ZA200501300B - Process for preparing paste-extruded sulfonamide compositions - Google Patents

Description

TITLE

PROCESS FOR PREPARING PASTE-EXTRUDED SULFONAMIDE COMPOSITIONS

BACKGROUND OF THE INVENTION

Since the discovery of the sulfonamide herbicides comprising the sulfonylureas and triazolopyrimidines, more than two dozen sulfonylurea and close to a half dozen triazolopyrimidine herbicides have been commercially developed for selective weed control in a wide variety of crops (The Pesticide Manual, Twelfth Edition, C.D. S. Tomlin, ed.,

British Crop Protection Council, Surrey, UK., 2000). As the mode of action of these sulfonamide herbicides is inhibition of the enzyme acetolactate synthase (ALS) found in plants but not animals, sulfonamide herbicides provide a valued combination of excellent efficacy against weeds with low use rates and very low toxicity to animals.

Sulfonamide herbicides like other agricultural chemicals can be formulated as concentrates in a variety of different forms, including liquid compositions such as emulsifiable concentrates and solid compositions such as wettable powders and granules.

Granular compositions can be conveniently transferred and measured like a liquid, but unlike liquids, very little residue adheres to the walls of the product container. Furthermore, organic solvents and vapors are avoided. Compared to wettable powders, granules are relatively dust-free. A particularly useful type of granules are those which are water- dispersible. Water-dispersible granules, sometimes described as “dry flowables™, readily disintegrate when added to water to form a solution or suspension, which can then be sprayed on the locus to be treated. It is also advantageous for granular compositions to have good attrition resistance, low tackiness, and uniform bulk density.

Water-dispersible granules can be manufactured by a variety of processes, including fluid-bed granulation, pan granulation, spray drying, intensive mixing, compaction, paste extrusion and heat extrusion (such as melt extrusion). The physical dimensions and porosity of water-dispersible granules depends upon the manufacturing process used. Fluid bed granulation, spray drying and intensive mixing give granules that very rapidly break up and disperse in water because of granule dimensional propertics such as small size, irregular surface and porosity. On the other hand, paste extrusion and heat extrusion provide granules of relatively consistent diameter and shape. The consistent diameter of extruded granules makes them useful in uniform blends as described in U.S. Patent No. 6,022,552.

Granule composition is an important factor for obtaining sufficiently rapid dispersion of extruded granules. The dispersed particles formed on dilution should be no larger than 50 microns in their largest dimension to avoid premature settling, which may result in uneven application of the pesticide. It is therefore necessary that all of the components of the formulated product rapidly and completely disperse or dissolve in the dilution water. (If all of the components completely dissolve, then they can be regarded as being dispersed at the molecular level.) Water dispersibility of granules is determined not only by the composition of the granules but also by the composition and other properties of the aqueous medium to which the granules are added. For example, low temperatures and high concentrations of solutes can greatly retard granule disintegration.

Extruded granules are often most conveniently and cost-effectively prepared through paste extrusion using water to plasticize a powder mixture, which is then dried after extrusion. Paste extrusion avoids need for including binders that soften at elevated temperatures, as is required for heat extrusion. However, the use in paste extrusion of water as a plasticizer precludes inclusion of water-activated gas-generating ingredients, which otherwise can be used for accelerating disintegration and dispersion of heat-extruded or compacted granules.

Besides achieving satisfactory granule disintegration and dispersion, spray equipment clean-out can also be important. As sulfonamide herbicides comprise a highly active class of herbicides, it is desirable to clean out spray equipment before the equipment is subsequently used to treat a crop sensitive to the sulfonamide herbicide used in the previous application.

Clean-out may require a rinsing procedure that is time-consuming and results in wastewater requiring proper environmental disposal. Furthermore, clean-out can be affected if the spray equipment contains organic deposits remaining from previous crop protection chemical applications or from other chemicals tank-mixed with the sulfonamide herbicide composition.

