GB2274393A

GB2274393A - Synergistic biocidal composition

Info

Publication number: GB2274393A
Application number: GB9301173A
Authority: GB
Inventors: John Frederick Carr; Brian Davis; Peter Jordan
Original assignee: Rhone Poulenc Chimie SA; Rhone Poulenc Chemicals Ltd
Current assignee: Rhodia Chimie SAS; Rhodia Ltd
Priority date: 1993-01-21
Filing date: 1993-01-21
Publication date: 1994-07-27
Also published as: GB9301173D0

Abstract

A synergistic biocidal composition comprises: (a) an ampholyte of formula: <IMAGE> in which R1 is an alkyl group of from 8 to 18 carbon atoms; X is oxygen or NH; R<2> is an alkylene group of 2 or 3 carbon atoms; R<3> is hydrogen or a group R<1>XR<2> - wherein R<1>, x and R<2> are as defined above; R<4> is an alkylene group of from 1 to 3 carbon atoms; p is O or 1; R<5> is as defined for R<2>; and M is an alkali metal, hydrogen or NH<4> group, and (b) an alkyl amine oxide of formula: <IMAGE> in which R<1> is as defined above and R' and R", which are the same or different, represent methyl or ethyl, optionally substituted by hydroxy.

Description

BIOCIDAL COMPOSITION The present invention relates to biocidal compositions and their use.

GB 2242190A describes biocidal ampholytes of the formula: R-O- (CH2) 3-N (R1) - (CH2) 3-N (R1)2 and betaines thereof, in which: R is an alkyl group of 10 to 15 carbon atoms; and R1 is hydrogen, -(CH2)aCOOX+ or -CH(R2)-CH(R2)-(CH2)ffi-COO + wherein n is 1 to 3, M is an alkali metal, hydrogen or N, R2 is hydrogen or a methyl, ethyl or phenyl group, and m is 0 to 2; the RX and R2 substituents being the same or different within the above definitions. Because of their low solubility, some of these biocidal ampholytes cannot conveniently be used alone or in formulations. This problem is overcome, according to the aforesaid British specification, by blending the ampholyte with a nonbiocidal alkyl betaine.

The present invention is based on the unexpected finding that a composition comprising a specific type of amine ampholyte and an alkyl amine oxide exhibits a surprisingly high biocidal activity in comparison with that of the individual components of the composition, i.e. there is a synergistic biocidal effect. The new composition also exhibits improved solubility over a wide pH range compared with the ampholyte alone.

The biocidal composition of the present invention comprises: (a) an ampholyte of formula:

in which Rl is an alkyl group of from 8 to 18 carbon atoms which may be unsaturated; X is oxygen or NH; R2 is alkylene of 2 or 3 carbon atoms; R3 is hydrogen or R1XR2- wherein Rl, X and R2 are as defined above; R4 is alkylene of 1 to 3 carbon atoms; p is 0 or 1; Rs is alkylene of 2 or 3 carbon atoms; and M is an alkali metal, hydrogen or an NH4 group, and (b) an alkyl amine oxide of formula

in which Rl is as defined above and R' and R", which are the same or different, represent methyl or ethyl, each optionally substituted by hydroxy.

The preferred ampholytes (a) are those in which X is oxygen, R3 is hydrogen and p is 1, or X is NH, R3 is R1XR2- and p is 0 or R3 is H and p is 0 or 1.

Preferably R4 is -CH2-, -CH2CH2- or -CH (CH3) CH2-. R2 and R5 are each preferably -(CH2)2- or -(CH2)3-.

Ampholytes of the following formulae are for example, suitable: R1-NH- (CH2) 3-NH-CH2-COON; R-NH-(CH2)3-NH-(CH2)2-COOM; R'-NH-( CH,) ,-NH-(CH2) ,-NH-CH,-COOM; [R-NH-(CH2)2]2N-CH2-COOM; R-O-(CH2)3-NH-(CH2)3-NH-CH2-COOM; R'-O-(CH2) 3-NH- (CH2) 3-NH-(CH,),-COOM; and R-O-(CH2)3-NH-(CH2)3-NH-CH(CH3)CH2-COOM, wherein Rl and M are as hereinbefore defined.

