Dicationic Ionic Liquids of Herbicide 2,4-Dichlorophenoxyacetic Acid

Subscriber access provided by University of Sunderland

Agricultural and Environmental Chemistry

Dicationic ionic liquids of herbicide 2,4D with reduced negative effects on environment Junfan Niu, Zhaopeng Zhang, Jingyue Tang, Gang Tang, Jiale Yang, Weichen Wang, Hong Huo, Na Jiang, Jianqiang Li, and Yongsong Cao J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.8b02584 • Publication Date (Web): 19 Sep 2018 Downloaded from http://pubs.acs.org on September 21, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 28

Journal of Agricultural and Food Chemistry

1

Dicationic Ionic Liquids of Herbicide 2,4-D with Reduced Negative Effects on

2

Environment

3 4

Junfan Niu, Zhaopeng Zhang, Jingyue Tang, Gang Tang, Jiale Yang, Weichen Wang, Hong Huo,

5

Na Jiang, Jianqiang Li, Yongsong Cao*

6 7

College of Plant Protection, China Agricultural University, Beijing, China

8

*Corresponding author: NO.2 Yuanmingyuan West Road, China Agricultural University, Beijing,

9

China

10

Zip/Postal code: 100193

11

Telephone number: 86-10-62734302 (O), 86-10-62734302 (FAX)

12

Email: [email protected], [email protected]

1

ACS Paragon Plus Environment


13

ABSTRACT

14

Due to high volatility and water solubility, 2,4-D can easily enter into the atmosphere

15

and water bodies by volatilization, drift, leaching or runoff, which results in potential

16

threats to the environment and human health. The physicochemical properties of

17

pesticides can be regulated by preparing their ionic liquids. In this work, a series of

18

dicationic ionic liquids (DILs) of 2,4-D were prepared to reduce its environmental

19

risk and enhance herbicidal activity. The solubility, octanol–water partition coefficient,

20

surface tension, and volatilization rate results of DILs showed that these properties

21

could be optimized by choosing appropriate counter cations. Compared to 2,4-D

22

ammonium salt, DILs have lower volatility, water solubility, and surface tension as

23

well as higher lipophilicity. Benefiting from optimized physicochemical properties,

24

DILs HIL8–12 exhibited better herbicidal activity against three typical broadleaf

25

weeds than 2,4-D ammonium salt, and their fresh weight inhibition rates increased by

26

2.74–46.84%. The safety assessment experiment indicated that DILs were safer to

27

wheat than commercialized forms of 2,4-D. The DILs could reduce environmental

28

risk of 2,4-D caused by high volatility and water solubility and would be potential

29

alternatives to its commercialized formulations.

30

KEYWORDS: dicationic ionic liquids, 2,4-D, volatility, herbicidal activity, safety

2


Page 2 of 28

Page 3 of 28


31

1. INTRODUCTION

32

2,4-Dichlorophenoxyacetic acid (2,4-D) was first reported in1942 and has been

33

widely used to control broadleaf weeds in cereal crop fields because of low cost,

34

broad spectrum, and high efficiency.1-3 However, due to high volatility and solubility,

35

2,4-D can easily reach into the environment (such as air and drinking water) after

36

application.4-6 It not only causes heavy loss of active ingredient of herbicide but also

37

threatens seriously human health.7,8 Moreover, high volatility can also lead to

38

off-target transport of 2,4-D and phytotoxicity to non-target crops such as cotton,

39

soybean and so on.9,10 Injury of 2,4-D drifting to tomato was reported to be 21% at 14

40

days after treatment.9 In the field experiment, 2,4-D at the rate of 16.8 g AI ha-1

41

reduced bell pepper and broccoli yields by 34%, 23% respectively in 2010.11 In recent

42

years, many controlled release formulations of 2,4-D were prepared to reduce its

43

volatility and leaching. For example, coumarin–2,4-D polymers, a kind of

44

photoresponsive coumarin polymer based on acrylate and polyethylene glycol, was

45

synthesized for controlled release of 2,4-D. The results showed that coumarin–2,4-D

46

polymer had good thermal stability, less leaching property, and higher herbicidal

47

effect than corresponding free 2,4-D. However, during the first four days after

48

treatment, this polymer showed a lower inhibitory effect on the growth of shoot and

49

root of pumpkin plant than 2,4-D. The results showed that the herbicidal activity of

50

2,4-D was delayed when this controlled release formulation was used.12 Another

51

controlled release formulation of 2,4-D is perylene-2,4-D nano-pesticides, which was 3



52

prepared by using perylene-3-ylmethanol as nanocarrier. Although the novel

53

nanoconjugate exhibited good fluorescence, cellular uptake property, and efficient

54

photoregulated release ability, its control efficacy on weeds was weakened.13

55

Ionic liquids (ILs), a kind of salts with melting points below 100 °C, entirely

56

consist of ions.14,15 Herbicidal ionic liquids (HILs) usually contain targeted herbicidal

57

anions and the counter cations.16,17 Preparing HILs through selecting appropriate

