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Metsulfuron-Methyl –based Herbicidal Ionic Liquids Juliusz Pernak, Micha# Niemczak, Julia L. Shamshina, Gabriela Gurau, Grzegorz G#owacki, Tadeusz Praczyk, Katarzyna Marcinkowska, and Robin D. Rogers J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/jf505782p • Publication Date (Web): 03 Mar 2015 Downloaded from http://pubs.acs.org on March 10, 2015

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Journal of Agricultural and Food Chemistry

1

METSULFURON-METHYL-BASED

2

HERBICIDAL IONIC LIQUIDS

3

Juliusz Pernak,†,* Michał Niemczak,† Julia L. Shamshina,‡,§ Gabriela Gurau,‡,§ Grzegorz

4

Głowacki, Tadeusz Praczyk, Katarzyna Marcinkowska, Robin D. Rogers‡,*

5

†

6 7

Department of Chemical Technology, Poznan University of Technology, Poznan 60-965, Poland

‡

8

Center for Green Manufacturing and Department of Chemistry, The University of Alabama, Tuscaloosa, AL 35487, USA

9

§

525 Solutions, Inc., 720 2nd Street, Tuscaloosa, AL 35401, USA

10



Institute of Plant Protection – National Research Institute, Poznan 60-318, Poland

*

Corresponding Author(s)

Juliusz Pernak, Tel: 00148-61-6653682. E-mail: [email protected] R. D. Rogers, Tel: +1-205-348-4323. E-mail: [email protected]

1 ACS Paragon Plus Environment


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ABSTRACT. Ten sulfonylurea-based herbicidal ionic liquids (HILs) were prepared by

12

combining the metsulfuron-methyl anion with various cation types including quaternary

13

ammonium

14

hydroxyethyltrimethylammonium]+), pyridinium ([1-dodecylpyridinium]+), piperidinium ([1-

15

methyl-1-propylpiperidinium]+), imidazolium ([1-allyl-3-methylimidazolium]+, [1-butyl-3-

16

methylimidazolium]+), pyrrolidinium ([1-butyl-1-methylpyrrolidinium]+), morpholinium ([4-

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decyl-4-methylmorpholinium]+) and phosphonium ([trihexyltetradecylphosphonium]+ and

18

[tetrabutylphosphonium]+). Their herbicidal efficacy was studied in both greenhouse tests and

19

field trials. Preliminary results for the greenhouse tests showed at least twice the activity for

20

all HILs when compared to the activity of commercial Galmet 20 SG®, with HILs with

21

phosphonium cations being the most effective. The results of two-year field studies showed

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significantly less enhancement of activity than observed in the greenhouse; nonetheless it was

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found that the herbicidal efficacy was higher than that of the commercial analog and efficacy

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varied depending on the plant species.

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KEYWORDS. Metsulfuron-methyl, MS-M, sulfonylurea, Herbicidal Ionic Liquids, efficacy,

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greenhouse test, field test, Galmet 20 SG®.

([bis(2-hydroxyethyl)methyloleylammonium]+,


[2-

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INTRODUCTION

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Sulfonylurea herbicides were discovered in 1975 by DuPont Crop Protection1 and

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commercialized in 1982.2 Soon thereafter sulfonylureas became one of the most widely used

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herbicides in the world, due to their high herbicidal activity coupled with very low application

31

rates.3 The herbicidal action of sulfonylureas is based on an interference with the activity of the

32

enzyme AHAS (acetohydroxyacid synthase), responsible for the biosynthesis of essential amino

33

acids - valine, leucine, and isoleucine, which are essential to proper plant function.4

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Sulfonylureas are commonly used to protect cereals (wheat, barley, oats, triticale, and rice) from

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broadleaf weed species, such as common chickweed (Stellaria media), red dead-nettle (Lamium

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purpureum), common poppy (Papaver rhoeas), and scentless mayweed (Matriciaria inodora).

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Sulfonylurea herbicides contain a sulfonylurea (-SO2-NH-C(O)-NH-) link between two

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substituted aromatic rings, with the urea side of the bridge connected to either a triazine

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(chlorsulfuron, metsulfuron, DPX-M 6316) or pyrimidine (sulfometuron, chlorimuron,

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bensulfuron), and the sulfonyl side of the bridge connected to either ortho-substituted aryl- or

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thiophene. A carboxylic ester substituent on the aromatic (or thiophene) ring is common to most

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of the sulfonylureas. “Metsulfuron-Methyl” or MS-M herbicide (systematic name: 2-{[(4-

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methoxy-6-methyl-1,3,5-triazin-2-yl)amino]oxomethyl]sulfamoyl}benzoic acid methyl ester, 1)

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is one of the representatives of sulfonylureas composed of an aryl- group, linked through the

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sulfonylurea bridge to the triazine derivative (Figure 1a). MS-M herbicide possesses an acidic

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proton on the nitrogen of the sulfonylamide group (denoted in Figure 1 as blue) and can therefore

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act as an acid, with a dissociation constant (pKa) of 3.3.

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Figure 1 here.



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The biggest problems with MS-M (and many other sulfonylureas) derive from its low stability

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in aqueous media, where it undergo hydrolysis under acidic conditions resulting in cleavage of

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the sulfonylurea-bridge and formation of sulfonamide and triazine derivatives.5-7 In acidic soils

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(soil pH levels below 6), only 4 weeks is enough to reduce the concentration of the herbicide

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50%.8 MS-M, however, is relatively stable to hydrolysis of the sulfonylurea bridge under neutral

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and moderately alkaline conditions (pH 7-10),9,10 although as the pH exceeds 10.2, hydrolysis of

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the ester on the benzene ring takes place.11

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The

anionic

form

of

MS-M,

(4-methoxy-6-methyl-1,3,5-triazin-2-ylcarbamoyl)[(2-

57

(methoxycarbonyl)phenylsulfonyl]amidate 2 (Figure 1b), however, is much less prone to

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hydrolysis than its neutral form12 and there are several reports of alkali or alkali earth metal salts

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of sulfonylurea compounds prepared by reaction of the corresponding N-protonated

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sulfonylureas with a solution of a corresponding base, such as alkali metal carbonates, alkali

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metal hydroxides, and alkaline earth metal hydroxides.13-18 Ammonium and quaternary

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ammonium salts of sulfonylureas have also been synthesized by treating the corresponding N-

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protonated sulfonylurea with ammonia, ethanolamine, or ammonium salt solution.14,19,20 We

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have not found evidence that these salts have been commercialized.

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Another challenging problem with sulfonylureas is obtaining a stable liquid formulation.21

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During storage, sulfonylurea herbicides (in the form of concentrated formulations of dissolved

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active ingredients) precipitate out of solution and crystal growth takes place. In these cases,

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solubility limits effective application or use of concentrates of the active herbicide.

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In 2011 we presented a strategy of converting a herbicide into an ionic liquid (IL, currently

70

defined as a salt which melt below 100 ºC22) and applied the approach to a variety of herbicides

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(e.g., 2,4-D, MCPA, triclopyr, cyhalofop, glyphosate and dicamba).23-2930 These herbicidal ionic


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liquids (HILs) were comprised of an active compound in ionic form, possessed low melting

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points (below 100 ºC22) and were designed with dual functionality where both cation and anion

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added to the beneficial properties of the salt. Such combinations of two active chemicals in a

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single entity, demonstrated improved (or in a few cases simply the same) herbicidal activity,

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while the physicochemical properties were modified. The second actives (cations) were chosen

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from food or cosmetic grade antibacterial cations, antifungal cations, surfactants, etc. These

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herbicides possessed greatly reduced volatility, showed improved efficacy, and demonstrated

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lower water solubility resulting in reduced environmental mobility.

