Oxidative Nitration of Styrenes for the Recycling of Low‐Concentrated Nitrogen Dioxide in Air

Abstract

The oxidative nitration of styrenes in ethyl acetate represents a metal-free, environmentally friendly, and sustainable technique to recover even low concentrations of NO2 in air. Favorable features are that the product mixture comprising nitroalcohols, nitroketones, and nitro nitrates simplifies at lower concentrations of NO2 . Experiments in a miniplant-type 10 L wet scrubber demonstrated that the recycling technique is well applicable on larger scales at which initial NO2 concentrations of >10 000 ppm were reliably reduced to less than 40 ppm.

Sustainable Synthesis of Balsalazide and Sulfasalazine Based on Diazotization with Low Concentrations of Nitrogen Dioxide in Air

“…Much lower concentrations of nitric dioxide could be utilized in the oxidative nitration of styrenes (down to 0.1 vol. %), at which dilution of the gas stream even led to a favorable increase in product selectivity (Scheme , (2)) . Aromatic nitroalcohols and nitroketones accessible in this way are direct precursors for widely applied amino alcohols.…”

“… Organic synthesis combined with denitrification: utilization of low concentrations of nitrogen monoxide and nitrogen dioxide …”

“… Concentrations of nitrogen dioxide in outgoing gas stream after diazotization of arylamines 4 – 6 and 4‐chloroaniline …”

“…[12] Althought he obtained products are comparably valuable, this first strategyw as limitedt og as streams containingn itric monoxide in concentrations of at least 10 vol. [13] Aromaticn itroalcohols andn itroketones accessible in this way are direct precursors for widely applied amino alcohols. Much lower con-centrationso fn itric dioxide could be utilized in the oxidative nitration of styrenes (down to 0.1 vol.…”

“…%), at which dilution of the gas stream even led to af avorable increase in product selectivity (Scheme1,( 2)). [13] Aromaticn itroalcohols andn itroketones accessible in this way are direct precursors for widely applied amino alcohols. Regarding possible fields of application, the third strategy combining denitrification with the diazotization of anilines, and thus with the preparation of aromatic diazonium salts, is certainly the most versatile.…”