58

counter ion is an excellent method to optimize the physicochemical properties of

59

herbicides, such as volatility, water solubility, surface activity, and so on.18,19 In

60

particular, with the improvement of physicochemical property, the herbicidal activity

61

of HILs also increased, which presents a new opportunity for reducing the dosage of

62

herbicides.20-22 In the previous reports, a series of monocationic HILs based on 2,4-D

63

were prepared and exhibited lower volatility and higher herbicidal activity than the

64

commercial forms of 2,4-D, including 2,4-D-sodium salt, 2,4-D-dimethylammonium,

65

and 2,4-D-2-ethylhexyl ester.23-26

66

The increasing of molecular mass of active ingredient would decrease the volatility

67

of 2,4-D by reducing its saturated vapor pressure.27-29 Based on this, dicationic ionic

68

liquids (DILs) consisting of two cationic moieties (counter cations) combined with a

69

spacer and two anionic moieties (targeted herbicidal anions) will be an fantastic

70

choice to reduce the volatility of 2,4-D.30 Possessing superior physical properties

71

compared to traditional monocationic ILs, DILs have recently received more and

72

more attention and have been widely used in the fields of catalysis, solar cells, 4


Page 4 of 28

Page 5 of 28


73

lubricants, and so on.31-34 Furthermore, the properties of DILs can be tuned, controlled,

74

or altered to a greater extent than traditional monocationic ILs, which provides more

75

possibility for optimizing their physicochemical properties.35

76

The objective of this study is preparing the DILs of 2,4-D through acid-base

77

neutralization or ion exchange reaction to optimize its physicochemical properties for

78

reducing environmental risk. Besides twelve DILs, one monocationic IL and one

79

tricationic IL of 2,4-D were prepared to investigate their structure-activity

80

relationships. And their solubility, octanol-water partition coefficient, surface activity,

81

volatilization rate, and safety to non-target crops were also tested in this paper.

82

2. MATERIALS AND METHODS

83

2.1. Chemicals and Materials. 2,4-D (99% purity) and 2,4-D ammonium salt

84

(2,4-D dimethylammonium salt, 99% purity) were provided friendly by Shandong

85

Runfeng Chemical Co., Ltd. The analytically pure chemicals used in this work were

86

purchased from Beijing, China. Chromatographic grade methanol and acetonitrile

87

were provided by J. T. Baker (Phillipsburg, NJ, USA). Buffered solutions at different

88

pH were prepared in our laboratory. 1H NMR spectra of tested compounds were

89

provided by a 300 MHz NMR spectrometer (Bruker, Germany). A Karl-Fischer

90

moisture titrator (Hogon Scientific Instrument Co., Ltd., China) was used to test the

91

water content. The melting points of compounds were measured by a SGWX-4B

92

microscopic melting point apparatus (SPSIC, China). A JK 99B analyzer (Powereach,

93

China) was used to test the surface tension of compounds. The thermogravimetric 5



94

analysis for tested compounds was carried out by a TA Instruments (New Castle, DE)

95

model 2950 thermogravimetric analyzer. A SHIMADZU LC-20ATvp HPLC system

96

equipped with an ultraviolet detector was employed for analysis. A C18

97

reversed-phase column (250 mm × 4.6 mm, 5 µm) was used and maintained at

98

ambient temperature. The mobile phases were acetonitrile and water with 0.1% acetic

99

acid (60:40, v/v) at a flow rate of 1.0 mL min-1. The injection volume was 20 µL and

100

the absorbance wavelength was 254 nm.

101

2.2. Preparation of HILs. Thirteen HILs of 2,4-D were synthesized via acid-base

102

neutralization and ion exchange reaction. In acid-base reaction, 0.01 mol of amine and

103

0.02 mol of 2,4-D were added to 50 mL of methanol in a round-bottom flask, the

104

mixture was stirred continuously at room temperature for 1 h. Then, the desirable

105

HILs were obtained via filtration and three times of washing with methanol and

106

anhydrous ether. In ion exchange reaction, 0.01 mol of 1,6-dibromohexane and 0.02

107

mol of selected counter cation were added to 50 mL of ethanol in a round-bottom

108

flask and the mixture was stirred continuously at reflux temperature for 24 h. After

109

filtration and three times of washing with methanol and anhydrous ether, the synthetic

110

precursor of HILs was obtained. Following, 0.01 mol of synthetic precursor of HILs

111

and 0.025 mol of KOH were added to 50 mL of ethanol and the mixture was stirred at

112

room temperature for 48 h. After filtering out white precipitation (KBr), 0.02 mol of

113

2,4-D was added to the mixture and the reactive mixture was stirred at room

114

temperature for 24 h. Finally, the desirable HILs were obtained after evaporation of 6


Page 6 of 28

Page 7 of 28


115

ethanol at 45 °C for 0.5 h.

