Classifications

• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N37/00—Biocides, pest repellants or attractants, or plant growth regulators containing organic compounds containing a carbon atom having three bonds to hetero atoms with at the most two bonds to halogen, e.g. carboxylic acids
  • A01N37/16—Biocides, pest repellants or attractants, or plant growth regulators containing organic compounds containing a carbon atom having three bonds to hetero atoms with at the most two bonds to halogen, e.g. carboxylic acids containing the group; Thio analogues thereof

Definitions

• the present invention relates to a disinfectant system for use, for example, in human and animal health applications.
• the system contemplates in-situ generation of an organic peroxyacid to function as disinfectant.
• Disinfectants are becoming more widely used in an increasing number of industries. Amongst the reasons for the increasing use is the need to comply with more stringent Health and Safety Regulations as well as the fact that the number of organisms resistant to certain disinfectants is increasing. Much research in this technical area is concerned with finding more active means of disinfection, usually chemical. Amongst the problems with such active chemical disinfectants, one which is particularly difficult to overcome is the long-term stability of the disinfectant. Often the chemical groups of a molecule which make it an effective disinfectant, are the groups which make the molecule inherently unstable.
• peroxyacetic acid often referred to as peroxyacetic acid or PAA
• PAA peroxyacetic acid
• This particular peroxyacid is rarely isolated and is normally encountered in solution in both aqueous and non-aqueous media.
• Peroxyacetic acid is often supplied as an equilibrium mixture including primarily water, acetic acid and hydrogen peroxide, together with a number of other minor components such as stabilisers.
• equilibrium systems of peroxyacetic acid are inherently thermodynamically unstable due to the decomposition of peroxyacetic acid into acetic acid and oxygen. Such decomposition can be slowed down if special measures are taken but cannot be completely prevented.
• a further property of peroxyacids which makes them difficult to use or store is that they can decompose rapidly and violently, particularly peroxyacids of low molecular weight and of high purity.
• peroxyacids are often generated in-situ to perform the particular desired function.
• Such in-situ generation has advantages in that the amount of peroxyacid produced can be controlled through control of the starting materials and also the consumption of starting materials is optimised.
• higher concentrations of peroxyacid can be achieved than are available from equilibrium systems due to the non- equilibrium nature of the in-situ systems.
• a peroxyacid precursor is reacted with a peroxide source, usually hydrogen peroxide.
• a peroxide source usually hydrogen peroxide.
• peroxide precursors molecules containing groups such as amides (including lactams), acyl halides, or esters - particularly gem-diesters, but also including lactones - can be named.
• activators molecules containing groups such as amides (including lactams), acyl halides, or esters - particularly gem-diesters, but also including lactones - can be named.
• Such a system will normally not be in an equilibrium state and the rate of peroxyacid generation will depend on, amongst other things, the concentration of the reactants and their reactivity.
• a method of production of a solution containing a peroxyacid including the steps of mixing together a first and second aqueous solution; the first solution having a pH of from 7 to 9.5 and comprising;
• an alkali metal borate salt at a concentration of up to 5% w / w
• the second solution having a pH of from 6 to 10;
• the first and second solutions being mixed together in water in a ratio of from 1 :100 - 100:1 by weight of the first solution to the second solution.
• the solution thus provided yields the peroxyacid rapidly at the desired concentration for the particular disinfection treatment being undertaken.
• the structuring electrolyte is preferably citric acid or an alkali metal salt thereof and is present in sufficient quantity to maintain the activator, where solid in suspension.
• Levels of structuring electrolyte of 7-12% w / w of the second solution have been found to be particularly suitable and preferably of 9-11% w / w.
• the borate salt is advantageously a tetraborate and preferably has a concentration of less than 4% w / w of the first solution.
• the surfactant can advantageously be a nonionic or an anionic surfactant or a mixture thereof.