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We have noted that the MS-M anion (Figure 1b) fits the normal design rules for choosing ions

81

that will form HILs (asymmetric, charge delocalized27) and, therefore, hypothesized that a

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similar strategy could be employed for the conversion of MS-M into the HILs, to improve its

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stability and precipitation problems. Here we report a series of new MS-M IL herbicides where

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we have paired the MS-M anion with several cations of a second biological activity, including:

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additional biological activity (e.g., 4,4-dialkyl morpholinium31), antimicrobial activity (e.g.,

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quaternary ammonium,32,33 pyridinium,34,35 and imidazolium,35 with longer alkyl chain lengths),

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penetration enhancers (e.g., linear saturated long chain alkyl substituents, soya32), or herbicidal

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activity (pyperidinium and morpholinium cations with longer N-alkyl group substituents31).

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Greenhouse testing and field studies of the synthesized compounds were evaluated to establish

90

their herbicidal activity.

91 92

MATERIALS AND METHODS

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Materials



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All materials were used as supplied unless otherwise noted. Deionized (DI) water was obtained

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from a commercial deionizer (Culligan, Northbrook, IL, USA) with specific resistivity of 16.82

96

MΩ·cm at 25 °C. KOH and all solvents (methanol, DMSO, acetonitrile, acetone, isopropanol,

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ethyl acetate, chloroform, toluene, hexane) and KOH were purchased from Aldrich (European

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market, Poznan, Poland) and used without further purification. Galmet 20 SG® was obtained

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from P.U.H. Chemirol (Chemirol Sp z o.o., Mogilno, Poland and contained 20% metsulfuron

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methyl (CAS 74223-64-6), and 5% dimethylamine (CAS 124-40-3) as active components.

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Bis(2-hydroxyethyl)oleylmethylammonium chloride (Ethoquad O/12, purity 75%) was

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obtained from Akzo Nobel (Akzo Nobel Head Office, Amsterdam, Netherlands). 2-

103

Hydroxyethyltrimethylammonium chloride (purity >98%), 1-dodecylpyridinium chloride,

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hydrate (purity 98%), 1-butyl-3-methylimidazolium chloride (purity 98%), 4-methylmorpholine

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(purity 98%), 1-bromodecane (purity 98%), tetrabutylphosphonium chloride (purity 96%), and

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dimidium bromide indicator (purity 95%) were obtained from Sigma-Aldrich (Sigma-Aldrich,

107

St. Louis, MO, USA). Compounds 1-methyl-1-propylpiperidinium chloride (purity 99%), 1-

108

allyl-3-methylimidazolium chloride (purity 98%), 1-butyl-1-methylpyrrolidinium chloride

109

(purity 99%), and trihexyltetradecylphosphonium chloride (purity >95%) were received from

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Ionic Liquids Technologies GmbH (IoLiTec, Heilbronn, Germany).

111

4-Decyl-4-methylmorpholinium bromide was synthesized via quaternization reaction of 4-

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methylmorpholine and 1-bromodecane as follows. 100 mL of acetonitrile were placed into a 250

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mL round bottom flask equipped with a teflon-coated stirring bar and a condenser. 4-

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Methylmorpholine (0.10 mol) and 1-bromodecane (0.11 mol) were added to the acetonitrile, and

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the reactants were stirred for 48 h at 60 °C. After 48 h the solvent was removed using a vacuum

116

evaporator. After solvent removal, 200 mL of ethyl acetate was added to the residue and the


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product precipitated as a white solid. The product was carefully separated by vacuum filtration

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through a glass filter funnel, thoroughly washed with small portions of ethyl acetate (6 x 10 mL)

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to remove unreacted 1-bromodecane, and dried under reduced pressure at 50 °C for 24 h.

120 121

Methods

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Thermal Gravimetric Analysis (TGA). Thermal gravimetric analysis was performed using a

123

Mettler Toledo Stare TGA/DSC1 unit (Leicester, UK) under nitrogen. Samples between 2 and 10

124

mg were placed in aluminum pans and heated from 30 to 450 oC at a heating rate of 10 oC/min.

125 126

Differential Scanning Calorimetry (DSC). Thermal transition temperatures were determined by

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DSC, with a Mettler Toledo Stare DSC1 (Leicester, UK) unit, under nitrogen. Samples between 5

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and 15 mg were placed in aluminum pans and heated from 25 to 120 oC at a heating rate of 10

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o

130

again to 120 oC.

C/min, cooled with an intracooler at a cooling rate of 10 oC/min to -100 oC and then heated

131 132

Melting point. Melting point for the compound 10 was obtained using a Buchi melting point

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apparatus B-540 (BÜCHI Labortechnik AG, Postfach, Switzerland). A sample of the test

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substance was placed into a glass capillary tube, and then heated at a constant heating rate (3

135

°C/min). Melting was determined visually with an accuracy ± 1°C.

136 137

Nuclear Magnetic Resonance Spectroscopy (NMR). 1H NMR spectra were recorded on a

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Mercury Gemini 300 spectrometer operating at 300 MHz. 13C NMR spectra were obtained with

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the same instrument at 75 MHz. TMS was used as the internal standard.



140 141

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Elemental analyses (CHN). Elemental analyses were performed at the Adam Mickiewicz University, Poznan (Poland).

142 143

The water content was determined using an Aquastar volumetric Karl Fischer titrator EMD

144

Millipore (Billerica, MA, USA) with Composite 5 solution as the titrant and anhydrous methanol

145

as the solvent.

146 147

Purity assay by EN ISO 2871-1:2010. As an alternative measure of purity, an assay was

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performed by direct two-phase volumetric titration, according to EN ISO 2871-1:2010.36 The

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salts were titrated with a standard solution of sodium dodecyl sulfate (Na[CH3(CH2)11SO4]) in a

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water-chloroform (H2O-CHCl3) biphasic system (or water-methanol-chloroform in the case of

151

compounds with limited solubility in water). The titration was conducted with the indicator

152

(dimidium bromide). In a 50 mL volumetric flask, 0.1 g of the MSM salt was dissolved in water

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(or in a mixture of water and methanol). Then, a 10 mL sample was taken from the prepared

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solution and blended with 15 mL of chloroform and 5 mL of pre-mixed indicator. The resulting

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biphasic system was titrated with a 0.004 M sodium dodecyl sulfate. After addition of a titrant

156

increment, the sample was stirred vigorously during 15 min to allow reaction of the titrant with

157

the analyzed compound and its extraction into the organic phase (chloroform). After 15 min, the

158

two phases were separated and the color analyzed. This was repeated until the pink color

159

disappeared from the chloroform lower phase at the equivalence point and a one-drop excess of

160

titrant formed a violet complex. The purity was calculated using eq. 1:

161 162

%‫= ݕݐ݅ݎݑ݌‬

ሺ௏௞×஼ௗ×௏ௗ×ெௐሻ௫ଵ଴଴ ௠×௏௣×ଵ଴଴଴

(1)


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where: %purity is the cationic content (% of available); VK is the total volume of the prepared

164

solution of analyzed substance in mL; Cd is the concentration of the titrant solution of sodium

165

dodecyl sulfate, Na[CH3(CH2)11SO4] in mol/L; Vd is the volume of the titrant solution in mL;

166

MW is the molecular weight of the analyzed compound in g/mol; m is the mass of the tested

167

sample in g; and Vp is the volume of titrated analyte in mL.