116

2.3. Solubility. The solubilities of the prepared HILs and 2,4-D ammonium salt at

117

different PH (PH = 5, 7, 9) were tested in phosphate buffer solutions (PBS) by the

118

flask method according to OECD Guideline (Test No.105: Water Solubility, 1995). In

119

brief, the prepared HILs were added separately to 10 ml of PBS in a glass vessel until

120

the observation of undissolved compounds. Then, the glass vessels were placed on a

121

shaker and kept shaking for 48 h at 25 °C. After centrifugation of the suspensions in

122

the glass vessels at 8000 rpm for 10 min, the filtrate was analyzed by HPLC. The

123

solubilities of the prepared HILs and 2,4-D ammonium salt in methanol, acetone, and

124

toluene were also tested by the same method.

125

2.4. Octanol-water Partition Coefficient. The octanol-water partition coefficients

126

(Kow) of the prepared HILs and 2,4-D ammonium salt were measured by the method

127

of shake flask.36 First of all, n-octanol and water saturated solution was prepared in

128

our lab. Following, dissolving prepared HILs or 2,4-D ammonium salt in n-octanol

129

and water saturated solution resulted in 0.01 mol L-1 of HILs or 2,4-D ammonium salt

130

solution. Then, 1.00 mL of above solution was added to 9.0 mL of n-octanol and

131

water saturated solution in tubes. The tubes were placed on a shaker and kept shaking

132

for 24 h at 25 °C. Finally, after centrifugation of the mixed solution, the water phase

133

of mixed solution was collected and the concentrations of tested compounds in mixed

134

solution were analyzed by HPLC.

135

2.5. Surface Activity. The surface tensions of the prepared HILs and 2,4-D 7



136

ammonium salt were tested by the method of Wilhelmy plate.37 The preparation of

137

sample, calibration of the instrument, and measuring method of critical micelle

138

concentration (CMC) and the surface tension at the CMC (γCMC) of tested compounds

139

were similar to that described in our previous work.38-40

140

2.6. Volatilization Rate. The volatility of 2,4-D acid and the prepared HILs were

141

determined by thermogravimetric analysis.18 The experiments were performed under a

142

nitrogen atmosphere. Samples between 5-10 mg were placed on a platinum pan for 12

143

h at 75 °C. The volatilization rate of samples was calculated as follow formula: Mass

144

loss (%) = (Ma – Mb) / Ma × 100 where Ma represents the mass of sample before

145

treatment and Mb represents the mass of sample after treatment.

146

2.7. Herbicidal Activity. Descurainia sophia, Amaranthus retroflexus, and

147

Chenopodium album are typical broad-leaved weeds in China, and 2,4-D has been

148

used for effectively controlling these weeds. The synthesized HILs and 2,4-D

149

ammonium salt were evaluated for their herbicidal activities against Descurainia

150

sophia, Amaranthus retroflexus, and Chenopodium album in the greenhouse and

151

no-till farmland. Descurainia sophia and Amaranthus retroflexus seeds were sown in

152

plastic pots (diameter was 12 cm) filled with nutrition soil and vermiculite (3/1, v/v)

153

in the greenhouse, the seedlings were thinned to 5 uniform plants for Descurainia

154

sophia or 10 uniform plants for Amaranthus retroflexus per pot within 10 days after

155

emergence. And average day/night temperature was 26/15 °C, humidity was at 60−80%

156

in the greenhouse during experiments. At rosette stage (Descurainia sophia) or 8


Page 8 of 28

Page 9 of 28


157

four-five leaf stage (Amaranthus retroflexus) of seedlings, the synthesized HILs and

158

2,4-D ammonium salt were applied at the concentration of 400 g AI ha-1 of 2,4-D.

159

HILs were dissolved in the mixture of methanol (< 0.1% of total volume) and water.

160

2,4-D ammonium salt was directly dissolved in water. Each pot was sprayed with 2.5

161

mL of solution by using a microaerosol sprayer. Spraying water as control and each

162

treatment had three replicates. The fresh weights of the above-ground part of the

163

seedlings at 14 days after treatment (DAT) were determined and recorded. The fresh

164

weight inhibition rates (FWI) was calculated as follows: FWI (%) = (Wa – Wb) / Wa ×

165

100 where Wa represents control fresh weight and Wb represents treated fresh weight.

166

The field experiments were carried out in no-till farmland located in Beijing

167

(40°02′25″N, 116°17′42″E) in July 2017. Chenopodium album with an average height

168

of about 13 cm in the field was the test plants. The dosage of HILs and 2,4-D

169

ammonium salt was 400 g AI ha-1 of 2,4-D. Each plot (2 m × 5 m) was sprayed with

170

600 mL of solution and water as the control. The experimental design was a

171

randomized block with three replications. At 21 DAT, six uniform seedlings from each

172

plot were selected, and the fresh weights of their above-ground part were determined

173

and recorded. Then the fresh weight inhibition rate was calculated.

174

2.8. Safety Assessment. The experiments were conducted in greenhouse. Wheat

175

seeds (Triticum aestivum L. cv. Nongda 211) were sown in 60 flower pots (12 cm in

176

diameter) filled with nutrition soil and vermiculite (3/1, v/v), and the seedlings of

177

each pot were thinned to 10 uniform plants within 10 days after emergence. At the 9



178

four-leaf stage of seedlings, 2,4-D ammonium salt and the synthesized HILs were

179

applied at dose of 1000, 2000, 4000 mg/L. Water was sprayed as the control. There

180

were three replicates for each treatment. The phytotoxicity of test compounds to

181

wheat seedlings was evaluated visually at 14 days after treatment.

