MRT - Staudinger Hydration

By: Matthias Junkers, Aldrich ChemFiles 2009, 9.4, 14.

Aldrich ChemFiles 2009, 9.4, 14.

Benefit from MRT & Flow Chemistry: Efficient phase transfer catalysis; safe & scale-independent handling of explosive intermediates in small hold-up volumes with instant conversion.

Organic azides are high-energy compounds, an substrates with multiple azide moieties and low carbon content have to be considered as potential explosives, the azide intermediate shown in Scheme 7 has a potential of 3.8 kJ/g at 114 °C (measured by DSC).

Scheme 7: Two-stage microreactor assembly for the safe production and immediate conversion of organic azides (711462)

A two-stage microreactor continuous flow system allows the handling organic azides safely in small hold-up volumes with immediate conversion in the 2nd microreactor. In the 1st microreactor the azide intermediate is formed by nucleophilic substitution.1 The azide intermediate is submitted to Staudinger hydration with triphenylphosphine in a subsequent 2nd microreactor. Notably, it is possible to work with biphasic systems in microreactors. A phase transfer catalyst moderates the initial reaction with efficient mixing by the microreactor.

Production capacity of o-Xylylenediamine (711462) in two subsequent glass microreactors exceeds 1 kg per day with an overall yield of 60%. Work-up and isolation of the potentially hazardous intermediate is completely avoided between reaction steps, saving time, money and offering scale-independent safety levels.

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  1. Kopach, M.; Murray, M.; Braden, T.; Kobierski, M.; Williams, O. Org. Process Res. Dev. 2009, 13, 152-160.

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