Commercially available ampholytes (a) and alkyl amine oxides (b) may be used in the present invention. Such ampholytes and alkyl amine oxides may be derived from natural or synthetic sources.

The alkyl radical R1 in the ampholyte (a) and the alkyl amine oxide (b) may be a simple such radical having from 8 to 18 carbon atoms, or a mixture of alkyls each of which has 8 to 18 carbon atoms. R1 as a simple alkyl radical may be even-numbered having for example, 12, 14, 16 or 18 carbon atoms, or odd-numbered having for example, 9, 11, 13 or 15 carbon atoms. When Rl is a simple such alkyl radical it preferably has 12, 13 or 14 carbon atoms. When Rl is a mixture of alkyl radicals, a mixture comprising from 8 to 18 or from 12 to 14 carbon atoms is preferred.

A mixture of alkyls having a narrow distribution of carbon atoms in Rl for example, 12 to 14 carbon atoms, may be prepared from a mixture having a broader distribution for example, 8 to 18 carbon atoms by known techniques such as partial fractionation.

The radical Rl may be derived from a natural starting material containing a mixture of alkyl radicals (or radicals convertible into alkyl radicals). For example a mixture of amines of formula C8lsNH2 can be manufactured from coconut oil and converted (by reaction with acrylonitrile and reduction) into a diamine of formula C8l8NHCH2CH2CH2NH2. In the following the term "C8-18alkyl" or "coco-alkyl" means this mixture of alkyl radicals obtainable from coconut oil. ''Cl2l4 alkyl" means a mixture of alkyls having from 12 to 14 carbon atoms.

It is within the scope of the invention to use ampholytes (a) and alkyl amine oxides (b) in which Rl is unsaturated.

The alkali metal M is for example, sodium or potassium, preferably sodium.

In the amine oxides (b), R' and R" are preferably the same and preferably represent methyl, ethyl or -CH2CH20H, more preferably methyl.

Examples of preferred ampholytes (a) include C8-l8 alkyl-NH-(CH2)3-NH-CH2COONa, C8-18 alkyl-MH-(CH2)3-NH-CH2CH2COONa, Csls alkyl-NH-(CH2)2-NH-(CH2)2-NH-CH2COONa, C,3Hn-O- (CH2) 3-NH-(CH,) 3-NH-CH2COONa, C13H27-O-(CH2)3-NH-(CH2)3-NH-CH2CH2COONa, and C13H27-O-(CH2)3-NH-(CH2)3-NH-CH(CH3)CH2OOONa, 08.18 alkyl-NH(CH2)3NHCH2COONa, i. e. coco-alkyl NH(CH2)3NHCH2COONa is particularly preferred.

Cl2l4alkyl-N(CH3)20 is a preferred alkyl amine oxide.

Typically the ratio of ampholyte component (a) to alkyl amine oxide component (b) in the composition is from 10:1 to 1:3, preferably from 3:1 to 1:3, more preferably about 3:1, or 1:1 based on the weight of each component. A ratio of ampholyte:alkyl amine oxide of 3:1 gives maximum synergism while 1:1 gives improved solubility of the ampholyte in alkaline systems and improved detergency.

The ampholytes described above may be prepared by known methods. For example, they may be prepared by reacting the corresponding alkylene diamine or triamine or alkyl ether diamine of formula RlXR2N(R3)(R5NH)pH with an alkali metal chloroacetate or-alkali metal bromopropionate, with crotonic acid or with acrylonitrile or an acrylic acid ester followed by hydrolysis.

The alkyl amine oxides may also be prepared by known methods, for example by reacting the corresponding tertiary alkyl amine with hydrogen peroxide.

The compositions of represent invention are potent biocides which are capable of controlling or killing a variety of microorganisms, for instance gram positive bacteria e.g. StaphYlococcus aureus and StrePtococcus faecium, gram negative bacteria e.g. Escherichia coli and Pseudomonas aerusinosa, fungi e.g. Asperaillus niaer, moulds, yeasts e.g. Saccharomvces cerevisiae, algae e.g.

Chorella and pathogenic food related bacteria e.g.