168 169

Solubility Measurements. The solubilities were determined via Vogel’s Textbook of Practical

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Organic Chemistry protocol.37 A sample of each HIL (0.1 g) was added to a certain volume of

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each solvent, and the samples were thermostatted (MEMMERT Water Bath, Model WNB 7,

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Schwabach, Germany) at 25 °C. Based on the volume of solvent used, 3 types of behavior were

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recorded: ‘soluble’ applies to compounds which dissolved in 1 mL of solvent, ‘limited solubility’

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applies to compounds that dissolved in 3 mL of solvent, and ‘not soluble’ applies to the

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compounds which did not dissolve in 3 mL of solvent. The solubility study results of the

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prepared HILs in the ten representative solvents are shown below in Table 2.

177 178

Statistics. A total of 5 experiments were statistically analyzed, including 2 greenhouse

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experiments (on Chemopodium album and Brassica napus) and 3 field experiments (field trials

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conducted in 2012 and 2013 in fields near Szczecinek and Szamotuly) on Matricaria inodora,

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Viola arvensis, Polygonum convolvulus, Galeopsis tetrahit, Capsella bursa pastoris, Papaver

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rhoeas, Veronica persica, stellaria media and Myosotis arvensis. In order to study the effect of

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the applied plant protection product on the value of weed destruction, a statistical analysis for

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each greenhouse and each field experiment was carried out. Each experiment was performed in a

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completely randomized design with r = 3 or 4 replications in greenhouse experiments and r = 4



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replications in all field trials. For each experiment the following number of groups (v, also called

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conditions) was used: v = 7 groups for greenhouse trials (six HILs, 6-8, 10-12 and the Galmet

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20SG® control) and v = 6 for field trials (five HILs, 6-8, 10, 11 and the Galmet 20SG® control)

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to determine if there was a significant difference between the efficacy data collected under each

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condition. For each experiment, the degree of freedom (df) that indicates the total number of data

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points collected (n) and the number of groups being compared (v) is reported in the in the

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American Psychological Association (APA) format, df = v-1; n-v. This means that for the

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greenhouse trials with seven groups being compared with each other, and three replicates

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collected for each of the groups, there were a total of n = 7 x 3 = 21 data points and, therefore, df

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= 6; 14. Similarly, for the greenhouse trials with seven groups being compared with each other,

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but four replicates collected for each, df = 6; 21. For the field study, only six groups were

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compared with each other, with four replicates collected for each of the groups resulting in n =

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24 data points and df= 5; 18.

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The program package R (3.0.2) was used for the statistical calculations (R Development Core

200

Team, 201338). Only normally distributed data can be analyzed by analysis of variance

201

(ANOVA). Here, the Shapiro -Wilk test was used first to test the null hypothesis that “the

202

samples come from a normal distribution” against the alternative hypothesis “the samples do not

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come from a “normal distribution.” In the case of normal distribution, the Fligner-Killeen test of

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homogeneity of variances was used to test the null-hypothesis that the variances in each of the

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groups - for each treatment in one trial - were the same. Before performing the test, a

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“significance level” (or test’s threshold value, α) of 0.01 was chosen, followed by calculation of

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a function of the observed sample results (p-value) and the null hypothesis was tested at the

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chosen α-level of 0.01. When the p-value obtained was more than the significance level (α), the


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tests suggested that the observed data were consistent with the assumption that the null

210

hypothesis was true. Subsequently, to study differences between studied treatments, a one-way

211

analysis of variance (ANOVA) was applied. When the p-value was less than 0.01, the null

212

hypothesis that the data were normally distributed was rejected, and the non-parametric Kruskal-

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Wallis (K-W) rank sum test that does not assume a normal distribution of the samples (unlike the

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analogous one-way ANOVA) was applied.

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Both ANOVA and the non-parametric Kruskal-Wallis (K-W) rank sum test are statistical

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procedures used for comparing sample means. The results allow for comparison of many sample

217

distributions using significance level α and p-values, however, the null hypothesis in the case of

218

ANOVA was different: “there is no relationship between the groups” against the alternative

219

hypothesis “there is relationship between the groups.” For quantification, the F-score (also called

220

F-statistic), equal to the ratio between the variance of the group means/the mean of the variances

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within the group, indicates how significant the effect of the independent variable is. For both

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ANOVA and the non-parametric Kruskal-Wallis tests, we have reported significance level α, p-

223

value, and F-score. The chosen test results are provided in Table 2 and Figure 3.

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ANOVA (or K-W) tests indicate whether we have an overall difference between the groups,

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but not which specific groups differed. In order to compare the HILs Galmet 20 SG® and

226

determine which groups have significant differences, we computed a post hoc test (Tukey’s post

227

hoc test or Wilcoxon rank sum test). Post hoc tests were only run when statistically significant

228

differences between HILs and Galmet 20 SG®-treatments were found (i.e., ANOVA resulted in

229

overall significant difference in group means). As a quantitative result of post hoc tests, we

230

report Honest Significant Difference (HSD) which represents the minimum difference between

231

two group means that must exist before the difference is to be considered statistically significant.



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The results of the statistical tests are shown by marking the individual value of each treatment by

233

an appropriate letter. The same letter in the columns of Tables 3 and 4 means there was no

234

significant differences between treatments.

235 236

Syntheses

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General synthesis (Method A) of 3-10 and 12. In a 50 mL round-bottom flask equipped with a

238

teflon-coated magnetic stirring bar, 0.01 mol of the corresponding halide of the desired cation

239

was dissolved in 10 mL of anhydrous methanol followed by adding an equimolar amount of

240

potassium hydroxide dissolved in 5 mL of anhydrous methanol. The mixture was then stirred for

241

1 h at room temperature. The inorganic potassium halide by-product precipitated as a white solid

242

and was carefully separated by vacuum filtration through a glass filter funnel. The filtrate (the

243

free base of the desired cation) was carefully transferred to a 50 mL round-bottom flask equipped

244

with a teflon-coated magnetic stirring bar followed by addition of a stoichiometric amount of

245

MS-M

246

methyl ester) which was added all at once. The mixture was then stirred for another 1 h at room

247

temperature and the solvent was removed using a rotary evaporator followed by adding 20 mL of

248

acetone to the residue. After filtration and evaporation of the solvent from the filtrate, the

249

products were dried under reduced pressure at 50 °C for 48 h.

(2-[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]-oxomethyl]sulfamoylbenzoic

acid

250

The synthesized salts were dried under vacuum (10 mbar) at 50 oC for 48 h and stored over

251

P4O10. The water contents of the dried salts were measured by Karl-Fischer titration and found to

252

be less than 500 ppm. The obtained salts were stable in air and in contact with water and tested

253

organic solvents. NMR spectra descriptions, purity assays and elemental analyses for compounds

254

3-10 and 12 are provided in the ESI.