182

3. RESULTS AND DISCUSSION

183

3.1. Synthesis and Characterization of HILs. In this study, one tricationic HIL

184

(HIL1), eleven dicationic HILs (HIL2–12), and one monocationic HIL (HIL13) of

185

2,4-D were synthesized by the acid-base neutralization (HIL1–7) or ion exchange

186

reaction (HIL8–13), and their structures are shown in Scheme 1. The water content of

187

the prepared HILs was measured by coulometric Karl-Fischer titration, and which was

188

less than 500 mg L-1. The melting point, yield, state, and counter cations of HILs are

189

summarized in Table 1.

190

In the 1H NMR spectroscopy, all results and analyses, such as the upfield chemical

191

shift for protons on the benzene ring and methylene of 2,4-D anion in all synthesized

192

HILs because of shielding effect, the disappearance of the alkali-NH2 peak and the

193

appearance of alkali-NH3+ peak of primary amine (HIL2–7), supported the fully

194

ionized nature of the obtained compounds and were consistent with the previous

195

reports.16,23,38-40 The synthesized HILs were solid or wax at room temperature and

196

most of them possessed more than 120 °C of melting points, which was consistent

197

with the property of DILs and previous report.35,41 In particular, their melting points

198

increased with the alkyl chain length, for instance, the alkyl chain length of HIL2–5 10


Page 10 of 28

Page 11 of 28


199

indicated HIL2 < HIL3 < HIL4 < HIL5 and their melting points also showed HIL2

200

(152–154 °C) < HIL3 (168–170 °C) < HIL4 (184–186 °C) < HIL5 (210–212 °C).

201

The differences in melting points between the HILs and 2,4-D acid (140.5 °C), and

202

the results of 1H NMR demonstrated the successful preparation of HILs.

203

3.2. Solubility. The water solubility of herbicides is a leading factor affecting their

204

environmental fate, and relatively low water solubility contributes to reduce the

205

environmental risks of herbicides caused by runoff and leaching.38 In this work,

206

except for HIL13, synthesized HILs exhibited lower water solubility than 2,4-D

207

ammonium salt (Table 2). The results also showed that the water solubility of

208

synthesized HILs could be regulated by the variation of the alkyl group on the counter

209

cation. In neutral (pH = 7) and alkaline (pH = 9) solutions, with the increase of alkyl

210

chain length, the water solubility of HILs decreased and HIL5 showed the lowest

211

water solubility. In addition, for low polar solvent (toluene), all the synthesized HILs

212

displayed poor solubility. And for high polar solvent (methanol and acetone), only

213

HIL6, HIL7, and HIL10 exhibited good solubility.

214

3.3. Octanol-water Partition Coefficient. The octanol-water partition coefficient

215

(Kow) of the synthesized HILs and 2,4-D ammonium salt at 25 °C were tested and the

216

results are presented in Table 1. The results showed that the Kow values of

217

synthesized HILs were higher than 2,4-D ammonium salt (0.245), and HIL12

218

displayed the largest Kow values (4.584). The synthesized HILs containing ring

219

structures (nitrogen heterocycle or aromatic ring) in cations exhibited higher Kow 11



220

values than HILs without ring structures in cations. For instance, the Kow values of

221

HIL6, HIL7, and HIL9–12 (3.075, 2.081, 3.308, 4.209, 4.047, and 4.584,

222

respectively) were higher than HIL2–5 (1.878, 1.773, 1.026, and 1.067, respectively).

223

Because of the relationship between Kow and the cuticle-water partition coefficient of

224

the plant cell membrane, HILs possessing good lipophilicity can get through easily

225

cell membrane of plants and exhibit satisfactory herbicidal activity.

226

3.4. Surface Activity. Surface tension is also an important factor affecting the

227

herbicidal activity of herbicides. The droplets with low surface tension can reduce the

228

contact angle and result in good wettability, adsorbability, and permeability of active

229

ingredients.16 Table 1 shows that the synthesized HILs exhibit lower surface tension

230

than 2,4-D ammonium salt (67.3 mN m-1). And the results indicated that the surface

231

tension of synthesized HILs highly depended on the structure of counter cations. For

232

example, the HILs with the cation containing five-member ring (HIL9–10) showed

233

lower surface tension than the HILs with six-member ring in cation (HIL6–7,

234

HIL11–12). And HIL10 exhibited the lowest surface tension (36.8 mN m-1). The

235

alkyl chain length of counter cations also played an important role on influencing the

236

surface tension of HILs. For instance, the alkyl chain length of HIL2–5 indicated

237

HIL2 < HIL3 < HIL4 < HIL5 and their surface tension showed HIL2 > HIL3 >

238

HIL4 > HIL5. Furthermore, the surface tension of monocationic IL (HIL13),

239

dicationic ILs (HIL2–12), and tricationic IL (HIL1) indicated monocationic IL

266

HIL10 (4.209) > HIL11 (4.047) > HIL8 (3.412) > HIL9 (3.308) > HIL1–7 (2.316,

267

1.878, 1.773, 1.026, 1.067, 3.075, and 2.081, respectively), HIL13 (2.412), and 2,4-D