Salmonella and Listeria. The compositions are therefore useful in applications in which the control of microorganisms is required.

The present invention accordingly provides a method of controlling microorganisms at a locus which comprises applying thereto an ampholyte and alkyl amine oxide as defined above.

The compositions of the invention may be used in detergents or cleaners which are to be used in any location where it is required to control or kill microorganisms, in particular, in hard surface disinfectant cleaners.

Detergents and cleaners which comprise a composition according to the present invention may be used in areas which may be infected by microorganisms, and are particularly useful in areas of food contact.

Generally, work surfaces, walls, floors and bathroom fittings for example toilets, baths and sinks may be cleaned using the detergents or cleaners comprising the present composition. Areas coming into contact with food, for example food processing equipment, bottle lines, glassware and crockery, may also be cleaned using the detergents or cleaners. The term "food" as used in this specification is intended to encompass both solid and liquid materials which are intended for human or animal comsumption.

The suitability of detergents and cleaners comprising the present composition for use in food contact areas means that they may be used in any location where food is prepared, processed or produced. They may be used in kitchens, for example domestic, hotel and restaurant kitchens, breweries, dairies, abattoirs and in the catering industry.

Some of the compositions of the invention are relatively mild to the skin and are therefore also ideal for use in antimicrobial soaps, in particular liquid hand cleaners.

As the compositions (unlike quaternary ammonium based disinfectants) are more stable in strong alkalis, they may be used in a variety of pH conditions ranging from weakly acidic, typically pH 4, to strongly alkaline conditions, typically pH 13.

The ampholyte and alkyl amine oxide components may be formulated with the usual ingredients to form detergents and cleaners. Formulation usually takes place by simple mechanical mixing.

The ampholyte and alkyl amine oxide may be formulated with water to form a simple concentrated blend. This blend may be diluted before use or formulated with other ingredients depending on the end use.

A simple concentrated blend typically comprises from 10 to 20% by weight of ampholyte, and from 1 to 60% by weight of alkyl amine oxide, made up to 100% weight with water. Preferably the concentrated blend comprises from 12.5 to 17.5% by weight ampholyte and from 1.25 to 52.5% by weight alkyl amine oxide.

A concentrated blend of 12.5% by weight ampholyte, 15% by weight alkyl amine oxide and 72.5% by weight water is particularly preferred and may be used alone at a concentration of, for example 0.58 by weight of the blend, e.g. to clean brewery equipment.

Alternatively, the concentrated blend may be used in other formulations for example, in hand cleaners, washingup liquids and floor and general surface cleaners.

The present invention also provides a combined preparation comprising an ampholyte as defined above and an alkyl amine oxide as defined above for simultaneous, sequential or separate use in the control of microorganisms. Simultaneous use means use of the ampholyte and alkyl amine oxide components at the same time for example, in a formulation comprising both components.

Sequential and separate use mean use of the ampholyte and alkyl amine oxide components individually one after the other. Sequential use implies a short period between application of the individual components. Separate use implies a greater period between the individual applications. It will also be understood that, with sequential and separate use, the biocidal effect will be observed only when the individual components are present in the appropriate proportions and sufficient concentrations.

The following Examples describe the preparation of representative ampholytes which may be used in the present invention.

EXAMPLE 1 1 mole of coco-alkyl-1,3-diaminopropane is reacted with 1 mole of sodium chloracetate at 80-850C in a water/diethylene glycol solvent for 8 hours, followed by neutralisation with sodium hydroxide.

coco-alkyl-NH- (CH2)3-NH2 + Ol-OH2OOONa+ 4 coco-alkyl-NH-(CH2)3-NH-CH2COONa+ + HCl t NaOH Nacl + H20 The product is used without isolation from solution.