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General synthesis (Method B) of 4, 7 and 11. In a 50 mL round-bottom flask equipped with a

256

teflon-coated magnetic stirring bar, 0.01 mol of the corresponding chloride of the desired cation

257

was dissolved in 10 mL of water followed by adding equimolar amount of the potassium salt of

258

MS-M

259

methyl ester) dissolved in 10 mL of water. The mixture was then stirred for 24 h at room

260

temperature and the water was removed using a rotary evaporator. Then, 20 mL of anhydrous

261

acetone was added to the residue. After filtration and evaporation of the solvent from the filtrate,

262

the products were dried under reduced pressure at 50 °C for 48 h. NMR spectra descriptions,

263

purity assays and elemental analyses for compounds 4, 7 and 11 are provided in the ESI.

(2-[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]-oxomethyl]sulfamoylbenzoic

acid

264 265

Greenhouse and Field Trials. Common lambsquarters (Clenopodium album) and oilseed rape

266

(Brassica napus) plants were grown in 0.5 L plastic pots filled with peat-based potting material

267

under controlled environmental conditions: a temperature of 20 ± 2 °C, relative humidity of 60%,

268

and a photoperiod of 16/8 h day/night. The plants were thinned to five per pot 10 days after

269

emergence, and watered as needed.

270

Plants were treated at the 6-8 leaf growth stage and a randomized complete block design was

271

used with four replicates for each treatment. HIL herbicides were mixed with deionized water ca.

272

24 h before application and the plants were treated with the aqueous solution only once, at a 4 g

273

ae/ha (active equivalents applied per hectare) rate. The applications were conducted using a

274

moving sprayer (APORO, Poznan, Poland) with a TeeJet® VP 110/02 flat-fan nozzle (TeeJet

275

Technologies, Wheaton, IL, USA) capable of delivering 200 L/ha of spray solution at 0.2 MPa

276

operating pressure. The sprayer was moved above the plants at a 40 cm distance and at a constant

277

speed of 3.1 m/s. A control group of plants was treated with standard Galmet 20 SG® herbicide,



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at the same application rate. Untreated plants were used for comparison, and were included in all

279

experiments. Efficacy was evaluated using the fresh weight reduction method two weeks after

280

treatment (2 WAT). Data were expressed as percent of fresh weight reduction compared with

281

untreated plants.

282

Field trials were carried out in two consecutive years 2012 and 2013 at winter wheat fields

283

located near Szczecinek (north-western part of Poland) and Szamotuly (western part of Poland).

284

Herbicide treatments were applied to plants as aqueous solutions prepared ca. 24 h before

285

application and the plants were treated at an 8 g ae/ha rate. Treatments were applied using a

286

knapsack sprayer (APORO, Poznan, Poland) equipped with TeeJet® DG110/02 VS flat-fan

287

nozzles (TeeJet Technologies, Wheaton, IL, USA) capable of delivering 200 L/ha of spray

288

solution at 0.3 MPa operating pressure. Weed control was evaluated visually four weeks after

289

herbicide applications (4 WAT) using a scale of 0 (no effect) to 100% (complete weed

290

destruction).

291 292

RESULTS/DISCUSSION

293

Synthesis of MS-M-based Ionic Liquids

294

Ten MS-M-based salts (Table 1) were prepared utilizing structurally variable quaternary

295

ammonium

296

hydroxyethyltrimethylammonium),

297

piperidinium cations (1-butyl-1-methylpyrrolidinium and 1-methyl-1-propylpiperidinium),

298

imidazolium cations with saturated and unsaturated side chains (1-allyl-3-methylimidazolium

299

and 1-butyl-3-methylimidazolium), a morpholinium cation (4-decyl-4-methylmorpholinium),

300

and

structurally

cations

different

(bis(2-hydroxyethyl)methyloleylammonium, pyridinium

phosphonium

(1-dodecylpyridinium),

cations

pyrrolidinium

(trihexyltetradecylphosphonium

2and

and


Page 15 of 38


301

tetrabutylphosphonium). All of the target MS-M HILs (except 11) were synthesized by direct

302

reaction between the cation hydroxide and MS-M free acid (Scheme 1, Method A); when the

303

hydroxide form of the cation was not commercially available, it was obtained by ion-exchange of

304

the cation halide with KOH. Two of the HILs prepared by method A (4 and 7) and 11 were

305

additionally synthesized by a metathesis route, i.e. reaction of the cation chloride with the

306

potassium salt of MS-M (Scheme 1, Method B), to verify the possibility of using this method.

307

Scheme 1 here.

308

The compounds were all obtained in high yields (>90%), and nine of the ten compounds (3-12)

309

were liquids at room temperature, while one (10) was a low-melting crystalline solid with a

310

melting point of 62-64 °C. (This compound had a tendency to supercool when melted.) The

311

structures of all compounds were confirmed by 1H and

312

analysis helped to validate the identity and purity of the synthesized compounds and all

313

compounds were obtained with high purities (>95%). The detailed synthesis of the compounds

314

and their characterization data are provided in the Experimental section.

315

Table 1 here.

13

C NMR spectroscopy. Elemental

316 317

Thermal Properties

318

Glass transitions were observed below 16 °C for all of the prepared HILs with no observed

319

crystallization or melting events (except for 10 as discussed below) as commonly seen for similar

320

alkylammonium and phosphonium ILs. Analysis of structure vs. glass transition relationships

321

revealed a known trend where the longer the alkyl chain substituent on the nitrogen or

322

phosphorus, the lower the glass transition of the resulting salt. The lowest glass transition

323

temperature

(Tg

=

-45

o

C)

was

observed

for

the

HIL

with

the

bis(2-



Page 16 of 38

324

hydroxyethyl)methyloleylammonium cation 3, which has the long unsaturated N-oleyl alkyl

325

chain

326

trihexyltetradecylphosphonium 11 (Tg = -32 oC) which contains a C14 alkyl group, while cation

327

5, 1-dodecylpyridinium with a C12 alkyl group was exhibited (Tg = -18 oC).

(C18

alkyl).

The

second

lowest

glass

transition

was

found

for

328

Glass transitions for all other compounds except 10, which was a crystalline low-melting

329

solid, were similar and varied between 1 and 7 oC. The 4-decyl-4-methylmorpholinium solid salt

330

10 had a melting point of 62-64 °C (determined using a melting point apparatus) and the highest

331

glass transition (Tg = 16 oC) of all of the compounds prepared. This HIL also exhibited

332

supercooling behavior; where a melting transition was observed on first heating, but could not be

333

reproduced within the design of the DSC experiment over several heating/cooling cycles.

334

Most of the investigated salts exhibited simple thermal decomposition behavior with a single

335

decomposition step. However, cholinium salt 4 exhibited a three-step decomposition and the

336

tetrabutylphosphonium salt (12) had a two-step decomposition.

337

Generally, the HILs decomposed between 150 °C and 200 °C, with cholinium MS-M (4) and

338

other aliphatic alkyl ammonium MS-M HILs (6 and 9) being the least thermally stable. HILs

339

with morpholinium (10) and phosphonium (11, 12) cations exhibited the highest thermal

340

stability. Moreover, it was noticed that all unsubstituted aromatic HILs exhibited higher

341

stabilities of ca. 20 °C, compared to aliphatic salts, varying from 182 °C (for imidazoliums 7 and

342

8) to 195 °C (for pyridinum 5).

343

From these results it could be concluded that the phosphonium salts were more thermally

344

stable than their ammonium equivalents, and that the aromatic HILs tend to be more stable than

345

those aliphatic, although the latter also have high thermal stability. In general, the thermal


Page 17 of 38


346

stability for each group of salts was more dependent on the structure of the cation core than on

347

the presence of, or chain length of the N-alkyl substituents.

