CA1055039A - Triorganotin compounds and method of combating fungi and mites using same - Google Patents

Abstract

--Abstract of the Disclosure - Triorganotin compounds of the general formulae and effectively combat fungi and mites when applied to objects, particularly plants, that are susceptible to attach by these organisms. The present compounds are particularly advantage-ous in that they are substantially non-phytotoxic and therefore will not damage plants to which they are applied. In the foregoing formulae each R1 and R2 is individually selected from hydrogen and lower alkyl radicals, X is a chlorine, bromine, fluorine, hydroxyl, carboxylate, phenoxy, alkoxy (-OR3) or mercaptide (-SR3) radical wherein R3 represents an alkyl or aryl radical containing between 1 and 12 carbon atoms, inclusive and Y is an oxygen, sulfur, or a sulfate radical.

i

Description

RS(984)JGC
~05S039 NOVEL TRIORGANOTIN C~MPOUNDS ~ND METHOD
FOR COMBATING FUNGI AND MITES USING SAME

This invention relates to a method for ~electively controlling fungi and mites using dicyclohexylphenyltin compounds. The organisms against which the compounds are effective are responsible for a considerable portion of the annual damage to agricultural crops, particularly tomatoes, apples, and rice. Over the years fungi and mites have deveLoped a resistance to many chemicals which had previously been effective in combating them. The development of resistant strains has mandated a search for new miticides and fungicides~ Some triorganotin compounds effectively eontrol these pets; however, with fe~ exceptions this class of compounds is relatively non-selective when applied to desirable plant crops, in that while the organism attacking the plant may be controlled, the plant itself is often killed or severely damaged.

~OSS~

It has now been found that dicyclohexylphenyltin derivatives of the general formulae ~ R2~ ~
~ X and ~ ~ 3J Y

effectively control fungi and mites yet do not substantially damage plants to which efficacious amounts of these compounds are applied. In the foregoing formulae, each Rl and R2 is individually selected from the group consisting of hydrogen atoms and linear and branched alkyl radicals containing between land 8 carbon ato~s, X represents a radical selected from the group consisting of chlorine, bromine, fluorine, hydroxyl, carboxylate, phenoxy, alkoxy (-oR3), and mercaptide (-SR3), wherein R3 represents an alkyl radical contain-ing between 1 and 12 carbon atoms, inclusive and Y is an oxygen, sulfur, orsulfate radical.
In particular, the invention relates to a dicyclohexylphenyltin compound of the general formula ~Z OT ~ Y

wherein each Rl and R2 is individually selected from the group consisting of hydrogen atoms and linear and branched alkyl radicals containing between 1 and 8 carbon atoms, Y is selected from the group consisting of oxygen, sulfur and sulfate radicals and Z represents a monovalent radical selected from the group consisting of fluorine, hydroxyl, carboxylate, phenoxy, alk-koxy (-oR3) and mercaptide (-SR3), wherein R3 represents an alkyl radical 2Q containing between 1 and 12 carbon atoms, inclusive.
The invention also provides a method for controlling fungi and mites ~ - 2 -~?
j lOS'~039 which comprises contacting said organism with a compound of the formula R5~
-X or ~ ~ Sn ~ Y

lR52~ \ R~b / 2 wherein each R and R is individually selected from the group consisting of hydrogen atoms and linear and branched alkyl radicals containing between 1 and 8 carbon atoms, X represents a monovalent radical selected from the group consisting of chlorine, bromine, fluorine, hydroxyl, carboxylate, phenoxy, alkoxy (-oR3) and mercaptide (-SR3), wherein R3 represents an alkyl radical containing between 1 and 12 carbon atoms, inclusive and Y
is selected from the group consisting of oxygen, sulfur and sulfate radicals.

- 2a -DETAIL~D DESCRIPTION OF THE INVENTION
The dicyclohexylphenyltin compounds of this invention wherein X is bromine are conveniently prepared by reacting the appropriate dicyclohe~yldiphenyltin compound with bromine. This is a well known type of reaction and has been described in the chemical literature for the preparation of numerous other triorganotin derivatives.
Tetraorganotin compounds which can be employed to prepare the corresponding triorganotin bromide exhibit the generic formula ~ ~ Sn ~

Preferably the tetraorganotin compound is dissolved in a suitable solvent or mixture of solvents ~o which a solution of bromine is gradually added. Suitable solvents include alcohols containing between 1 and 8 carbon atoms and Liquid halogenated hydrocarbons.
Any compound which is a liquid at the reaction temperature and does not react with bromine or the tetraorganotin compound can be employed as a solvent for the tetraorganotin compound. The temperature of the reaction mixture is maintained below ambient temperature, preferably between -30 and 25C., during addition of the bromine to control the degree of hydrocarbon radical cleavage, and maximize the yield of the desired product. The reaction is believed to proceed in accordance with the follow-ing form~la:

