Investigation of the Acidity and Nucleophilicity of Ionic Liquid Mixtures and Their Effects on Reaction Rates
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Is There an Acid Strong Enough to Dissolve Glass? – Superacids
ARTICLE Is there an acid strong enough to dissolve glass? – Superacids For anybody who watched cartoons growing up, the word unit is based on how acids behave in water, however as acid probably springs to mind images of gaping holes being very strong acids react extremely violently in water this burnt into the floor by a spill, and liquid that would dissolve scale cannot be used for the pure ‘common’ acids (nitric, anything you drop into it. The reality of the acids you hydrochloric and sulphuric) or anything stronger than them. encounter in schools, and most undergrad university Instead, a different unit, the Hammett acidity function (H0), courses is somewhat underwhelming – sure they will react is often preferred when discussing superacids. with chemicals, but, if handled safely, where’s the drama? A superacid can be defined as any compound with an People don’t realise that these extraordinarily strong acids acidity greater than 100% pure sulphuric acid, which has a do exist, they’re just rarely seen outside of research labs Hammett acidity function (H0) of −12 [1]. Modern definitions due to their extreme potency. These acids are capable of define a superacid as a medium in which the chemical dissolving almost anything – wax, rocks, metals (even potential of protons is higher than it is in pure sulphuric acid platinum), and yes, even glass. [2]. Considering that pure sulphuric acid is highly corrosive, you can be certain that anything more acidic than that is What are Superacids? going to be powerful. What are superacids? Its all in the name – super acids are intensely strong acids. -
Acid-Base Theories and Frontier Orbitals
Arrhenius Theory Svante Arrhenius (Swedish) 1880s Acid - a substance that produces H+(aq)in solution Base - a substance that produces OH–(aq) in solution Brønsted-Lowry Theory Johannes Brønsted (Danish) Thomas Lowry (English) 1923 Acid - a substance that donates protons (H+) Base - a substance that accepts protons (H+) Proton Transfer Reaction + + H3O (aq) + NH3(aq) 6 H2O(l) + NH4 (aq) hydronium ion ammonia water ammonium ion + H + H H H H H H O + N O + H N H H H H proton donor proton acceptor = acid = base L In general terms, all acid-base reactions fit the general pattern HA + B º A– + HB+ acid base Conjugate Acid-Base Pairs L When an acid, HA, loses a proton it becomes its conjugate base, A–, a species capable of accepting a proton in the reverse reaction. HA º A– +H+ acid conjugate base L When a base, B, gains a proton, it becomes its conjugate acid, BH+, a species capable of donating a proton in the reverse reaction. B+H+ º HB+ base conjugate acid Acid-Base Reactions L We can analyze Brønsted-Lowry type proton transfer reactions in terms of conjugate acid-base pairs. The generic reaction between HA and B can be viewed as HA º A– +H+ H+ +B º HB+ —————————————————— HA + B º A– +HB+ acid1 base2 base1 acid2 • Species with the same subscripts are conjugate acid-base pairs. Acid Hydrolysis and the Role of Solvent Water L When any Brønsted-Lowry acid HA is placed in water it undergoes + hydrolysis to produce hydronium ion, H3O , and the conjugate base, A–, according to the equilibrium: – + HA + H2O º A +H3O acid1 base2 base1 acid2 • The acid HA transfers a proton to H2O, acting as a base, thereby – + forming the conjugates A and H3O , respectively. -
Superacid Chemistry
SUPERACID CHEMISTRY SECOND EDITION George A. Olah G. K. Surya Prakash Arpad Molnar Jean Sommer SUPERACID CHEMISTRY SUPERACID CHEMISTRY SECOND EDITION George A. Olah G. K. Surya Prakash Arpad Molnar Jean Sommer Copyright # 2009 by John Wiley & Sons, Inc. All rights reserved Published by John Wiley & Sons, Inc., Hoboken, New Jersey Published simultaneously in Canada No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 750-4470, or on the web at www.copyright.com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, (201) 748-6011, fax (201) 748-6008, or online at http://www.wiley.com/go/permission. Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives or written sales materials. The advice and strategies contained herein may not be suitable for your situation. -
Title a Hydronium Solvate Ionic Liquid
