CA1305050C - Thermally stabilized bis alkylthio-alkylamino-n-alkyl carbamates - Google Patents

Abstract

THERMALLY STABILIZED
BIS ALKYLTHIO-ALKYLAMINO-N-ALKYL CARBAMATES

Abstract of the Invention Sulfur-linked bis alkylthio alkylamino N-alkyl carbamate pesticides can be stabilized against thermal decomposition induced and accelerated by a variety of contaminants. Thermally stable wettable powder, dispersible granular and liquid formulations of these pesticides can be prepared.

Description

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THERMALLY STABILIZED
BIS_ALKYLTHIO-ALKYLAMINO-N-ALKYL CARBAMATES
Field of the Invention This invention relates to thermQl stabiliz~tion of AlXylthio-~lXylimino carb~m~te pesticides. More p~rticul~rly, it rel~tes to the retardation or prevention of thermal decomposition o~ sulfur-linked bis ~lXylthio-alkylimino c~rbam~tes by incorpor~tion of multioxygen inor~nic compounds into formul~tions containin~ these pesticldes.
Back~round of the Invention Sulfur-linked bis alkylthio alkylimino-N-~lkyl carbamste pesticides of the formul&

( R2 C = N - O - C - N --t S
SR3 Rl 2 h~ve fi wide r~nge of uses ln controlling insects and other ~gronomic pests. Active compounds exhibit very hi~h level of pesticidsl sctivity and subst~nti~lly reduced mamm~ n toxicity ~nd phytotoxicity when comp~red to o~her pesticidal compounds havin~ a compar~ble spectrum of ~ctivi~y ~BainSt the ~ove mentioned pests.
These compounds ~re thermally unstable in the presence of a variety of contamin~nts. Heavy metals ~nd thelr s~lts, particul~rly chloride s~lts, are especially undesir~ble. Decomposition is extremely severe in the presence of copper met~l, ' ' ,., . .~ .

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copper chlorides, iron metal, iron chlorides ~nd iron oxide in the form of rust. Other problematic metals include cobalt, nickel and ~luminum.
Concentrations o~ as llttle ~s 10 ppm Rre effective if 8iven enough time at temperatures of 60~C or higher. Sulfur and sulfide salts can also induce decomposition, ~lthough usually ~t rates slower than those of chlorlde-containing systems. Some organ~c decomposition initiators hsve ~lso been identif~ ed, including pyrldine, pyridine hydrochloride, di- and trlsulfides, amines, peroxides and acids (e.g.
acetic and citric acids). Presence of 5% or more methomyl or its ox1me c~n also induce decomposition.
The principal ob~ect of th~s invention to provide a method to inhibit or retard the thermal decomposition processes that may occur in bulk qusntities of sulfur-l~nked bis alkylthio-alkylamino-N-alXyl pesticides when they ~re dried at elevated temperatures or stored for extended periods of time, especially in warmer climates. It is a further ob~ect to provide stable wettable powders ~ : ~nd dispersible granul~r formul~tions of these : pesticides.
Detailed Descri~tion of the Invention Thi invention provides a method of retarding or inhibiting thermal decomposition of pesticides of the fo~mul~

~ (R2 - C = N - O - C - N ~ S (I) ::; SR3 Rl .

