Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Biocides; animal or insect repellents or attractants
Patent
1989-11-20
1991-08-06
Page, Thurman
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Biocides; animal or insect repellents or attractants
514531, 514521, A01N 2500
Patent
active
050376535
DESCRIPTION:
BRIEF SUMMARY
This invention relates to chemical formulations which are useful as water-miscible preparations of compounds which are normally regarded as water-insoluble and to their use as pesticidal formulation.
Some of the most useful compounds in industry and agriculture are not water soluble This often inhibits or curtails their use, particularly when the application of the compound in solution is desirable. Although the compound may well be soluble in organic solvents, their use in large quantities is not always desirable from the economic or environmental point of view.
One such group of compounds comprises pesticides, for example the pyrethroid pesticides, which are widely used commercially either as: water; or as areas.
Typical solvents used in these systems include hydrocarbons such as xylene, heavy aromatic naphtha, kerosene and various paraffins or alkanes.
One synthetic pyrethroid is deltamethrin, which is the common name for 3-(2,2-dibromoethenyl)-2,2-dimethylcyclopropane carboxylic acid cyano(3-phenoxyphenyl)methyl ester. Deltamethrin is a potent synthetic pyrethroid pesticide, the preparation of the racemic mixture of which is described in DE-A-2439177. Deltamethrin is insoluble in water, but is soluble in organic solvents such as ethanol, acetone, dioxane, xylene and certain petroleum fractions
Other synthetic pyrethroids include cypermethrin (3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylic acid cyano(3-phenoxyphenyl)-methyl ester), permethrin (3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylic acid (3-phenoxyphenyl)-methyl ester) and fenvalerate (4-chloro-alpha-(1-methylethyl)benzeneacetic acid cyano(3-phenoxyphenyl)methyl ester. Cypermethrin may be prepared as described in DE-A-2326077, permethrin may be prepared as described in DE-A-2437882 and DE-A-2544150, and fenvalerate may be prepared as described in DE-A-2335347. Other pesticides include non-pyrethroid insecticides and acaricides (such as organophosphorus compounds) and herbicides and fungicides. Organophosphorus compounds include chlorpyritos (0,0-diethyl-0-3,5,6-trichloro-2-pyridyl phosphorothioate), chlorpyrifos-methyl (0,0-dimethyl-0-3,5,6-trichloro-2-pyridyl phosphorothioate), fenitrothion (0,0-dimethyl-0-4-nitro-m-tolyl phosphorothioate) and pirimiphos-methyl (0-2-diethylamino-6-methylpyrimidin-4-yl-0,0-dimethyl phosphorothioate).
The present invention is broadly speaking directed to formulating water-insoluble oil-soluble substances in water as small particles whose Z average mean size particle size is less than 200 nm. The Z average mean size can be defined as the model free mean of light scattering. Such formulations include microemulsions, micellar solutions and molecular solutions.
Microemulsions are in themselves known. They are one of three identified types of dispersion (as distinct from a molecular solution) of oil, water and surfactant. (The term "oil" is used in this specification to mean any non-aqueous solvent in which a substance of interest is soluble and which is immiscible with water.) These three types of dispersion are: microemulsions, micellar solutions and normal emulsions (or macroemulsions).
Macroemulsions appear white or opaque and are characterised by their property to separate into their two original liquid phases on standing; the average particle diameter will generally be above 200 nm. Microemulsions and micellar solutions are translucent and do not separate. Microemulsions can be considered as having average droplet (or particle) diameters of from 10 to 200 nm, micellar solutions as having average particle diameters of from 2 nm to 10 nm and molecular solutions as having average particle diameters of less than 2 nm. Recent evidence, however, does suggest that microemulsions with droplet diameters below 10 nm are possible.
Micelles occur when surfactants form large aggregates in water when their concentration is above the critical micelle concentration (cmc); a sharp transition in the physical properties of such solutions occurs at this concentration. In contrast, the physical properties of s
REFERENCES:
patent: 3954967 (1976-05-01), Urton
patent: 4500348 (1985-02-01), Hausmann et al.
patent: 4567161 (1986-01-01), Posanski et al.
patent: 4737520 (1988-04-01), Naik et al.
NC Development Inc.
Page Thurman
Phelan D. Gabrielle
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