Flux of Polynuclear Aromatic Compounds (PAHs) from the Atmosphere and from Reindeer/Bird Feces to Arctic Soils in Ny-Ålesund (Svalbard)

Catalytic deoxygenation of coal enhances the stability and combustion performance of coal-derived liquids. However, determination of the selectivity of removal of oxygen atoms incorporated in or residing outside of aromatic rings is challenging. This limits the ability to evaluate the success of catalytic deoxygenation processes. A mass spectrometric method, in-source collision-activated dissociation (ISCAD), combined with high resolution product ion detection, is demonstrated to allow the determination of whether the oxygen atoms in aromatic compounds reside outside of aromatic rings or are part of the aromatic system, because alkyl chains can be removed from aromatic cores via ISCAD. Application of this method for the analysis of a subbituminous coal treated using a supported catalyst revealed that the catalytic treatment reduced the number of oxygen-containing heteroaromatic rings but not the number of oxygen atoms residing outside the aromatic rings.<br>

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Tandem Mass Spectrometric Evaluation of Core Structures of Aromatic Compounds after Catalytic Deoxygenation

10.26434/chemrxiv.5410807 ◽

2017 ◽

Author(s):

Xueming Dong

Keyword(s):

Aromatic Compounds ◽

Supported Catalyst ◽

Mass Spectrometric ◽

Spectrometric Method ◽

Mass Spectrometric Method ◽

Aromatic Rings ◽

Tandem Mass Spectrometric ◽

Catalytic Deoxygenation ◽

Oxygen Atoms

Catalytic deoxygenation of coal enhances the stability and combustion performance of coal-derived liquids. However, determination of the selectivity of removal of oxygen atoms incorporated in or residing outside of aromatic rings is challenging. This limits the ability to evaluate the success of catalytic deoxygenation processes. A mass spectrometric method, in-source collision-activated dissociation (ISCAD), combined with high resolution product ion detection, is demonstrated to allow the determination of whether the oxygen atoms in aromatic compounds reside outside of aromatic rings or are part of the aromatic system, because alkyl chains can be removed from aromatic cores via ISCAD. Application of this method for the analysis of a subbituminous coal treated using a supported catalyst revealed that the catalytic treatment reduced the number of oxygen-containing heteroaromatic rings but not the number of oxygen atoms residing outside the aromatic rings.<br>

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Photocatalytic Alkylation of Pyrroles and Indoles with α-Diazo Esters

10.26434/chemrxiv.8230235 ◽

2019 ◽

Author(s):

Łukasz Ciszewski ◽

Jakub Durka ◽

Dorota Gryko

Keyword(s):

Aromatic Compounds ◽

Reaction Pathway ◽

Alkylating Agents ◽

Catalytic Amount ◽

Radical Formation ◽

Reaction Selectivity ◽

Diazo Esters ◽

Electron Withdrawing Substituents

This article describes direct photoalkylation of electron-rich aromatic compounds with diazo compoiunds. C-2 alkylated indoles and pyrroles are obtained with good yields even though the photocatalyst (Ru(bpy)3Cl2) loading is as low as 0.075 mol %. For substrates bearing electron-withdrawing substituents the addition of a catalytic amount of N,N-dimethyl-4-methoxyaniline is required. Both EWG-EWG and EWG-EDG substituted diazo esters are suitable as alkylating agents. The reaction selectivity and mechanistic experiments suggest that carbenes/carbenoid intermediates are not involved in the reaction pathway, instead radical formation is proposed.

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A Simplified Protocol for the ortho-Deuteration of Acidic Aromatic Compounds in D2O

10.26434/chemrxiv.8292296.v1 ◽

2019 ◽

Author(s):

Alyssa Garreau ◽

Hanyang Zhou ◽

Michael Young

Keyword(s):

Carboxylic Acid ◽

Aromatic Compounds ◽

Large Scale ◽

Simplified Approach ◽

Directing Group ◽

Large Scale Synthesis

<div>Methods to catalytically introduce deuterium in synthetically useful yields ortho to a carboxylic acid directing group on arenes typically requires D2 or CD3CO2D, which makes using these approaches cost prohibitive for large scale synthesis (equipment and reagent costs respectively). Herein we present a simplified approach using catalytic RhIII and D2O as deuterium source, and show its application to H/D exchange on various acidic substrates.</div>

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A Simplified Protocol for the ortho-Deuteration of Acidic Aromatic Compounds in D2O

10.26434/chemrxiv.8292296 ◽

2019 ◽

Author(s):

Alyssa Garreau ◽

Hanyang Zhou ◽

Michael Young

Keyword(s):

Carboxylic Acid ◽

Aromatic Compounds ◽

Large Scale ◽

Simplified Approach ◽

Directing Group ◽

Large Scale Synthesis

<div>Methods to catalytically introduce deuterium in synthetically useful yields ortho to a carboxylic acid directing group on arenes typically requires D2 or CD3CO2D, which makes using these approaches cost prohibitive for large scale synthesis (equipment and reagent costs respectively). Herein we present a simplified approach using catalytic RhIII and D2O as deuterium source, and show its application to H/D exchange on various acidic substrates.</div>

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Eco-friendly and fast bromination of industrially-important aromatic compounds in water using recyclable AlBr3-Br2 system

10.31221/osf.io/5skq2 ◽

2019 ◽

Author(s):

Chem Int

Keyword(s):

Aromatic Compounds ◽

Molecular Bromine ◽

Economical Method ◽

System P

A fast, efficient, simple, eco-friendly, regioselective, controllable and economical method for the bromination of aromatic compounds using AlBr3-Br2 system was invetigated. The direct bromination of anilines and phenols with molecular bromine in solution frequently results in polybromination, and when brominated in the existence of oxidants, they also get oxidized rather than experiencing substitutions and in some cases, require fortification of the amino (-NH2) group.

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