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wherein Rl is ~lkyl containin~ from one to five cAr~on atoms; R~ is alkyl, ~lkylthio, alkoxy, alkanoyl or alkoxyc~rbonyl, ~ll of which may contain from one to five c~rbon ~toms &nd which may be unsubstituted or aliphatic~lly substituted in ~ny combination with one or more cyAno, nitro, alkylthio, ~lkylsulfinyl, ~lkylsulfonyl, alkoxy or R4R5-NCO- ~roups; or R2 is phenyl, R4R5-NCO- or R6CON~R4), wherein R4 and R5 are individually hydrogen or &lkyl, R6 is hydrogen, alkyl or alkoxy; ~nd R3 is hydrogen, cyano, alkyl or alkylthio containing from one to five c~rbon atoms; provided th~t the total number of carbon ~toms in R2 ~nd R3 may not exceed ei8ht and provided further that when R2 is alkyl substituted with slkylthio, R3 is alkyl, the inhibition or retardatlon of thermal decomposition of this compound being achieved by mixing the pesticide with from about 0~01% to about ~5% by weight o~ a substantially non-alkal~ne inorg~nic compound containing ~t least two oxygen ~toms bound to a multivalent cationic ~tom~
Thls invention also provides ~ pesticid~l composition which comprises:
~ pestidic~lly effective amount of ~ pesticide compound of the formul~ set $orth ~bove and (b) a substantially non-fllkaline inorgan~c compound cont~ining ~t least two oxygen atoms bound to 8 multiv~lent cationic ~tom, in ~n amount effective to retard or inhibit thermal decomposition of s~id compound.

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Definitions -The term "powdered or gr~nular composltion"
embraces ~11 solid formulations which range in slze from fine dusts ~e.g., thos~ which pass through U~S.
Sieve screens No. 400 up to No. 100) to substQntial particles ~s l~rge as 5 mm in their l~rgest dimension ~e.g. those which pass throu~h a No. 4 U.S. Sieve screen).
A "substanti~lly non-alkaline inorg~nic compound" ~s one which, when d$ssolved or dispersed in water in ~n amount useful to this invention, does not create ~ pH greater than 9 or which can be buffered to a pH less than 9.
"Thiodicarb" is the generic name of pesticide having the formul~ set ~orth below:

O O
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CH3- C = N - O - C - N - S - N - C - O - N = C - CH3 The term "comp~tability ~gent" encomp~sses ~dditives th~t permit di~ferent pesticides to be oombined in ~ single liquid formul~tion. Such ~gents m~y be incorpor~ted into solid or liquid compositions cont~ining one or all of the pesticides to be combined.
B. Pesticides , The organlc compounds of this invention are ylthio-alXylimino-N-alkyl carb~mates. They are widely used to control ~ variety of insect pests.
They m~y be prepared by welI known methods, such 8S
those set forth in U.S. Pstents No. 4,004,031 and 4,382,957.

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In the preferred compounds of this ln~ent1On Rl ~nd R3 or ulkyl and R2 is ~lkyl or alkylthio. The compound thiodicarb is especi~lly preferred for the pr~ctice ~f this invention.
C. Thermodynsmic Stabilit~
Typical decomposition times for thioc~rb in the presence of a variety of contRminants are shown ~n Table I. These dat~ were collected usin~ the following procedure. A one-gr~m sample of thiodicarb was intimately m1xed with the indicated weight percent of contamin~nt. The solid W2S placed in a test tube that was then covered with a rubber septum cap and immersed in a const~nt temperature b~th maint~ined at 100C. An uncontaminated standard was run under similar cond~tions.
Decomposition was m~nifested in a variety of forms.
Some samples exhibited ~ rapid change from solid to flark liquid; dense yellow smoke was usually observed. Others underwent ~r~dusl discoloration and moistening. In these experiments the time of decomposltion was the point when the s~mple was a dark-~rown semi-solid. Reported v~lues were averages of several repetitions for eaoh sample.
The dest~bilizing effect of methomyl and ~ other sulfur compounds is app~rent ~rom Section B