PCT Patent Application Publication WO 93/16596 describes a method for reducing residual sulfonylurea herbicide contamination of spray equipment by requiring as the first step the formulation of the sulfonylurea active ingredient in the form of an agriculturally suitable water soluble salt. Although a variety of methods are known for preparation of salts 95 of sulfonamide herbicides from the corresponding free acid forms, as processes to prepare sulfonamide herbicide active ingredient often provide the free acid form either directly or as part of isolation, conversion to a salt would require an additional process step. Preferable would be formulations with improved spray equipment clean-out properties whereby the free acid form of the sulfonamide herbicide is directly used in the formulation process.

Now discovered is a process for conveniently preparing paste-extruded granular sulfonamide herbicide formulations that not only have satisfactory water dispersibility but also improved spray equipment clean-out properties.

SUMMARY OF THE INVENTION

This invention relates to a process for preparing a paste-extruded sulfonamide herbicide composition comprising (a) preparing a mixture comprising (i) from 2 to 90% by weight on a water-free basis of one or more active ingredients comprising at least one sulfonamide herbicide free acid;

(i) from O to 95% by weight on a water-free basis of one or more additives selected from the group consisting of wetting agents, dispersants, lubricants, anticaking agents, chemical stabilizers and diluents; and (iif) at least about 50 equivalent % of base selected from inorganic base equivalents having conjugate acid pKs at least 2.1 units greater than the highest pK, of the sulfonamide herbicide free acid component; the sum of the weight percents of all the ingredients in the mixture totaling 100% on a water-free basis; and (iv) sufficient water to make the mixture an extrudable paste; (b) extruding the mixture prepared in (a) through a die or screen to form extrudate; and (c) drying the extrudate.

The invention also relates to a paste-extruded sulfonamide herbicide composition prepared by the aforementioned process.

DETAILED DESCRIPTION OF THE INVENTION

It has been discovered that a paste-extruded sulfonamide herbicide composition having not only excellent water dispersibility but significantly improved spray equipment clean-out properties is obtained from extrusion of a mixture comprising at least one sulfonamide herbicide free acid by including in the mixture for extrusion at least about 50 equivalent % of base selected from inorganic base equivalents having conjugate acid pKps at least 2.1 units greater than the pK, of the sulfonamide herbicide free acid with the highest pK,. By sulfonamide herbicide free acid is meant the free acid form of the sulfonamide herbicide and not the salt form (wherein the sulfonamide herbicide is deprotonated at its acidic sulfonamide center). The mixture for extrusion can also comprise the salt form of one or more sulfonamide herbicides among the mixture components, but only the sulfonamide herbicide acid form present is considered to calculate the at least about 50 equivalent % of base selected from inorganic base equivalents. Commonly the sulfonamide herbicides added to prepare the mixture for extrusion are at least 10% in the acid form, typically at least 50%, more typically at least 80% and most typically at least 90% in the acid form.

The pK, values of the sulfonamide herbicides are determined in water at ambient temperatures, typically about 20 to 25 °C. pK, values can be determined by standard methods such as the procedure taught below in Analytical Example 1, and measured values for commercial herbicides are generally published in such references as The Pesticide

Manual, Twelfth Edition edited by C. D. S. Tomlin (British Crop Protection Council, Surrey,

UK, 2000). For the convenience of the reader, Table A below lists pK, values for many of the commercially available sulfonamide herbicides. ]

TABLE A

Molecular Weights and pK, Values of Some Sulfonamide Herbicides

Sulfonamide Mol, Wt. pK, Sulfonamide Mol. Wt. pK,

Sulfonylureas } } : amidosulfuron 3694 3.6 pyrazosultfuron-cthyl 4144 3.7 azimsulfuron 4244 3.6 rimsulfuron 4314 40 bensulfuron-methyl 4104 5.2 sulfometuron-methyl 3164.4 5.2 chlorimuron-ethyl 414.8 4.2 sulfosulfuron 470.5 3.5 chlorsulfuron 357.8 3.6 thifensulfuron-methyl 387.4 4.0 cinosulfuron 4134 47 triasulfuron 401.8 4.6 cyclosulfamuron 421.4 5.0 tribenuron-methyl 395.4 5.0 ethametsulfuron-methyl 410.4 4.56 trifloxysulfuron 437.1 4.8 flazasulfuron 4073 4.4 triflusulfuron-methyl 4924 44 flupyrsulfuron-methyl 465.4 4.9 halosulfuron-methyl 434.8 34 Triazolopyrimidines imazosulfuron 412.8 4.0 florasulam 359.3 4.5 iodosulfuron-methyl 507.3 3.2 metosulam 4183 48 metsulfuron-methyl 381.4 33 flumetsulam 3253 4.6 nicosulfuron 410.4 4.6 diclosulam 406.2 4.0 oxasulfuron 406.4 5.1 cloransulam-methyl 4298 4.8 primisulfuron-methy!l 468.3 3.5 penoxsulam 483.4 5.1 prosulfuron 419.4 3.8

