Warming up for mechanosynthesis – temperature development in ball mills during synthesis

Kulla, Hannes; Wilke, Manuel; Fischer, Friedrich; Röllig, Mathias; Maierhofer, Christiane; Emmerling, Franziska

doi:10.1039/c6cc08950j

Cited by 130 publications

(116 citation statements)

References 37 publications

Supporting

Mentioning

113

Contrasting

Unclassified

Order By: Relevance

“…Most probably, 2 melts directly after the start of the reaction. Based on previous thermography investigations [25], we can assume that the temperature in the milling jar rises quickly to 35 °C which is above the melting point of 2 (32 °C). The intensity of the 1 reflections decreases continuously and vanishes after 45 minutes.…”

Section: Resultsmentioning

confidence: 99%

Mechanochemical Knoevenagel condensation investigated in situ

Haferkamp

Fischer

Kraus

et al. 2017

Beilstein J. Org. Chem.

Self Cite

View full text Add to dashboard Cite

The mechanochemical Knoevenagel condensation of malononitrile with p-nitrobenzaldehyde was studied in situ using a tandem approach. X-ray diffraction and Raman spectroscopy were combined to yield time-resolved information on the milling process. Under solvent-free conditions, the reaction leads to a quantitative conversion to p-nitrobenzylidenemalononitrile within 50 minutes. The in situ data indicate that the process is fast and proceeds under a direct conversion. After stopping the milling process, the reaction continues until complete conversion. The continuous and the stopped milling process both result in crystalline products suitable for single crystal X-ray diffraction.

show abstract

Section: Resultsmentioning

confidence: 99%

Mechanochemical Knoevenagel condensation investigated in situ

Haferkamp

Fischer

Kraus

et al. 2017

Beilstein J. Org. Chem.

Self Cite

View full text Add to dashboard Cite

show abstract

“…[1] This approach to chemical synthesis is now being successfully scaled in continuous processes and even commercialised. [3,4] As such the field advances largely through trial and error. Forexample,even the kinetics of such reactions have yet to be broadly investigated and interpreted, and as ar esult general reaction models are lacking.…”

mentioning

confidence: 99%

“…[2] However,m any basic aspects of mechanochemical reactions remain poorly understood. [3] However, mechanochemical reactions are highly diverse,a nd reaction mixtures can undergo changes in their rheological properties during reactions, [4,5] which are not taken into account in the above reaction models. [3,4] As such the field advances largely through trial and error.…”

mentioning

confidence: 99%

Feedback Kinetics in Mechanochemistry: The Importance of Cohesive States

et al. 2017

View full text Add to dashboard Cite

Although mechanochemical synthesis is becoming more widely applied and even commercialised, greater basic understanding is needed if the field is to progress on less of a trial-and-error basis. We report that a mechanochemical reaction in a ball mill exhibits unusual sigmoidal feedback kinetics that differ dramatically from the simple first-order kinetics for the same reaction in solution. An induction period is followed by a rapid increase in reaction rate before the rate decreases again as the reaction goes to completion. The origin of these unusual kinetics is found to be a feedback cycle involving both chemical and mechanical factors. During the reaction the physical form of the reaction mixture changes from a powder to a cohesive rubber-like state, and this results in the observed reaction rate increase. The study reveals that non-obvious and dynamic rheological changes in the reaction mixture must be appreciated to understand how mechanochemical reactions progress.

show abstract

“…[11] Dissociation of this simple compound led to water and HCN, [12] making formamide and its derivatives appealing candidates for cyanationr eactions in prebiotic terrestrial chemistry.S eeing an opportunity,w ea pplied formamide as potential cyanide source in amechanochemical Strecker-type reaction with benzaldehyde (1a)a nd benzylamine (2a)i nt he presence of SiO 2 using ah igh-speed mixer mill with at ungsten carbide (WC) jar and one WC ball (d = 15.6 gcm À3 )a t3 0Hzf or 90 min. To our disappointment, 1 HNMR spectroscopy of the reaction mixture revealed (besides remaining formamide) only the formation of imine 4aa,w hile a-aminonitrile 3aa remained undetected Apparently,n either the energetic impact nor the natural rise in temperature inside the ball mill [13] had led to ap roductive reaction pathway.…”

mentioning

confidence: 99%

Mechanochemical Activation of Iron Cyano Complexes: A Prebiotic Impact Scenario for the Synthesis of α‐Amino Acid Derivatives

et al. 2018

View full text Add to dashboard Cite

Mechanochemical activation of iron cyano complexes by ball milling results in the formation of HCN,w hich can be trapped and incorporated into a-aminonitriles.T his prebiotic impact scenario can be extended by mechanochemically transforming the resulting a-aminonitriles into a-amino amides using ac hemical route related to early Earth conditions.Scheme 2. Mechanosynthesis of a-aminonitriles 3 using K 3 [Fe(CN) 6 ]. [23] Scheme 3. Mechanochemical hydration of 3aa.

show abstract

Warming up for mechanosynthesis – temperature development in ball mills during synthesis

Cited by 130 publications

References 37 publications

Mechanochemical Knoevenagel condensation investigated in situ

Mechanochemical Knoevenagel condensation investigated in situ

Feedback Kinetics in Mechanochemistry: The Importance of Cohesive States

Mechanochemical Activation of Iron Cyano Complexes: A Prebiotic Impact Scenario for the Synthesis of α‐Amino Acid Derivatives

Contact Info

Product

Resources

About