Impact Is Important—Systematic Investigation of the Influence of Milling Balls in Mechanochemical Reactions

Fischer, Friedrich; Fendel, Nicole; Greiser, Sebastian; Rademann, Klaus; Emmerling, Franziska

doi:10.1021/acs.oprd.6b00435

Cited by 52 publications

(54 citation statements)

References 58 publications

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“…Recently, salts of MEH + _NO 2 were obtained by slow evaporation of a solution of SP_NO 2 mixed with an equimolar amount of an acid (i.e. HCl, HBr, HNO 3 , H 2 SO 4 , or H 3 PO 4 ) …”

Section: Resultsmentioning

confidence: 99%

“…HCl, HBr,H NO 3 ,H 2 SO 4 ,o rH 3 PO 4 ). [25] The crystal-structure conformationsw ere compared to conformations obtained by ab initio energy optimizations[ B3LYP/ 6-311g(d)].T his approach allowedu st oe xplore the stabilities of the different possible stable conformers. Our calculations predict that TTTand TTC are favored for MEH + _NO 2 and MEH + _Br,r espectively (Table 1).…”

Section: Structural Characterizationmentioning

confidence: 99%

“…In the present work, we directly synthesized the protonated merocyanine forms of nitro‐ and bromo‐substituted SP (MEH + , X=NO 2 , Br) by mechano‐ and sonosynthesis. Mechanosynthesis consists in the use of mechanical energy to trigger chemical reactions between solids . Solid‐state reactions are therefore performed in mixer mills .…”

Section: Introductionmentioning

confidence: 99%

“…Mechanosynthesis consists in the use of mechanical energy to trigger chemical reactions between solids. [25][26][27] Solid-state reactions are therefore performed in mixer mills. [28] Among the advantages of mechanosynthesis are:l arge quantitieso fs tarting materials can be used, timesaving properties, and the possibility to reduce side reactions, af actor that can lead to higher yields and better conversions.…”

Section: Introductionmentioning

confidence: 99%

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Direct Access by Mechanochemistry or Sonochemistry to Protonated Merocyanines: Components of a Four‐State Molecular Switch

Colaço¹,

Carletta

Gysel

et al. 2018

ChemistryOpen

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Direct access to the protonated merocyanine forms of two substituted spiropyrans by mechanosynthesis or sonochemistry was explored. The compounds were formed by the condensation reaction of the methyleneindolium iodide salt with salicylaldehyde derivatives. X‐ray crystallography, 1H NMR spectroscopy, ab initio geometry optimization, and absorption spectroscopy were combined to provide a better understanding of the four‐state molecular switch system in which the newly synthesized protonated merocyanines were found to play a central role. The results of this study suggest that the stability of the protonated merocyanines requires acidic conditions, as treatment with base led to the corresponding unprotonated merocyanines, which in turn spontaneously converted into photochromic closed spiropyrans.

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“…Recently, salts of MEH + _NO 2 were obtained by slow evaporation of a solution of SP_NO 2 mixed with an equimolar amount of an acid (i.e. HCl, HBr, HNO 3 , H 2 SO 4 , or H 3 PO 4 ) …”

Section: Resultsmentioning

confidence: 99%

Section: Structural Characterizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Direct Access by Mechanochemistry or Sonochemistry to Protonated Merocyanines: Components of a Four‐State Molecular Switch

Colaço¹,

Carletta

Gysel

et al. 2018

ChemistryOpen

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“…These issues prompted the rapid development of techniques to probe mechanochemical reactions in situ and in real time. To date, this has been performed using X-ray powder diffraction at synchrotron sources, laboratory-based Raman spectroscopy, or a simultaneous combination of the two [3,[15][16][17][18][19]. In situ, real-time monitoring has proven a great advantage to identifying processes and control parameters in mechanochemistry.…”

Section: Introductionmentioning

confidence: 99%

The effect of ball mass on the mechanochemical transformation of a single-component organic system: anhydrous caffeine

2018

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ABSTARCTMechanochemical methodologies, particularly ball milling, have become commonplace in many laboratories. In the present work, we examine the effects of milling ball mass on the polymorphic conversion of anhydrous caffeine. By investigating a single-phase system, the rate-limiting step of particle-particle contact formation is eliminated. It is found that larger milling balls lead to considerably faster conversion rates. Modelling of the transformation rate suggests that a single, time-independent rate constant is insufficient to describe the transformation. Instead, a convolution of at least two rate-determining processes is required to correctly describe the transformation. This suggests that the early stages of the transformation are governed only by the number of particle-ball collisions. As the reaction proceeds, these collisions less frequently involve reactant, and the rate becomes limited by mass transport, or mixing, even in originally single-phase systems, which become multi-phase as the product is formed. Larger milling balls are less hindered by poorly mixed material. This likely results from a combination of higher impact energies and higher surface areas associated with the larger milling balls. Such insight is important for the selective and targeted design of mechanochemical processes.

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4.8 In Situ Methods for Monitoring Solid‐State Processes in Molecular Materials

Michalchuk

Kabelitz

Emmerling

2021

Solid State Development and Processing of Pharmaceutical Molecules

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Impact Is Important—Systematic Investigation of the Influence of Milling Balls in Mechanochemical Reactions

Abstract: Experimental data, powder diffraction, and NMR and Raman data (PDF)

Cited by 52 publications

References 58 publications

Direct Access by Mechanochemistry or Sonochemistry to Protonated Merocyanines: Components of a Four‐State Molecular Switch

Direct Access by Mechanochemistry or Sonochemistry to Protonated Merocyanines: Components of a Four‐State Molecular Switch

The effect of ball mass on the mechanochemical transformation of a single-component organic system: anhydrous caffeine

4.8 In Situ Methods for Monitoring Solid‐State Processes in Molecular Materials

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