The at least about 50 equivalent % of base in the mixture for extrusion according to this invention is selected from base equivalents that are inorganic, i.e. provided by inorganic bases. Particularly suitable inorganic bases are described in further detail below. The terms “equivalent % of base” and “base equivalents” refers to the fact that some inorganic bases can provide more than one equivalent of basicity per mole. In the context of the present invention, the number of base equivalents per mole of base is limited to the base equivalents having conjugate acid pKgs at least 2.1 units greater that the highest pK, of the one or more sulfonamide free acid components in the mixture. Calculation of number of moles of base needed to provide at least 50 equivalent % of base is described further below.

The pK, values of conjugate acids of bases can be determined by standard methods.

Published values can be found in a variety of references, such as The Chemist's Companion by A. J. Gordon and R. A. Ford (Wiley-Interscience, New York, 1972). For the convenience of the reader, Table B lists conjugate acid pK, values for some common bases.

TABLE B

Formula Weights and Conjugate Acid pK, Values of Some Bases

Base Form Wt. First pK, Second pK, Third pK,

LiOH 23.95 14.0 - —-

Li»CO3 73.89 10.2 6.4 -

Li3POy4 115.79 12.7 7.2 2.1

NaOH 40.00 14.0 - —-

NaHCO3 84.01 6.4 - -

NayCO3 105.99 10.2 6.4 -

NayCOj - Hy0 124.01 10.2 6.4 :

NapHPO4 141.96 7.2 2.1 -

Na3POy 163.94 12.7 7.2 2.1

Na3POy - 12H,0 380.13 127 7.2 2.1

NagPy0- 265.90 9.0 7.0 2.0

KOH 56.11 14.0 — -

KHCO;3 100.12 6.4 - -

K,COs3 138.21 10.2 6.4 —

KoHPO, 174.18 7.2 2.1 -

K3POy 212.28 12.7 7.2 2.1 : K4P,07 330.35 90 7.0 2.0

The equivalent % of base selected from inorganic base equivalents is calculated relative to the total number of moles of the onc or more sulfonamide herbicides added to the 5 mixture in their free acid forms (i.e. not salts), with consideration of the basicity of the inorganic base equivalents for which conjugate acid pKj in water is a least 2.1 units greater than the pK, of the sulfonamide herbicide with highest pK,. For example, if one mole of thifensulfuron-methyl and one mole of tribenuron-methyl in their free acid forms is added to the mixture, the pK, of tribenuron-methyl (5.0) is considered instcad of the pK, of thifensulfuron-methyl (4.0), as the former pK, is higher. In this example, the total number of moles of sulfonamide herbicides in free acid form is two moles, and 50 equivalent % of an inorganic base would require one equivalent of base. Phosphoric acid contains three acidic hydrogen atoms, with respective aqueous pK, of 2.1, 7.2 and 12.7. As only 7.2 and 12.7 are least 2.1 units greater than 5.0, sodium phosphate is dibasic (i.e. provides two base equivalents per mole) relative to the requirement that pK, difference be at least 2.1 units.

Accordingly one equivalent of base would be provided by one-half mole (i.e. one-half formula weight amount) of sodium phosphate. Carbonic acid contains two acidic hydrogen atoms, with respective aqueous pK of 6.4 and 10.2. As only 10.2 is at least 2.1 units greater than 5.0, sodium carbonate is monobasic (i.e. provides one base equivalent per mole) relative to the requirement that the pK, difference be at least 2.1 units. Therefore one mole (i.e. one formula weight amount) of sodium carbonate would provide one equivalent of base.

