The “η-sweet-spot” (ηmax) in liquid-assisted mechanochemistry: polymorph control and the role of a liquid additive as either a catalyst or an inhibitor in resonant acoustic mixing (RAM)

Gonnet, Lori; Borchers, Tristan H.; Lennox, Cameron; Vainauskas, Jogirdas; Teoh, Yong; Barrett, Christopher J.; Koenig, Stefan G.; Nagapudi, Karthik; Friščić, Tomislav

doi:10.1039/d2fd00131d

Cited by 24 publications

(29 citation statements)

References 79 publications

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“…Furthermore, we found that the higher the η-value, the more p-HAP is formed. From this, we conclude that with 0.1 we have hit a sweet spot 37 with which we can achieve both high conversion and selectivity while also predominantly forming the desired p-HAP.…”

Section: Reaction Development In the Ball Millmentioning

confidence: 74%

The Mechanochemical Fries Rearrangement: Manipulating Isomer Ratios in the Synthesis of p-Hydroxyacetophenone at Different Scales

Baier

Rensch

Bergheim

et al. 2022

Preprint

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Here, we present the first mechanochemical Fries rearrangement for the industrially important synthesis of para hydroxyacetophenone, inside a ball mill and a twin-screw extruder. Our approach leads to quantitive conversion in as little as 90 minutes. Furthermore, the utilisation of liquid-assisted grinding can shift the isomer ratio resulting in an excess of the desired para product. The multigram scale-up via a continuous extrusion process leads to similar results in only three minutes of residence time while completely avoiding solvents. The extrusion temperature of 75-100 °C can even further be reduced by combining extrusion at 50°C with a subsequent ageing step.

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Section: Reaction Development In the Ball Millmentioning

confidence: 74%

The Mechanochemical Fries Rearrangement: Manipulating Isomer Ratios in the Synthesis of p-Hydroxyacetophenone at Different Scales

Baier

Rensch

Bergheim

et al. 2022

Preprint

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“…73 The systematic analysis of the coupling reactions conducted by RAM, as well as ball milling, revealed the appearance of an "η sweet-spot", i.e., an η-value at which the reaction conversion at a given time achieves a maximum (Figure 3). 73,74 Single time point analysis has been used extensively in development and screening of mechanochemical organic synthesis, with recent examples including screening of the catalyst and reaction scope for catalytic coupling of an amine, aldehyde, and acetylene 75 ("A3 coupling", Figure 4), creation of a protocol for mechanochemical ruthenium-catalyzed olefin metathesis, or development of a solvent-free activation of noble metals. 76,77 Notably, single time point analysis was used by the Mack and Blair groups to gain fundamental insight into energy delivery in mechanochemical reactions, by recording the conversion of Diels−Alder reactions conducted in milling assemblies made of different materials and at different frequencies.…”

Section: Monitoring Reactions At a Single Time Pointmentioning

confidence: 99%

“…The systematic analysis of the coupling reactions conducted by RAM, as well as ball milling, revealed the appearance of an “η sweet-spot”, i.e., an η-value at which the reaction conversion at a given time achieves a maximum (Figure ). , …”

Section: Monitoring Milling Reactionsmentioning

confidence: 99%

Methods for Monitoring Milling Reactions and Mechanistic Studies of Mechanochemistry: A Primer

Julien

Friščić

2022

Crystal Growth & Design

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Mechanochemistry by ball milling is garnering significant attention as an efficient and versatile means of chemical synthesis which minimizes the need for solvents and reduces the amount of energy required to conduct many molecular transformations. Understanding milling reactions often requires monitoring the reaction of solid forms, with little or ideally no disruption of the milling process. Herein, we provide a broad but succinct summary of how different ex situ and the more recently developed in situ techniques have been applied to monitor mechanochemical reactions, revealing reaction pathways and the mechanisms driving different solid-state molecular and materials transformations by milling. The rapidly evolving field of monitoring milling reactions has already revolutionized our understanding of mechanochemical reactions, revealing complex self-assembled phases as intermediates in catalytic and other types of synthesis through ball milling. The multitude of recently reported techniques for investigating ball milling reactions, many of which are touched upon in this summary, promise to dramatically increase the pace of mechanochemical reaction development and the understanding of solid-state chemistry.

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“…1E). Attempts to further optimize the reaction through screening η -values between 0 and 1.5 μL mg −1 revealed maximum conversion ( η max ) 14 at η = 0.25 μL mg −1 (Fig. 1D).…”

mentioning

confidence: 99%

Resonant acoustic mixing (RAM) for efficient mechanoredox catalysis without grinding or impact media

Effaty

Gonnet

Koenig³

et al. 2023

Chem. Commun.

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The “η-sweet-spot” (η_max) in liquid-assisted mechanochemistry: polymorph control and the role of a liquid additive as either a catalyst or an inhibitor in resonant acoustic mixing (RAM)

Abstract: Resonant Acoustic Mixing (RAM) offers a simple, efficient route for mechanochemical synthesis in the absence of milling media or bulk solvents. Here, we show the use of RAM to conduct...

Cited by 24 publications

References 79 publications

The Mechanochemical Fries Rearrangement: Manipulating Isomer Ratios in the Synthesis of p-Hydroxyacetophenone at Different Scales

The Mechanochemical Fries Rearrangement: Manipulating Isomer Ratios in the Synthesis of p-Hydroxyacetophenone at Different Scales

Methods for Monitoring Milling Reactions and Mechanistic Studies of Mechanochemistry: A Primer

Resonant acoustic mixing (RAM) for efficient mechanoredox catalysis without grinding or impact media

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