UN sustainable development goals: How can sustainable/green chemistry contribute? By doing things differently

Until now, much Green and Sustainable Chemistry has been focused on how chemicals are made. Here we suggest that, if chemistry is to contribute effectively to achieving the SDGs, we need to change the way that things are done at both ends of the chemical supply chain. For chemical research at the start of the chain, we need to rethink how we build the laboratories in which we carry out the research so as to minimize the use of energy. At the other end of the chain, we advocate the adoption of a Moore's Law for Chemistry (MLFC), which we recently proposed that, wherever possible, the amount of chemical(s) used to achieve a given effect should be decreased by a factor of 2 every five years

Probing the electronic environment of binary and ternary ionic liquid mixtures by x-ray photoelectron spectroscopy

X-ray photoelectron spectroscopy is used to probe the electronic environment of cations and anions for three binary and one ternary chlorostannate ionic liquid mixtures. The impact of the weighting of Cl on the electronic environment of the cation-based nitrogen atom is revealed in detail. With the increasing of the concentration of Cl , the N 1s binding energy is decreased. The electronic environment of the anion- based component is also compared based upon Sn 3d5/2 and Cl 2p3/2 binding energies. It is found that with the increasing of the weighting of Cl , binding energies of Sn 3d5/2 and Cl 2p3/2 both decrease

Study of the stability of 1alkyl-3-methylimidazolium hexafluoroantimonate(V) based ionic liquids using xray photoelectron spectroscopy

A series of highly pure 1-alkyl-3-methylimidazolium hexafluoroantimonate (V) ionic liquids was firstly investigated by XPS. Reliable binding energy values for all elements within the samples were obtained by applying a C 1s fitting model previously employed for other imidazolium ionic liquids, based on setting the C 1s aliphatic component to 285.0 eV when alkyl chains are longer than 8 carbons. We also observed a straightforward X-ray-mediated photoreduction of Sb (V) to Sb (III) species, i.e. reduction of [SbF6]- anion to volatile SbF3. Thus, binding energies values observed at 542.5 eV and 533.1 eV were attributed to Sb 3d3/2 (V) and Sb 3d5/2 (V), respectively, whereas values at 541.0 eV and 531.7 eV were found for Sb 3d3/2 (III) and Sb 3d5/2 (III), respectively. The SbF3 being formed can be lost either by evaporation and/or redistribution to the bulk. Providing the sample is cooled to freezing temperatures, the SbF3 is prevented from escaping the ionic liquid and it accumulated on the surface of cooled [C4C1Im][SbF6] and [C8C1Im][SbF6]. Particularly in the case of prolonged X-ray exposure of a cooled [C4C1Im][SbF6], an unprecedented further reduction of Sb (III) to Sb (0) was noticed. This study provides fundamental knowledge on the XPS data for antimony compounds as well as providing a step towards the surface analysis of materials composed by antimony species, notably the hexafluoroantimonate (V) anion

Tuning the electronic environment of the anion by using binary ionic liquid mixtures

The electronic environment of the anion is tuned by using binary ionic liquid mixtures employing a com- mon anion and two cations with large difference in acidity. X-ray photoelectron spectroscopy is used to monitor the change of the electronic environment of the anion by measuring the binding energy of elements present in the anion. It is found that due to the large difference in acidity of the two cations, noticeable shifts can be observed for all anion-based components, no matter how basic the anion is

Ecotoxicity assessment of dicationic versus monocationic ionic liquids as a more environmentally friendly alternative

One of the reasons why ionic liquids have received growing interest from researchers is their environmentally interesting characteristics, such as their negligible vapour pressure and their good chemical and thermal properties. In particular, dicationic ionic liquids whose thermal and electrochemical stability is higher than that of monocationic ionic liquids have begun to gain attention during recent years. In this work, monocationic and dicationic ionic liquids were synthesized, characterized and tested for their toxicity, which was assessed using the luminescent bacterium Vibrio fischeri. The results revealed that the toxicity of the ionic liquids mainly depends on the head groups and linkage chain length of their cationic structure. Introduction of a new cationic head decreased the EC50 (concentration which leads to 50% reduction in bioluminescence of the bacteria) of the ionic liquids. The results present a promising picture of dicationic ionic liquids as alternatives with lower environmental impact than their monocationic counterparts and underline the significance of designing particular structures for ionic liquids

Quaternary ammonium and phosphonium based ionic liquids: a comparison of common anions

A series of ammonium-based ionic liquids and their phosphonium analogues have been investigated using X-ray Photoelectron Spectroscopy (XPS). A robust C 1s peak fitting model has been developed and described for the tetraalkylphosphonium and tetraalkylammonium families of ionic liquid, with comparisons made between the two series. Cation–anion interactions have been investigated to determine the impact of changing the cationic core from nitrogen to phosphorus upon the electronic environment of the anion. Comparisons between long and short chain cationic systems are also described

Tuning the Reactivity of TEMPO during Electrocatalytic Alcohol Oxidations in Room-Temperature Ionic Liquids

2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) is a promising, sustainable, metal-free mediator for oxidation of alcohols. In this contribution, we describe how the selectivity of TEMPO for electrocatalytic alcohol oxidations in room-temperature ionic liquids (RTILs) can be changed by design of the solvent medium. Cyclic voltammetry of TEMPO in a series of ammonium-, phosphonium-, and imidazolium-based RTILs reveals that the potential at which TEMPO is oxidized increases from 677 mV (vs. the potential of the decamethylferrocene/ decamethylferrocinium, dmFc/dmFc+, redox couple) to 788 mV as the H-bond basicity of the RTIL anions decreases. The increase in potential is accompanied by an increase in the rate constant for oxidation of benzyl alcohol from about 0.1 dm3 mol−1 s−1 to about 0.7 dm3 mol−1 s−1, demonstrating the ability to manipulate the reactivity of TEMPO by judicious choice of the RTIL anions. The rate of alcohol oxidation in a series of RTILs increases in the order 2-butanol < 1phenylethanol < octanol < benzyl alcohol, and the RTIL 1-octyl-3-methylmidazolium bis(trifluoromethanesulfonyl)imide ([NTf2]–) shows clear selectivity towards the oxidation of primary alcohols. In addition, the reaction kinetics and selectivity are better in [NTf2]–-based RTILs than in acetonitrile, often the solvent-of-choice in indirect alcohol electrooxidations. Finally, we demonstrate that electrolytic TEMPO-mediated alcohol oxidations can be performed using RTILs in a flow-electrolysis system, with excellent yields and reaction selectivity, demonstrating the opportunities offered by such systems