategies are now available to generate highly specific and robust biocatalysts for applications in the production of fine chemicals and functional materials (10,41). It is envisaged that such biocatalysts could be used in the chemical synthesis of complex molecules, where they could be used to selectively introduce or cleave silyl protecting groups (6) or to recycle these relatively expensive silyl groups by transetherification (13). In the area of materials chemistry, they could be applied for the synthesis of silicone polymers from nonhalogenated feedstocks (42).…”

Section: Discussionmentioning

confidence: 99%

“…The use of enzymes to manipulate the Si-O bond would therefore potentially offer more sustainable routes to the synthesis of many compounds, as well as for the eventual recycling and reuse of organosiloxanes. Several attempts have been made to use hydrolytic enzymes such as lipases and proteases for the hydrolysis and condensation of the Si-O bond (11)(12)(13). Although they clearly demonstrate the feasibility of the general concept, the range of enzymes tested have so far met with only limited success in regard to synthetic yield and substrate scope.…”

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confidence: 99%

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Recombinant silicateins as model biocatalysts in organosiloxane chemistry

Dakhili

Caslin

Faponle

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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The family of silicatein enzymes from marine sponges (phylum Porifera) is unique in nature for catalyzing the formation of inorganic silica structures, which the organisms incorporate into their skeleton. However, the synthesis of organosiloxanes catalyzed by these enzymes has thus far remained largely unexplored. To investigate the reactivity of these enzymes in relation to this important class of compounds, their catalysis of Si-O bond hydrolysis and condensation was investigated with a range of model organosilanols and silyl ethers. The enzymes' kinetic parameters were obtained by a high-throughput colorimetric assay based on the hydrolysis of 4-nitrophenyl silyl ethers. These assays showed unambiguous catalysis with k cat /K m values on the order of 2-50 min. Condensation reactions were also demonstrated by the generation of silyl ethers from their corresponding silanols and alcohols. Notably, when presented with a substrate bearing both aliphatic and aromatic hydroxy groups the enzyme preferentially silylates the latter group, in clear contrast to nonenzymatic silylations. Furthermore, the silicateins are able to catalyze transetherifications, where the silyl group from one silyl ether may be transferred to a recipient alcohol. Despite close sequence homology to the protease cathepsin L, the silicateins seem to exhibit no significant protease or esterase activity when tested against analogous substrates. Overall, these results suggest the silicateins are promising candidates for future elaboration into efficient and selective biocatalysts for organosiloxane chemistry.silicatein | biocatalysis | organosilicon | organosiloxane | silyl ether T he organosiloxanes, compounds containing C-Si-O moieties, represent a class of compounds with a truly diverse range of applications. They are commonly used in the form of polysiloxane "silicone" polymers as components of industrial and consumer products for a variety of purposes such as bulking agents, separation media, protective coatings, lubricants, emulsifiers, and adhesives (1-3). Their use as auxiliaries in the chemical synthesis of complex molecules is also long-established (4-6). However, the production and synthetic manipulation of these compounds are almost entirely dependent on chlorosilane feedstocks, which are environmentally undesirable and energyintensive to produce (7,8). Furthermore, organosiloxanes, which are entirely anthropogenic in origin, are now known to be persistent environmental contaminants because little attempt is made to recover and recycle them (3). Synthetic routes that use, and ultimately recycle, siloxanes and silanols as alternatives would in principle be more environmentally sound.One possible strategy toward improved sustainability is to harness enzymes for chemical processing. Such biocatalysts are attractive because they offer highly efficient synthesis in terms of yields and regio-and stereospecificity, together with an ability to promote reactions under mild conditions and a minimal reliance on halogenated or metallic feedstocks (...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Recombinant silicateins as model biocatalysts in organosiloxane chemistry

Dakhili

Caslin

Faponle

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…Bioprocessing methods, as examples of "green manufacturing" are receiving interest, which stems from replacing chemical processes with those that use enzymes [27]. More than 1500 different enzymes have been identified till now, and many have been isolated in pure form [28]. According to the type of reaction involved, enzymes were categorized into six main classes and a number of subclasses by biochemists.…”