~ ~ (R, ~ , Sn~nr~ l R, ~ Br+ ~ ~ r The resultant dicyclohexylphenyltin bromide may be a liquid or solid at ambient temperature depending upon the substituents P~ and R and can readily be converted to other derivatives such as the oxide or hydroxide, acetate, and sulfate using kno~n reactions. The desired anionic radical can be introduced by reacting the correspondin~ bromide, oxide, or hydroxide with the reagent indicated in the following table.

~L055039 ORG~NOTIN DERIVAl'IVE ~ REAGENT ~ DESIRED PRODUCT
Bromide Carboxylic acid ~ carboxylate, acid acceptor~ e.g. e.g. acetate pyridine " alkali metal ~alt of "
carboxylic acid " aqueous solution of hydroxide or alkali metal hydroxide oxide S " alkali metal alkoxide alkoxide or alcohol I acid acceptor " alkali metal phenoxide phenoxide or phenol ~ acid acceptor " potas~ium fLuoride or fluoride hydrofluoric acid " alkali metal sulfide ~ul~ide " alkali metal sulfate sulfate " mercaptan + acid mercap~ide acceptor Oxide (or hydroxide) carboxylic acid or carboxylate anhydride " alcohol (or phenol) alkoxide (or pheno~ide) It hydrofluoric acid fluoride " dilute (10-25 weight sulfate %) aqueous 6ulfuric acid " hydrogen 6ulfide ~ulfide " alkyl or aryl mercaptan mercaptide " aqueous hydrochloric chloride acid lC~55039 The identity of the substituents R and R and the conditions under which the compound i8 stored will determine whether the bis(triorganotin) oxide or the corresponding triorganotin hydroxide is the more stable compound.
The reaction conditions such as preferred solvents, temperatureæ and reaction times for preparing the derivatives summarized in the preceeding table are known in the art and, therefore, do not require a detailed description in the present specification. A comprehensive treatment of this subject matter is contained in an article by R. K. Ingham et al~ that appeared in the October, 1960 issue of CHEMICAL REVIEWS
(P.P. 459-539).
The dicyclohexylphenyltin compounds are liquids or solid materials at ambient temperature, depending upon the type of substituents represented by Rl, R , X and Y.
Dicyclohexylphenyltin compounds effectively combat undesirable mites and fungi without significantly damaging the plants to which the compounds are applied. A single application of these compounds can provide re6idual and extended control of fungi and mites for a considerable period of time, the duration of which i6 dependent to some extent upon mechPnical and biological influences, including weather, but is sometimes as long as several mon~hs.
I~ preparing compositions for application to plantsJthe tin compound is often augmented or modified by combining it with one or more commonly employed pesticide ~055039 additives or adjuvants including organic ~ol~ents, water or other liquid carriers, surface active dispersing ag~nts or particulate and finely comminuted or divided solid carriers.
Depending upon the concentration of the tin compound in these compositions, they can be employed either directly to control the organisms or as concentrates which are subsequently diluted with one or more additional inert carriers to produce the ultimate treating compositions. In compositions to be employed as concentrates, the dicyclohexylphenyltin compound can be present at a concentration of from about 5 to about 98~
by weight. Baits, attractants and the like can also be included for combating mites. Other biologically active agents that are chemically compatible with the present tin compounds can also be added.
The optimum concentration of tin compounds to be employed as toxicant in a composition for application to the organism directly or by employing its habitat or food as carrier, may vary pro~ided that the organism is contacted with an effective dose of the toxicant. The actual weight of compound constituting an effective dose is primarily dependent upon the susceptibility of a particular organism to the tin compound. Good control of bean mildew is obtained with liquid or dust compositions containing O.OOO~ percen~ or less weight of toxicant in the formulation as it is applied to the plant.
Compositions containing as high as 90 percen~ by weight of toxicant an sometimes be employed in the treatment of a mite-infested environment.