268

ammonium salt (0.245), and their FWI also showed the same trend (Table 3). The

269

results demonstrated that relatively high lipophilicity of synthesized HILs contributed

270

to improving their herbicidal activities. It could be explained by the high lipophilicity

271

of compound leading to the active ingredients penetrating easily the cell membrane of

272

the plant and enhancing their herbicidal activities. Furthermore, low surface tension of

273

HILs may also be a contributing factor in their enhanced herbicidal activities, for

274

example, HIL10 possessing the lowest surface tension exhibited the best herbicidal

275

activity.

276

In the previous report, four monocationic ILs of 2,4-D ([CCC][ 2,4-D],

277

[Arq][ 2,4-D], [Etq C][ 2,4-D], and [Etq O][ 2,4-D]) were prepared and showed

278

higher control efficacy (47.08%, 51.01%, 48.08%, and 55.48%, respectively) on

279

Descurainia sophia at the concentration of 400 g ha-1 of 2,4-D than the choline, and

280

dimethylammonium salts forms of 2,4-D.24 In this work, compared to 2,4-D

281

ammonium salt and choline salt of 2,4-D, the synthesized dicationic ILs (HIL8–12)

282

also displayed enhanced herbicidal activities (71.18%, 75.03%, 77.15%, 73.13%, and 14


Page 14 of 28

Page 15 of 28


283

77.84%, respectively) against Descurainia sophia at the concentration of 400 g ha-1 of

284

2,4-D. In the field study, [Arq][2,4-D] and [Etq O][2,4-D] showed 95% of control

285

efficacy on Chenopodium album at four weeks after treatment. And in this study,

286

HIL10–12 exhibited more than 95% of fresh weight reduction against Chenopodium

287

album at 21 days after treatment with the same rate of 2,4-D (400 g ha-1). These

288

results demonstrated that the herbicidal activity of 2,4-D could be improved by

289

preparing its dicationic ILs forms. Particularly, the dicationic ILs forms of 2,4-D

290

exhibited higher and faster control efficacy against weeds than its synthesized

291

monocationic and tricationic ILs forms as well as its commercialized formulation.

292

3.7. Safety Assessment. In the safety assessment experiment, HIL10 was chosen

293

as the test HIL because of its lower water solubility, surface tension and volatility, and

294

higher herbicidal activity. The results showed that HIL10, HIL13 (choline salt of

295

2,4-D), and 2,4-D ammonium salt were safe to wheat at concentration of 1000 mg/L

296

and 2000 mg/L. Figure 2 shows that when the concentration is 4000 mg/L, 2,4-D

297

ammonium salt shows medium phytotoxicity, the blade tips of the wheat seedling turn

298

yellow and slightly curled. Figure 2(a) shows that HIL13 exhibits very slight

299

phytotoxicity. HIL10 didn’t cause any symptoms of injury on the wheat seedling in

300

Figure 2(b) and was proved to be safe to wheat at concentration of 4000 mg/L.

301

In summary, a series of novel HILs based on 2,4-D were synthesized by choosing

302

different counter cations. Compared to 2,4-D ammonium salt, the synthesized DILs

303

exhibited lower volatility, water solubility and surface tension as well as higher 15



304

lipophilicity. Benefiting from these optimized physicochemical properties, the

305

synthesized DILs not only reduced the environmental risk of 2,4-D caused by high

306

volatility and water solubility, but also displayed faster and higher herbicidal activities

307

against Descurainia Sophia, Amaranthus retroflexus, and Chenopodium album than

308

2,4-D ammonium salt, and the biggest increase of herbicidal efficacy was 46.84%.

309

Moreover, the synthesized DILs were proved to be safe to wheat. Hence, DILs of

310

2,4-D would be a potential alternative to commercialized formulation of 2,4-D.

311

ASSOCIATED CONTENT

312

Supporting Information.

313

1

314

AUTHOR INFORMATION

315

Corresponding Author

316

*E-mail: [email protected], [email protected]. Phone: 86-10-62734302. Fax:

317

86-10-62734302

318

Funding

319

This work was supported by the National Key R&D Program of China

320

(2017YFD0200301) and National Natural Science Foundation of China (31672067).

321

Notes

322

The authors declare no competing financial interest.

323

ABBREVIATIONS USED

324

ILs, ionic liquids; DILs, dicationic ionic liquids; HILs, herbicidal ionic liquids; FWI,

H NMR spectra of the HILs.

16


Page 16 of 28

Page 17 of 28


325

fresh weight inhibition rate.

326

REFERENCES

327

(1) Zimmerman, P. W.; Hitchcock, A. E. Substituted phenoxy and benzoic acid growth

328

substances and the relation of structure to physiological activity. Contr. Boyce

329

Thompson Inst. 1942, 12 (5), 321-343.

