Flow chemistry specialist Uniqsis has introduced a gas addition module for the Flowsyn and other continuous flow reactors.
The new module enables the fast, controllable pre-saturation of liquid reagents with a range of gases and so promotes gas-dependent reactions in flow, such as the hydrogenation, ozonolysis, carbonylation and direct synthesis of carboxylic acids.
Mixing gas and liquids in a controllable and reliable manner has always posed a challenge for flow chemists, particularly the prevention of undissolved gas bubbles, which have an adverse effect on the control of pressure and residence time in flow chemistry.
The pressurised tube-in-tube design of the gas addition module overcomes this problem by ensuring continuous interaction between the gas and liquid at every point along its length, according to the company.
The tube-in-tube design is based on semi-permeable membrane technology, whereby the semi-permeable inner tube containing the liquid (typically a solvent) is bathed by a stream of pressurised gas that is enclosed within a thick-walled impermeable outer tube.
The pressurised gas is able to cross the semi-permeable membrane of the inner tube and dissolve into the liquid carried within.
However, because of the semi-permeable nature of the inner tube material, the liquid is unable to cross in the opposite direction.
The design was developed in a collaboration effort between chemists in Prof Steven Ley's group at Cambridge University and is being jointly commercialised by Uniqsis and Cambridge Reactor Design.
The module is compatible with a range of reactive gases (such as CO, CO2, H2, D2, ethene, ethyne and SO2) and organic solvents (including THF, MeCN, MeOH and PrOH).
Capable of generating a continuous gas-saturated solvent stream in typically less than 10 seconds, it enables flow chemists to carry out a variety of applications with little effort, including heterogeneous and homogeneous gas-liquid reactions such as the hydrogenation, ozonolysis, carbonylation and direct synthesis of carboxylic acids.
The gas addition module features an optional portable gas reservoir.
This space-saving device is said to be easy and safe to charge with gas from a larger reservoir and obviates the need to bring bulky pressurised gas cylinders into the immediate experimental area.
The module can be added in line to any Flowsyn system and other continuous flow reactors to provide a solvent feed stream pre-saturated with gas, although it can also be used as a reactor in its own right.
