Biphasic Catalytic Hydrogen Peroxide Oxidation of Alcohols in Flow: Scale-up and Extraction

Abstract

We report continuous solvent-free biphasic alcohol oxidation with hydrogen peroxide and in-line separation of the tungsten polyoxometalate catalyst and phase transfer catalyst from the product. Zinc-substituted polyoxotungstate in combination with the selected phase transfer catalyst drives the oxidation reaction to completion within a short residence time (5−10 min) in a silicon Pyrex microreactor. This continuous and small-scale reactor allows for fast optimization of reaction conditions for each substrate and selection of the phase transfer catalyst. Scaling of the production rate (up to 650 times) is achieved with a Corning low flow reactor (LFR) and an advanced flow reactor (AFR). New scaled-up, in-line membrane-based liquid−liquid extraction units at the reactor outlet first separate the tungsten polyoxometalate catalyst with the aqueous waste stream from the organic product stream. A three-stage countercurrent liquid−liquid extraction then removes more than 90% of the phase transfer catalyst from the desired organic effluent stream while reducing the amount of extraction solvent required.

Oxidative Neutralization of Mustard‐Gas Simulants in an On‐Board Flow Device with In‐Line NMR Monitoring

“…Continuous flow devices fulfil all these requirements: they are compact systems which allow high control on reaction time as well as on heat and mass transfer, and the process can be easily up‐scaled without optimization of new conditions . Moreover, hazardous chemicals such as oxidants are easily handled in a flow system, and it offers the possibility of automation and in‐line analysis . Herein we show that the fast neutralization of sulfur mustard simulants can be achieved by fully selective oxidation in a flow apparatus monitored by an in‐line 1 H NMR low‐field instrument (Scheme ).…”

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

“…The same group later developed a flow system using hydrogen peroxide which was able to quantitatively transform 250 into acetophenone ( 289 , Scheme 82 ). The authors pointed out the simplicity of scaling up the process from an 160 μL microreactor to an 100 mL reactor (AFR) retaining the same processing efficiency [ 331 ]. To improve the phase separation, the authors employed a set of in-line PTFE membranes which enabled over 90% of the PTC to be extracted from the product.…”

Perspectives on the Use of Liquid Extraction for Radioisotope Purification

“…The advantages of flow extraction have led to considerable attentions over the last two decades. As a result, flow extraction has been employed for numerous applications including extraction of metals [29,30,31], extraction of rare earth elements [32], microextraction of radionuclides [33,34], purification of nanoparticles [35], separation of catalysts and phase-transfer agents [36], and flow chemistry [37,38,39,40]. Recently, Pedersen et al applied flow extraction for the extraction of the titanium-45 radioisotope [41].…”