• the nonionic surfactant is particularly advantageously a fattyalcoholethoxylate or polyethoxylate with preferably 12-15 carbon atoms in the chain.
• the anionic surfactant is particularly advantageously an organosulphonic acid or salt thereof such as an alkylbenzenesulphonate, for example dodecylbenzenesulphonic acid.
• the peroxide stabiliser is added at a level sufficient to sequester peroxide decomposition catalysts, for example, transition metal ions such as iron
• stabiliser Typical levels of stabiliser are from 0.3 to 0.6% w / w of the first solution.
• the stabiliser can be chosen from one or more of groups well known in the art such as phosphates, organophosphonic acids, carboxylic acids or the alkali metal salt thereof and can include a mixture of two or more stabilisers.
• the activator is preferably selected from the group which releases peroxyaceticacid on reaction with hydrogen peroxide. Exemplifying of this group are tetraacetylethylenediamine (TAED), pentaacetylglucose (PAG), N- acetylcaprolactam. More generally, sodium nonanoyloxybenzenesulphonate, (producing peroxynonanoic acid on reaction with hydrogen peroxide) ethylidenebenzoateacetate and ethylideneheptanoate acetate can be used or mixtures thereof.
• the activator is advantageously present at a level of from 5- 10% w / w and particularly advantageously at 7-9% w / w.
• the second solution can include a corrosion inhibitor such as benzotriazole or other inhibitors known in that art.
• the corrosion inhibitors find particular use where the disinfection use is to include application to a metal surface, and will be present at a level of from 0.4% to 0.8% by weight of the second solution.
• the first solution includes an organic diol.
• the diol enables higher concentration solutions of borates to be achieved.
• the diol is particularly advantageously a cis - 1, 2 - diol, or a -1, 3- diol which can bond more readily with borate.
• Suitable diols for consideration are sorbitol, mannitol, xylitol, gluconic acid or salt thereof, dextrins, maltoses etc.
• the diol is conveniently present at a level of from 0.5% to 2% w / w .
• the ratio of first solution to second solution is preferably between 1 :3 and 3: 1 by volume, and particularly preferably 1 : 1.
• the invention also includes a two pack system for use in disinfecting surfaces, the system including a first pack comprising hydrogen peroxide at a concentration of up to 8% w /w, an alkali metal borate salt, and a peroxide stabiliser, the second pack comprising an activator reactable with hydrogen peroxide to form a peroxyacid; a structuring electrolyte, the second pack having a pH of from 6 to 10.
• a disinfectant composition comprising a non-equilibrium solution of peroxyacid and hydrogen peroxide, the composition having a pH of from 7 to 10, and including a borate salt, and a peroxide stabiliser.
• Figure 1 is a line plot of peroxyacetic acid generation for the systems of Table 1.
• One solution to the first problem is to provide a system in which the reaction elements are maintained separately until required. Such a solution to the problem is contemplated in the invention described herein.
• peroxide In order to generate a peroxyacid, the most commonly used source of the peroxide moiety is hydrogen peroxide itself.
• the peroxyacid is generated through the reaction of hydrogen peroxide via a nucleophilic pathway, with an acyl containing molecule.
• Carboxylic acids themselves are not normally sufficiently reactive and so an activated form of acyl group is often used. Compounds which include such an activated acyl group are normally referred to as activators.
• peroxyacid generation is described predominantly in relation to peroxyacetic acid. It will be appreciated that the method is applicable to other peroxyacids.
• a soluble borate increases the rate at which peroxyacid is generated.
• hydrogen peroxide and borate anions react together to form an anionic peroxoborate species in solution.
• Peroxoborate anions are better nucleophiles than hydrogen peroxide itself, and so react more readily with the activator, to generate peroxyacid at pHs of 7 to 9.5, and especially so in the more acidic solutions.
• the peroxyacetic acid level was determined by first titrating against cerium (IV) sulphate to remove hydrogen peroxide and subsequently titrating against sodium thiosulphate in the presence of potassium iodide. The results obtained are shown in Table 1 as follows:
• composition A TAED as activator and exemplifying the invention.