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TABL~ I
STABILITY_OF CONTAMINAT~D THIODICPRB STORED AT 100C
~dentity Amount of Time to Thiodicarb Contaminant Contaminant Decompo tion at 100C
A. Standard ~~ 12-13 days B. AutocatalYtic Products Methomyl lS 13 days 5~ 10 days 10~ 7 days Methomyl oxime 5% 3 days 10% 7 hours Methyltrisul~ide 1~ 8 days 3% 6 days Dimethyl disulfide 1-3~ 10 days C. Mlscellaneous Im~urities CuC12 2 ppm 8-9 days 2% 5 mins.
FeC13 3-300 pp~ 8-9 days 3% 10 mins 10~ 4S sec.
Ben7Oyl peroxide 1% 5 days 3~ 3-5 days Citric acid 1-3% 2 d~ys Acetic acid 1~ 4-6 days ;~ 3% 2 days : 2-~thylhexanoic acid 1-3~ 6-10 days Pyridine 1-3% 1-3 days .
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of Table I. Thlodlcarb iR st~ble ~t low concentrations ~1~ by wei~ht or less~ of one of its principal decomposition products, methomyl.
However, ~s the concentration of methomyl is rQ~sed, the r~te of decomposition incresses signifiG~ntly.
Likewise, the effect of methomyl oxime is ~ls~
subst~ntial. As ~mounts of other decompositi~n products, such as dimethyltrisulfide and ~imethyldisulfide lncrease, the rate of decomposition is substanti~lly ~cceler~ted.
In Section C of Table I are included results of studies using contaminants that mi~ht be introduce~ during the preparation or stor~ge of the pesticidal substance. As mentioned previously, heavy metal ions, particularly copper and irnn, are especially deleterious. Use of manufQcturing equipment or stor~ge containers made of these metsls in forms that c~n corrode to produce deleterious salts should be avoided if at ~11 possible. The other organic materi~ls are included to demonstrate the effects that such oompounds might h~ve on the product if they should be present, e.~. because they are found in the solvents th~t ~re used in the manuf~cturin~ process.
The ~bility of cert~in silicon-based carriers to reverse the decomposition of contamin~ted thiocarb i ~pparent from Table II. In these experiments one-gr~m ssmples of thiodicarb were first cont~minated w~th the indic~ted welght percen~s of cupric and ferric chlorida ~nd then intimately mixed with ~ v~riety of silicas Rnd silic~tes. The samples were then placed in test '"'' :

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tubes and immersed in w~ter baths et 50~C, 70~C and 100C until decomposition was observed;
decomposition time w~s measured when the solid h~d turned in~o a dRrk brown liquid. All v~lues represented averages o~ several repetitions. In some ~nst~nces st~bilization of several orders of magnitude was observed relative to standards containina no sil$cQ.

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TALLL II
THIODICAR~ STABILIZATION ~Y SILICA-BASED CARRI~RS
Tlme to Decompos~tion at Contaminant Stabilizer 5DC 70C 100C
-- -- >20 days 12 days 11-27 hrs.
1% CuC12 -- --4 mins. --1~ CuC12 10~ Barden clay -->19 hrs. --1~ CuC12 10~ Celite -->22 hrs~ --1~ anh FeC13 --13-52 mins. -- 3 mins.
1~ anh. ~eC13 5~ Hi-Sil16-19 days 7-21 hrs. 4 mins.
1~ anh. FeC13 10~ Hi-Sil>30 days 30-45 hrs. 100 mins.

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` Thermodynamic inst~bility was more accur~tely and reproducibly evalu~ted by detection of ~n exo~herm in ~ du~l ~hermocouple test conducted ~s follows. A test mixture w~s prepared by intlm~tely mixing the pesticide standard ~nd the desired quan~ity of st~bilizer. (The pestici~e st~ndard was thiodic~rb containing sulfur as 8 synthesis impurity;
no ~ddition~l contaminants were ~dded.) A
thermocouple was pl~ced into two grams of dried sample in a measuring vi~l. A second thermocouple was placed in the vial one inch above the sur~ace of the mixture. The vial w~s then placed in ~ heating block ~nd heated ~s quickly as possible to 160C; the r~te of heatin8 w~s not important ~s long as it was reproducible and the mix~ure reached 160C before the exotherm occurred for untre~ted pesticide. The time to exotherm for the mixture was compared to that for ~n untreated st~ndard, i.e. one cont21ning pesticide ~lone. Me~surements for a single mixture of additive and pesticide were usually taken five to ten times to assure reproducibility. In all cases the pesticide was tsken from the same b~tch to ~void differences in contsmination levels that Are o$ten observed from one batch to the next. The time to exotherm was directly proportional to the thermal stability of the mixture.
As a ~roup substanti~lly non-alkaline inorganic compounds containing at least two oxygen atoms bound to ~ multivalent cationic atom ~re surpr~s~ngly effective ~t retsrdin8 or inhibiting the occurrence of the exotherm in sulfur-linked c~rbamate pesticides such as thiodic~rb. Included in this group ~re the phosphorous aclds; alkali met~l ' ' :~ :

