Acidity and basicity of halometallate-based ionic liquids from X-ray photoelectron spectroscopy

Taylor, Alasdair W.; Men, Shuang; Clarke, Coby J.; Licence, Peter

doi:10.1039/c3ra40260f

Cited by 50 publications

(84 citation statements)

References 62 publications

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“…[21][22][23] In particular, many studies on polymerization progresses catalyzed by ILs have been done with high catalytic activities. [24][25][26] Nevertheless, little attention has been paid to the study of the synthesis of lactide from PLA oligomer using ILs as catalysts.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of chlorostannate(ii) ionic liquids and their novel application in the preparation of high-qualityl-lactide

et al. 2015

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Polylactic acid (PLA) is a representative biodegradable polymer, which is expected to be a promising replacement for some petroleum-based materials. Noticeably, the properties of PLA products depend strongly on the quality of the lactide monomer, a crucial precursor of PLA production. In this work, a large range of different chlorostannate(II) ionic liquids (ILs), prepared by mixing 1-butyl-3-methylimidazolium chloride and tin(II) chloride in various molar ratios, x SnCl 2 , were firstly applied for the preparation of L-lactide of high chemical and optical purity. The cation-anion interaction, the thermal stability and the acidity of imidazolium-based chlorostannate(II) ionic liquids were experimentally determined and systematically analyzed. Compared with the conventional SnCl 2 catalyst, the depolymerization of oligomeric poly(L-lactic acid) catalyzed by chlorostannate(II) ionic liquids occurred in a moderate yield. Interestingly, using [Bmim]Cl-SnCl 2 (x SnCl 2 ¼ 0.63) as a catalyst, L-lactide of 99.9% optical purity was obtained, simultaneously leaving a high-M w oligomeric residue with high isotacticity (99.1%). Furthermore, the effects of various reaction parameters were investigated in order to obtain the highest possible yield of lactide. A plausible reaction mechanism was suggested and discussed. Finally, owing to the reutilization of PLLA residue of high isotacticity, a reiterative lactide synthesis was realized.The recycled catalyst showed no notable loss of activity. By combining this chlorostannate(II)-based IL (x SnCl 2 ¼ 0.63) catalyst technology with the cyclic resynthesis process, high-quality L-lactide could be selectively produced in high yield (>80%, based on L-lactic acid replenished).

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Section: Introductionmentioning

confidence: 99%

Synthesis of chlorostannate(ii) ionic liquids and their novel application in the preparation of high-qualityl-lactide

et al. 2015

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“…XPS analysis has also been used to provide detailed information on metal-based speciation formed in ionic liquids, through interaction between metal complexes and either the cation [14] or the anion [16] of ionic liquids. In some cases, metal complexes are innocent in ionic liquids.…”

Section: Introductionmentioning

confidence: 99%

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

Men

Licence

2017

Chemical Physics Letters

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“…Due to the changes in the spectrum of [C 8 mim][AuCl 4 ] after Xray irradiation, peaks corresponding to two different states of Cl were observed: a dominant peak at 198.9 eV, which is consistent with the Cl 2p 3/2 peak in the [AuCl 4 ] À anion (label as Cl anion ); [61,73] and an inconspicuous peak at 200.1 eV, which corresponds to Cl 2p 3/2 of organic Cl (label as Cl organic ). [74,75] The organic Cl signal only accounted for 5.4 % of the Cl 2p peak.…”

Section: Resultsmentioning

confidence: 67%

“…[60,61] The IL precursors [C n mim] Cl (n = 4, 6, 8, 10) were added to tetrachloroauric acid (HAuCl 4 ·4H 2 O) at the appropriate molar ratio. A one-step synthetic method was adopted to prepare all gold-based ILs [C n mim][AuCl 4 ] (n = 4, 6, 8, 10) based upon the reported method.…”

Section: Synthesis Of Ilsmentioning

confidence: 99%

“…A one-step synthetic method was adopted to prepare all gold-based ILs [C n mim][AuCl 4 ] (n = 4, 6, 8, 10) based upon the reported method. [60,61] The IL precursors [C n mim] Cl (n = 4, 6, 8, 10) were added to tetrachloroauric acid (HAuCl 4 ·4H 2 O) at the appropriate molar ratio. The mixture was stirred under gentle heating at 60 8C in a water bath to form a homogeneous liquid.…”

Section: Synthesis Of Ilsmentioning

confidence: 99%

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In Situ Tracking of Organic Reactions at the Vapor/Liquid Interfaces of Ionic Liquids

Song

Huo

et al. 2018

ChemPhysChem

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The molecular structures of ionic liquids at interfaces play a crucial role in determining their chemical activities in applications. In situ X-ray photoelectron spectroscopy (XPS) was used to track the evolution of X-ray irradiation-induced chemical reactions in a series of ionic liquids ([C mim][AuCl ]; n=4, 6, 8, 10) on the Si (111) single-crystal surface. Analyses of microstructure and chemical bonding based on the XPS results indicated that reactions occurred at the vapor/liquid interfaces of the ionic liquids. The time-resolved XPS spectra revealed that with increasing irradiation time, the intensity of the peak corresponding to trivalent Au anion decreased for the four ionic liquids as Au was continually reduced to a lower chemical state and finally converted to gold nanoparticles. The rate and conversion of the reaction were associated with the length of the alkyl chain of the ionic liquids cation. Molecular dynamics simulations further revealed that the alkyl chain of the cation in the ionic liquids was oriented towards the vacuum environment at the vapor/liquid interface. Our results provide a real-time atomic-scale experimental evidence of organic reactions at the vapor/liquid interfaces of ionic liquids. The findings are important for understanding the roles of ionic liquids in catalysis, separation, electrochemistry, functional materials, and so on.

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Acidity and basicity of halometallate-based ionic liquids from X-ray photoelectron spectroscopy

Cited by 50 publications

References 62 publications

Synthesis of chlorostannate(ii) ionic liquids and their novel application in the preparation of high-qualityl-lactide

Synthesis of chlorostannate(ii) ionic liquids and their novel application in the preparation of high-qualityl-lactide

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

In Situ Tracking of Organic Reactions at the Vapor/Liquid Interfaces of Ionic Liquids

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