Use of citric acid derivatives as pesticidal adjuvants

Details Use of citric acid derivatives as pesticidal adjuvants Use of citric acid derivatives as pesticidal adjuvants

2001-07-20

2003-04-22

Clardy, S. Mark (Department: 1616)

Plant protecting and regulating compositions

Plant growth regulating compositions

Designated nonactive ingredient containing

C514S784000

Reexamination Certificate

active

06551964

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to the novel use of citric acid derivatives in association with pesticides and also pesticidal compositions containing citric acid derivatives. In particular, the invention relates to compositions having fungicidal, herbicidal, insecticidal and acaricidal activity.
BACKGROUND OF THE INVENTION
Pesticidal compounds are typically used in the form of compositions containing one or more co-formulants, for example surfactants. For example, WO96/22020 discloses the use in a pesticidal composition of at least one aliphatic mono-, di- or tri-ester, with no mention of citric acid derivatives. WO90/13222 discloses plant-protecting preparations comprising certain citric acid derivatives that are different from those of the present invention. EP 0 579 052 deals with plant-protecting compositions comprising a biocide and an accelerator, for example linear diacid and esters thereof. GB 2 002 635 and DE 27 38 878 disclose pyrethroid-containing insecticidal compositions comprising citric acid esters to reduce the volatility of the active ingredient. JP 52 141853 provides plastic films containing trialkyl acetylcitrate with good resistance to fungus growth. We have found a new group of compounds, not previously used in association with pesticidal compounds, that can be used with advantage in association with pesticidal compounds.
DESCRIPTION
In a first aspect, the invention provides the use as a pesticidal adjuvant of at least one citric acid derivative, which has a log octanol-water coefficient (log P) of 2.6 to 11 (preferably 2.7 to 11, particularly 4 to 10.7, especially 4 to 10.3) and an equivalent hydrocarbon (EH) value of 29 to 47 (preferably 32 to 44).
We have found that the use of citric acid derivatives according to the invention which have little or no pesticidal activity in their own right, surprisingly aid the penetration of the pesticidal compound into the plant or plant tissue, thereby enhancing the efficacy of the pesticide in the pesticidal composition. This enhanced efficacy enables lower application rates. Lower application rates coupled with low toxicity of citric acid derivatives, leads to a reduction in the environmental impact.
In the context of the invention, the term adjuvant is a compound which enhances. the bioactivity of a pesticide, having no bioactivity in its own right.
In accordance with its normal meaning, the term pesticide, pesticidal etc, includes plant growth regulators (PGRs).
Advantageously, we have found that citric acid derivatives used as part of the invention as well as improving penetration of the pesticidal compound into the plant, are also effective solvents or co-solvents for use in pesticidal compositions. Citric acid derivatives are particularly effective in conjunction with those pesticides that are conventionally formulated as emulsifiable concentrates or emulsions in water, i.e. low to intermediate lipophilic pesticides.
Further advantages of citric acid derivatives include their low flash point and negligible odour compared with many other currently used adjuvants.
The log P value (octanol/water partition coefficient) of a compound is a measure of the solubility of the compound in water. The higher the log P the less soluble is the compound. The log P is calculated from the structure of the compound using the “clog P Program” (Pomona CollegeMed Chem Release 3.54, January 1988, provided by Daylight Chemical Information Systems Inc., Claremont, Calif.). The values generated by this program correlate well in general with those determined experimentally by methods well-known to those skilled in the art. Such experimental methods are difficult to apply accurately to compounds within the scope of this invention, and we therefore use the calculated values.
