Topics in Current Chemistry (2019) 377:2
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7.1 Tube‑in‑Tube Reactor
Ley and co‑workers pioneered the tube‑in‑tube reactor gas‑loading concept to ena‑
ble the safer introduction of gases into the liquid‑phase [75]. A semipermeable poly‑
meric membrane is permeable to gases but impermeable to liquids. The nature of
the contacting method ensures that the use of pure O 2 is inherently safe, because
it avoids the direct mixing of gaseous O 2 with the liquid phase. Teflon AF‑2400 (a
fluoropolymer) was selected as an appropriate membrane material due to its high
permeability to a wide range of gases while remaining impermeable to (nonfluori‑
nated) liquids, its thermal stability and for its resistance to corrosion. The tube‑in‑
tube reactor was successfully demonstrated by Ley and co‑workers on the synthesis
of phenylacetaldehydes from functionalized styrenes using an aerobic anti‑Marko‑
vnikov Wacker oxidation involving pure O 2 (Scheme 20a) [76]. The O 2 was loaded
(a)
(b)
(c)
(d)
Scheme 20 Continuous flow oxidation using a tube‑in‑tube reactor as the gas addition module
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