With many sulfonamide herbicides, particularly those with a solubility in pH 7 buffered water at ambient temperature (i.e. about 20 to 30 °C) of greater than about 1000 mg/L, compositions prepared according to the process of this invention to include about 50 equivalent % of base relative to the sulfonamide herbicide free acids will substantially reduce residues in spray equipment. The addition of base is particularly beneficial for paste- extruded compositions of sulfonamide herbicides with a solubility in pH 7 buffered water of less than about 10,000 mg/L, because for more soluble sulfonamide herbicides spray tank residues are rarely encountered. (Illustrative examples of sulfonamide herbicides having a solubility in pH 7 buffered water between 1000 and 10,000 mg/L. are chlorimuron-ethyl, metsulfuron-methyl, thifensulfuron-methyl and tribenuron-methyl.) With sulfonamide herbicides having a solubility in pH 7 buffered water of less than about 1000 mg/L, more than 50 equivalent % of base relative to the sulfonamide herbicide free acids may be needed in the compositions prepared according to the process of this invention to significantly reduce residues in spray equipment. (Illustrative examples of sulfonamide herbicides having a solubility in pH 7 buffered water less than 1000 mg/L are bensulfuron-methyl and sulfometuron-methyl.) For compositions of these sulfonamide herbicides, typically about 75 to 100 equivalent % of base significantly reduces spray residues, and greater amounts (i.e. up to about 200 equivalent %) of base may be useful in reducing residues to negligible levels.

Solubility of sulfonamide herbicides in pH 7 buffered water can be determined by standard methods such as the procedure taught below in Analytical Example 2.

Therefore to improve spray equipment clean-out properties, the mixture for extrusion according to the process of this invention preferably contains at least about 75 equivalent % of base, and more preferably at least about 100 equivalent % of base relative to the one or more sulfonamide herbicide free acids. Furthermore, if the mixture contains acidic substances besides the sulfonamide herbicide free acids, correspondingly more base should be added. More than 100 equivalent % of base can be included relative to the one or more sulfonamide herbicide free acids, provided that the mixture does not include ingredients unstable to the base.

The base in the mixture for extrusion according to the process of this invention comprises at least one inorganic base. Inorganic bases particularly suitable for this invention include those having cations derived from alkali metals or ammonium, and counterions selected from carbonate, phosphate, oxide, hydroxide and silicate anions, including dimeric, trimeric and polymeric forms such as pyrophosphate, tripolyphospbate, polyphosphate, trisilicate, etc. Illustrative inorganic bases include but are not limited to sodium phosphate (NazPOy4), sodium hydrogen phosphate (Na,HPO,), potassium phosphate (K3POy), potassium hydrogen phosphate (K,HPO,), ammonium hydrogen phosphate ((NH4),HPO,),

sodium carbonate (NayCOj3), sodium hydrogen carbonate (NaHCOs3), potassium carbonate (K5CO3), potassium hydrogen carbonate (KHCO3), lithium oxide (Li,0), lithium hydroxide (LiOH), lithum carbonate (LiyCOs3), sodium hydroxide (NaOH), lithium phosphate (LisPOy), lithium metasilicate (Li,SiOz), lithium orthosilicate (LiySiO,), potassium hydroxide (KOH), sodium metasilicate (Na,SiO3), sodium orthosilicate (NasSiOy), potassium pyrophosphate (K4P,04), sodium trimetaphosphate ((NaPOs);), sodium hexametaphosphate ((NaPO3)¢), sodium polyphosphate (NaPOs),), sodium pyrophosphate (Nay4P,0+), sodium tripolyphosphate (sodium triphosphate, NasP;01) and sodium trisilicate (Na, Si304), including their anhydrous and hydrated forms.