monob~sic phosph~tes, met~phosph~tes, sul$ites or bisul~1tes; alk~li metal or ~lkaline e~rth aluminosilicates (zeolites or molecular sieves~;
~lkali me~al bic~rbon~tes; and silicon dioxide in the form of silic~s and sllic~tes. The compounds th~t ~re especially ef~ective at ret~rding the exotherm are sodium or potasslum monobasic phosph~te, sulfite or bisulflte; hex~met~phosph~te; and phosphoric acid. Mixtures of th2se compounds ~re also e~fective. The ~bilitie~ of sever&l of the preferred stabilizers to retard the exotherm in thiodicarb AS
me~sured in the dual thermcouple test described ~bove are apparent from the results shown in T~ble III.
These results indicate that potAssium monobasic phosphate is an especially preferred st~bilizer for thiodicarb.
TABLE III
TIME TO EXO~HERM FOR STABILIZED TH IODICARB
Time to Exotherm Additive (minutes) -- 54 (st~nd~rd) 4% molecular sieves 4A 9l l~ N82S3 75 5% Na2SO3 ll7 S~ N~HSO3 94 0.5% KH2PO4 >300 ~: 3~ N~2HPO4 58 The decomposition of thiodicarb and the incre~sing concentration of methomyl h~ve been monitored at 100C in the presence of sod~um monobaslc phosphate (Table IV). Samples of D-l4637 ~3~

thiodicsrb untre~ted ~nd treated with varyinB
~mounts of sodium monobasic phosphate were maintained ~ 100C for seversl days. They were periodically analyzed by st~ndard HPLC methods for thiodicarb ~nd methomyl. As thiodic~rb concentration decre~sed, methomyl concentration lncreased However, ~he results ~ndicated th~t ~s the decompoqition process continued, other products formed as well; the sum of the weight percentages of methomyl ~nd thiodic~rb became progressively sm~ller ~s decomposition proceeded. Incre~sing ~mounts of the monobaslc phosphate appear to stabilize the thiodicarb ~s the decomposition re~ction proceeds over several dsys; decomposition products, especially methomyl, accelerate the process. These results ~lso support the hypothesis that bis ~lkylthio-~lkylemino-N-alkyl carbamates undergo an ~utocat~lytic decomposition process involving ~
number o$ sulfide species, ~lso cstalyze the process.
Stabilization of sulfur-linked bis alkylthio-~lkylamino-N-~lkyl c~rbamAtes m~y be ~chieved by incorpor~ting the stAbilizers of this invention in amounts rQn8in~ from 0.01 to 95 percent by weight of total mixture. Although the concentr~tion of a particular inor~anic stabillzer must be evalu~ted emplric~lly, as a ~eneral rule preferred concentrations r~n~e from abvut 0.01 to about 10~ by weight ln solid formul~tions and from O.OQOl~ to about 6S by weight in liquid formulations. When the st~bilizer is one of the above mentloned phosphate compounds, st~bilization will be o~served with as little as 0.01 to 2% by weight. Sulfite at~bilizers ~re e~fective ln the r~nge o~ 0.1 to 5~ by weight.