• the system has two aqueous compositions A and B which are constituted as follows: Composition A
• Composition A is a structured liquid having a pH of around 7.
• the user therefore has two obvious problems in using a two pack system as herein contemplated. Firstly, the user will not be certain of delivering the correct amount of borate or peroxoborate species into the mixed composition, as a significant proportion of the borate species will have settled to the bottom of the pack. The amount and rate of generation of peroxyacetic acid will therefore be inconsistent between batches. Secondly, even if agitation of the borate-containing composition is undertaken prior to its being mixed with the other composition, the production of peroxyacetic acid is slowed down. The slowing is due to the introduction of a dissolution step in which the borate dissolves, prior to conversion of borate to peroxoborate. The time required to reach a required concentration of peroxyacetic acid will therefore be longer.
• a dissolution aid often in the form of a diol.
• the diol undergoes a dehydration reaction with the hydroxy groups of the borate.
• the resultant species is more soluble than the original borate, effectively rendering a higher concentration borate solution, but does not, surprisingly, decrease the reactivity with hydrogen peroxide to form peroxoborate solutions.
• Such an increased concentration of borate species therefore increases the equilibrium concentration of peroxoborate species in solution.
• peroxyacetic acid generation is more rapid.
• less of the two compositions is required to achieve a given peroxyacetic acid concentration inside a given time-scale.
• Table 5 shows the number of moles of disodium tetraborate which can be dissolved in a Standard volume of the particular solution before the solution becomes saturated. As can be seen from the results, a higher concentration of tetraborate can be achieved in the presence of a molecule having a diol group.
• a structuring agent such as citric acid or a salt thereof is included in the solution.
• a suitable concentration for the structuring agent is from 7-12% w / w and preferably 9-11% w / w .
• a first composition C was prepared by mixing together the following:
• Tetraacetylethylenediamine 8.50% w/w.
• Dodecylbenzenesulphonic acid 6.95% w/w.
• Trisodium Citrate (40% w/w) 24.82% w/w.
• the overall composition formed was a white suspension having a pH of approximately 8.
• anionic surfactants para - dodecylbenzenesulphonic acid, with minor amounts of Cio - C B secondary alkylbenzenesulphonic acids, can be cited.
• a suitable fattyalcohol ethoxylate is one derived from an isodecylalcohol with minor amounts of Ci 2 - C15 alcohols.
• a second composition D was prepared by mixing together the following:
• Hydrogen Peroxide (35% w/w) 21.53% w/w.
• the diethylenetriaminepenta(methylenephosphonic acid) is normally supplied as its sodium salt solution (32% as sodium salt).
• the second composition was a clear solution having a pH of approximately 9.
• a sodium hydroxide solution was also prepared containing the following:
• composition D The sorbitol solution and the sodium hydroxide solution were then mixed with the other constituents shown for composition D in the following amounts to form composition D.
• Sorbitol Solution 70.00% w/w.
• composition C 17.0% w/w.
• composition D 17.0% w/w.
• a solution containing approximately 0.1%w/w peroxyacetic acid was generated after 10 minutes.
• benzotriazole has been included as a corrosion inhibitor.
• Such corrosion inhibitors would normally be used in, for example, instrument sterilisation in hospitals, where they reduce pitting of metal instruments.
• the corrosion inhibitor can be dispensed with and so not included in the compositions.
• the benzotriazole may contain one or more substituents on either the benzene ring or on one or more of the nitrogens of the triazole group.
• substituents are lower alkyl groups having up to six carbon atoms, carboxy groups, hydroxy groups, or combinations thereof.
• corrosion inhibitors include alkali metal borates, phosphates or polyphosphates, sodium molybdate, benzoic acid or salts thereof.
• the activator is included as a source of peracid precursor.
