Continuous flow photooxidation of alkyl benzenes using fine bubbles for mass transfer enhancement

Gary Morrison; Ruairí Bannon; Scott Wharry; Thomas S. Moody; Nobuyuki Mase; Masayuki Hattori; Haresh Manyar; Megan Smyth

doi:10.1016/j.tetlet.2021.153613

Continuous flow photooxidation of alkyl benzenes using fine bubbles for mass transfer enhancement

Gary Morrison, Ruairí Bannon, Scott Wharry, Thomas S. Moody, Nobuyuki Mase, Masayuki Hattori, Haresh Manyar^*, Megan Smyth

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

9 Citations (Scopus)

99 Downloads (Pure)

Abstract

Selective photooxidation of alkyl benzenes was studied in a custom-built continuous flow photochemical reactor equipped with fine bubble generator and a low power UV light source. Fine bubbles of air were used as an oxidizing agent along with water-soluble sodium anthraquinone sulfonate as catalyst. The fine bubble containing slug-flow system using air was 1.4 times more efficient at lower feed-flow rate of 2 mL/min and 1.8 times more efficient at higher feed-flow rate of 5 mL/min. Ethylbenzene was selectively oxidized in continuous flow to acetophenone at room-temperature, with 90% ethylbenzene conversion and 92% selectivity to acetophenone, with a short residence time of 5 min. The enhanced gas/liquid mass transfer afforded by the fine bubble generator significantly increased reactor productivity, giving rise to high conversion and yield. Due to enhanced mass transfer and greater efficiency, compressed air can be used as oxidant instead of pure O₂, thus alleviating potential safety concerns and making the process safer and more amenable for scale up.

Original language	English
Article number	153613
Journal	Tetrahedron Letters
Volume	90
Early online date	29 Jan 2022
DOIs	https://doi.org/10.1016/j.tetlet.2021.153613
Publication status	Published - 02 Feb 2022

Bibliographical note

Funding Information:
The authors gratefully acknowledge the financial support from Innovate UK under the Knowledge Transfer Partnership (KTP) for KTP Associate funding for GM for the project, Flow-assisted Synthesis Technology Platform (FAST).

Publisher Copyright:
© 2021 Elsevier Ltd

Keywords

Benzylic oxidation
Continuous flow
Fine bubbles
low power UV
Photooxidation

ASJC Scopus subject areas

Biochemistry
Drug Discovery
Organic Chemistry

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Continuous flow photooxidation of alkyl benzenes using fine bubbles for mass transfer enhancement
Copyright 2022 Elsevier. This manuscript is distributed under a Creative Commons Attribution-NonCommercial-NoDerivs License (https://creativecommons.org/licenses/by-nc-nd/4.0/), which permits distribution and reproduction for non-commercial purposes, provided the author and source are cited.
Accepted author manuscript, 542 KBLicence: CC BY-NC-ND

Cite this

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title = "Continuous flow photooxidation of alkyl benzenes using fine bubbles for mass transfer enhancement",

abstract = "Selective photooxidation of alkyl benzenes was studied in a custom-built continuous flow photochemical reactor equipped with fine bubble generator and a low power UV light source. Fine bubbles of air were used as an oxidizing agent along with water-soluble sodium anthraquinone sulfonate as catalyst. The fine bubble containing slug-flow system using air was 1.4 times more efficient at lower feed-flow rate of 2 mL/min and 1.8 times more efficient at higher feed-flow rate of 5 mL/min. Ethylbenzene was selectively oxidized in continuous flow to acetophenone at room-temperature, with 90% ethylbenzene conversion and 92% selectivity to acetophenone, with a short residence time of 5 min. The enhanced gas/liquid mass transfer afforded by the fine bubble generator significantly increased reactor productivity, giving rise to high conversion and yield. Due to enhanced mass transfer and greater efficiency, compressed air can be used as oxidant instead of pure O2, thus alleviating potential safety concerns and making the process safer and more amenable for scale up.",

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AU - Moody, Thomas S.

AU - Mase, Nobuyuki

AU - Hattori, Masayuki

AU - Manyar, Haresh

AU - Smyth, Megan

N1 - Funding Information: The authors gratefully acknowledge the financial support from Innovate UK under the Knowledge Transfer Partnership (KTP) for KTP Associate funding for GM for the project, Flow-assisted Synthesis Technology Platform (FAST). Publisher Copyright: © 2021 Elsevier Ltd

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N2 - Selective photooxidation of alkyl benzenes was studied in a custom-built continuous flow photochemical reactor equipped with fine bubble generator and a low power UV light source. Fine bubbles of air were used as an oxidizing agent along with water-soluble sodium anthraquinone sulfonate as catalyst. The fine bubble containing slug-flow system using air was 1.4 times more efficient at lower feed-flow rate of 2 mL/min and 1.8 times more efficient at higher feed-flow rate of 5 mL/min. Ethylbenzene was selectively oxidized in continuous flow to acetophenone at room-temperature, with 90% ethylbenzene conversion and 92% selectivity to acetophenone, with a short residence time of 5 min. The enhanced gas/liquid mass transfer afforded by the fine bubble generator significantly increased reactor productivity, giving rise to high conversion and yield. Due to enhanced mass transfer and greater efficiency, compressed air can be used as oxidant instead of pure O2, thus alleviating potential safety concerns and making the process safer and more amenable for scale up.

AB - Selective photooxidation of alkyl benzenes was studied in a custom-built continuous flow photochemical reactor equipped with fine bubble generator and a low power UV light source. Fine bubbles of air were used as an oxidizing agent along with water-soluble sodium anthraquinone sulfonate as catalyst. The fine bubble containing slug-flow system using air was 1.4 times more efficient at lower feed-flow rate of 2 mL/min and 1.8 times more efficient at higher feed-flow rate of 5 mL/min. Ethylbenzene was selectively oxidized in continuous flow to acetophenone at room-temperature, with 90% ethylbenzene conversion and 92% selectivity to acetophenone, with a short residence time of 5 min. The enhanced gas/liquid mass transfer afforded by the fine bubble generator significantly increased reactor productivity, giving rise to high conversion and yield. Due to enhanced mass transfer and greater efficiency, compressed air can be used as oxidant instead of pure O2, thus alleviating potential safety concerns and making the process safer and more amenable for scale up.

KW - Benzylic oxidation

KW - Continuous flow

KW - Fine bubbles

KW - low power UV

KW - Photooxidation

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DO - 10.1016/j.tetlet.2021.153613

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VL - 90

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JF - Tetrahedron Letters

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ER -

Continuous flow photooxidation of alkyl benzenes using fine bubbles for mass transfer enhancement

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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