FUNCTIONALIZATION OF SEMICONDUCTOR SURFACES BY ORGANIC LAYERS: CONCERTED CYCLOADDITION VERSUS STEPWISE FREE-RADICAL REACTION MECHANISMS

<div> <p></p><p>Supercritical water gasification is a promising waste-to-energy technology with the ability to convert aqueous and/or heterogeneous organic feedstocks to high-value gaseous products. Reaction behavior of complex molecules in supercritical water can be inferred through knowledge of the reaction pathways of model compounds in supercritical water. In this study methanol, ethanol, and isopropyl alcohol are gasified in a continuous supercritical water reactor at temperatures between 500 and 560 °C, and for residence times between 3 and 8 s. <i>In situ</i> Raman spectroscopy is used to rapidly identify and quantify reaction products. The results suggest the dominance of chain-branching, free radical reaction mechanisms that are responsible for decomposing primary alcohols in the supercritical water environment. The presence of a catalytic surface is proposed to be highly significant for initiating radical reactions. Global reaction pathways are proposed, and mechanisms for free radical reaction initiation, propagation, and termination are discussed in light of these and previously published experimental results.</p><br><p></p></div>

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Gasification Pathways and Reaction Mechanisms of Primary Alcohols in Supercritical Water

10.26434/chemrxiv.10062515.v2 ◽

2019 ◽

Author(s):

Brian Pinkard ◽

John Kramlich ◽

Igor V. Novosselov

Keyword(s):

Free Radical ◽

Supercritical Water ◽

Reaction Mechanisms ◽

Radical Reaction ◽

Water Environment ◽

Waste To Energy ◽

Reaction Pathways ◽

Free Radical Reaction ◽

Reaction Products ◽

Primary Alcohols

<div> <p></p><p>Supercritical water gasification is a promising waste-to-energy technology with the ability to convert aqueous and/or heterogeneous organic feedstocks to high-value gaseous products. Reaction behavior of complex molecules in supercritical water can be inferred through knowledge of the reaction pathways of model compounds in supercritical water. In this study methanol, ethanol, and isopropyl alcohol are gasified in a continuous supercritical water reactor at temperatures between 500 and 560 °C, and for residence times between 3 and 8 s. <i>In situ</i> Raman spectroscopy is used to rapidly identify and quantify reaction products. The results suggest the dominance of chain-branching, free radical reaction mechanisms that are responsible for decomposing primary alcohols in the supercritical water environment. The presence of a catalytic surface is proposed to be highly significant for initiating radical reactions. Global reaction pathways are proposed, and mechanisms for free radical reaction initiation, propagation, and termination are discussed in light of these and previously published experimental results.</p><br><p></p></div>

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Free-radical reaction of cyanogen bromide with alkanes

Canadian Journal of Chemistry ◽

10.1139/v70-244 ◽

1970 ◽

Vol 48 (10) ◽

pp. 1492-1497 ◽

Cited By ~ 9

Author(s):

Dennis D. Tanner ◽

G. Lycan ◽

N. J. Bunce

Keyword(s):

Free Radical ◽

Benzoyl Peroxide ◽

Hydrogen Cyanide ◽

Reaction Mechanisms ◽

Cyanogen Bromide ◽

Hydrogen Bromide ◽

Radical Reaction ◽

Free Radical Reaction ◽

Alkyl Bromides ◽

High Yields

The photolysis of cyanogen bromide with cyclohexane yielded cyclohexyl bromide, hydrogen cyanide, and small amounts of cyanogen, while the benzoyl-peroxide-promoted reactions of cyanogen bromide with various alkanes yielded approximately equal amounts of alkyl bromides and alkyl cyanides, often in high yields. Both hydrogen cyanide and hydrogen bromide were shown to react with benzoyl peroxide and an added hydrocarbon to yield the corresponding alkyl cyanide and alkyl bromide. Possible reaction mechanisms for these reactions are discussed.

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