348 349

Solubilities

350

The solubilities of the prepared HILs were tested in ten solvents, varied from low polarity to

351

high polarity with both protic and aprotic solvents studied. The solvents chosen for study were

352

selected in order of decreasing polarity expressed as the Snyder polarity index: water - 9.0,

353

methanol – 6.6, DMSO – 6.5, acetonitrile – 6.2, acetone – 5.1, isopropanol – 4.3, ethyl acetate –

354

4.3, chloroform – 4.1, toluene – 2.3, and hexane – 0.0.

355

Table 2 here.

356

Ionic liquids are generally miscible with liquids with medium to high dielectric constants and

357

immiscible with apolar compounds.39 Thus, as expected, all the tested compounds were soluble

358

in polar protic methanol and aprotic DMSO, though 1-allyl-3-methylimidazolium 7 had limited

359

solubility in DMSO. Slightly less polar aprotic acetonitrile and acetone also dissolved all

360

compounds albeit two, 1-butyl-3-methylimidazolium 8 and 4-decyl-4-methylmorpholinium 10

361

demonstrated

362

hydroxyethyltrimethylammonium 4 was less soluble in acetone. Interestingly, only phosphonium

363

HILs (11, 12) and two of the ammonium HILs, bis(2-hydroxyethyl)methyloleylammonium 3 and

364

1-dodecylpyridinium 5, were soluble in ethyl acetate. Isopropanol did not work as methanol,

365

though

366

hydroxyethyltrimethylammonium 4. The chlorinated solvent, chloroform, even though of

367

relatively low-polarity, dissolved all HILs, although 1-butyl-3-methylimidazolium 8 and 4-decyl-

368

4-methylmorpholinium 10 had limited solubilities. For non-polar solvents, all the tested

it

limited

dissolved

solubility

all

in

HILs

both

(some

acetonitrile

to

and

the

acetone,

certain

limits)

and

HIL

except

2-

2-



Page 18 of 38

369

compounds were insoluble in hexanes and only bis(2-hydroxyethyl)methyloleylammonium 3 out

370

of ammonium HILs and trihexyltetradecylphosphonium 11 were freely soluble in toluene. HILs

371

with

372

trihexyltetradecylphosphonium and tetrabutylphosphonium 11 and 12 had solubility in almost all

373

of the tested solvents.

bis(2-hydroxyethyl)methyloleylammonium

3

and

the

phosphonium

cations,

374 375

Efficacy

376

Greenhouse tests were conducted using MS-M HILs 6-8 and 10-12 and field trials were

377

conducted with HILs 6-8 and 10 and 11. Both types of trials were compared to the use of a

378

commercial formulation of Galmet 20 SG® and to control plants which were not treated.

379

Greenhouse Experiments

380

The HILs were studied for their herbicidal activity against dicotyledonous weeds (common

381

lambsquarters and rapeseed) in a greenhouse. HILs 6-8 and 10-12 were selected for efficacy

382

comparison against free MS-M as a commercial product Galmet 20 SG®. The tests were

383

conducted under controlled conditions of temperature 20 ± 2 °C, relative humidity 60%, and

384

photoperiod 16/8 h day/night.

385

Common lambsquarters and rapeseed plants were separated into three groups 1) those

386

sprayed with the MS-M HILs (as aqueous solutions), 2) those sprayed with commercially

387

available Galmet 20 SG® (at the same application rate, 4 g ae/ha, and 3) those not sprayed (the

388

control group). Two weeks after treatment (2 WAT), plants from four pots were selected from

389

each group and their fresh weight was determined. The efficacy data is expressed as percent

390

fresh weight reduction compared to the control group (see Experimental for additional detail).

391

Figure 2 here.


Page 19 of 38


392

The HIL forms of MS-M applied to lambsquarters (Chenopodium album) showed a much

393

higher activity that the Galmet 20 SG® commercial herbicide, except for 6 whose activity was

394

slightly lower than that of the reference herbicide. All HILs except 6 demonstrated at least twice

395

the activity of commercial Galmet 20 SG®, with 11 and 12 as much as two and a half times more

396

effective. On rapeseed, the herbicidal activities of HILs 6 and 7 were, respectively, 5 and 13%

397

lower than that of Galmet SG 20®. HIL 11 demonstrated activity comparable to commercial

398

analog and HILs 8, 10, and 12 were substantially more effective (ca. 1.5 times greater activity).

399

Statistically, the HIL forms of MS-M applied to lambsquarters (Chenopodium album)

400

showed significant differences in the mean effects of action for the tested substances in ANOVA.

401

For HILs used on Chemopodium album, values of F = 51.87 and p-value = 0.000 were obtained

402

indicating high significant difference between the treatment with HILs and commercial Galmet

403

20 SG®; while for HILs used on Brassica napus, F = 11.91 and p-value = 0.000 (Table 3) the

404

difference between the treatment with HILs and commercial Galmet 20 SG® was significant but

405

not that large. To determine which HILs among all the experiments had significant differences,

406

post-hoc comparisons using the Tukey HSD test (α = 0.05) were conducted and indicated that the

407

mean score for both Chemopodium album and Brassica napus treated with Galmet 20 SG® was

408

significantly lower than those plants treated with some of the HILs. The details are provided as

409

follows.

410

On Chemopodium album, the mean value of Galmet 20 SG® (36 ± 23) was significantly

411

lower than the mean effects for all HILs except 6. Specifically, the mean values of plants treated

412

with HIL 11 (93 ± 23) and HIL 12 (94 ± 23) were the highest and significantly higher than the

413

mean effects of action of HIL 8 (67 ± 23) and HIL 10 (71 ± 23).



Page 20 of 38

414

On Brassica napus, Galmet 20SG®-treated plants gave a significantly lower mean effect (39

415

± 9) than HIL 8 and HIL 12. HIL 12 in this trial gave the highest mean effect on weed

416

destruction (67 ± 9) which was significantly different than the mean effects of action of HILs 6,

417

7, and 11.

418

Table 3 here.

419

Field Trials

420

After greenhouse testing, HILs 6-8 and 10 and 11were studied for their herbicidal activity in

421

the field. The trials (a two year field investigation) were conducted in 2012 and 2013 in the

422

winter wheat fields near Szczecinek (north-western part of Poland) and Szamotuly (western part

423

of Poland). The tests were conducted on a variety of weeds, particularly on mayweed

424

(Matricaria inodora), field pansy (Viola arvensis), wild buckwheat (Polygonum convolvulus),

425

hemp-nettle (Galeopsis tetrahit), and shepherd’s-purse (Capsella bursa pastoris), field poppy

426

(Papaver rhoeas), chickweed (Stellaria media), field forget-me-not (Myosotis arvensis), and

427

persian speedwell (Veronica persica).

428

The herbicides were applied at a rate of 8 g ae/ha at the beginning of stem elongation, at the

429

end of tillering stage or the BBCH (Biologische Bundesanstalt, Bundessortenamt und Chemische

430

Industrie) 30 stage on the plant phenological development stage scale for cereals. All herbicidal

431

treatments were conducted with an application rate of 8 g ae/ha. Weed control was evaluated

432

visually 4 weeks after herbicide applications (4 WAT) using a scale of 0 (no effect) to 100%

433

(complete weed destruction). The results are presented in Table 4.