EXAMPLE 2 1 mole of N- (isotridecyloxypropyl) -1, 3-diaminopropane is reacted with 1 mole of methyl acrylate in methanol under reflux for up to 8 hours, before dropwise addition to hot sodium hydroxide solution to effect hydrolysis of the ester. The reactions involved are:

O13H-O- (CH2) 3-NH- (OH2) 3-NH2 + CH2=CH-COOCH3 4 C,,H,-O-(CH,) 3-NH-(CH2) ,-NH-CH,-CH2-COOCH3 l NaOH Cl3H27-O-(CH2)3-NH-(CH2)3-NH-CH2-CH2-COONa The synergistic effect observed with the compositions of the invention may be illustrated by comparing the biocidal activity of the individual components with that of the composition.Biocidal activity is assessed in accordance with BS6471 which is the British Standard method for determining the effectiveness of disinfectants based on quaternary ammonium compounds. In BS6471 the greatest biocidal dilution which is 99.99% effective against Escherichia coli (ATCC accession no. 11299) is determined after 10 minutes contact at 220C in hard water (200 ppm hardness) in the presence of sterile horse serum (5%) and an inactivator (3% Tween 80 and 2% soya lecithin). The maximum biocidal dilution which is effective against the bacteria may be converted to a minimum effective bactericidal concentration. The results for the individual components are shown in Table 1.

TABLE 1

Caraponent Hinimum Bactericidal 30ncentration (ppm) I A. C=18 alkyl-Nll- (2) 1-NH-OH2COONa B. CK 18 aIkyl~NE~(CH2)3-NH-CH2CH2COONa 360 i c. Ckl6 alkyl-NE- (CR2) 2-NH- (CR2) 2-NH-CR2COONa 182 D. C-u- (CR2) 3NR (cur2) (CH2)3-NH-CH2COONa | 167 E. C*n-o-(cH2)3-NH-(cH2)3-NH-cH2cH2cooNa 167 F. 0D0 (CH) ,-NH- (CR 3-NE-CR CH2OOONa 167 I CH, CE3 U 10,000 g G. C > X8 alkyl-CONH-(CH2)3-N- > O CR3 Cft3 U I l 10,000 HX Cnl4aIkyl-N > O c-H, Component G is not representative of the components used in the invention. As can be seen components G and H are only weakly biocidal.

Table 2 shows the results for three compositions.

TABLE 2

Composition Maximum Maximum biocidal dilution 12.5% F + 15% G 1:750 12.5% F + 159 H 1:1506 12.5% A + 15% G 1:347 The above percentages and ratios are by weight.

On the basis of the maximum biocidal dilution it is possible to calculate the Fractional Biocidal Concentration (FBC) for each component. The FBC is calculated as follows: p FBC = q where p = effective bactericidal concentration of component in composition q = effective bactericidal concentration of component used alone The sum of the individual FBC values illustrates whether a synergistic effect has occurred. If s FBC < 1 then synergy exists between the components.

For components F and G the effective bactericidal concentration of component F alone = 167 ppm and that of component G alone = 10,000 ppm (from Table 1).

At a dilution of 1:750 12.5% F + 15% G contains 167 ppm F and 200 ppm G FBC (F) = 167/167 = 1 FBC (G) = 200/10,000 = 0.02 s FBC = 1.00 + 0.02 = 1.02 This indicates that no synergism exists between components F and G.

Similarly (FBO (F) + FBC (H)) = 0.507 SYNERGISM (FBO (A) + FBC (G)) = 1.043 NO SYNERGISM Various ratios of ampholyte A and alkyl amine oxide H were tested and the S FBC calculated in each case. The results are shown in the following Table.

TABLE 3

Conc.A Conc. H Biocidal Conc. A Conc. H FBC FBC iFBC dii. of at at A H blend biocidal biocidal dii. (ppm) dil. (ppm) 25 0 1:700 360 0 20 6 1:1000 200 60 0.556 0.006 0.562 17.5 9 1:800 219 112.5 0.608 0.011 0.619 15 12 1:800 187 150 0.519 0.015 0.534 12.5 15 1:800 156 187 0.433 0.019 0.452 11.25 16.5 1:800 141 206 0.392 0.021 0.413 10 18 1:700 143 257 0.397 0.026 0.423 7.5 21 1:600 125 350 0.347 0.035 0.382 0 30 1::30 0 10,000 The test results show that the compositions of the present invention exhibit a synergistic effect over the individual components and that very effective synergism is exhibited over a wide range of component ratios.