'' THIODICARB DLCOMPOSITION AND M~THOMYL
FORMATION IN TH~ PR~SENCE OF NaH2Po4 at 100~C

Day Stabllizer _ 0 1 2 3 4 _ Thlodicarb % 93.1 44.1 28 -- Methomyl ~0.3 12.312.1 0.2S~ Thiodicarb ~ 93.182.0 78.8 54.5 NaH2PO4 Methomyl S0.3 2.55.7 12.2 0.5~ Thiodicarb ~ 93.181.7 77.6 55.7 56.0 NaH2PO4 Methomyl ~0.3 3.68.3 8.2 12.9 1~ Thiodicarb ~ 93.181.6 85.9 84.8 63.9 NaH2PO~ Methomyl 0.3 2.23.9 4.3 8.5 :
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D. Formulations The compositions of thls invention may be applied ~s solids or ~s liquld dispersions or solutions to both field snd tur~ to control pests.
Applicatlon is by methods re~dily known to those skilled in the art. Effective amounts r~nge from ~bout 0.05 to ~bout 20 lbs. per acre of active pesticide.
Formul~tions useful in the practice of this invention Are solids, as wett~ble powders or dispersible granul~rs, Rnd liquids, as solutions or dispersions. The preferred wettable powders and dispersible gr~nular formulations comprise: (a) from about 1~ to about 98% by weight of a bls alkylthio-alkylsmino-N-~lkyl carb~mate pesticide;
~b) from ~bout 0.01% to about 10% by weight of a substanti~lly non-~lkaline inorganic compound containing at least two oxygen ~toms bound to e multiv~lent c~tionic ~tom; (c) from ~out 0.01% to about 20% by weight of wetting Qgent; ~nd (d) from about 1~ to about 12~ by weight dispersant.
Preferred liquid formulAtions comprise:
(a) from ~bout 0.01% to ~bout 75~ by weight of a bis ~lkylthio-~lkylamino-N-~lkyl carb~mate pesticide;
(b) from ~bout 0.0001~ to ~bout 6~ by weight o$ a : : substant$ally non-alkal$ne inorganic compound containing at least two oxygen atoms bound to a multiv~lent cationic atom; (c) from about 0.01% to about 20~ by weight wetting Agent; (d) from 0% to about 10~ by weight dispers~nt; ~nd (e) from ~bout 5% to about 80% by wei~ht inert liquid c~rrier.
Suitable carriers include w~ter, unsubstituted :~ :
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Aliphatic and arom~tic hydrocarbons or snalogues cont~ining, for ex~mple, alkyl, h~lo or hydroxy substltuents, fatty acids, and oils> such as linseed and cottonseed oil, derived from natural extr~cts.
Of the pesticides useful in this invention, the preferred compound is thiodic~rb. The preferred oxygen-containing inorganic compounds are phosphoric acid and sodium or potassium monobasic phosphate, metaphosph~te, sulflte or bisulfite.
Many wetting agents, anianic, cationic or nonionic, are available for these formulations.
Illustrative wettin~ agents are Rlkali metal salts of fatty alkyl or ~lkenyl sulfates or sulfonates cont~ining ei8ht to twenty carbon atoms; alk~li metal salts of alkylbenzyl or alkylnaphthyl sulfonates wherein the alkyl chain contains eight to twelve carbon atoms; ethoxylsted alkylphenols wherein the ~lkyl groups cont~in ei8ht to twelve carbon atoms; dialkylesters of sodium sulfonsuccinic acids wherein the dialkyl groups contain five to ten carbon atoms; or polyalXylene ox$de modified dimethypolysiloxane in which ~he ~lkylene groups are ethylene or propylene or a mixture of both. Other suitable wetting agents may also be used.
Dispersants ~re m~teri~ls which interact with solid ingredients in the formulations and the liquid medium that is used to suspend those solids for purposes of application. They must be soluble in that liquid phase and they usually behave as blnder for the solid powder or granular.
Representative dispersants useful in the prsctice of .