434

Overall the results were slightly different from the greenhouse data. In the field, the HILs

435

tested and Galmet 20 SG® were all 100% effective against Matricaria inodora, Viola arvensis,

436

Polygonum convolvulus, Galeopsis tetrahit, and Stellaria media. The HILs were more effective


Page 21 of 38


437

that Galmet 20 SG® for Capsella bursa pastoris, Papaver rhoeas, Veronica persica, and

438

Myosotis arvensis demonstrating they can be used for weed control in winter wheat fields.

439

The efficacy of the HILs in greenhouse and field trials depended on species. On rapeseed, the

440

herbicidal activities of the HILs were only slightly higher than that of the commercial herbicide,

441

while on lambsquarters (Chenopodium album) all but one of the HILs exhibited at least twice the

442

activity of commercial Galmet 20 SG®. In three field studies over two years (winter wheat

443

fields), the herbicidal activity of the HILs again varied depending on the plant species but all

444

tested HILs were at least as effective and in some cases more effective than the reference

445

herbicide.

446

Statistically, for all field trials, the analyzed HILs 6-8, 10, and 11 demonstrated high

447

efficiency (some as high as 100%) in plant reduction (Table 4). ANOVA test indicated

448

significant differences in the mean effects of the action of the HILs used on Matricaria inodora

449

- 2012b (F = 4.364; p-value = 0.0089), Viola arvensis - 2012b (F = 4.687; p-value = 0.0065),

450

Papaver rhoeas – 2013c (F = 8.907; p-value = 0.0002), and Veronica persica- 2013c (F = 13.15;

451

p-value = 0.0000), Table 4.

452

To determine which HILs in all of the experiments had significant differences, post-hoc

453

comparisons using the Tukey HSD test (α = 0.05) were conducted similarly to those noted

454

above for the greenhouse trials. The post-hoc comparisons (α = 0.05) indicated that the mean

455

scores for Viola arvensis treated with HIL 6 (90 ± 4) and HIL 11 (93 ± 4) were significantly

456

different from the identical plants treated with Galmet 20 SG® (81 ± 4, Table 4). The mean

457

score for Papaver rhoeas - 2013c treated with Galmet 20 SG® (64 ± 5) was significantly lower

458

than all HILs except HIL 11; the identical situation occurred in the Veronica persica- 2013c

459

field trial. Although the mean values of the weed destruction for Matricaria inodora - 2012b



Page 22 of 38

460

treated with HILs 6, 8, and 11 were higher than in the case of Galmet 20 SG® (90 ± 3), the

461

differences were not statistically significant. For Matricaria inodora - 2012b, the highest mean

462

effect of action was observed for HIL 11 (95 ± 3) which was significantly different from the

463

mean effects for HILs 7 and 10.

464

Papaver rhoeas - 2013c treated with HIL 7 (66 ± 5) and HIL 10 (68 ± 5) had mean scores

465

significantly lower than the identical plant treated with HIL 6 (85 ± 5). The mean effect of

466

action for HIL 10 (78 ± 5) used on Veronica persica- 2013c was significantly higher than in the

467

case of HILs 7 and 11. While the Kruskal-Wallis tests used to analyze the other field

468

experiments didn’t indicate significant differences between treatments, it is worth noting, that in

469

all cases, HILs were 100% or almost 100% effective. Taken together, these results suggest that

470

for some plants, the efficacies of some of the HILs were significantly higher than Galmet

471

20SG®.

472 473

ABBREVIATIONS

474

AHAS

Enzyme acetohydroxyacid synthase;

475

MS-M

Herbicide “Metsulfuron-Methyl”;

476

pKa

Acid dissociation constant;

477

pH

Acidity of solution;

478

2,4-D

2,4-Dichlorophenoxyacetic acid;

479

MCPA

2-Methyl-4-chlorophenoxyacetic acid;

480

IL

Ionic liquids;

481

HILs

Herbicidal ionic liquids;

482

TGA

Thermal Gravimetric Analysis;


Page 23 of 38


483

DSC

Differential Scanning Calorimetry;

484

NMR

Nuclear Magnetic Resonance Spectroscopy;

485

EN ISO

International Standard, in English;

486

%purity

Cationic content (% of available);

487

MW

Molecular weight;

488

ae

Active equivalents;

489

WAT

Weeks after treatment;

490

BBCH

Biologische

491

Bundesanstalt,

Bundessortenamt

und

Chemische Industrie;

492

Tg

Glass transition temperature;

493

T5%onset

Onset to 5 wt% total mass loss decomposition;

494

T50%onset

Onset to 50 wt% total mass loss decomposition;

495

Tm

Melting point;

496

S

Compound is soluble;

497

L

Compound has limited solubility;

498

N

Compound is not soluble.

499 500 501 502

ACKNOWLEDGMENT Studies were supported by Grant PBS2/A1/9/2013, The National Centre for Research and Development, Warszawa, Poland.

503 504

FUNDING SOURCES

505

Grant PBS2/A1/9/2013. 23 ACS Paragon Plus Environment


Page 24 of 38

506 507

SUPPORTING INFORMATION. 1H, 13C and 31P spectra, purity assays and elemental

508

analyses results of all the compounds are provided in Electronic Supporting Information. This

509

information is available free of charge via the Internet at http://pubs.acs.org.

510

REFERENCES

1

Levitt, G. Agricultural Sulfonamides. U.S. Patent 4,383,113, November 30, 1979.

2

Count on DuPont. http://www.dupont.com/products-and-services/crop-protection/cereals-

protection/articles/count-on-dupont.html, last accessed October 1, 2014. 3

For a review see: Obrigawitch, T. T.; Cook, G.; Wetherington, J. Assessment of Effects

on Non-target Plants from Sulfonylurea Herbicides Using Field Approaches. Pestic. Sci. 1998, 52, 199È217. 4

McCourt, J. A.; Pang, S. S.; Guddat, L. W.; Duggleby, R. G. Elucidating the specificity

of binding of sulfonylurea herbicides to acetohydroxyacid synthase. Biochemistry 2005, 44, 2330-8. 5

Blair, A. M.; Martin, T. D. A review of the activity, fate and mode of action of

sulfonylurea herbicides. Pestic. Sci. 1988, 22, 195È219. 6

Brown, H. M. Mode of action, crop selectivity and soil relations of the sulfonylurea

herbicides. Pestic. Sci. 1990, 29, 263È81.


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7

Berger, B. M.; Wolfe, N. L. Hydrolysis and biodegradation of sulfonylurea herbicides in

aqueous buffers and anaerobic water-sediment systems: assessing fate pathways using molecular descriptors. Environ. Toxic. Chem. 1996, 15, 1500-1507. 8

Wauchope, R. D.; Butler, T.M.; Hornsby, A.G.; Augustijn-Beckers, P.W.M.; Burt, J.P.