330

(2) Islam, F.; Farooq, M. A.; Gill, R. A.; Wang, J.; Yang, C.; Ali, B.; Wang, G.; Zhou,

331

W. 2,4-D attenuates salinity-induced toxicity by mediating anatomical changes,

332

antioxidant capacity and cation transporters in the roots of rice cultivars. Sci. Rep.

333

2017, 7, 10443.

334

(3) Islam, F.; Xie, Y.; Farooq, M. A.; Wang, J.; Yang, C.; Gill, R. A.; Zhu, J.; Zhou, W.

335

Salinity reduces 2,4-D efficacy in Echinochloa crusgalli by affecting redox balance,

336

nutrient acquisition, and hormonal regulation. Protoplasma 2018, 255 (3), 785-802.

337

(4) Cox, L.; Celis, R.; Hermosin, M. C.; Cornejo, J. Natural soil colloids to retard

338

simazine and 2,4-d leaching in soil. J. Agric. Food Chem. 2000, 48 (1), 93-99.

339

(5) Sutherland, D. J.; Stearman, G. K.; Wells, M. J. M. Development of an analytical

340

scheme for simazine and 2,4-D in soil and water runoff from ornamental plant nursery

341

plots. J. Agric. Food Chem. 2003, 51 (1), 14-20.

342

(6) Li, J.; Jiang, M.; Wu, H.; Li, Y. Addition of Modified Bentonites in Polymer Gel

343

Formulation of 2,4-D for Its Controlled Release in Water and Soil. J. Agric. Food

344

Chem. 2009, 57 (7), 2868-2874.

345

(7) Tayeb, W.; Nakbi, A.; Trabelsi, M.; Attia, N.; Miled, A.; Hammami, M.

346

Hepatotoxicity induced by sub-acute exposure of rats to 2,4-Dichlorophenoxyacetic

347

acid based herbicide “Désormone lourd”. J. Hazard. Mater. 2010, 180 (1-3), 225-233.

348

(8) Islam, F.; Wang, J.; Farooq, M. A.; Khan, M. S. S.; Xu, L.; Zhu, J.; Zhao, M.;

349

Munos,

350

2,4-dichlorophenoxyacetic acid on human and ecosystems. Environ. Int. 2018, 111,

351

332-351.

352

(9) Bauerle, M. J.; Griffin, J. L.; Alford, J. L.; Iii, A. B. C.; Kenty, M. M. Field

353

Evaluation of Auxin Herbicide Volatility Using Cotton and Tomato as Bioassay Crops.

354

Weed Technol. 2015, 29 (2), 185-197.

355

(10) Sosnoskie, L. M.; Stanley, C. A.; Bo, B. L.; Richburg, J. S. Evaluating the

356

Volatility of Three Formulations of 2,4-D When Applied in the Field. Weed Technol.

S.;

Li,

Q.

X.;

Zhou,

W.

Potential

impact

17


of

the

herbicide


357

2015, 29 (2), 177-184.

358

(11) Mohsen, M. M.; Douglas, D. Response of Bell Pepper and Broccoli to Simulated

359

Drift Rates of 2,4-D and Dicamba. Weed Technol. 2015, 29 (2), 226-232.

360

(12) Singh, P. N. D.; Atta, S.; Paul, A.; Banerjee, R.; Bera, M.; Ikbal, M.; Dhara, D.

361

Photoresponsive polymers based on coumarin moiety for the controlled release of

362

pesticide 2,4-D. RSC Adv. 2015, 5 (121), 99968-99975.

363

(13) Atta, S.; Bera, M.; Chattopadhyay, T.; Paul, A.; Ikbal, M.; Maiti, M. K.; Singh, N.

364

D. P. Nano-pesticide formulation based on fluorescent organic photoresponsive

365

nanoparticles: for controlled release of 2,4-D and real time monitoring of

366

morphological changes induced by 2,4-D in plant systems. RSC Adv. 2015, 5 (106),

367

86990-86996.

368

(14) Hardacre, C.; Holbrey, J. D.; Mullan, C. L.; Nieuwenhuyzen, M.; Reichert, M. W.;

369

Seddon, K. R.; Teat, S. J. Ionic liquid characteristics of 1-alkyl-n-cyanopyridinium

370

and 1-alkyl-n-(trifluoromethyl) pyridinium salts. New J. Chem. 2008, 32 (11),

371

1953-1967.

372

(15) Sun, B. C.; Won, S. W.; Yun, Y. S. Use of ion-exchange resins for the adsorption

373

of the cationic part of ionic liquid, 1-ethyl-3-methylimidazolium. Chem. Eng. J. 2013,

374

214 (1), 78-82.

375

(16) Pernak, J.; Syguda, A.; Janiszewska, D.; Materna, K.; Praczyk, T. Ionic liquids

376

with herbicidal anions. Tetrahedron 2011, 67 (26), 4838-4844.