Section: Introductionmentioning

confidence: 99%

The Use of Biobased Surfactant Obtained by Enzymatic Syntheses for Wax Deposition Inhibition and Drag Reduction in Crude Oil Pipelines

Wang

et al. 2016

Catalysts

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Abstract:Crude oil plays an important role in providing the energy supply of the world, and pipelines have long been recognized as the safest and most efficient means of transporting oil and its products. However, the transportation process also faces the challenges of asphaltene-paraffin structural interactions, pipeline pressure losses and energy consumption. In order to determine the role of drag-reducing surfactant additives in the transportation of crude oils, experiments of wax deposition inhibition and drag reduction of different oil in pipelines with a biobased surfactant obtained by enzymatic syntheses were carried out. The results indicated that heavy oil transportation in the pipeline is remarkably enhanced by creating stable oil-in-water (O/W) emulsion with the surfactant additive. The wax appearance temperature (WAT) and pour point were modified, and the formation of a space-filling network of interlocking wax crystals was prevented at low temperature by adding a small concentration of the surfactant additive. A maximum viscosity reduction of 70% and a drag reduction of 40% for light crude oil flows in pipelines were obtained with the surfactant additive at a concentration of 100 mg/L. Furthermore, a successful field application of the drag-reducing surfactant in a light crude oil pipeline in Daqing Oilfield was demonstrated. Hence, the use of biobased surfactant obtained by enzymatic syntheses in oil transportation is a potential method to address the current challenges, which could result in a significant energy savings and a considerable reduction of the operating cost.

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“…[80] They were able to expand upon this work by utilizing enzymatics ystemst op erformt ransetherifications at silicon centers;t his wast he first example of the hydrolysis and condensation of SiÀOb onds that yieldeda lkoxysilane species, rather than particulate or monolithic silicates. [81] Similarly,G arakani et al recently reportedt he combination of alkoxysilane and polyalkoxysilane speciesi na ne mulsion system with lysozyme to generate highly ordered and uniform silicon-based nanoparticles. [82] 4.…”

Section: Small-molecule Silane Systemsmentioning

confidence: 98%

“…were able to mimic the biological processing of silicon substrates by using a molecularly imprinted polymer that could facilitate the hydrolysis and condensation of siloxane bonds . They were able to expand upon this work by utilizing enzymatic systems to perform transetherifications at silicon centers; this was the first example of the hydrolysis and condensation of Si−O bonds that yielded alkoxysilane species, rather than particulate or monolithic silicates . Similarly, Garakani et al.…”

Section: Enzymatic Reactions For Which Silicon Compounds Are Not Natumentioning

confidence: 99%

Biocatalysis in Silicon Chemistry

Frampton

Zelisko

2017

Chemistry An Asian Journal

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The application of biocatalytic or chemoenzymatic techniquesi ns ilicon chemistry serves two roles:i tp rovides ag reater understanding of the processing of silicon species by natural systems, such as plants, diatoms, and sponges, as well openingu pa venues to green methodologies in the field. In the latter case, biocatalytic approaches have been applied to the synthesis of small-molecule systems and polymeric materials. Often these biocatalytic approaches allow access to molecular structures under mild conditions and, in some cases, molecular structures that are not accessible throught raditional chemical methodologies. Ar eview of recent advances in the applications of biocatalysis in silicon chemistry is presented.

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Enzyme-Catalyzed Transetherification of Alkoxysilanes

Cited by 11 publications

References 11 publications

Recombinant silicateins as model biocatalysts in organosiloxane chemistry

Recombinant silicateins as model biocatalysts in organosiloxane chemistry

The Use of Biobased Surfactant Obtained by Enzymatic Syntheses for Wax Deposition Inhibition and Drag Reduction in Crude Oil Pipelines

Biocatalysis in Silicon Chemistry

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