The equivalent hydrocarbon (EH) value of a compound is a measure of the volatility of a compound. The EH value is arrived at by adding the total number of carbon atoms in the molecule, adding five for any hydroxy group, one for any ether group, eight for any carboxyl group, and then adding three for each ester group. It has been found that EH values determined in this way correlate well with actual volatilities.
Preferred citric acid derivatives are those having the general formula (I)
wherein,
R
1
, R
2
and R
3
, which may be the same or different, are C
1
to C
20
alkyl, C
2
to C
20
alkenyl or C
2
to C
20
alkynyl, each of which may be substituted by —OR
6
, where R
6
is hydrogen or alkyl; or hydrogen;
R
4
is hydrogen or —C(═O)R
5
, where R
5
is as defined for R
1
; and
R
1
, R
2
, R
3
and R
4
are chosen such that the log P and EH value of the citric acid derivative is as defined hereinabove.
Any alkyl group may be straight or branched and is preferably of 1 to 10 carbon atoms, especially 1 to 7 and particularly 1 to 5 carbon atoms.
Any alkenyl or alkynyl group may be straight or branched and is preferably of 2 to 7 carbon atoms and may contain up to 3 double or triple bonds which may be conjugated, for example vinyl, allyl, butadienyl or propargyl.
Preferably, at least two R
1
, R
2
and R
3
groups are not hydrogen.
Preferably R
1
, R
2
and R
3
, which may be the same or different, are C
1
to C
20
alkyl, especially C
3
to C
8
alkyl.
Particularly preferred compounds are tri-n-butyl citrate (log P=4.3, EH=32) and O-acetyl tri-n-butyl citrate (log P=4.8, EH=32).
The citric acid derivative of the invention may exist as a single compound, however more commonly it exists as a mixture of compounds. Often, citric acid derivatives are only commercially available as mixtures obtained by fractional distillation. In cases such as these, the log P and EH values are average values.
In a further aspect, the invention provides a pesticidal composition comprising at least one pesticidal compound and at least one citric acid derivative defined hereinabove.
In another aspect, the invention provides a method of combating pests at a locus infested or liable to be infested therewith which comprises applying to said locus an effective amount of a pesticidal composition which comprises a pesticidal compound and at least one citric acid derivative as hereinabove described.
Suitable active ingredients which can be combined with the citric acid derivatives are especially those disclosed in “The Pesticidal Manual”, 11th Edition, published by Crop Protection Publications, and may for example be a herbicide, fungicide, insecticide, acaricide or PGR.
A suitable fungicide is for example
(i) a conazole sterol &Dgr;
14
-demethylase inhibitor,
(ii) a sterol &Dgr;
14
-reductase/&Dgr;
8,7
-isomerase reduction inhibitor based on a 1-[3-(4-tert-butylphenyl)-2-methylpropyl] group which is attached via the N-atom to piperidine or 2,6-dimethylmorpholine
(iii) a dithiocarbamate fungicide
(iv) a phthalimide fungicide in which a chloroalkylthio group is attached via the N-atom to the optionally hydrogenated phthalimide group.
(v) an anilide fungicide
(vi) an mbc fungicide.
(vii) a carbamate fungicide
(viii) a copper compound fungicide
(ix) a tin compound fungicide
(x) a strobilurin type fungicide,
(xi) a 2-anilinopyrimidine fungicide
(xii) a compound which causes systemic activated resistance, or
(xiii) a fungicide selected from the group consisting of chlorothalonil, dimethomorph, fenamidone, fenpiclonil, fluazinam, hymexazol, nuarimol, pencycuron, pyrifenox, thicyofen, probenazole, pyroquilon, tricyclazole, quaternary ammonium compounds, fludioxonil, quinoxyfen, famoxadone, diclocymet, spiroxamine, flumetover, fenhexamid, furametpyr, diflumetorim, fencaramid, carpropamid, sulfur and 5-chloro-6-(2-chloro-6-fluorophenyl)-7-N-(4-methylpiperidin-1-yl)[1,2,4]triazolo[1,5-a]pyrimidine.
Conazoles are defined in ISO standard 257 as compounds based on imidazole or 1,2,4-triazole and containing a halogenated phenyl group. Examples include prochloraz (and its metal complexes—especially the zinc, manganese or copper complex), propiconazole, flusilazole, hexaconazole, tebuconazole, difenoconazole, bromuconazole, cyproconazole,

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