3,836,643 United States Patent Office Patented Sept. 17, 1974 2 amines and low nitrogen heterocycles; another useful 3,836,643 class of stabiliser comprises azoic and hydrozonic com PESTCDAL COMPOSETIONS CONTAIN ENG PHOS PHORIC ESTERS AND DEWALENT SULEPHUR pounds but these have a strong colouration power so that COMPOUNDS they cannot always be used. The use of anhydrides or Claude Hennart, Aubervilliers, France, assignor to Ciba epoxides has also been used but it is known that these com Geigy AG, Basel, Switzerland pounds act by fixation, either of a molecule of water or a No Drawing. Filed Sept. 13, 1971, Ser. No. 180,137 molecule of free acid; it can be seen that this process is Int, C. A01n 9/36, 11/06 limited stoichiometrically and that the stabilisation ceases U.S. C. 424-175 8 Claims when all the stabiliser has entered into reaction; this leads IO to the necessity of using substantial proportions of these stabilisers which is not economic. ABSTRACT OF THE BESCLOSUERE The present invention has as its object the stabilisation Pesticidal composition comprising: a pesticidal, phos of pesticidal phosphoric esters by using substances more phoric ester the molecule of which has at least one alkyl efficacious than those noted above and which do not group of 1 to 3 carbon atoms, 0.05 to 10% of an agent possess the inconveniences: these substances are sulphur stabilising the said ester against decomposition by pro compounds; they are suitable in particular at relatively tonisation, together with adjuvants characterised in that low concentrations for preserving phosphoric esters the stabilising agent comprises at least one sulphur com against protonisation. Thus the invention comprises pesti pound containing per molecule at least one divalent sul cidal compositions comprising: phur atom of which one valence is bonded to an atom chosen from sulphur, carbon, nitrogen, hydrogen, and (A) 5 to 99.95%, calculated on the weight of the compo metals capable of giving a salt, the other valence being sition, of a pesticidal, phosphoric ester the molecule of bonded to an atom chosen from hydrogen, the carbon which has at least one alkyl group of 1-3 carbon atoms, atom already noted, a second carbon atom, the nitrogen (B) 0.05 to 10%, calculated on the weight of the phos atom already noted, a second nitrogen atom, the metal 25 phoric ester, of an agent stabilising said ester against atom already noted in the case of a metal of valence decomposition by protonisation, greater than one, a second atom of metal and oxygen (C) 0 to 90%, calculated on the weight of the compo when the first valence is not attached to an atom of sition, one of more solvents for the phosphoric ester, hydrogen, the proportion of sulphur calculated with liquid or solid under pressure or otherwise, and reference to the weight of the sulphur compound being 30 (D) 0 to 50%, calculated on the weight of the compo between 5 and 99%. Process for stabilising a phosphoric sition of one or more inert adjuvants chosen from ester of which the molecule possesses at least one alkyl mineral adjuvants and organic adjuvants compatible group containing 1 to 3 carbon atoms characterised in with the phosphoric ester, that there is added to the phosphoric ester or to a mix said composition being characterised in that the stabilising ture which contains it 0.05 to 10% calculated on the agent comprises at least one sulphur compound contain weight of the phosphoric acid ester of an agent capable ing per molecule at least one divalant sulphur atom of of stabilising the said phosphoric ester against protonisa which one valence is bonded to an atom chosen from tion and comprising at least one sulphur compound such sulphur, carbon, nitrogen, hydrogen, and a metal capable as that defined thereupon. of giving a salt, the other valence being bonded to an 40 atom chosen from hydrogen, the carbon atom already noted, a second carbon atom, the nitrogen atom already This invention concerns a process for stabilising pesti noted, a second nitrogen atom, the metal atom already cidal phosphoric esters, and compositions based on phos noted in the case of a metal of valence greater than one, phoric esters so stabilised. a second atom of metal and oxygen when the first valence Phosphoric esters are nowadays very widespread for is not attached to an atom of hydrogen, the proportion pesticidal use, particularly for insecticides. Their value is of Sulphur calculated with reference to the weight of the due principally to speed of action and the absence of sulphur compound being between 5 and 99%. accumulation of these compounds in living tissue as a The present invention also includes a process for stabi result of their rapid hydrolysis in situ. lising a phosphoric ester of which the molecule possesses This latter characteristic which gives them a net advan 50 at least one alkyl group containing 1-3 carbon atoms in tage over the so called chlorinated pesticides, presents