Synthesis and Phytotoxicity of New Ionic Liquids Incorporating Chiral Cations and/or Chiral Anions

Abstract

The aim of this work was to synthesize chiral ionic liquids as chiral solvents for organic synthesis and to evaluate the phyto(eco)toxicity of the new products and starting N-alkylimidazoles and their potential environmental influence on soil and plants. Chiral ionic liquids containing anions such as Cl-, Br-, TsO-, PF6(-), NO3(-), CF3SO3(-), and (+)- and (-)-C6H5CH(OH)C(O)O- were synthesized using (-)-(1R)-6,6-dimethylbicyclo[3.1.1]hept-2-ene-2-ethyl [(-)-(1R)-nopyl] halides (X = Cl, Br) and tosylate in 62-100% yields. The chloride 7 and the nitrate 13 ionic liquids possessed a toxicity dependent on the applied concentration. The lowest concentration causing a distinct reduction in plant germination/growth was 100 mg/kg. Spring barley better tolerated the ionic liquids (200 mg/kg) than common radish (100 mg/kg). The nitrate liquid did not exhibit an inhibiting effect on the germination ability of seeds. The starting N-methylimidazole used in lower concentrations (1 and 10 mg/kg of soil dry weight) was not phytotoxic, in contrast to higher doses (>1000 mg/kg).

Comparison of Phytotoxicity of Selected Phosphonium Ionic Liquid

“…A greater interest was aroused by ionic liquids only in the 90s with the obtaining of salts stable in the presence of air and moisture. First ionic liquids went on sale in 1999, and a dramatic increase in research activity related to the synthesis and practical applicability of these compounds has been seen from that time [2,[6][7][8].…”

“…With reference to this problem, along with scientific reports on the synthesis, physical and chemical properties and the potential for practical utilization of ionic liquids, a large number of studies have come up, which are concerned with the examination of the potential toxicity of these substances. Studies described in available literature reveal varied influences of ionic liquids on microorganisms [1,2,[17][18][19][20][21][22], plankton [21,[23][24][25][26], invertebrates [27][28][29], vertebrates [27,30], algae [2,21,23,29,[31][32][33], fungi [19,34,35] or higher land plants [8,21,31,[36][37][38][39]. The quoted literature shows that a likely toxic influence of a ionic liquid is determined by a number of factors, of which the primary role is played the cation type and the length of the substituent in the cation (as a rule, the longer alkyl chain, the higher toxicity).…”

Biodegradable, non-bactericidal oxygen-functionalised imidazolium esters: A step towards ‘greener’ ionic liquids

“…Toxicity and antimicrobial studies have been performed on a range of bacteria and fungi, 14-17 acute toxicity studies have been carried out on fish, 18 growth inhibition studies have been carried out on algae, 19,20, 21 and also on terrestrial plants. 22, 23 The variety of organisms studied now extends to higher classes such as the soil nematode 24 and the freshwater snail.…”

Toxicity of Quaternary Ammonium Salts with Iodide Anion: Growth Inhibition and Changes in Pigments Assimilation in Plants

“…Oddziaływanie toksyczne substancji chemicznych zastosowanych w formie oprysku uzależnione było w dużym stopniu również od stężenia związku zastosowanego w eksperymencie. Znajduje to potwierdzenie w dostępnej literaturze [12,14,[29][30][31][32]. W pracach tych dowodzi się niemalże liniowej zależności pomiędzy toksycznością cieczy jonowych dla roślin a zastosowanym stężeniem związku.…”

“…Odmienny wpływ na zawartość suchej masy u roślin miał jodek tetrametyloamoniowy, który spowodował istotny wzrost zawartości suchej masy jedynie w przypadku komosy białej, po zastosowaniu oprysku roztworem o stężeniu 2%, natomiast w pozostałych przypadkach nie obserwowano istotnych zmian w wartościach tego parametru. O wzroście poziomu suchej masy roślin po zastosowaniu ILs w wyższych stężeniach donoszą Biczak i inni [29][30][31][32][33].…”