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this invention include starches, ~lk~li metal or ~lk~line earth salts of lignin sulfon~tes; and condensates of alkali metal ~lkylnaphthalene sulfon~tes and organic compounds containing one to three c~rbon atoms and ~t lesst one oxy~en atom, such as the condensate of form~ldehyde and sodium naphthalene sulfonic acid.
An sdditional component particularly useful in the formul~tions of this inventlon is an antifoaming agent. It prevents or reduces fo~m during the prep~ration of the powder or gr~nulars and during dispersion and applic~tion of the composition. It al~o stabilizes the resulting dispersion and permits more rapid redispersion if coQgul~tion of solids occurs in a dispersion. An especially useful antifoamer is a dialkylpolysiloxane. Particulsrly effective are dimethylpolysiloxanes formulated as emulsions or pastes. Such addltives do not act as stabilizers for the pesticides.
Pesticidal ~ormulations containin~ multiple pesticides are popular for the obYious reason of convenience--only one application is necessary to deposit all of the ~ctives. While m~ny multiple formulations are easily prepared simply by mixing all of the active ingredients, the formulations of this ~nvention may require the presence of a comp~t~bllity ~gent that preYents ~loccul~tion in the final solution or dispersion that is applied to the t~rget plQnts. The presence of ~n additional, chemic~lly unrelated pesticide such QS parathion m~y destabilize ~ dispersion prep~red for sprQy ~ .

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~ppllcation. The preferre~ compst~bility ~gents for these composltions are condensstes of alkylene oxide and hydrophobic bases made by condensing an ~lkylene oxide with an alkylene glycol whereln ~ll aklyl substituents contain from two to four c~rbon atoms.
A particularly effective agent is ~ p~ste condensate of ethylene oxide with hydrophobic bases formed by condensin~ propylene oxide with propylene glycol.
A number of other well known ingredients c~n be incorpor~ted into the wettable powders and dispersible granulars of this invention as the need arises, provided, o~ course, that they do not 8f fect the ~bility of the inorganic compound to stabilize the pestlcide or the st~bility ~nd ~ispersibility or wettab11ity of the powder or granular. These additives might include buffers, carriers or diluents, dyes, frsgrQnces, humectants, thickeners, biocides ~nd anti-evapor~tive agents.
The solid compositions of this invention can be prep~red by v~rious methods well known in the ~rt, such ~s pan gr~nul~tion, fluidized bed mixing and drying, spray drying, intensive mlxinB
~8810meration. extrus~on, compaction or pelletizing. For p~n 8ranul~tion and fluidized bed processes, a mixture of dry ingredients is prepared and transferred into the mixing/drying ch~mber that cont~ins water ~nd any liquid lngredlents; the slurry is thoroughly mixed ~nd then d~$ed.
Psrticles ~re then Kround to a desired size. If a spr~y drying process is used, grinding of the mixture of dry ingredients or of the slurry is preferred.
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The various process~s yield solids cont~ining ~ spectrum of particle sizes and moisture contents. A useful product is one which meets the particle size requirements for a particular ~pplicstion, which contains less than 5% by weight water, and prefer~bly less than 2%, and which disperses well in water or oil. For granular compositions good dispersibility is obtalned with particles retained on a U.S. Screen No. lOO (149 microns), ~nd optimum particle stabillty is obtained with less th&n 2% moisture. Any particles that ~re too small, too large or too wet c~n be returned to the manuf~cturlng or drying apparatus and recyled.
Preparation of the liquid compositions of this invention m~y be uccomplished by methods known in the art. Useful disp rsion formulations will not separhte into liquid and solid phases`during extended storage at ambient temperatures. To enhance stability the size of dispersed particles m~y be reduced by techniques, such ~s alr and wet m~lling, known in the art.
The followin~ exsmples are offered to illustrat2 useful formul~tions of this invention and to demonstr~te the effects of various st~bilizers.