A Hydronium Solvate Ionic Liquid: Facile Synthesis of Air- Title Stable Ionic Liquid with Strong Bronsted Acidity Kitada, Atsushi; Takeoka, Shun; Kintsu, Kohei; Fukami, Author(s) Kazuhiro; Saimura, Masayuki; Nagata, Takashi; Katahira, Masato; Murase, Kuniaki Journal of the Electrochemical Society (2018), 165(3): H121- Citation H127 Issue Date 2018-02-22 URL http://hdl.handle.net/2433/240665 © The Author(s) 2018. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, Right http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. Type Journal Article Textversion publisher Kyoto University Journal of The Electrochemical Society, 165 (3) H121-H127 (2018) H121 A Hydronium Solvate Ionic Liquid: Facile Synthesis of Air-Stable Ionic Liquid with Strong Brønsted Acidity Atsushi Kitada, 1,z Shun Takeoka,1 Kohei Kintsu,1 Kazuhiro Fukami,1,∗ Masayuki Saimura,2 Takashi Nagata,2 Masato Katahira,2 and Kuniaki Murase1,∗ 1Department of Materials Science and Engineering, Kyoto University, Yoshida-honmachi, Sakyo, Kyoto 606-8501, Japan 2Institute of Advanced Energy, Gokasho, Uji, Kyoto 611-0011, Japan + A new kind of ionic liquid (IL) with strong Brønsted acidity, i.e., a hydronium (H3O ) solvate ionic liquid, is reported. The IL can + + be described as [H3O · 18C6]Tf2N, where water exists as the H3O ion solvated by 18-crown-6-ether (18C6), of which the counter – – + anion is bis(trifluoromethylsulfonyl)amide (Tf2N ;Tf= CF3SO2). The hydrophobic Tf2N anion makes [H3O · 18C6]Tf2N stable + in air. -
X Amino Acid Ionic Liquids
molecules Article The Proton Dissociation of Bio-Protic Ionic Liquids: [AAE]X Amino Acid Ionic Liquids Ting He 1, Cheng-Bin Hong 2, Peng-Chong Jiao 1, Heng Xiang 1, Yan Zhang 1, Hua-Qiang Cai 1,*, Shuang-Long Wang 2 and Guo-Hong Tao 2,* 1 Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang 621900, China; [email protected] (T.H.); [email protected] (P.-C.J.); [email protected] (H.X.); [email protected] (Y.Z.) 2 College of Chemistry, Sichuan University, Chengdu 610064, China; [email protected] (C.-B.H.); [email protected] (S.-L.W.) * Correspondence: [email protected] (H.-Q.C.); [email protected] (G.-H.T.); Tel.: +86-28-85470368 (G.-H.T.) Abstract: [AAE]X composed of amino acid ester cations is a sort of typically “bio-based” protic ionic liquids (PILs). They possess potential Brønsted acidity due to the active hydrogens on their cations. The Brønsted acidity of [AAE]X PILs in green solvents (water and ethanol) at room temperature was systematically studied. Various frameworks of amino acid ester cations and four anions were investigated in this work from the viewpoint of structure–property relationship. Four different ways were used to study the acidity. Acid dissociation constants (pKa) of [AAE]X determined by the OIM (overlapping indicator method) were from 7.10 to 7.73 in water and from 8.54 to 9.05 in ethanol. The pKa values determined by the PTM (potential titration method) were from 7.12 to 7.82 in water. Their 1 Hammett acidity function (H0) values (0.05 mol L− ) were about 4.6 in water. -
Solvent Effects on the Thermodynamic Functions of Dissociation of Anilines and Phenols
University of Wollongong Research Online University of Wollongong Thesis Collection 1954-2016 University of Wollongong Thesis Collections 1982 Solvent effects on the thermodynamic functions of dissociation of anilines and phenols Barkat A. Khawaja University of Wollongong Follow this and additional works at: https://ro.uow.edu.au/theses University of Wollongong Copyright Warning You may print or download ONE copy of this document for the purpose of your own research or study. The University does not authorise you to copy, communicate or otherwise make available electronically to any other person any copyright material contained on this site. You are reminded of the following: This work is copyright. Apart from any use permitted under the Copyright Act 1968, no part of this work may be reproduced by any process, nor may any other exclusive right be exercised, without the permission of the author. Copyright owners are entitled to take legal action against persons who infringe their copyright. A reproduction of material that is protected by copyright may be a copyright infringement. A court may impose penalties and award damages in relation to offences and infringements relating to copyright material. Higher penalties may apply, and higher damages may be awarded, for offences and infringements involving the conversion of material into digital or electronic form. Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong. Recommended Citation Khawaja, Barkat A., Solvent effects on the thermodynamic functions of dissociation of anilines and phenols, Master of Science thesis, Department of Chemistry, University of Wollongong, 1982. -