377

(17) Lawniczak, L.; Syguda, A.; Borkowski, A.; Cyplik, P.; Marcinkowska, K.; Wolko,

378

L.; Praczyk, T.; Chrzanowski, L.; Pernak, J. Influence of oligomeric herbicidal ionic

379

liquids with MCPA and Dicamba anions on the community structure of autochthonic

380

bacteria present in agricultural soil. Sci. Total Environ. 2016, 563, 247-255.

381

(18) Cojocaru, O. A.; Shamshina, J.; Gurau, G.; Syguda, A.; Praczyk, T.; Pernak, J.;

382

Rogers, R. Ionic liquid forms of the herbicide dicamba with increased efficacy and

383

reduced volatility. Green Chem. 2013, 15 (8), 2110-2120.

384

(19) Pernak, J.; Niemczak, M.; Chrzanowski, L.; Lawniczak, L.; Fochtman, P.;

385

Marcinkowska, K.; Praczyk, T. Betaine and Carnitine Derivatives as Herbicidal Ionic

386

Liquids. Chem.-Eur. J. 2016, 22 (34), 12012-12021.

387

(20) Ding, G.; Liu, Y.; Wang, B.; Punyapitak, D.; Guo, M.; Duan, Y.; Li, J.; Cao, Y.

388

Preparation and characterization of fomesafen ionic liquids for reducing the risk to the

389

aquatic environment. New J. Chem. 2014, 38 (11), 5590-5596. 18


Page 18 of 28

Page 19 of 28


390

(21) Pernak, J.; Czerniak, K.; Niemczak, M.; Chrzanowski, L.; Lawniczak, L.;

391

Fochtman, P.; Marcinkowska, K.; Praczyk, T. Herbicidal ionic liquids based on

392

esterquats. New J. Chem. 2015, 39 (7), 5715-5724.

393

(22) Pernak, J.; Niemczak, M.; Sharrishina, J. L.; Gurau, G.; Glowacki, G.; Praczyk,

394

T.; Marcinkowska, K.; Rogers, R. D. Metsulfuron-Methyl-Based Herbicidal Ionic

395

Liquids. J. Agric. Food Chem. 2015, 63 (13), 3357-3366.

396

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

397

based herbicidal ionic liquids. Tetrahedron 2012, 68 (22), 4267-4273.

398

(24) Marcinkowska, K.; Praczyk, T.; Gawlak, M.; Niemczak, M.; Pernak, J. Efficacy

399

of herbicidal ionic liquids and choline salt based on 2,4-D. Crop Protect. 2017, 98,

400

85-93.

401

(25) Praczyk, T.; Kardasz, P.; Jakubiak, E.; Syguda, A.; Materna, K.; Pernak, J.

402

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

403

(26) Pernak, J.; Niemczak, M.; Materna, K.; Marcinkowska, K.; Praczyk, T. Ionic

404

liquids as herbicides and plant growth regulators. Tetrahedron 2013, 69 (23),

405

4665-4669.

406

(27) Katritzky, A. R.; Wang, Y.; Sulev Sild, A.; Tamm, T.; Karelson, M. QSPR Studies

407

on Vapor Pressure, Aqueous Solubility, and the Prediction of Water−Air Partition

408

Coefficients. J. Chem Inf. Model. 1998, 38 (4), 720-725.

409

(28) Voutsas, E.; Lampadariou, M.; Magoulas, K.; Tassios, D. Prediction of vapor

410

pressures of pure compounds from knowledge of the normal boiling point temperature.

411

Fluid Phase Equilib. 2002, 198 (1), 81-93.

412

(29) Westwell, M. S.; Searle, M. S.; Wales, D. J.; Williams, D. H. Empirical

413

Correlations between Thermodynamic Properties and Intermolecular Forces.

414

J.am.chem.soc 1995, 117 (18), 5013-5015.

415

(30) Yang, X.; Wang, J.; Fang, Y. Synthesis, Properties and Applications of Dicationic

416

Ionic Liquids. Prog. Chem. 2016, 28 (2-3), 269-283.

417

(31) Anderson, J. L.; Ding, R.; Arkady Ellern, A.; Armstrong, D. W. Structure and

418

Properties of High Stability Geminal Dicationic Ionic Liquids. J. Am. Chem. Soc.

419

2005, 127 (2), 593-604.

420

(32) Brennan, L. J.; Barwich, S. T.; Satti, A.; Faure, A.; Gun'ko, Y. K. Graphene-ionic

421

liquid electrolytes for dye sensitised solar cells. J. Mater. Chem. 2013, 1 (29),

422

8379-8384. 19



423

(33) Somers, A. E.; Howlett, P. C.; Macfarlane, D. R.; Forsyth, M. A Review of Ionic

424

Liquid Lubricants. Lubricants 2013, 1 (1), 3-21.

425

(34) Muskawar, P. N.; Thenmozhi, K.; Gajbhiye, J. M.; Bhagat, P. R. Facile

426

esterification of carboxylic acid using amide functionalized benzimidazolium

427

dicationic ionic liquids. Appl. Catal. A-Gen. 2014, 482 (28), 214-220.

428

(35) Payagala, T.; Huang, J.; Breitbach, Z. S.; Sharma, P. S.; Armstrong, D. W.