The SCS/ARS/CES Pesticide Properties Database for Environmental Decision-Making. In: Reviews of Environmental Contamination and Toxicology, Springer-Verlag Publishers. NY. 1992. 9

Song, N.; Wang, D.; Shan, Z.; Shi, L. Influence of pH and Dissolved Organic Matter on

Photolysis of Metsulfuron-Methyl. Proceed. Environ. Sci. 2013, 18, 585–591. 10

Sarmah, A. K.; Sabadie, J. Hydrolysis of Sulfonylurea Herbicides in Soils and Aqueous

Solutions: a Review. J. Agric. Food Chem. 2002, 50, 6253-6265. 11

Sarmah, A. K.; Kookana, R. S.; Duffy, M. J.; Alston, A. M.; Harch, B. D. Hydrolysis of

triasulfuron, metsulfuron-methyl and chlorsulfuron in alkaline soil and aqueous solutions. Pest. Manag. Sci. 2000, 56, 463-471. 12

Wang, H.; Xu, J.; Yates, S. R.; Zhang, J.; Gan, J.; Ma, J. Wu, J.; Xuan, R. Chemosphere

2010, 78, 335–341. 13

Chen, C. C.; Tocker, S. Process for preparing sulfonylurea salts. Patent WO1989001477,

August 17, 1988. 14

Sandell, L. S. Process for preparation of sulfonylurea solution formulations. U.S Patent

4,599,412, March 21, 1985.

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Moore, E. P. Herbicidal complexes with ureas. U.S. Patent 4,659,823, November 12,

1985. 16

Föry, W. Sulfonylurea salts as herbicides. Patent WO 1997041112, April 14, 1997.

17

Ort, O.; Bauer, K.; Bieringer, H. Sulfonylureas and their use as herbicides and growth

regulators. U.S. Patent 5,688,745, June 6, 1995. 18

Process for preparing sulfonylurea salts. Patent EP 0304282, August 17, 1988

19

Schnabel,

G.;

Willms,

L.;

Bauer,

K.;

Bieringer,

H.

Nitrogen-substituted

phenylsulfonylureas; processes for their preparation, and their use as herbicides and plant growth regulators. U.S. Patent 5,696,053, May 30, 1995. 20

Wysong, R. D.; Chen, C. C.; Tseng, C. A.; Tirol, A. A. Quaternary ammonium salts of a

sulfonylurea. US Patent 6,225,260 B1, May 20, 1999. 21

Reap, J. J. Liquid sulfonylurea herbicide formulations. Patent EP 2114143 A1, August

31, 2006. 22

Ionic Liquids: Industrial Applications for Green Chemistry; Rogers, R. D.; Seddon, K.R.,

Eds.; ACS Symposium Series 818, American Chemical Society: Washington, DC, 2002. 23

Pernak, J.; Syguda, A.; Materna, K.; Janus, E.; Kardasz, P.; Praczyk, T. 2,4-D based

herbicidal ionic liquids. Tetrahedron 2012, 68, 4267-4273. 24

Praczyk, T.; Kardasz, P.; Jakubiak, E.; Syguda, A.; Materna, K.; Pernak, J. Herbicidal

Ionic Liquids with 2,4-D. Weed Sci. 2012, 60, 189-192.

26


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Pernak, J.; Syguda, A.; Janiszewska, D.; Materna, K.; Praczyk, T. Ionic liquids with

herbicidal anions. Tetrahedron 2011, 67, 4838-4844. 26

Pernak, J.; Shamshina, J.; Tadeusz, P.; Syguda, A.; Janiszewska, D.; Smiglak, M.; Gurau,

G.; Daly, D. T.; Rogers, R. D. PCT Int Appl 2012 WO006313A2. 27

Cojocaru, O. A.; Shamshina, J. L.; Gurau, G.; Syguda, A.; Praczyk, T.; Pernak, J.;

Rogers, R. D. Ionic liquid forms of the herbicide dicamba with increased efficacy and reduced volatility. Green Chem. 2013, 15, 2110-2120. 28

Pernak, J.; Niemczak, M.; Giszter, R.; Shamshina, J.; Gurau, G.; Cojocaru, O. A.;

Praczyk, T.; Marcinkowska, K.; Rogers, R. D. Glyphosate-Based Herbicidal Ionic Liquids with Increased Efficacy. ACS Sustainable Chem. Eng., 2014, In press. 29

Kordala-Markiewicz, R.; Rodak, H.; Markiewicz, B.; Walkiewicz, F.; Sznajdrowska, A.;

Materna, K.; Marcinkowska, K.; Praczyk, T.; Pernak, J. Phenoxy herbicidal ammonium ionic liquids. Tetrahedron 2014, 32, 4784-4789. 30

Pernak, J.; Borucka, N.; Walkiewicz, F.; Markiewicz, B.; Fochtman, P.; Stolte, S.;

Steudte, S.; Stepnowski, P. Synthesis, toxicity, biodegradability and physicochemical properties of 4-benzyl-4-methylmorpholinium-based ionic liquids. Green Chem. 2011, 13, 2901-2910. 31

Brycki, B.; Dega-Szafran, Z.; Mirska, I. Synthesis and antimicrobial activities of some

quaternary morpholinium chlorides. Polish J. Microbiol. 2010, 59, 49-53. 32

Singer E. J. “Biological evaluation” in “Cationic Surfactants: Analytical and Biological

Evaluation,” Eds.: J. Cross, E. J. Singer, New York, Marcel Dekker, 1994.

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Matejuk, J.; Rogers, R.D. Long alkyl chain quaternary ammonium-based ionic liquids and potential application. Green Chem. 2006, 8, 798-806. 34

Docherty, K. M.; Kulpa, C. F. Jr. Toxicity and antimicrobial activity of imidazolium and

pyridinium ionic liquids. Green Chem. 2005, 7, 185–189. 35

Pernak, J.; Branicka, M. The Properties of 1-Alkoxymethyl-3-hydroxypyridinium and 1-

Alkoxymethyl-3-dimethylaminopyridinium chlorides. J. Surfactants & Detergents 2003, 6, 119123. 36

International Standards Organization. International Standard ISO 2871-1: Surface active

agents - Detergents - Determination of cationic-active matter content - Part 1: High-molecularmass cationic-active matter, 2nd ed.; Reference Number: ISO 2871-1:2010(E). ISO, Geneva, Switzerland, 2010. 37

Vogel, A. I., Furniss, B. S., Eds. Vogel's Textbook of Practical Organic Chemistry, 4th

ed.; Wiley, John & Sons, Inc.: New York, 1984. 38

http://www.r-project.org/, last accessed 02-23-15.

39

Freemantle, M. An Introduction to Ionic Liquids, 1st ed.; RSC Publishing: Cambridge,

UK, 2010.

28


Page 29 of 38


FIGURE CAPTIONS. Figure 1. Structure of “Metsulfuron-Methyl” or MS-M herbicide: a) free acid form with the acidic NH group denoted in blue (1) and b) anionic form (2). Figure 2. Greenhouse efficacy of HILs 6-8 and 10-12 compared to Galmet 20 SG® on lambsquarters. Figure 3. Greenhouse efficacy (measured as fresh weight reduction two weeks after treatment) of MS-M HILs 6 (black), 7 (red), 8 (green), 10 (yellow), 11 (blue), and 12 (fuschia) compared to Galmet 20 SG® (aqua) on common lambsquarters and rapeseed at an application rate of 4 g ae/ha. Scheme 1. Synthetic strategies to prepare MS-M-based salts: Method A (top) - acid base reaction with corresponding hydroxides (prepared from the appropriate halide salt if the hydroxide was not commercially available) and Method B (bottom) – metathesis.