To demonstrate the effect of a phosphate stabilizer ln a dispersible granular, th~ ~ollowing two formulations were prep~red (by mixing ingredients in an aqueous slurry ~nd spray drying to less th~n 2~ water) and ~helr thermal stabllity compared; (ull values are percent by weight of the dry ingredients.

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Formulation Formulatlon A B
(no thermal) (thermal stabilizer2 stabilizer~ In~redient 87.4% 86.8% thiodicarb 8.6 8.6 dispersant (sodium salt of sulfonated naphthylene formaldehyde condensate) 1.3 1.3 dispersant (starch) 2.5 2.5 wetting agent (sodium salt of sul~onated lauryl acid) 0.2 0.2 buffer (citric acid) -- 0.5 thermal stsbilizer (N~H2P04 ) -- 0.2 antifoamer (dimethyl-polysiloxane emulsion) Time to Exotherm 46 mins. >120 mins.
It is clear th~t as little as 0.5% NaH2PO4 greatly enh~nces the thermal stability o~ this formul~tion. Formul~tion B can be stored for much longer times at elevated temperatures (~pproximately 45-55C) than Formulation A, and Formulation B ~s much less likely to decompose during drying than is Formulation A.

A dispersible grsnular .~t~bilized with silica was prapared by mixing 86.5~ by weight thiodicarb containing approxim~tely 3% silic~ and 3~ sulfur; dispersants (1.5% by w~ight starch, 6.a~
by welght sodium salt of sulfonated naththalene :

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form~ldehyde condensAte, and 3.0~ by weight poly~lkylene glycol ether); wetting agent (1.0% by weight dioctyl ester of sodium sulfosuccinic acid);
antlfoamer (1.0% by weight m~gnesium stearate); snd buffer (0.2~ by weight citric ~cid~. In this formul~tion stabilizer (i.e., silica) content w~s spproxim~tely 2.6% by weight. The mixture WQS
ground to a powder of ~verage particle size less th~n 10 microns and then transferred to ~ fluidized bed chamber for mixing with water And subsequent drying.
A~ter screenin~ the product to A ran8e of -12 to +40 mesh (U.S. Sieve size)/ it hsd the followin~ characterlstics:
CIPAC suspendibillty 76~
Time to exotherm 104 minutes EX~MPLE 3 A very stable s~mple containing two stabilizers was prepared by slurrying, in water, the following ingredients (all weight percents are b~sed on added weights of the in~redients except w~ter):
86.1% thlodic~rb cont~ining 5% sulfur and 1.0%
silica; 10.1% dispers~nt (so~ium salt of sulfon~te,d naphth~lene form~ldehyde condensate); 2.5% wetting ~gent (sodlum salt of a sulfon~ted lauryl acid);
0.6~ antifoaming emulsifier (dlmethylpolysiloxane emulsion); ~nd 0.7~ therm~l stabilizer (KH2PO4). The slurry is wet groun~ to p~ss through a No. 325 screen (U.S. Sieve size) and spr~y dried to ~ moisture content of less than 2~.
Approxim~tely 95~ of the resulting granular h~s a .

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p&rticle slze distribution sp~nning the narrow rsnge of -14 to ~100 mesh ~U.S. Sleve size).
The granular within this particle SiZ2 range exhibits the following ch~racteristics:
CIPA~ suspen~ibil$ty 90%
Time to exotherm >120 minutes , .. ~ . .. . .. ... . .. ...... ... . . . .. . . . . .

