Roy van Hal

1-n-Butyl-3-methylimidazolium ([bmim]) octylsulfate—an even ‘greener’ ionic liquid

Ionic liquids are considered as green solvents mainly due to their lack of vapour pressure. In fact, environmental and safety problems arising through the volatility of organic solvents can be avoided by the use of these innovative liquids. However, typical ionic liquids consist of halogen containing anions (such as [AlCl4]−, [PF6]−, [BF4]−, [CF3SO3]− or [(CF3SO2)2N]−) which in some regard limit their ‘greenness’. The presence of halogen atoms may cause serious concerns if the hydrolysis stability of the anion is poor (e.g. for [AlCl4]− and [PF6]−) or if a thermal treatment of spent ionic liquids is desired. In both cases additional effort is needed to avoid the liberation of toxic and corrosive HF or HCl into the environment. In this context, we present here the synthesis and application of 1-n-butyl-3-methylimidazolium ([bmim]) [n-C8H17OSO3] which represents a halogen-free and relatively hydrolysis-stable ionic liquid. Moreover, the technical availability and the well documented toxicology of the octylsulfate anion make this ionic liquid a highly interesting candidate for industrial application.

Transesterification of methylsulfate and ethylsulfate ionic liquids—an environmentally benign way to synthesize long-chain and functionalized alkylsulfate ionic liquids

A new environmentally friendly method to synthesize long-chain and functionalized alkylsulfate ionic liquids is reported. The two-step synthesis comprises the synthesis of a methylsulfate or ethylsulfate ionic liquid by direct alkylation in the first step. In the second step, this intermediate is transformed in a transesterification reaction, using different functionalized and non-functionalized alcohols, to the corresponding new alkylsulfate melts. The entire reaction sequence is halide-free and liberates methanol or ethanol as the only by-products. Moreover, it is carried out in a solvent-free manner and scale-up is straight forward.

Thermomorphic phase separation in ionic liquid–organic liquid systems—conductivity and spectroscopic characterization

Electrical conductivity, FT-Raman and NMR measurements are demonstrated as useful tools to probe and determine phase behavior of thermomorphic ionic liquid-organic liquid systems. To illustrate the methods, consecutive conductivity measurements of a thermomorphic methoxyethoxyethyl-imidazolium ionic liquid/1-hexanol system are performed in the temperature interval 25-80 degrees C using a specially constructed double-electrode cell. In addition, FT-Raman and 1H-NMR spectroscopic studies performed on the phase-separable system in the same temperature interval confirm the mutual solubility of the components in the system, the liquid-liquid equilibrium phase diagram of the binary mixture, and signify the importance of hydrogen bonding between the ionic liquid and the hydroxyl group of the alcohol.

New, functionalised ionic liquids from Michael-type reactions?a chance for combinatorial ionic liquid developmentElectronic supplementary information (ESI) available: NMR and MS spectra consistent with the indicated structures for the compounds illustrated in Table 1. See http://www.rsc.org/suppdata/cc/b3/b306084e/

We describe for the first time an alternative and far more efficient method to synthesise functionalised ionic liquids in a simple, straightforward, two-step synthesis.