Preferred for reason of cost, effectiveness and convenience are inorganic bases containing an alkali metal cation selected from sodium (Na') and potassium (K+), more preferably sodium. Also preferred for reason of cost, effectiveness and convenience are inorganic bases containing a counterion selected from hydrogen carbonate (HCOs™), carbonate (CO32-), hydrogen phosphate (HPO42~) and phosphate (PO43-), more preferably carbonate and phosphate. Preferred inorganic bases thus include sodium hydrogen carbonate, sodium carbonate, sodium hydrogen phosphate, sodium phosphate, potassium hydrogen carbonate, potassium carbonate, potassium hydrogen phosphate and potassium phosphate. These inorganic bases include hydrated forms such as sodium carbonate monohydrate, sodium hydrogen phosphate heptahydrate, sodium phosphate dodecahydrate, potassium carbonate sesquihydrate, potassium hydrogen phosphate trihydrate and potassium phosphate octahydrate. Inorganic bases more preferred are sodium carbonate, sodium phosphate, potassium carbonate and potassium phosphate, including hydrated forms thereof.

A most preferred inorganic base is sodium carbonate, including hydrated forms thereof.

Another most preferred inorganic base is sodium phosphate, including hydrated forms thereof. While inorganic bases are useful alone, mixtures of inorganic bases may be advantageous.

During the addition of water to prepare an extrudable paste, the heat of hydration of anhydrous bases can, depending upon amount and nature of base and the cooling capacity of the mixing or kneading equipment, cause considerable increase in temperature with potentially undesirable effect on the chemical constitution and/or extrudability of the paste.

If the temperature increase caused by anhydrous bases would be excessive, hydrated instead of anhydrous forms of bases are preferred for preparing the mixture for extrusion. As the heat of hydration of anhydrous sodium phosphate is particularly large, the dodecahydrate is a preferred form of sodium phosphate for the process of this invention.

Sulfonamide herbicides have as an essential molecular structure feature a sulfonamide moiety (—S(O),NH-). As referred to herein, sulfonamide herbicides particularly comprise sulfonylurea herbicides wherein the sulfonamide moiety is a component in a sulfonylurea moiety (-S(O);NHC(O)NH(R)-) and triazolopyrimidine herbicides wherein the sulfonyl end of the sulfonamide moiety is connected to the 2-position of a substituted [1,2,4]triazolopyrimidine ring system and the amino end of the sulfonamide moiety is connected to a substituted aryl, typically phenyl, group. In sulfonylurea herbicides the sulfonyl end of the sulfonylurea moiety is connected either directly or by way of an oxygen atom or an optionally substituted amino or methylene group to a typically substituted cyclic or acyclic group. At the opposite end of the sulfonylurea bridge, the amino group, which may have a substituent such as methyl (R being CH3) instead of hydrogen, is connected to a heterocyclic group, typically a symmetric pyrimidine or triazine ring, having one or two substituents such as methyl, ethyl, trifluoromethyl, methoxy, ethoxy, methylamino, dimethylamino, ethylamino and the halogens.

Representative of the sulfonylureas contemplated for use in this invention are those of the formula:

X

=

I-SOpNHON z

R N=

Y wherein:

J is selected from the group consisting of

RI R3 R4

RZ R L

J-1 J-2 J-3

R4 RS 13 RS $3 § 29)

RS , Rr4 , ,

J-4 1-5 J-6

RY ri0

R7

R6 ; / W / je , * Rl N H K N

I kL

J-7 J-8 J-9

R2 R10 RY R3 R6

DSSS GRD 5 GI

N° N R10 R7

HN

R8 le lg

J-10 J-11 I-12 11 RO /\ , / \ and FN =N ; or

R7 RO RY RI / R12 xX

R} Rl

J-13 J-14 J-15

J is R13SO,N(CHa3)-;

Ris H or CHj;

RlisF, Cl, Br, NO,, C;—C, alkyl, C;—C, haloalkyl, C3—C4 cycloalkyl, C;—Cq4 haloalkenyl, C;—C,4 alkoxy, C;—Cj4 haloalkoxy, Cy—C4 alkoxyalkoxy, CO,R14,

C(O)NRI5R16, SO,NRI7R18, S(O) R19, C(O)R?0, CH,CN or L;

R2is H, F, Cl, Br, 1, CN, CH;, OCHs, SCH3, CF3 or OCF H;

R3 is Cl, NO,, CO,CH3, CO,CH,CHj, C(O)CH3, C(O)CH,CHj3, C(O)-cyclopropyl,

SO,N(CHs),, SO,CHj, SO,CH,CH;, OCH; or OCH,CH3;