• activators known in the art can also be used therefore either alone or in combination with TAED or other such activators.
• oxybenzenesulphonic acid such as nonanoyloxybenzenesulphonic acid, or the salts thereof can be used.
• N-acylcaprolactams or N- acylvalerolactams such as N-acetylcaprolactam.
• peracid precursors suitable for use are pentaacetylglucose or N,N,N,N- tetraacetylglycoluril (TAGU).
• the diol can be chosen to achieve the desired concentration of borate in solution.
• -1,2-diols are particularly suitable as they are stereochemically in the correct configuration to form a borate ester.
• - 1,3- ; -1,4 - and other diols can also be used.
• polyhydroxy molecules can also function in the same manner as diols themselves, through the use of two of their hydroxy groups to engage with the borate molecule.
• diol-containing molecules are fructose, galactose, glucose, mannose, ribose, erythrose, lactose, sucrose, saccharose, sorbitol, xylitol, xylulose, glycerol, glycerol monoalkyl ether, gluconic acid, galactonic acid, mannonic acid, glucuronic acid, dextrins, maltoses or a cellobiose.
• Diethylenetriamine ⁇ entamethylenephosphonicacid other chelating agents, to stabilise peroxide, can be included in the compositions.
• chelating agents are other alkylideneaminophosphonic acids or salts thereof, some of which are marketed under the name Dequest .
• Exemplary thereof are 1- hydroxyethylidene-1 , 1 -diphosphonic acid, 1 -amino- 1 -cyclohexylmethane- 1,1- diphosphonic acid, 1 -amino- 1-phenylmethanediphosphonic acid, amino (trimethylenephosphonic acid), dimethylaminomethanediphosphonic acid, and 1- hexamethylenediaminetetra(methylenephosphonic) acid.
• a further class of compounds suitable for use are the aminocarboxylicacids or salts thereof.
• members of this class are ethylenediaminetetraacetric acid, nitrilotriacetic acid, ethylenediaminedisuccinic acid, diethylenetriaminopentaa- cetic acid, N-di(methylenephosphonic acid)-aminoacetic acid.
• chelating agents are dipicolinic acid, ethane-1, 1,2- triphosphonic acid, ethylidene- 1,1 -diphosphonic acid, phosphono-succinic acid, 1- phosphono-lmethylsuccinic acid.
• chelating agents are phosphates, polyphosphates and pyrophosphates of monovalent cations, primarily sodium.
• polymeric carboxylates such as polyacrylic acid or salts thereof can also function as chelating agents.
• the stabiliser or stabilisers should be present in sufficient amounts to inhibit breakdown of hydrogen peroxide to allow the solutions to be stored. Levels of stabiliser of 0.3-0.6% w / w have been found to be suitable for this purpose.
• anionic surfactant p- dodecylbenzensulphonic acid exemplified
• other anionic surfactants can be included in the compositions.
• anionic surfactants are linear alkylbenzenesulphonates under the name NANSATM from Albright and Wilson, or HOSTAPURTM from Hoechst.
• suitable anionic surfactants are for example naphthalenesulphonic acid, alkylnaphthalene sulphonic acids, or alkali metal salts thereof.
• a further group of anionic surfactants which are suitable for use are alkylether sulphates.
• alkyl(ethylether)sulphates characterised by the general formula R 2 -O-(C m H 2m O) n - SO 3 M in which:
• M is an alkali metal, ammonium, substituted ammonium ion, but is preferably sodium.
• anionic surfactants the class derived from sarcosine can be named.
• borate is the anion of choice
• other inorganic anions which are suitable are phosphates and sulphates.

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• 2005
  • 2005-08-08 CA CA002580440A patent/CA2580440A1/en not_active Abandoned
  • 2005-08-08 WO PCT/GB2005/003123 patent/WO2006016145A1/en active Application Filing
  • 2005-08-08 EP EP05794167A patent/EP1781100A1/de not_active Withdrawn
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