219 results found
Perkin S, Crowhurst L, Niedermeyer H, et al., 2011, Self-assembly in the electrical double layer of ionic liquids, CHEMICAL COMMUNICATIONS, Vol: 47, Pages: 6572-6574, ISSN: 1359-7345
Welton T, 2011, Ionic liquids in Green Chemistry, GREEN CHEMISTRY, Vol: 13, Pages: 225-225, ISSN: 1463-9262
Brandt A, Ray MJ, To TQ, et al., 2011, Ionic liquid pretreatment of lignocellulosic biomass with ionic liquid-water mixtures, Green Chem., Vol: 13, Pages: 2489-2499-2489-2499
Ground lignocellulosic biomass (Miscanthus giganteus, pine (Pinus sylvestris) and willow (Salix viminalis)) was pretreated with ionic liquid-water mixtures of 1-butyl-3-methylimidazolium methyl sulfate and 1-butyl-3-methylimidazolium hydrogen sulfate. A solid fraction enriched in cellulose was recovered, which was subjected to enzymatic hydrolysis. Up to 90% of the glucose and 25% of the hemicellulose contained in the original biomass were released by the combined ionic liquid pretreatment and the enzymatic hydrolysis. After the pretreatment, the ionic liquid liquor contained the majority of the lignin and the hemicellulose. The lignin portion was partially precipitated from the liquor upon dilution with water. The amount of hemicellulose monomers in the ionic liquid liquor and their conversion into furfurals was also examined. The performance of ionic liquid-water mixtures containing 1,3-dialkylimidazolium ionic liquids with acetate, methanesulfonate, trifluoromethanesulfonate and chloride anions was investigated. The applicability of the ionic liquid 1-butylimidazolium hydrogensulfate for lignocellulose pretreatment was also examined. It was found that ionic liquid liquors containing methyl sulfate, hydrogen sulfate and methanesulfonate anions were most effective in terms of lignin/cellulose fractionation and enhancement of cellulose digestibility.
The polarities of a wide range of ionic liquids have been determined using the Kamlet-Taft empirical polarity scales [small alpha], [small beta] and [small pi]*, with the dye set Reichardt’s Dye, N,N-diethyl-4-nitroaniline and 4-nitroaniline. These have been compared to measurements of these parameters with different dye sets and to different polarity scales. The results emphasise the importance of recognising the role that the nature of the solute plays in determining these scales. It is particularly noted that polarity scales based upon charged solutes can give very different values for the polarity of ionic liquids compared to those based upon neutral probes. Finally, the effects of commonplace impurities in ionic liquids are reported.
Schrems Michael, Brandt Agnieszka, Welton Tom, et al., 2011, Ionic liquids as media for biomass processing: opportunities and restrictions
Reichardt C, Welton T, 2010, Solvents and Solvent Effects in Organic Chemistry, Publisher: Wiley-VCH, ISBN: 9783527324736
Reichardt C, Welton T, 2010, Solvents and Solvent Effects in Organic Chemistry: Fourth Edition, ISBN: 9783527324736
Now in its 4th edition, this book remains the ultimate reference for all questions regarding solvents and solvent effects in organic chemistry. Retaining its proven concept, there is no other book which covers the subject in so much depth, the handbook is completely updated and contains 15% more content, including new chapters on "Solvents and Green chemistry", "Classification of Solvents by their Environmental Impact", and "Ionic Liquids". An essential part of every organic chemist's library. © 2011 Wiley-VCH Verlag GmbH & Co. KGaA.
Hunt P, Niedermeyer H, Welton T, 2010, What happens when you functionalise an ionic liquid with a "silicone" side chain?, ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, Vol: 239, ISSN: 0065-7727
Brandt A, Hallett JP, Leak DJ, et al., 2010, The effect of the ionic liquid anion in the pretreatment of pine wood chips, Green Chem., Vol: 12, Pages: 672-679-672-679
The effect of the anion of ionic liquids on air-dried pine (Pinus radiata) has been investigated. All ionic liquids used in this study contained the 1-butyl-3-methylimidazolium cation; the anions were trifluoromethanesulfonate, methylsulfate, dimethylphosphate, dicyanamide, chloride and acetate. Using a protocol for assessing the ability to swell small wood blocks (10 [times] 10 [times] 5 mm), it was shown that the anion has a profound impact on the ability to promote both swelling and dissolution of biomass. Time course studies showed that viscosity, temperature and water content were also important parameters influencing the swelling process. We used Kamlet-Taft parameters to quantify the solvent polarity of the ionic liquids and found that the anion basicity described by the parameter [small beta] correlated with the ability to expand and dissolve pine lignocellulose. It is shown that 1-butyl-3-methylimidazolium dicyanamide dissolves neither cellulose nor lignocellulosic material.