i~O55039 In the preparation of dust compositions, the dicycLohexylphenyltin compound can be blended with many commonly employed finely divided solids, such as fuller~s earth, attapulgite, bentonite, pyrophyllite, vermiculite, diatomaceous earth, talc, chalk, gypsum, wood flour, and the like. In such operations, the finely divided carrier is ground or mixed with the toxicant or wet~ed with a dispersion of the toxicant in a volatile li~uid. Depending upon the proportions of ingredients, these compositions can be employed as concentrates and subsequently diluted with additional solid of the types indica~ed hereinbefore, to obtain the desired amount of active ingredient in a comminuted composition adapted for the control of pests. Also~ su~h concentr~te dust compositions can be incorporated in intimate admixture with surface active dispersing agents such as ionic and non-ionic emulsifying or dispersing agents to form spray concentrates. Such concentrates are readily disper~ible in liquid carriers to form spray com-positions or liquid formulations containing the toxicants in any desired amount. The choice of surface active agent and amount thereof employed are determined by the ability of the agent to facilitate the dispersing of the concentrate in the liquid carrier to produce the desired liquid composition.
Suitable liquid carriers include water, methanol, ethanol, isopropanol, methyl ethyl ketone, acetone, methylene chloride, chlorobenzene~ toluene, xylene, and petroleum distillates. Among the preferred petroleum distillates ~ 0 5 5~ 3 9 are those boiling almost entirely ~mder 400F. at atmospheric pressure and havin~ a flash point above about 80F.
Alternatively, the dicyclohe~ylphenyltin compound can be dissolved in a suitable water-immiscible organic liquid and a surface active dispersing agent to produce emulsifiable concentrates which may be further diluted with water and oil to form spray mixtures in the form of oil-in-water emulsions.
In such compositions, the carrier comprises an aqueous emulsion, i.e. a mixture of water-immiscible solvent, emulsify-ing agent and water. Preferred dispersing agents which may be employed in these compositions are oil soluble and include the concensation products of alkylene oxideæ with phenols and organic and inorganic acid~, polyoxyethylene derivatives of sorbitan esters~ aLkylarylsulfonates, complex ether alcohols, mahogany soaps and the like. Suitable organic liquids to be employed in the compositions include petroleum distillates, hexanol, liquid halohydrocarbons and synthetic organic oils.
m e surface active dispersing agents are usually employed in the liquid dispersions and aqueous emulsions in the amount of from about 1 to about 20 percent by weight of the combined weight of the di~persing agent and the active toxicant.
When operating in accordance with the present invention, the dicyclohexylphenyltin compound or a composition containing the compound can be applied directly to the undesirable organism when mites are being controlled, or to their habitat or food in an~ convenient fashion, i.e. by means of hand dusters or sprayers or by simple mixing with the food to be ingested by the mites. Applications to the foliage of plant~ i8 conveniently carried out using power dusters, boom sprayers and spray dusters. t~hen employed in this manner the composi -tions should not contain any significant amounts of phytotoxic diluents. In large scale operations, dusts or Low volume sprays may be applied from an aircraft.
- The following examples represent the best embodiments of the present invention now kno~n, and tell how to practice them.

This example discloses the preparation of dicyclohexyl-phenyl tin bromide.
A &olution containing 171.g g~ (0.5 moLe) of diphenyltin dichloride and 500 c.c. of toluene was added gradually o~er 1.25 hours to 1 liter of mixture containing 1.5 moles of cyclohexyl magnesium chloride and tetrahydrofuran as the diluent. The reaction vessel was equipped with a mechanically driven agitator, water-cooled reflux condenser, addition funnel, thermometer and nitrogen inlet. The temperatures of the reaction mixture gradually increased to 61C. during the addition~following which a 250 c.c. portion of toluene was added.

The reaction mixture was heated at the boiling point for 1.5 hours, then cooled to ambient temperature, at which time n solution containing 55 gO of citric acid and 400 c.c of water was added. The organic phase was separated and dried by combining it with a quantity of anhydrous magnesium sulfate, after which the liquid phase was concentrated under reduced pressure until it appeared turbid. The addition of 250 c.c.
of methanol yielded a precipitate which was isolated and washed with-methanol. The dried solid weighed 207.5 g. (94~5% of theoretical yield)0 The solid wa~ found to contain 27.27% by weight of tin. The theoretical tin content of dicyclohexyldi-phenyl tin is 27.02%.
A solution containing 16.0 g. (0.1 mole) bromine, S0 c.c. methanol, and 50 c.c. chloroform was added drop-wise to a solution containing 43.9 g. (0.1 mole) of dicyclohexyl-diphenyltin , S0 c.c. methanol and 110 c.c. chlorofonm. The addition required 1.75 hour6, during which time the temperature of the reaction mixture was maintained at 0C. Each drop of bromine wa~ added onLy after the color imparted by the pre-ceding drop had disappeared. Following completion of the addition the resultant clear solution wa~ concentrated under reduced pres6ure. The colorless liquid residue w~ighed 51.3 g. and exhibited a refractive index (ND ) of 1.5826. The unreacted dicyclohexyldiphenyltin precipitated following the addition of 150 c.c. of methanol to the crude product. The solid .