429

Unsymmetrical Dicationic Ionic Liquids: Manipulation of Physicochemical Properties

430

Using Specific Structural Architectures. Chem. Mater. 2007, 19 (24), 5848-5850.

431

(36) OECD. Test No. 107: Partition Coefficient (n-octanol/water): Shake Flask

432

Method. OECD Guidelines for the Testing of Chemicals; OECD Publishing: Paris,

433

1995.

434

(37) Decroos, K.; Vincken, J. P.; Gavan, K.; Gruppen, H.; Verstraete, W. Preparative

435

chromatographic purification and surfactant properties of individual soyasaponins

436

from soy hypocotyls. Food Chem. 2007, 101 (1), 324-333.

437

(38) Zhu, J.; Ding, G.; Yao, L.; Wang, B.; Zhang, W.; Guo, M.; Geng, Q.; Cao, Y.

438

Ionic liquid forms of clopyralid with increased efficacy against weeds and reduced

439

leaching from soils. Chem. Eng. J. 2015, 279, 472-477.

440

(39) Tang, G.; Liu, Y.; Ding, G.; Zhang, W.; Liang, Y.; Fan, C.; Dong, H.; Yang, J.;

441

Kong, D.; Cao, Y. Ionic liquids based on bromoxynil for reducing adverse impacts on

442

the environment and human health. New J. Chem. 2017, 41 (16), 8650-8655.

443

(40) Tang, G.; Wang, B.; Ding, G.; Zhang, W.; Liang, Y.; Fan, C.; Dong, H.; Yang, J.;

444

Kong, D.; Cao, Y. Developing ionic liquid forms of picloram with reduced negative

445 446

effects on the aquatic environment. Sci. Total Environ. 2018, 616, 128-134. (41) Rogers, R. D.; Seddon, K. R. Chemistry. Ionic liquids--solvents of the future? Science 2003, 302 (5646), 792.

447 448

20


Page 20 of 28

Page 21 of 28


449

FIGURE AND TABLE CAPTIONS

450

Scheme 1. The structures of HIL1–13.

451

Table 1. The physicochemical properties of HILs.

452

Table 2. The solubility of HILs in water and solvents.

453

Table 3. The fresh weight inhibition rates of HILs against Descurainia sophia, Amaranthus

454

retroflexus, and Chenopodium album.

455

Figure 1. The volatilization rate of 2,4-D acid and HILs at 75 °C after 12 h.

456

Figure 2. The safety assessment of (a) HIL10 and (b) HIL13 to wheat (2,4-D represents 2,4-D

457

ammonium salt).

458

21



459 460 461

Scheme 1. The structures of HIL1–13.

22


Page 22 of 28

Page 23 of 28


462

Table 1. The physicochemical properties of HILs. γCMC

Melting point

Yeild

State

(mN m )

(°C)

(%)

(25 °C)

2.316

57.9

202–204

95

Solid

ethylenediamine

1.878

51.9

152–154

99

Solid

HIL3

1,4-butanediamine

1.773

50.2

168–170

98

Solid

HIL4

1,6-hexanediamine

1.026

44.7

184–186

98

Solid

HIL5

1,8-octanediamine

1.067

42.3

210–212

98

Solid

HIL6

1,4-dimethylpiperazine

3.075

50.6

98–100

93

Solid

HIL7

p-phenylenediamine

2.081

60.2

178–180

94

Solid

HIL8

triethylamine

3.412

61.3

182–184

90

Solid

HIL9

N-methylpiperidine

3.308

41.6

124–126

91

Solid

HIL10

N-methylimidazole

4.209

36.8

82–84

90

Wax

HIL11

N-methylpyrrolidine

4.047

47.1

170–172

90

Solid

HIL12

N-methylmorpholine

4.584

48.7

100–102

92

Wax

HIL13

choline chloride

2.412

39.5

124–126

97

Solid

0.245

67.3

Kow

HILs

Counter cations

HIL1

tris(2-aminoethyl)amine

HIL2

2,4-D ammonium salt

-1

463

23



464

Page 24 of 28

Table 2. The solubility of HILs in water and solvents. HILs

Solubility at different pH

Acetone

Toluene

+

+

+

+++

++

+

+

+++

+++

++

++

+

+

++

++

++

++

+

HIL4

+

++

++

+

+

+

HIL5

+

+

+

+

+

+

HIL6

++

+++

+

++++

++++

+

HIL7

+

+++

++

+++

++++

+

HIL8

+

+++

++

++

++

+

HIL9

+

++

++

++

+

+

HIL10

++

++++

+++

+++

+++

+

HIL11

+

++

++

++

++

+

HIL12

++

+++

++

++

++

+

HIL13

++++

++++

++++

+++

+

+

5.0

7.0

9.0

2,4-D ammonium salt

+ + + +[a]

++++

++++

HIL1

+

+++

HIL2

+

HIL3

Methanol

465

[a] “+” means solubility < 30%, “+ +” means 30% < solubility < 70%, “+ + +” means 70%

Dicationic Ionic Liquids of Herbicide 2,4-Dichlorophenoxyacetic Acid

Recommend Documents