Niedermeyer H, Ab Rani MA, Lickiss PD, et al., 2010, Understanding siloxane functionalised ionic liquids, Phys. Chem. Chem. Phys., Vol: 12, Pages: 2018-2029-2018-2029
Welton T, 2009, Topics in Current Chemistry: Foreword, ISBN: 9783642017797
Bini R, Chiappe C, Mestre VL, et al., 2009, A theoretical study of the solvent effect on Diels-Alder reaction in room temperature ionic liquids using a supermolecular approach, THEORETICAL CHEMISTRY ACCOUNTS, Vol: 123, Pages: 347-352, ISSN: 1432-881X
Wells TP, Hallett JP, Williams CK, et al., 2009, ORGN 201-Esterification in ionic liquids: The influence of solvent basicity, ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, Vol: 237, ISSN: 0065-7727
Hallett JP, Liotta CL, Ranieri G, et al., 2009, Charge Screening in the S(N)2 Reaction of Charged Electrophiles and Charged Nucleophiles: An Ionic Liquid Effect, JOURNAL OF ORGANIC CHEMISTRY, Vol: 74, Pages: 1864-1868, ISSN: 0022-3263
Correia I, Welton T, 2009, An old reaction in new media: kinetic study of a platinum(II) substitution reaction in ionic liquids, DALTON TRANSACTIONS, Pages: 4115-4121, ISSN: 1477-9226
Hallett JP, Welton T, 2008, How polar are ionic liquids?, Pages: 33-38, ISSN: 1938-5862
Ionic liquids have recently become extremely popular solvents for a wide range of applications from electrochemistry to synthesis. From a solvation standpoint, ionic liquids are generally considered to be 'very polar' solvents. However, attempts to quantify the polarity of ionic liquids have yielded a confusing mixture of results - moderate dielectric constants, mixed solvatochromic parameters and adjustable water solubilities defy a simple classification of the polarity of ionic liquids. We attempt to clarify this confusing and conflicting picture by using the Kamlet-Taft polarity scales to shed light on the solution behaviour and explain how ionic liquids interact with a variety of solutes. Using these various parameters, different solution behaviours can be quantified and correlated, thus painting a descriptive picture of what 'polarity' means for an ionic solvent. ©The Electrochemical Society.
Wells TP, Hallett JP, Williams CK, et al., 2008, Esterification in ionic liquids: The influence of solvent basicity, Pages: 103-106, ISSN: 1938-5862
The rate of esterification is reported in a range of ionic and molecular solvents. The effects of solvent on esterification rate are examined by using a linear solvation energy relationship based on the Kamlet-Taft solvent polarity descriptors (α, β, and π*). It is shown that the basicity (β) of the solvent is the major factor in determining esterification rate and that the highest rates are observed in low basicity solvents. ©The Electrochemical Society.
The application of liquids that are salts at room temperature to chemicals synthesis has become a hugely exciting field of study. Thousands of papers are now generated each year and several industrial chemicals processes are now running. The greatest promise that these ionic liquids hold is that they might offer process advantages, even novel behaviors that cannot be achieved in molecular solvents. However, until now no behavior that is unique to ionic liquids has been observed. For such an "ionic liquid effect" to be seen it would need to be the result of the medium being composed solely of ions in motion. We have been searching for an ionic liquid effect, which we can now report here, for most the last decade. We demonstrate that when two dissolved salts react with each other in ionic liquids they follow a fundamentally different pathway to when the same salts react in any molecular solvent. ©The Electrochemical Society.
Oromi-Farrus M, Eras J, Villorbina G, et al., 2008, [BMIM][PF6]Promotes the Synthesis of Halohydrin Esters from Diols Using Potassium Halides, ANALYTICAL SCIENCES, Vol: 24, Pages: 1341-1345, ISSN: 0910-6340
Wells TP, Hallett JP, Williams CK, et al., 2008, Esterification in ionic liquids: The influence of solvent basicity, JOURNAL OF ORGANIC CHEMISTRY, Vol: 73, Pages: 5585-5588, ISSN: 0022-3263
Welton T, 2008, The sustainable chemist, MATERIALS TODAY, Vol: 11, Pages: 56-56, ISSN: 1369-7021
Olivier-Bourbigou H, Vallée C, Welton T, et al., 2008, Catalysis in Nonaqueous Ionic Liquids (ILs): State-of-the-Art, Multiphase Homogeneous Catalysis, Pages: 413-546, ISBN: 9783527307210
Ranieri G, Hallett JP, Welton T, 2008, Nucleophilic reactions at cationic centers in ionic liquids and molecular solvents, INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, Vol: 47, Pages: 638-644, ISSN: 0888-5885
Crosthwaite JM, Farmer VA, Hallett JR, et al., 2008, Epoxidation of alkenes by Oxone(TM) using 2-alkyl-3, 4-dihydroisoquinolinium salts as catalysts in ionic liquids, JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL, Vol: 279, Pages: 148-152, ISSN: 1381-1169
Wasserscheid P, Welton T, 2008, Ionic Liquids in Synthesis: Second Edition, ISBN: 9783527312399
The second, completely revised and enlarged edition of what has become the standard reference work in this fascinating field brings together the latest developments, supplemented by numerous practical tips, providing those working in both research and industry with an indispensable source of information. New contributions have been added, to reflect the fact that industrial processes are already established, and ionic liquids are now commercially available. A must for everyone working in the field. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.
Haddleton DM, Welton T, Carmichael AJ, 2008, Polymer Synthesis in Ionic Liquids, Ionic Liquids in Synthesis: Second Edition, Pages: 619-640, ISBN: 9783527312399
Wasserscheid P, Welton T, 2008, Outlook, Ionic Liquids in Synthesis: Second Edition, Pages: 689-704, ISBN: 9783527312399
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