weighed 4.0 grams. The methanol was removed from the liquid phase under reduced pressure. The liquid was then treated with gaseous ammonia to precipitate dicyclohexyltin dibromide as the ammoni~ complex, and the resultant ~olid removed. The remaining liquid was concentrated under reduced pres~ure to yield 22.2 g. of a liquid which upon analysis by vapor phase chromatography was found to contain 96% by weight of dicyclo-hexylphenyltin bromide.
EXAMPLE 2 - Preparation of Dicyclohexglphenyltin Hydroxide Dicyclohexylphenyltin hydroxide was prepared by adding a solution containing 3.0 g. (0.075 mole) sodium hydroxide and 25 c.c. water to a solution containing 20.7 g. (0.047 mole) dicyclohexylphenyltin bromide and 205 c.c. methanol. Following completion of the addition the resultant mixture was heated at the boiling point for one hour, then allowed to cool to ambient temperature with agitation. A 200 c.c. portion of water wa~
added to the resultanL mixture, which contained a white solid precipitate. The solid material was isolated, washed with deionized water until free of bromide and then dried in a ciculating air oven. The product weighed 16~7 g. (93.8% of theoretical yield) and was found to contain 31.65 % by weight of tin. The calculated tin content for the hydroxide is 31.31%.

BIO~OGIC~L ~CTIVI'~Y OF DICYCLOHEXYLP~ENYL TIN DERIV~TIVES
_ . . . ,, . --. - - _ , 1. General Evaluation Methods Dicyclohexylphenyltin hydroxide was evaluated in the form of sprayable compositionR prepared by dissolving or dispersing the compound in a 90/10 weight ratio water/acetone mixture containing a small amount of a non-ionic surfactant.
The resultant stock solution or dispersion was then diluted using a water-sur~actant mixture to obtain ~he desired con-centration of tin compound while maintaining ~he surfactant concentration at 100 parts per million (ppm). Samples which proved difficult to emulsify were homogenized using a colloid mill or tissue homogenizer.

2. Evaluation of the Effectiveness of Dicyclohexylphenyltin ~ydroxide Against Specific Organisms.
The efficacy of the triorganotin compounds of this invention as fungicides and ~iticides was investigated and the results are summarized in the following section. The test organisms employed were powdery bean mildew, apple scab and the two-spotted spider mite.
The rating system employed to determine control of the organi~ms was based on a numerical scale wherein a rating of 10 indicated 100% control (no 3urviving organisms) and a rating of O indicated no control, i.e. the plant was heavily infested with the organism. The control rating employed for the bean mildew and apple scab is R function of the fraction of total leaf area which i8 unaffected by these fungi.

.,_, ,~ ,, .

Ao Powd~ry Bean Mildew Tender ~reen bean plants with fully expanded primary leaves are inoculated with spores of the powdery mildew fungus (erysiphe polygoni) 48 hours prior to the ap-¦ plication of dicyclohexylphenyltin hydroxide. The tin ¦ compound is applied at the concentrations indicated in the ¦ following table by placing the plants on a revolving turntable ~ and spraying them with a formulation containing the ¦ triorganotin compound. I~hen the spray deposit dries, ¦ the plants are placed in a greenhouse for 28 days~ during ¦ which time the amount of mildew on the primary le2ves i8 ¦ rated at intervals of 7 days following the spraying. Untreated plants serve as controls, which exhibit a rating of 1.0 or less.
¦ 'rhe formulations tested contained 100, 20, and 4 parts per mil-~ lion ~p.p.m.~ of dicyclohexylphenyltin hydroxide.
151 CONCENTRATION D.~YS FOLLOWING
(P.p-m-? INITIAL SPRAYING CONTROL RATING
100 7 LO.O
14 10.0 21 10.0 l , _ _ 1 20 7 10.0 14 9.8 . . . , , 1 4 7 g.5 1 14 5.9 21 4.0 1 28 1.9 I _.

