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A Two-step Telescoped Continuous Flow Switchable Process Leading to Nitriles, Diaziridine or Hydrazine Derivatives

Abstract

Primary and benzylic alcohols were cost-effectively transformed into their corresponding nitriles using classical batch and a continuous flow process implemented on a multi-jet oscillating disk (MJOD) reactor platform. The alcohol as substrate was treated with (2,2,6,6-tetra-methylpiperidin-1-yl)oxidanyl free radical (TEMPO) as a pre-catalyst with 1,3-dichloro-5,5-dimethylhydantoine (DCH) as the terminal oxidant to produce the corresponding carbonyl compound. The reaction was conducted at a reaction temperature of 35 oC and a flow reactor residence time of 5 min. This alcohol to carbonyl oxidation step was telescoped with a subsequent step that involved treatment with aqueous ammonia and 1,3-diiodo-5,5-dimethylhydantoine (DIH) at a reaction temperature of 65 oC with concomitant oxidation to nitrile using a flow reactor residence time of 15 min. A solvent exchange was conducted in-between the two synthetic reaction steps by means of an in-line extraction with ethyl acetate, a step that was concatenated by using an in-line liquid-liquid separation using a hold-up tank. The second synthetic step was revealed to be tuneable, since four distinct products might be produced at varying degree of selectivity. When DIH was used as the terminal oxidant, a high selectivity towards the original target nitrile was achieved, but if DIH was replaced with DCH as the terminal oxidant, 1,2-di((E)-benzylidene)hydrazine and two different stereo isomers of the 1,3,5-triazabicyclo[3.1.0]hexane scaffold were produced. The selectivity towards the various products was highly influenced by the reaction temperature. A scope and limitation study of the nitrile process with an assortment of primary alcohols as substrates provided excellent yields revealed good functional group tolerance.

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Publication details

The article was received on 16 Jul 2018, accepted on 31 Oct 2018 and first published on 01 Nov 2018


Article type: Paper
DOI: 10.1039/C8RE00129D
Citation: React. Chem. Eng., 2018, Accepted Manuscript
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    A Two-step Telescoped Continuous Flow Switchable Process Leading to Nitriles, Diaziridine or Hydrazine Derivatives

    A. Drageset, N. Å. Frøystein, K. W. Törnroos and H. Bjørsvik, React. Chem. Eng., 2018, Accepted Manuscript , DOI: 10.1039/C8RE00129D

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