PTFE microreactor

The microreactor system used was the commercial CYTOS College System [18]. The reactor is made of stainless steel, has 100 ptm channels and 2 ml volume. It has two inlets operated by two piston pumps. An additional 45 ml residence time unit (RTU) is coimected to the system after the reactor itself to increase the reaction time. The parts of the device are comiected by polytetrafluoroethylene (PTFE) tubings. 

The connections for fluid contact have the task of ensuring ingress of the starting materials to the microreactor and egress of the products. They are normally miniature hoses made of PTFE or pipes made of chemically resistant stainless steel. Common diameters are 1 /8 and 1 /16 in fittings with 1/4 in UNF thread are employed for PTFE hoses and the steel tubing is fixed with jubilee dips. A variety of methods are used to fix compatible connection points on the microreactor. Here three of them will be described. 

The industrially important nitration of aromatic compounds in a microreactor using two immiscible liquid phases was demonstrated in different studies using either parallel [220] or segmented flow [221]. In all studies, a PTFE capillary microchannel, connected to an inlet junction, was used in which either segmented or parallel flow can be created. The use of PTFE tubing is desirable as it is commercially available and no complicated microfabrication methods are involved. 

Fig. 32 Flow microreactor system consisting of a polydimethylsiloxane (PDMS) multilayered laminar micromixer and PTFE microtubes for polymerization of amino acid A-carboxyanhydride (NCA) initiated by triethylamine...

Extraction devices with parallel flow have been integrated into reaction and separation systems [24—26]. Honda etal. [26] developed a microreaction system for the optical resolution of racemic amino adds. Figure 12.7 shows a schematic of the system. The microreactor used for the enzymatic reaction is a PTFE tube (500 mm inner diameter) with immobilized acylase on the inner wall. The channel for extraction has 200 pm width, 100 jm depth and 40 mm length and the space between plates is made of glass (bottom) and silicon (top). The charmel surface of sflicon is coated with Au and octadodecyl groups. Consequently, the resulting microchannel has a hydrophilic... 

A schematic of a microreactor unit is shown in Figure 11.2. Upstream from the microreactor is a preheating unit and downstream is a unit for adjusting the reaction time. A polytetrafluoroethylene (PTFE) tube 500 pm in diameter is rolled in outside the cylinder in both units. The microreactor can be used for many lands of chemical reactions by adjusting the preheating and reaction times. 

PTFE tube Figure 11.2 Schematic of microreactor unit. 

However, microreactor research can be conducted on simple microbore tubing fabricated from stainless steel (Figure 1.2a), polytetrafluoroethylene (PTFE), or any material compatible with the chemical processing conditions employed [4]. For instance, inexpensive fluoroelastomeric tubing was employed to prepare a packed-bed microreactor for the catalysis of oxidized primary and secondary alcohols [5]. As such, microreactor technology is related to the much wider field of microfluidics, which involves an extended set of microdevices and device integration strategies for fluid and particle manipulation [6]. 

TADH FDH as Capillary microreactor segmented flow PTFE cofactor tubing with T-piece connector... 

Stainless steel and PTFE capillary Borosilicate glass microreactor PTFE capillary PTEE capillary... 

PMMA microreactor and PTFE tubing PMMA microreactor... 

There is another type of electrochemical flow microreactors that can be used for electrolyte-free electrolysis (Figure 9.5) [24]. In this system, two carbon fiber electrodes are separated by a spacer (porous PTFE membrane, pore size 3 pm, thickness 75 pm) at a distance of micrometer order. A substrate solution is introduced into the anodic chamber. The anodic solution flows through the spacer membrane into the cathodic chamber. The product solution leaves the system from the cathodic chamber. In this system, the electric current flow and the liquid flow are parallel. Using this electrochemical flow microreactor having a serial electrode configuration, the anodic methoxylation of p-methoxytoluene was accomplished effectively without intentionally added electrolyte. Protons generated by the anodic oxidation acted as carriers of the electricity. This process will be discussed in detail in the practical part of this chapter. The device could also be used for the anodic methoxylation of N-methoxycarbonyl pyrrolidine and acenaphthylene. 

They examined the [2+2] cycloaddition using a flow microreactor system consisting of standard Y-shaped mixers and poly(tetrafluoroethylene) (PTFE) microtube reactors, as represented in Figure 4.4. First, solutions of silyl enol etherl... 

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