R# is C;-C; alkyl, C;~Cy haloalkyl, C;—C, alkoxy, Cy—C4 haloalkenyl, F, Cl, Br,

NO,, COR 14, C(O)NR1I5R16, SO,NRI7R 18, S(0);R 1%, C(O)R?0 or L;

RS is H, F, Cl, Br or CH;

R6 is Ci—Cs alkyl, CC, alkoxy, Cry haloalkenyl, F, Cl, Br, CO,R14,

C(O)NRI5R 16 SO,NR17R18, S(0),R1%, C(O)R?V or L;

R7is H, F, Cl, CH; or CFs;

R8 is H, C,—C;5 alkyl or pyridyl;

RY is C,—C; alkyl, C;—C, alkoxy, F, Cl, Br, NO3, CO,R14, SO,NRI7RI8, S(O),RY,

OCF,H, C(O)R20, C,—C4 haloalkenyl or L;

R10 is H, Cl, F, Br, C,—Cj alkyl or C;—C, alkoxy;

R11 is H, C,~C; alkyl, C;—C, alkoxy, C;~C4 haloalkenyl, F, Cl, Br, COR,

C(O)NRI5R16, SO,NRI7RI8, S(0),R1%, C(O)R20 or L;

R12 is halogen, C1—Cj4 alkyl or C,—C3 alkylsulfonyl;

R13 is C1—C4 alkyl;

R14 is selected from the group consisting of allyl, propargyl, oxetan-3-yl and C,—Cs alkyl optionally substituted by at least one member independently selected from halogen, C{—C, alkoxy and CN;

R15 is H, C;-C; alkyl or C1—C, alkoxy;

R16 is C;—C, alkyl;

R17 is H, C;—-Cj alkyl, C;—C, alkoxy, allyl or cyclopropyl;

R18 is H or C;~Cj alkyl;

R19 is C,—~Cj alkyl, C;—~Cj haloalkyl, allyl or propargyl;

R20 js C;—C, alkyl, C;—C, haloalkyl or C3—Cs cycloalkyl optionally substituted by halogen; nis 0,1 or 2;

Lis

R21

N—N

J \ ; he

L1 is CHp, NH or O;

R2! is selected from the group H and C\—Cj alkyl;

X is selected from the group H, C;—Cy alkyl, C;—C4 alkoxy, C1—Cy haloalkoxy, C14 haloalkyl, C;—C4 haloalkylthio, C;—C, alkylthio, halogen, Co—Cs alkoxyalkyl,

C,~Cs alkoxyalkoxy, amino, C,—-Cj alkylamino and di(C;—C3 alkyl)amino;

Y is selected from the group H, C;—Cy alkyl, C;—Cy4 alkoxy, C,—C, haloalkoxy, C;-Cq4 alkylthio, C,—-C4 haloalkylthio, C,—Cs alkoxyalkyl, C,—Cs alkoxyalkoxy, amino,

C;~Cj5 alkylamino, di(C;~Cj alkyl)amino, C3-C4 alkenyloxy, C3-Cyg alkynyloxy, C,—Cs alkylthioalkyl, C;—Cs alkylsulfinylalkyl, C,—Cs alkylsulfonylalkyl, C;—Cy4 haloalkyl, C;—C4 alkynyl, C3—Cjs cycloalkyl, azido and cyano; and

Z is selected from the group CH and N; provided that (i) when one or both of X and Y is Cy haloalkoxy, then Z is CH; and (ii) when X is halogen, then Z is CH and Y is OCH;, OCH,CHj, N(OCH;3)CH3, NHCH3,

N(CH3), or OCF,H.

Representative of the triazolopyrimidines contemplated for use in this invention are those of the formula:

Claims (17)

CLAIMS What is claimed is:

1. A process for preparing a paste-extruded sulfonamide herbicide composition comprising (a) preparing a mixture comprising (i) from 2 to 90% by weight on a water-free basis of one or more active ingredients comprising at least one sulfonamide herbicide free acid, (i) from 0 to 95% by weight on a water-free basis of one or more additives selected from the group consisting of wetting agents, dispersants, lubricants, anticaking agents, chemical stabilizers and diluents; and (iii) at least about 50 equivalent % of base selected from inorganic base equivalents having conjugate acid pK,s at least 2.1 units greater than the highest pK; of the sulfonamide herbicide free acid component; the sum of the weight percents of all the ingredients in the mixture totaling 100% on a water-free basis; and (iv) sufficient water to make the mixture an extrudable paste; (b) extruding the mixture prepared in (a) through a die or screen to form extrudate; and (c) drying the extrudate.

