Process for the separation of organic nitrosonium and/or hydroxylamine compounds by means of cation exchange resins and recovery and oxidation processes based thereon

Abstract

A process for the separation of a secondary organic nitrosonium compound and/or a secondary organic hydroxylamine compound from an acidic aqueous medium containing them in dissolved form, includes the step of bringing into contact said acidic aqueous medium with a cation exchange resin. The process is used in a process for the recovery of secondary organic nitroxy compounds from an aqueous medium containing the nitroxy compound and oxidation processes for hydroxy compounds.

Description

CROSS REFERENCE TO RELATED APPLICATION [0001] This application claims the 35 USC 119(e) benefit of prior U.S. Provisional application Ser. No. 60 / 527,281 filed on Dec. 8, 2003.FIELD OF THE INVENTION [0002] The present invention relates to a process for the separation of organic nitrosonium and / or hydroxylamine compounds by means of a cation exchange resin, a recovery process for the corresponding nitroxy compounds based thereon as well as a process for the nitroxy-mediated oxidation of hydroxy compounds that also makes use of this separation process. BACKGROUND OF THE INVENTION [0003] Nitroxy-mediated oxidations are a useful tool to convert primary alcohols to aldehydes and / or carboxylic acids or secondary alcohols to ketones. Organic nitroxy compounds suitable for this purpose must be capable of forming stable radicals and therefore, as a rule, are secondary nitroxy compounds sterically shielded by at least one bulky group having a quaternary carbon atom in α-position to the nitrog...

AI Technical Summary

Benefits of technology

[0020] It is one further object of the present invention to provide a separation process for organic nitrosonium and / or hydroxylamine compounds wherein organic solvents can be avoided.

[0021] It is a further object of the present invention to provide a process for the recovery of organic nitroxy compounds, such as TEMPO wherein the volatility of some nitroxy compounds does not cause any problems.

[0022] It is one further object of the present invention to provide a recovery process for organic nitroxy compounds with which the use of organic solvents can be avoided.

[0023] It is a further object of the present invention to provide a process for the oxidation of hydroxy compounds wherein the reaction mixture can be easily purified and the nitroxy mediator and / or the corresponding nitrosonium ion is easily recovered.

[0024] Finally, it is an object of the present invention to provide a process for the oxidation of a hydroxy compound that facilitates the recycling of various starting materials if these are not fully reacted.

[0025] Moreover, it is an object of the present invention to provide a closed cycle oxidation process for hydroxy compounds wherein the loss of organic nitroxy compound due to its volatility is minimised.

Problems solved by technology

If TEMPO and related nitroxy compounds are used as a catalyst in the oxidation of alcohols, for instance carbohydrates, the nitroxy compound is often lost during the isolation of the reaction product due to the relatively high volatility of nitroxy compounds such as TEMPO.

This is an undesired situation for an economical process.

However, this method requires distillation devices and creates high costs due to its energy consumption.

Further, this method is not applicable to less volatile nitroxy compounds.

However, the reaction rate of immobilized organic nitroxy compounds is typically lower than in homogeneous systems.

Nevertheless, this recovery process creates new problems insofar as, after eluting the organic nitroxy compound from the column, the organic solvent (eluent) has to be removed by evaporation.

At this point in time, the high volatility of some organic nitroxy compounds such as TEMPO or 3,4-dehydro-TEMPO leads again to an undesired loss of this costly material.

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