A particularly preferred composition in accordance with the present invention comprises a blend of 12.5% by weight of coco-alkyl-NH-(CH2)3NHCH2COONa (described in Example 1 above) and 15t by weight of CX2l4 alkyl-N(CH3)2O (component H above), the remainder being water. As noted above, for some purposes this blend may be used as such after simple dilution with water to a concentration of 0.5% by weight of the blend. For other purposes the concentrated blend may be mixed with other ingredients.

Examples of such formulations comprising the concentrated blend include: a) Biocidal hand cleaner Blend 15% Hydroxyethyl cellulose 0.5% Water to 100% b) Biocidal Washina-up Liquid Blend 30% Alcohol ethoxylate 10% (1 mole lauryl alcohol - 7 moles ethoxylate) Water to 100% c) General Surface Cleaner (concentrate) Blend 5% Nitrilotriacetic acid sodium salt 1% Sodium metasilicate.5H20 3% Water to 100% This concentrate is typically used at a dilution of 10 to 20 times.

d) Floor Cleaner (concentrate) Blend 12.5% Nonylphenol ethoxylate 2.5% (1 mole nonylphenol - 9 moles ethoxylate) Nitrilotriacetic acid sodium salt 2.5% Dipropylene glycol monomethyl ether 10% Water to 100% This concentrate is typically used at a dilution of 25 times.

The percentages given in the above formulations are by weight. When used as a concentrate the formulation is typically diluted with water before use.

Claims

1. A biocidal composition comprising: (a) an ampholyte of formula:

in which R1 is an alkyl group of from 8 to 18 carbon atoms; X is oxygen or NH; R2is an alkylene group of 2 or 3 carbon atoms; R3 is hydrogen or a group R1XR2- wherein R1, X and R2 are as defined above; R4is an alkylene group of from 1 to 3 carbon atoms; p is 0 or 1; R5is as defined for R2; and M is an alkali metal, hydrogen or NH4 group, and (b) an alkyl amine oxide of formula:

in which Rl is as defined above and R' and R", which are the same or different, represent methyl or ethyl groups, each optionally substituted by hydroxy.

2. A composition according to claim 1 wherein X is oxygen, R3 is hydrogen and p is 1.

3. A composition according to claim 1 wherein X is NH, R3 is R1XR2- and p is 0, or R3 is H and p is 0 or 1.

4. A composition according to claim 1, 2 or 3 wherein R4 is -CH2-, -CH2CH2-, or -CH(CH3)CH2-.

5. A composition according to any one of the preceding claims wherein RX is straight chain alkyl of 12, 14, 16 or 18 carbon atoms or a mixture thereof.

6. A composition according to claim 1 wherein the ampholyte (a) is of the formula: R1-NH-(CH2) 3-NH-OH2-OOOM; R-NH-(CH2)3-NH-(CH2)2-COOM; Rl-NH- ( CH2) 2-NH- ( CH2) 2-NH-CH2-COOM [R'-NH- (CH2)22N-CH2-COOM; R'-O-(CH2) ,-NH-(CH2) 3-NH-CHCOOM; R-O-(CH2)3-NH-(CH2)3-NH-(CH2)2-COOM; or R-O-(CH2)3-NH-(CH2)3-NH-CH(CH3)CH2-COOM wherein R and M are as defined in claim 1 or 5.

7. A composition according to any one of the preceding claims wherein M is sodium.

8. A composition according to claim 1 wherein the ampholyte (a) is coco-alkyl-NH(CH2)3NHCH2COONa, where "cocoalkyl" is a mixture of alkyls derived from coconut oil.

9. A composition according to any one of the preceding claims wherein the ratio of ampholyte (a) to alkyl amine oxide (b) is from 10:1 to 1:3.

10. A composition according to any one of the preceding claims wherein the alkyl amine oxide (b) is (012.14alkyl) dimethylamine oxide.

11. A method for controlling microorganisms at a locus which comprises applying thereto an ampholyte and alkyl amine oxide as defined in any one of claims 1 to 10.

12. A combined preparation comprising an ampholyte as defined in claim 1 and an alkyl amine oxide as defined in claim 1 for simultaneous, sequential or separate use in the control of microorganisms.