Peracid compounds

Details Peracid compounds Peracid compounds

1995-04-21

1997-12-16

Nakarani, D. S.

Stock material or miscellaneous articles

Coated or structually defined flake, particle, cell, strand,...

Particulate matter

427215, 427218, 427219, 427220, 428404, 428405, 428446, 428447, C07C40940, C07C40700

Patent

active

056983263

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

This invention concerns organic peracids, and more specifically, organic peracids bonded to an inorganic support.
Organic peracids have found many applications throughout industry because of their oxidative nature. For example, they are widely employed as oxidants in organic reactions, including use in epoxidation reactions, where certain examples have been found to be useful selective oxidants. Examples are also used to disinfect and reduce the chemical oxygen demand of aqueous effluent streams.
In the majority of applications for peracids, in order for the peracid to have an effect on the desired substrate it has often been found necessary for the peracid to be employed as either a solution, or in some other form, for example a powder, which is capable of producing an in-situ solution of the peracid. Once the peracid has acted on the substrate, it is often reduced to form the corresponding acid, which has no further oxidative activity. Such spent reagent can then either be discarded or can be recovered from the oxidation medium for possible recycling or use in other processes. When the peracid is a cheap and readily produced one such as peracetic acid, it is often acceptable for the peracid to be discarded, unless there are special circumstances necessitating or permitting its easy recovery. However, in many cases, it is desirable that discarding the spent reagent is avoided, if possible, because it represents a waste of chemical raw materials and also adds to process and effluent treatment costs. This is particularly so in cases where the peracid employed is more complex and/or more expensive to produce than simple peracids such as peracetic acid.
One option for reducing the wastage of chemicals is to regenerate the peracid from the acid in the oxidation medium by adding an oxidising agent. Unfortunately, this approach suffers from the drawback that the concentration of acid remaining in the oxidation medium is often relatively low. This means that the reaction kinetics and/or equilibrium for the production of the peracid are unfavourable for a rapid and economic reaction to occur.
Another option for reducing chemical wastage is to separate the remaining acid from the reaction medium for conversion back to peracid, or for use in other processes. There are many disadvantages to this where conventional peracids are employed. For example, if both the oxidation product and the spent reagent are solids, purification stages are necessary. If the spent reagent remains in solution in the oxidation medium, it may be necessary, for example, to evaporate off the solvent until the spent reagent precipitates, but even this does not guarantee the purity of the acid produced and further purification can be necessary. In many cases, such separations require specialised plant, which adds to the cost of the process, as well as increasing the need for space.
Nevertheless, it remains desirable that the spent reagent should be recoverable from the oxidation medium, preferably by the use of a relatively simple separation process such as filtration. One option to achieve this is to employ the peracid in a form such that the recovery of the acid could easily be achieved. One possibility that has been explored is to physically absorb a peracid on an insoluble support, but this approach has the problem that the peracid is attached to the support by relatively weak intermolecular forces only, so that it is relatively easy for the peracid or corresponding acid to dissolve and therefore to be lost from the support.
An alternative approach was suggested by Sherrington et al in European Polymer Journal Vol 16, pp293-8. Sherrington's process comprised chemically bonding an aromatic organosilane containing a benzyl chloride moiety to an inorganic macromolecular support containing pendant hydroxy groups, or modifying an inorganic-supported organic group to include a benzyl chloride moiety. The benzyl chloride moiety was then converted to a benzaldehyde moiety, which was then oxidised to produce a peracid. Th

REFERENCES:
Greig et al. "Preparation of Polymer Resin and Inorganic Oxide Supported Peroxy-acids and their use in the Oxidation of tetrahydrothiophene" European Polymer Journal, vol. 16, pp. 293-298 (1980).

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