Application of temperature cycling for crystal quality control during crystallization

Wu, Zhaohui; Yang, Sui; Wu, W.

doi:10.1039/c5ce02522b

Cited by 64 publications

(53 citation statements)

References 111 publications

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“… 9 , 69 Only recently, attempts have been made to influence not only the size, but also the shape of crystals via this approach. 8 , 9 , 56 , 70 , 71 Still, most studies on crystal shape tuning are of theoretical nature. Limitations of analytical tools to quantify the multidimensional shape of microcrystals have been recognized as a major bottleneck in controlling the crystal shape.…”

Section: Crystal Shape Tuningmentioning

confidence: 99%

Crystal Engineering in Continuous Plug-Flow Crystallizers

Besenhard

Neugebauer

Scheibelhofer

et al. 2017

Crystal Growth & Design

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Size, shape, and polymorphic form are the critical attributes of crystalline particles and represent the major focus of today’s crystallization process design. This work demonstrates how crystal properties can be tuned efficiently in solution via a tubular crystallizer that facilitates rapid temperature cycling. Controlled crystal growth, dissolution, and secondary nucleation allow a precise control of the crystal size and shape distribution, as well as polymorphic composition. Tubular crystallizers utilizing segmented flow such as the one presented in our work can provide plug flow characteristics, fast heating and cooling, allowing for rapid changes of the supersaturation. This makes them superior for crystal engineering over common crystallizers. Characterization of particle transport, however, revealed that careful selection of process parameters, such as tubing diameter, flow rates, solvents, etc., is crucial to achieve the full benefits of such reactors.

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Section: Crystal Shape Tuningmentioning

confidence: 99%

Crystal Engineering in Continuous Plug-Flow Crystallizers

Besenhard

Neugebauer

Scheibelhofer

et al. 2017

Crystal Growth & Design

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“…Other processes to achieve homochirality in the solid phase have also been proposed, and fluctuations in temperature or energy are critical in most of these processes. − The use of ultrasound for deracemization and several other methods to reach a pure enantiomorph have also been demonstrated. − Recently, an interesting process that combines grinding and temperature fluctuations has been proposed …”

Section: Introductionmentioning

confidence: 99%

Use of Programmed Damped Temperature Cycles for the Deracemization of a Racemic Suspension of a Conglomerate Forming System

Suwannasang

Flood

Rougeot

et al. 2017

Org. Process Res. Dev.

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The current research has developed a potential route toward process optimization for the deracemization of a racemizable conglomerate forming system. The use of damped temperature cycleswhere the magnitude of the temperature cycles is reduced as the enantiomeric excess (ee) in the solid phase increasesis a promising methodology for optimizing the temperature cycle induced deracemization process. This process requires significantly less time and energy to reach an enantiopure state compared with the use of constant amplitude temperature cycles. There was evidence of some crystal breakage occurring in the system; however, the limited amount of breakage did not produce any change in the enantiomeric excess in the solid phase in the absence of temperature cycles in the system. Hence, the primary mechanism in this process is neither Viedma ripening nor Ostwald ripening. Scanning electron micrographs of the crystals taken during the series of temperature cycles show that the amplification of the ee in the solid phase is caused by dissolution and growth phenomena induced by the temperature cycles. The promotion of the larger or faster growing crystals at the expense of the smaller or slower growing crystals during the cycles and entrainment from a mother liquor having ee = 0 are both responsible for this deracemization.

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“…The definition of TC refers to successive heating–cooling cycles employed for dissolution–recrystallization. 109,110 Under the TC technology, fine crystals or one classified species are destroyed by the heating temperature, and the remaining crystals or dominant species are expected to further grow circularly. Therefore, the crystal size increases under TC operation, and also contributes to a large pore size, in which more impurities can be discharged from the crystal pillar.…”

Section: Process Intensification Approachesmentioning

confidence: 99%