Page 30 of 38

TABLES. Table 1. New MS-M-based Herbicidal Ionic Liquids

Salt

Cation

3

Synthetic Method

Tga (°C)

Tonset 5%b (°C)

Tonsetc (°C)

Yield %

Form at 25 °C

A

-45

180

300

90

Yellow liquid

A and B

4

150

135, 270d, 400e

98

Colorless liquid

A

-18

195

398

97

Colorless liquid

A

5

176

285

96

Colorless liquid

Bis(2-hydroxyethyl)methyloleylammonium

4 2-Hydroxyethyltrimethylammonium

5 1-Dodecylpyridinium

6 1-Methyl-1-propylpiperidinium

30


Page 31 of 38


7

A and B

1

190

304

91

Yellow liquid

A

7

182

313

99

Colorless liquid

A

-1

167

283

90

Colorless liquid

A

16, (Tm = 62-64)f

196

268

93

Crystalline solid

B

-32

194

393

98

Colorless liquid

A

-1

195

220, 410d

96

Yellow Liquid

1-Allyl-3-methylimidazolium

8 1-Butyl-3-methylimidazolium

9 1-Butyl-1-methylpyrrolidinium

10 4-Decyl-4-methylmorpholinium

11 Trihexyltetradecylphosphonium

12 Tetrabutylphosphonium a

Glass transition temperature, bOnset to 5 wt% total mass loss decomposition, cOnset to 50 wt% mass loss first stage decomposition, Onset to 50 wt% mass loss of second stage decomposition, eOnset to 50 wt% mass loss of third stage decomposition, fMelting point

d

31



determined using a melting point apparatus (see Experimental Section); DSC analysis did not detect a melting point fot this compound due to glass formation.

32


Page 32 of 38

Page 33 of 38


Cloroform (4.1a) Toluene (2.3a) Hexane (0.0a)

S S S S S

S S N

4

2-Hydroxyethyltrimethylammonium

S

S

S S L N N

S N N

5

1-Dodecylpyridinium

L

S

S S S S S

S L N

6

1-Methyl-1-propylpiperidinium

S

S

S S S S N

S N N

7

1-Allyl-3-methylimidazolium

S

S

L S S S N

S N N

8

1-Butyl-3-methylimidazolium

S

S

S L L L N

L N N

9

1-Butyl-1-methylpyrrolidinium

S

S

S S S S N

S N N

10

4-Decyl-4-methylmorpholinium

L

S

S L L L N

L N N

11

Trihexyltetradecylphosphonium

N

S

S S S S S

S S N

12

Tetrabutylphosphonium

S

S

S S S S S

S N N

a

Snyder

polarity

index;

b

S:

soluble;

L:

limited

solubility;


Isopropanol (4.3a)

Sb S

DMSO (6.5a) Acetonitrile (6.2a) Acetone (5.1a)

Bis(2-hydroxyethyl)methyloleylammonium

Cation

Methannol (6.6a)

3

Salt

Water (9.0a)

Ethyl acetate (4.3a)

Table 2. The solubilities of the prepared HILs in ten representative solvents

N:

not

soluble.


Table 3. Weed control (%, 4 WAT) in Chemopodium album and Brassica napus greenhouse tests

Chemopodium album*

Brassica napus

General Analysis: Degrees of freedom (df), the F value and the significance value (p) Analysis

ANOVA

ANOVA

df

6; 21

6; 14

F

51.87

11.91

p-value

0.000

0.000

Mean Values for Treatments Results of Post Hoc Tests (α=0.05) Replications

4

3

General mean

65.9

46.3

6

21 c

34 d

7

80 ab

26 d

8

67 b

60 ab

10

71 b

54 abc

11

93 a

44 bcd

12

94 a

67 a

Standarda

36 c

39 cd

HSD for Treatments with Observed Statistical Differences ± B**

23

9

HSD

*231

20

a

Galmet 20 SG® (%active metsulfuron-methyl - 20%) was used as the reference herbicide; *Analysis after Box-Cox transformation of data (λ= 1.64); **Treatment mean ± B gives lower and upper 95% confidence bounds (CI); ***The same letter in the column means no statistical differences between treatments.


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Table 4. Weed control (%, 4 WAT) in winter wheat from 2012-2013 Szczecinek and 2013 Szamotuly field trials

Matricaria inodora Treatmenta

2012b

2013c

2013b

Viola arvensis

Polygon. convolvulus

Gale- Capsel. opsis bursa tetrah. pastoris

Papav. rhoeas

Veronica persica

Stellaria media

Myosotis arvensis

2012b

2012b

2012b

2013c

2013c

2013c

2013b

2013c

2013b

AN. 5; 18 13.150 0.0000

K-W 5 5.000 0.4159

-f -

K-W 5 5.000 0.4159

K-W 5 19.087 0.0019

2013c 2013b

2012b

General Analysis: Degrees of freedom (df), the F value and the significance value (p) AN.d 5; 18 4.364 0.0089

Analysis df F / χ2 p-value

K-We 5 7.667 0.1756

K-W 5 1.305 0.9344

AN. 5; 18 4.687 0.0065

-f -

K-W 5 9.570 0.8838

K-W 5 3.790 0.5800

-f -

K-W 5 2.302 0.8060

AN. 5; 18 8.907 0.0002

Mean Values for Treatments/ Results of Post Hoc Tests (α=0.05) General Mean 6 7 8 10 11 Standarda

90.8

99.5

97.0

87.4

100.0

96.8

96.8

100.0

94.7

72.0

68.1

99.8

100.0

99.7

93.3

92 ab** 88 b 91 ab 89 b 95 a 90 ab

100 a 100 a 100 a 99 a 100 a 98 a

98 a 96 a 97 a 98 a 97 a 96 a

90 a 85 ab 88 ab 89 ab 93 a 81 b

100 100 100 100 100 100

90 a 98 a 98 a 98 a 98 a 99 a

95 a 97 a 97 a 97 a 97 a 98 a

100 100 100 100 100 100

94 a 95 a 96 a 96 a 96 a 91 a

85 a 66 bc 76 ab 68 bc 74 abc 64 c

71 abc 66 bc 76 ab 78 a 63 cd 55 d

99 a 100 a 100 a 100 a 100 a 100 a

100 100 100 100 100 100

100 a 98 a 100 a 100 a 100 a 100 a

87 a 100 a 92 a 96 a 100 a 85a

HSD for Treatments with Observed Statistical Differences 3 6

± B* HSD

4 9

5 12

5 11

a

Galmet 20 SG® (%active metsulfuron-methyl - 20%); bSzczecinek; cSzamotuły; dOne-way ANOVA was applied; eNon-parametric Kruskal-Wallis (K-W) rank sum test was applied; fThe measured effectiveness of 100%, ANOVA or non-parametric Kruskal-Wallis tests not applicable, *Treatment mean ± B gives lower and upper 95% confidence bounds (CI); **The same letter in the column means no statistical differences between treatments.



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FIGURE GRAPHICS O

O O

CH3

O H S N C O2 * HN

O

CH3

O S N C O2 HN

N N N

pKa 3.3

CH3 CH3 N N N

O CH3

O CH3

2

1

Figure 1.

Untreated

8

10

6

11

7

12

Galmet 20 SG®

Figure 2.


Page 37 of 38


Figure 3. Method A: HILs 3-10 and 12

H3C O O O HN C O S HN O

CH3 N N N O CH3

Cation OH

Method B: HILs 4, 7, and 11

- H2O

K H2C O OO N C O S HN O

CH3

H3C O OO N C Cation O S HN O

N N

CH3 N N N O CH3

N O CH3

Cation Cl - KCl

Scheme 1.



Page 38 of 38

Graphic for Table of Content


Metsulfuron-Methyl-Based Herbicidal Ionic Liquids - American

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