admixture with 0.05 to 10% calculated on the weight of however a very grave inconvenience; the sensitivity of the phosphoric ester, of an agent stabilising the said ester certain phosphoric esters to humidity, even simply that against decomposition by protonisation, 0 to 90%, cal of the atmosphere, is such that their decomposition takes culated on the weight of the composition, of one or more place without their being able to act on the pest organ solvents for the phosphoric ester which are solid or liquid isms: the phosphoric esters which are sensitive are more under pressure or otherwise and 0 to 50%, calculated particularly those which contain one or more low alkyl on the weight of the composition, of one or more inert groups, such as methyl, ethyl, propyl or isopropyl groups adjuvants selected from mineral adjuvants and organic attached to the phosphoric anion; this produces, on con adjuvants compatible with the phosphoric ester, the said tact with molecules of water, an at least partial decom 60 process being characterised in that there is added to the position of these esters by protonisation, i.e. by displace phosphoric ester or to a mixture which contains it, 0.05 ment of one low alkyl group in favour of a hydrogen to 10% calculated on the weight of the phosphoric acid atom. ester of an agent capable of stablising said phosphoric Among the sensitive phosphoric esters special mention ester against protonisation and comprising at least one should be made of O-2,2-dichlorovinyl-O,O-dimethylphos 65 sulphur compound Such as that defined above. phate, better known under the common name Dichlorvos The quantities of stabilising agent used according to and the abbreviation DDVP, the use of which in perma the present invention are preferably between 0.05 and nent insecticidal devices known as evaporators has under 4% based on the weight of the phosphoric ester. gone a tremendous increase in recent years. In the sulphur compounds such as those defined accord Various means of stabilisation have already been sug ing to the invention the valences of the atom of sulphur gested for limiting the decomposition of these phosphoric which are bonded to another atom or to other atoms in esters but they are generally toxic, for example phenols, a molecule of the sulphur compound according to the 3,836,643 3 4. invention can be constituted by a homopolar bond result 2,4,5-trichloro benzenethiol ing from the displacement from a Tr electron doublet, by 2,4,6-tribromo benzenethiol one or two heteropolar bonds resulting from an exchange 2-chloro propanethiol of electrons between the sulphur and the atom to which bis-mercaptoacetate of ethane-1,2-diyl it is bonded or by one or two electrovalences resulting methanethiol from electrostatic attraction between two ions of opposite butanethiol polarity. dodecanethiol The sulphur compounds preferred for use in the present 1,10-decanedithiol invention are as follows: 1,12-dodecanedithiol (1) Sulfanes defined by formula I O benzylmercaptain 1,2-butanedithiol (I) H-(S)-H 1,4-butanedithiol in which n is a whole number between 1 and 6; such 4-tertiobutyl benzenethiol compounds are for example: 1,3-benzenedithiol 5 4-chloro benzenethiol hydrogen monosulfide 3,4-toluenedithiol hydrogen bisulfide 4,5-diphenyl-2-imidazolethiol hydrogen trisulfide ethyl-2-mercapto acetate hydrogen tetrasulfide methyl-3-mercapto propionate hydrogen pentasulfide 2-mercapto benzoic acid hydrogen hexasulfide (sulphur content 98.9% by weight) 20 3-amino-5-mercapto-1,2,4-triazole (2) Mercaptains defined by formula II 2-amino benzenethiol 2-N-decylamino ethanethiol (II) H-S-R 2-quinoleinethiol in which R is chosen from 2-mercapto benzoxazole (i) a group Ra chosen from: 25 2-mercapto benzimidazole (a) a phenyl group, 2-mercapto pyridine (b) a benzyl group, 3-mercapto-1,2,4-triazole (c) a phenyl group and a benzyl group bearing 1-3 2-N-N-diethylamino ethanethiol substituents chosen from alkyl residues containing 5-chloro-2-mercapto benzimidazole 1-6 atoms of carbon, 30 5,6-dichloro-2-mercapto benzimidazole (d) an alkyl group containing 1-18 carbon atoms, 2-mercapto-1-methyl benzimidazole (e) a heterocyclic group chosen from monocyclic 1-butyl-2-mercapto benzimidazole and bicyclic heterocyclic groups comprising 5 to 2-mercapto-2-phenyl benzimidazole 10 ring atoms in which 1-3 of the ring members 2-mercapto ethyl-2-mercaptoacetate are chosen from nitrogen, the group 35 2-mercaptopentyl-3-mercapto propionate -N-R 2-mercapto-1-methyl imidazole and oxygen, a second and a third ring member (3) Sulfides defined by formula III: being chosen from the group 40 (III) (Rb-(S)-R --R", in which Ranh R', are independently chosen from: (a) an alkyl of 1 to 18 carbon atoms, in which R' is a group chosen from hydrogen, (b) phenyl phenyl, and an alkyl or cycloalkyl group contain (c) benzyl ing 1-10 carbon atoms and R' is hydrogen, 45 (d) morpholinyl phenyl, or an alkyl group containing 1-4 carbon (e) piperidyl atoms.