Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – Using disinfecting or sterilizing substance
Reexamination Certificate
1997-02-28
2001-03-27
Thornton, Krisanne (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
Using disinfecting or sterilizing substance
C252S186380, C424S616000, C510S367000, C510S375000, C514S547000, C562S002000
Reexamination Certificate
active
06207108
ABSTRACT:
This invention concerns peroxygen compositions. More specifically, this invention concerns solutions of peracids, and still more specifically, this invention concerns solutions of ester peracids.
It is well known that certain classes of compound exert a very strong microbicidal effect which renders them suitable for use as disinfectants in a wide range of applications, especially domestic and industrial hard surface disinfection. One of the most commonly employed compounds is sodium hypochlorite solution, because it is readily available at low cost and is reasonably effective as a disinfectant over short contact times. In recent years, however, there has been increasing concern expressed at the possible environmental consequences of the use of hypochlorite solutions, including the possible formation of chlorinated organic compounds, such as trihalomethanes, and so attempts have been made to identify alternative disinfectants.
One group of chemicals which it has hitherto been proposed to employ as an alternative to hypochlorite disinfectants comprises organic peroxygen compounds, particularly aliphatic C
1
to C
3
peracids such as peracetic acid. Although very effective microbicides, some people find the odour of these aliphatic peracids to be offensive or irritating, and so for applications in which the disinfectant is likely to be employed in the proximity of people, it is desirable to find alternative disinfectants.
Many disinfectant compositions, particularly household disinfectants employ a concentrated solution of disinfectant which is diluted to the required concentration in use. Many such concentrated solutions employ water as the solvent on account of its low cost, ready availability and ease of safe handling compared with organic solvents. It is obviously desirable that the disinfectant forms a single phase system in the concentrated solution because this avoids the need for the solution to be agitated before use. The formation of a single phase system reduces the possibility of the disinfectant becoming unevenly distributed throughout the composition and hence the possibility of inadequate or excessive dosing of the disinfectant.
Ester peracids are known in the prior art. For example, European Patent application No. EP-A-0 166 571 teaches the use of ester peracids of the general formula [RX]
m
AOOH, where R is hydrocarbyl or alkoxylated hydrocarbyl, X is a heteroatom moiety, preferably oxygen, A is a wide range of organic moieties containing one or two carbonyl groups and m is one or two, for use in bleaching and laundry applications.
European Patent application No. EP-A-0 426 217 teaches the use of ester peracids of the general formula X-O
2
C-A-CO
3
H, where A is a C1 to C12 alkyl, aryl or alkaryl radical and X is a C1 to C20 alkyl, aryl, alkyl aryl radical, optionally including a heteroatom, for use in bleaching and cleaning systems.
Both French Patent application no. 2324626 and a paper by Nedelec et al, Synthesis, 1976, pp821-3 teach a method for the preparation and isolation of ester peracids from the reaction between acid chlorides and hydrogen peroxide in organic solvents.
A paper by C. Lion et al, Bull. Soc. Chim. Belg. 1991, 100, pp555-559 discloses the preparation and isolation of ester peracids by the reaction between ester acid and hydrogen peroxide in the presence of high concentrations of sulphuric acid, and quenching into ice. The ester peracids so produced are employed in the destruction of toxic organophosphorus compounds in aqueous alkaline solution.
None of the prior art references specifically disclose the storage stable, aqueous acidic ester peracid solutions of the present invention, or the use of solutions of such ester peracids as disinfectants.
It is an objective of the present invention to provide novel storage stable, aqueous acidic ester peracid solutions.
It is another objective of the present invention to provide a peracid microbicide with reduced odour compared with C1 to C3 aliphatic peracids.
It is yet another objective of the present invention to provide a method for preparing storage stable, aqueous acidic ester peracid solutions.
It is a further objective of the present invention to provide a method for disinfecting using low odour peracids.
According to the present invention, there are provided storage stable, aqueous acidic solutions having a pH in the range of from 1 to 5 comprising at least one ester peracid having the general formula:
where R represents an alkyl group having from 1 to 4 carbons and x is from 1 to 4.
According to another aspect of the invention, there is provided a process for preparing storage stable, aqueous acidic solutions comprising at least one ester peracid, characterised in that the process comprises contacting an aqueous solution of one or more carboxylic compounds having the general formula:
where x is from 1 to 4, R represents an alkyl group having from 1 to 4 carbons and x is from 1 to 4 with an inorganic peroxygen compound at a pH of less than 4, preferably 3 or less, until at least some ester peracid has been produced and, thereafter, where the pH of the resultant ester peracid solution produced is less than 1, its pH is adjusted to be in the range of from 1 to 5.
A further aspect of the invention provides a method for disinfecting characterised in that a substrate to be disinfected is contacted with a disinfectant prepared from a storage stable, aqueous acidic solution as hereinbefore defined.
The aqueous acidic solutions according to the present invention comprise at least one ester peracid defined by having the general chemical formula:
where R represents an alkyl group having from 1 to 4 carbons and x is from 1 to 4. When R has 3 or 4 carbons, the alkyl group can be linear or branched, i.e. the alkyl group can be n- or isopropyl, or n-, iso- or tertiary butyl. Preferably, R is a methyl group. In many cases, the value of x is 2, 3 or 4.
In a particular embodiment, the solution according to the present invention comprises a mixture of the ester peracids where x is 2, 3 and 4, i.e. a mixture of the monoesters of peradipic, perglutaric and persuccinic acids. In a particularly preferred embodiment, the major fraction of the ester peracids present in the composition has x equal to 3.
The solutions according to the present invention have a pH in the range of from 1 to 5, and preferably from 1.5 to 4. In certain embodiments, the pH of the solutions is greater than 1.75, and may be greater than 2, for example 2.5 or more. A pH in the range of from 3 to 3.5 may be advantageous in certain embodiments. The ester peracid solutions according to the present invention can often exist as equilibrium mixtures in aqueous solution, in which the ester peracid is in equilibrium with water, hydrogen peroxide and the non-peroxidised acid. The equilibrium obeys the following general equation:
where R represents hydrogen or an organic radical. It will be readily apparent that, for a fixed concentration of one component, the relative concentrations of the individual components can vary over a wide range and still be at equilibrium. When a solution of an ester peracid is not at equilibrium, chemical reaction takes place such that the composition of the mixture changes towards that of the equilibrium composition.
The solutions according to the present invention have the advantage of storage stability, ie the activity of the ester peracid component of the solution is retained through extended periods of storage. Depending on the application, the desired storage stability can range from periods of several days, for example 10 or more days, to periods of several, for example 4 or more, weeks, and even several, for example, 3 or more, months.
The ester peracids are often present in the solutions, either in use or in storage, at a total concentration of from about 0.0001 to about 15% by weight of the solution, preferably from about 0.05 to about 10% by weight, and more preferably from about 0.1 to about 5% by weight. It will be recognised that ester peracid solutions for storage and/or transportation, particul
Carr Graham
James Alun Pryce
Larson & Taylor PLC
Solvay Interox Limites
Thornton Krisanne
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