2. The process of Claim 1 wherein the mixture comprises at east about 75 equivalent % of base.

3. The process of Claim 2 wherein the mixture comprises at least about 100 equivalent % of base.

4. The process of Claim 1 wherein the base comprises an inorganic base selected from the group consisting of sodium hydrogen carbonate, sodium carbonate, sodium hydrogen phosphate, sodium phosphate, potassium hydrogen carbonate, potassium carbonate, potassium hydrogen phosphate and potassium phosphate.

5. The process of Claim 4 wherein the base comprises an inorganic base selected from the group consisting of sodium carbonate, sodium phosphate, potassium carbonate and potassium phosphate.

6. The process of Claim 5 wherein the base comprises sodium carbonate.

: 7. The process of Claim 5 wherein the base comprises sodium phosphate.

8. The process of Claim 7 wherein the sodium phosphate is in the form of the dodecahydrate.

9. The process of Claim 1 wherein the mixture comprises from about 0.5 to about 50% by weight of a saccharide on a water-free basis.

10. The process of Claim 1 wherein at least one sulfonamide herbicide free acid is selected from the group consisting of amidosulfuron, azimsulfuron, bensulfuron-methyl, : chlorimuron-ethyl, chlorsulfuron, cinosulfuron, cyclosulfamuron, ethametsulfuron-methyl, ethoxysulfuron, flupyrsulfuron-methyl, flazasulfuron, foramsulfuron, halosulfuron-methyl, imazosulfuron, iodosulfuron-methyl, mesosulfuron-methyl, metsulfuron-methyl, nicosulfuron, oxasulfuron, primisulfuron-methyl, prosulfuron, pyrazosulfuron-ethyl, rimsulfuron, sulfometuron-methyl, sulfosulfuron, thifensulfuron-methyl, triasulfuron, tribenuron-methyl, trifloxysulfuron, triflusulfuron-methyl, tritosulfuron, cloransulam-methyl, diclosulam, florasulam, flumetsulam, metosulam and penoxsulam.

11. The process of Claim 10 wherein at least one sulfonamide herbicide free acid is selected from the group consisting of azimsulfuron, bensulfuron-methyl, chlorimuron-ethyl, chlorsulfuron, ethametsulfuron-methyl, flupyrsulfuron-methyl, metsulfuron-methyl, nicosulfuron, rimsulfuron, sulfometuron-methyl, thifensulfuron-methyl, tribenuron-methyl and triflusulfuron-methyl.

12. The process of Claim 1 wherein at least one sulfonamide herbicide free acid is sulfometuron-methyl and the base comprises sodium phosphate.

13. The process of Claim 1 wherein at least one sulfonamide herbicide free acid is thifensulfuron-methyl and the base comprises sodium carbonate.

14. The process of Claim 1 wherein at least one sulfonamide herbicide free acid is tribenuron-methy! and the base comprises sodium carbonate.

15. The process of Claim 1 wherein in (a) sufficient water to make an extrudable paste is added to a solid composition comprising from 2 to 90% by weight on a water-free basis of one or more active ingredients comprising at least one sulfonamide herbicide free acid, from 0.5 to 94% by weight on a water-free basis of a saccharide, from 1 to 20% by weight on a water-free basis of surfactant component, at least about 50 equivalent % of base selected from inorganic base equivalents having conjugate acid pKgys at least 2.1 units greater than the highest pK, of the sulfonamide herbicide free acid component, and optionally other ingredients; the sum of the weight % of all the ingredients in the solid composition totaling 100% of a water-free basis; and at least 10% of the sulfonamide herbicide content in the solid composition being in free acid form.

16. The process of Claim 1 further comprising a step of sifting the dried extrudate.

17. A paste-extruded sulfonamide herbicide composition prepared by the process of Clam Il.