Enantioselective reduction of sparingly water-soluble ketones: continuous process and recycle of the aqueous buffer system

Leuchs, Susanne; Na’amnieh, Shukrallah; Greiner, Lasse

doi:10.1039/c2gc36558h

Cited by 21 publications

(30 citation statements)

References 38 publications

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“…In 2010, solvent recovery in combination with recycling of the opposite enantiomer via a new base-catalyzed epimerization further reduced the E factor to only 8 [48]. The prospects of solvent recycling in biocatalysis and industrial biotechnology in general have been reviewed elsewhere [50,51]. It should also be noted that the E factors reported by Dunn do not include process water.…”

Section: Biocatalysis and The Issue Of Solvent Wastementioning

confidence: 94%

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The E Factor and Process Mass Intensity

Dicks

Hent

2014

SpringerBriefs in Molecular Science

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The environmental (E) factor and process mass intensity (PMI) metrics are introduced and thoroughly analyzed. As indispensable green metrics widely applied throughout the chemical industry, the E factor and PMI are calculated for numerous industrial processes throughout the chapter. A perspective on waste in the context of academic research, industrial synthesis and reactivity within alternative reaction media highlights the importance of material recovery, in particular with regard to reaction solvents. The section on catalysis further expands on the question of waste reduction by considering several important points. Advantages of heterogeneous catalysis which include catalyst recycling and simple product isolation and purification are described. Issues and potential solutions encountered with homogeneous catalysts and potential solutions are also discussed. Finally, the biocatalytic synthesis of pregabalin sheds light on the notions of solvent recovery and water intensity. Limitations of the E factor (which include failure to address the nature of the waste produced) provide for an introduction to process mass intensity. After explaining the simple relationship between PMI and E factor, the chapter turns to the benefits of PMI as a more robust front-end approach for evaluating the material efficiency of a process. This idea is captured by considering the biocatalytic synthesis of Singulair. defined as "anything that is not the desired product" [1], in the years following its conception, the E factor metric has contributed to significant industrial waste reduction [2][3][4][5]. In tandem with atom economy, the E factor has provided the global view of synthetic efficiency. Typical industrial E factors first published by Sheldon (Table 3.1) [1] have enhanced understanding about the problem of waste and enabled various solutions to address it. Modern techniques are now starting to show potential in bypassing certain synthetic limitations once perceived in Sheldon's original conclusions. In recent years, efforts toward waste reduction have enabled many innovations such that the majority of process chemists today consider determining an E factor as essential to process development [6]. Keywords Intrinsic and Global E FactorsThe E factor approach to waste complements the atom economy metric because it offers both intrinsic and global evaluations of a synthetic process. The intrinsic method is one which Andraos calls the environmental impact factor based on molecular weight (E mw ) [7]. This metric is calculated as the ratio of the molecular weight of all by-products divided by the molecular weight of the desired product. The E factor based on mass (E factor) offers a global perspective and is calculated as the ratio of the total mass of all waste to the mass of the desired product [1]. Figure 3.1 outlines the calculations for both metrics in the context of a balanced stoichiometric reaction. From the conservation of mass law it is possible to derive simple mathematical relationships between the E factor me...

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Section: Biocatalysis and The Issue Of Solvent Wastementioning

confidence: 94%

“…In order to change this perception, efforts have been focused on developing green assessment tools for ionic liquid synthesis [64]. Concerning waste reduction, enantioselective alcohol syntheses in ILs with significantly improved E factors were recently reported [50,65].…”

Section: Perspectives On Waste In Alternative Reaction Mediamentioning

confidence: 99%

The E Factor and Process Mass Intensity

Dicks

Hent

2014

SpringerBriefs in Molecular Science

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“…Remarkably, very few publications actually consider recycling of the aqueous reaction mixture. As an example of this, Greiner et al demonstrated that recycling the aqueous reaction mixture can reduce the E-factor (Kg of waste produced per Kg of product) by more than 10-fold (Leuchs et al, 2013 ). This impressive reduction deserves further investigation to extend it to other biocatalytic applications in aqueous media.…”

Section: Water As Solvent: Scope and Limitationsmentioning

confidence: 99%

On the (Un)greenness of Biocatalysis: Some Challenging Figures and Some Promising Options

Marı́a

Hollmann

2015

Front. Microbiol.

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Biocatalysis is generally regarded as a “green” technology. This statement is justified by the mild reaction conditions, the use of aqueous reaction media—with water as the paradigm of green solvents—, and the renewable nature of the biocatalysts. However, researchers making these statements frequently do not take into account the entire picture of their processes. Aspects like water consumption, wastewater production, titers, and metrics of the (diluted?) biocatalytic processes are important as well. With those figures at hand, many biocatalytic reactions do not appear so green anymore. This article critically discusses some common wrong assumptions given for biocatalytic approaches, with regard to their environmental impact, and actual greenness. Some promising biocatalytic approaches, such as the use of biphasic systems involving biogenic solvents, deep-eutectic-solvents (and biogenic ionic liquids), water-free media, solvent-free processes, are briefly introduced, showing that enzyme catalysis can actually be a robust sustainable alternative for chemical processes.

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“…⋅ co‐factor re‐generation by either substrate‐coupled approach (often a high excess of alcohol (e.g., 2‐propanol)) or enzyme‐coupled approach (e.g. enoate reductase, GDH)…”

Section: Case Studymentioning

confidence: 99%

Application of Enzyme Coupling Reactions to Shift Thermodynamically Limited Biocatalytic Reactions

Abu

Woodley

2015

ChemCatChem

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In recent years, much interest has been shown in the use of multi‐enzyme cascades as a tool in organic synthesis. Such enzymatic cascades can provide added value to a synthetic scheme by starting from cheaper raw materials or making more valuable products. Additionally, they can be used to help shift the equilibrium of otherwise thermodynamically unfavourable reactions to give a higher conversion of the target product. By coupling an energetically unfavourable reaction with a more favourable one, the multi‐enzyme cascade mimics the approach taken in nature in metabolic pathways. Nevertheless, it can be challenging to combine several engineered enzymes in vitro for the conversion of non‐natural substrates. In this mini‐review we focus on enzyme coupling reactions as a tool to alleviate thermodynamic constraints in synthetically useful biocatalytic reactions. The implications of thermodynamic parameters such as the equilibrium constant on the multi‐enzyme cascades and the conventional methods of equilibrium shifting are also discussed in addition to methods used to estimate such values.

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Enantioselective reduction of sparingly water-soluble ketones: continuous process and recycle of the aqueous buffer system

Cited by 21 publications

References 38 publications

The E Factor and Process Mass Intensity

The E Factor and Process Mass Intensity

On the (Un)greenness of Biocatalysis: Some Challenging Figures and Some Promising Options

Application of Enzyme Coupling Reactions to Shift Thermodynamically Limited Biocatalytic Reactions

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