Claims (15)

1. A pesticidal composition substantially free of water comprising an effective amount of an organic pesticide compound of the general formula:

wherein:
R1 represents C1-5-alkyl;
R2 represents a group selected from (i) Cl-5-alkyl, (ii) C1-5-alkylthio, (iii) C1-5-alkoxy, (iv) C1-5 alkanoyl, (v) C1-5-alkoxycarbonyl, (vi) any one of groups (i) to (v) aliphatically substituted with a group selected from cyano, nitro, alkythio, alkylsulfinyl, alkylsulfonyl, alkoxy, R4R5NCO- and a mixture thereof, (vii) phenyl, (viii) R4R5NCO- and (ix) R6CON(R4)-, wherein R4 and R5, independently, represent a group selected from H and alkyl, and R6 represents a group selected from H, alkyl and alkoxy; and R3 represents a group selected from H, cyano, C1-5-alkyl and C1-5-alkylthio;
with the proviso that:
(a) the total number of carbon atoms in R2 and R3 does not exceed eight; and (b) when R2 represents alkyl substituted by alkylthio, R3 does not represent alkyl;
wherein the composition comprises, as a thermal decomposition inhibitor for retarding or inhibiting thermal decomposition, a compound selected from a phosphorous acid, phosphoric acid, an alkali metal monobasic phosphate, an alkali metal metaphosphate, an alkali metal sulfite, an alkali metal bisulfite, an alkali metal carbonate and a mixture thereof, in an amount of 0.01 to 95 mass-percent based on the mass of the pesticide compound.

2. The composition of claim 1, wherein the thermal decomposition inhibitor is selected from (i) sodium and potassium monobasic phosphate, sulfite, bisulfite and hexametaphosphate, (ii) phosphoric acid, and (iii) a mixture thereof.

3. The composition of claim 1, wherein the thermal decomposition inhibitor is present in an amount of 0.01 to 10 mass-percent.

4. The composition of claim 1, in the form of a wettable powder or a dispersible granular composition.

5. The composition of claim 1, 2, 3 or 4, wherein the pesticide compound is thiodicarb of the formula:

.

6. A method for retarding or inhibiting thermal decomposition of an organic pesticide compound as defined in claim 1, comprising: intimately mixing the pesticide compound with a thermal decomposition inhibitor selected from a phosphorous acid, phosphoric acid, an alkali metal monobasic phosphate, an alkali metal metaphosphate, an alkali metal sulfite, an alkali metal bisulfite, an alkali metal carbonate and a mixture thereof, in an amount of 0.01 to 95 mass-percent based on the mass of the pesticide compound.

7. The method of claim 6, wherein the thermal decomposition inhibitor is selected from (i) sodium and potassium monobasic phosphate, sulfite, bisulfite and hexametaphosphate, (ii) phosphoric acid, and (iii) a mixture thereof.

8. The method of claim 6, wherein the thermal decomposition inhibitor is present in an amount of 0.01 to 10 mass-percent.

9. The method of claim 6, wherein the composition is in the form of a wettable powder or a dispersible granular composition.

10. The method of claim 6, 7, 8 or 9, wherein the pesticide compound is thiodicarb of the formula:

.

11. Use of a thermal decomposition inhibitor selected from a phosphorous acid, phosphoric acid, an alkali metal monobasic phosphate, an alkali metal metaphosphate, an alkali metal sulfite, an alkali metal bisulfite, an alkali metal carbonate and a mixture thereof, for retarding or inhibiting thermal decomposition of an organic pesticide compound as defined in claim 1, in an amount of 0.01 to 95 mass-percent of the mass of the pesticide compound.

12. Use of a compound selected from (i) sodium and potassium monobasic phosphate, sulfite, bisulfite and hexametaphosphate, (ii) phosphoric acid, and (iii) a mixture thereof, as a thermal decomposition inhibitor according to claim 11.

13. Use of a thermal decomposition inhibitor according to claim 11, in an amount of 0.01 to 10 mass-percent.

14. Use of a thermal decomposition inhibitor according to claim 11, for stabilizing a composition in the form of a wettable powder or a dispersible granular composition.

15. Use of a thermal decomposition inhibitor according to claim 11, 12, 13 or 14, for stabilizing a composition of thiodicarb of the formula:

.