None o~ the formulations tested were phytotoxic to plants.
B. Apple Scab Frozen apple leave~ which were infested with conidia spores were soaked in cool water for about 30 minutes, fol-lowing which the liquid phase was filtered through a single layer of cheesecloth. A nu~ber of apple seedlings in the fifth leaf stage were sprayed with the water containing the dispersed conidia spores. The seedlings were stored in a high humidity environment [relative humidity (R.H.) = 100%]
at ambient temperature for two days, after which they were stored at a temperature of 24~3C. for 6even days, then in the high humidity environment for between one and two days, and finally at 24~3C. for 10 to 15 days, during which time the infested leaves were harves~ed. The leaves were extracted with cool water to prepare a stock solution which when viewed under a microscope at 100 X magnification exhibited a field containing not Less than 20 conidia spores.
The plants to be tested were sprayed with a liquid fo~mulation containing dicyclohexylphenyltin hydroxide.
The formulation was prepared as previously described. After the solvent had evaporated the leaves were sprayed with the suspen~ion of conidia spores prepared as described in the preceeding paragraph. The plants were then pLaced in a high humidity (100% R.H.) environment at smbient temperature for two days, after which they were stored under conditions o~ ambient humidity and a $emperature of 24+3C. until evidence oE apple scab was observed on the untreated control, as indicatcd by hrownish Lesions on the leaves. The resul~s of the test are summarized below.

Concentration of Control Or~,anotin ComT~ound (p.p.m.) Ratina 9,9 12.5 9,1 C. Two-spotted S~ider Mite Bean plants were sprayed with formulations contain-ing a dispersed form of dicyclohexylphenyltin hydroxide at concentrations of 50 and 200 p.p.m.. The ~article size of the dispersion was between 50 and 100 microns. Between one and three days following the spraying a number of nymph stage and adult spider mites were transferred onto the upper surface of the plant leaves. The plants remained undisturbed at 24~3C.
for between 12 and 14 days following exposure to the mites, at which time the percentages of dead nymphs and adult mites were observed and the results recorded as the initial controL
test. The long-term effect of the tin compound was evaluated by placing a new supply of adult and nymph stage mites onto the bean plant leaves following the initial observations. No additional triorganotin compound was applied. The percentages of dead nymph and adult mites were again observed between 21 and 30 days following the initial application of the spider mites, and the results recorded as the residual control test.

CONCENT~TION OF TIN INITIAL RESIDU~L
OMPOUND IN SPRAY (P.P.M. ) CO~TROL CONTROL
. .. .
200 10 (A); 10 (N) 10 (A); 9.9 (N) 10 (A); 9.9 (N) 10 (A); 9.9 (N) A = adult mites; N - nymph ~tage mites Although all of the compounds employed to determine biological activity were triorgano~in hydroxides, other derivatives including fluorides, chlorides, brom~des, carboxyl-ates, mercaptides, alkoxides, phenoxide~, ~ulfide~ and sulfates are expected to be at leas~ equally efficaciou~ in combating fungi and mites since it ha~ been shown that the anionic radioal of the present triorganotin compound~, represented by X and Y
in the foregoing generic formulae, have little, it any, effect of the degree of biological activity exhibited b~ the co~pound unless the anion it~elf possesses significant biological activity.

Claims (8)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A dicyclohexylphenyltin compound of the general formula or wherein each R1 and R2 is individually selected from the group consisting of hydrogen atoms and linear and branched alkyl radicals containing between 1 and 8 carbon atoms, Y is selected from the group consisting of oxygen, sulfur and sulfate radicals and Z represents a monovalent radical selected from the group consisting of fluorine, hydroxyl, carboxylate, phenoxy, alk-koxy (-OR) and mercaptide (-SR3), wherein R3 represents an alkyl radical containing between 1 and 12 carbon atoms, inclusive.

2. A dicyclohexylphenyltin compound as defined in claim 1 wherein each R1 and R2 represents a hydrogen atom and Z represents a hydroxyl radical.

3. A dicyclohexylphenyltin compound as defined in claim 1 wherein Y represents oxygen.

4. A method for controlling fungi and mites which comprises contact-ing said organism with a compound of the formula or wherein each R1 and R2 is individually selected from the group consisting of hydrogen atoms and linear and branched alkyl radicals containing between l and 8 carbon atoms, X represents a monovalent radical selected from the group consisting of chlorine, bromine, fluorine, hydroxyl, carboxylate, phenoxy, alkoxy (-OR3) and mercaptide (-SR3), wherein R3 represents an alkyl radical containing between 1 and 12 carbon atoms, inclusive and Y
is selected from the group consisting of oxygen, sulfur and sulfate ra-dicals.

5. A method according to claim 4 wherein each R1 and R2 represents a hydrogen atom.

6. A method according to claim 4 wherein X is a bromine or a hydroxyl radical.

7. A method according to claim 4 wherein Y is oxygen.

8. The method of claim 4 wherein the compound is applied to a plant which is susceptible to attack by fungi and mites.