Chapter Outline
11/16/2016 Aqueous Equilibria: Chemistry of the Water World Chapter Outline • 15.1 Acids and Bases: The BrØnsted–Lowry Model • 15.2 Acid Strength and Molecular Structure • 15.3 pH and the Autoionization of Water • 15.4 Calculations Involving pH, Ka, and Kb • 15.5 Polyprotic Acids • 15.6 pH of Salt Solutions • 15.7 The Common-Ion Effect • 15.8 pH Buffers • 15.9 pH Indicators and Acid–Base Titrations • 15.10 Solubility Equilibria 2 1 11/16/2016 Acids Have a sour taste. Vinegar owes its taste to acetic acid. Citrus fruits contain citric acid. React with certain metals to produce hydrogen gas. React with carbonates and bicarbonates to produce carbon dioxide gas Bases Have a bitter taste. Feel slippery. Many soaps contain bases. Nomenclature Review – Ch 4, Section 4.2 You are only responsible for nomenclature taught in the lab. These ions are part of many different acids and you need to know them! 3- 2- - PO4 , HPO4 , H2PO4 H3PO4 2- - SO4 , HSO4 H2SO4 2- - SO3 , HSO3 H2SO3 2- - CO3 , HCO3 H2CO3 - - HNO HNO NO3 , NO2 3, 2 2- - S , HS H2S - - C2H3O2 (CH3COO ) HC2H3O2 binary acids, oxoacids HCl, HClO4 2 11/16/2016 Strong and Weak Acids A Brønsted acid is a proton donor A Brønsted base is a proton acceptor Strong Acid: Completely ionized - + HNO3(aq) + H2O(ℓ) → NO3 (aq) + H3O (aq) (H+ donor) (H+ acceptor) Weak Acid: Partially ionized - + HNO2(aq) + H2O(ℓ) ⇌ NO2 (aq) + H3O (aq) (H+ donor) (H+ acceptor) 3 11/16/2016 Hydronium Ion Conjugate Acid-Base Pairs 4 11/16/2016 Weak Acids reordered stronger − + CH3COO (aq) [H3O (aq)] Kc = CH3COOH(aq) [H2O(l)] 5 11/16/2016 Strong and Weak Bases Strong and Weak Bases 6 11/16/2016 Weak Bases 7 11/16/2016 Relative Strengths of Acids/Bases Leveling Effect: + • H3O is the strongest H+ donor that can exist in water. -
Acidity of Keggin-Type Heteropolycompounds Evaluated by Catalytic Probe Reactions, Sorption Microcalorimetry, and Density Functional Quantum Chemical Calculations
J. Phys. Chem. B 1998, 102, 10817-10825 10817 Acidity of Keggin-Type Heteropolycompounds Evaluated by Catalytic Probe Reactions, Sorption Microcalorimetry, and Density Functional Quantum Chemical Calculations Billy B. Bardin, Shailendra V. Bordawekar, Matthew Neurock, and Robert J. Davis* Department of Chemical Engineering, UniVersity of Virginia, CharlottesVille, Virginia 22903 ReceiVed: May 22, 1998; In Final Form: October 5, 1998 The acidity and its effects on reactivity of Keggin-type heteropolycompounds were examined by catalytic probe reactions, microcalorimetry of ammonia sorption, and density functional quantum chemical calculations. Phosphotungstic, phosphomolybdic, silicotungstic, and silicomolybdic acids were used as model compounds. The specific rates of double-bond isomerization of both 1-butene and cis-2-butene were orders of magnitude greater on the tungsten heteropolyacids than on molybdenum heteropolyacids, which suggests the tungsten- containing solids are stronger acids. The rate of double-bond isomerization over silicotungstic acid was similar to that over phosphotungstic acid, indicating the minor role of the heteroatom. Results from ammonia sorption -1 microcalorimetry showed ∆Hsorp on tungsten-based heteropolyacids was approximately 40 kJ mol higher than the corresponding enthalpy obtained on molybdenum-based heteropolyacids. Residual waters of hydration significantly affected both reaction rates and sorption enthalpies. Quantum chemical calculations revealed the most energetically favorable site of the acidic proton to be a bridging oxygen atom in the anhydrous heteropolyacid. Calculations on structurally optimized small metal oxide clusters, as well as the complete Keggin unit, were used to determine the proton affinities by DFT methods. Regardless of cluster size, the proton affinity of a tungsten cluster was always lower than that of an analogous molybdenum cluster by about 20-40 kJ mol-1. -
Acid Dissociation Constant - Wikipedia, the Free Encyclopedia Page 1
Acid dissociation constant - Wikipedia, the free encyclopedia Page 1 Help us provide free content to the world by donating today ! Acid dissociation constant From Wikipedia, the free encyclopedia An acid dissociation constant (aka acidity constant, acid-ionization constant) is an equilibrium constant for the dissociation of an acid. It is denoted by Ka. For an equilibrium between a generic acid, HA, and − its conjugate base, A , The weak acid acetic acid donates a proton to water in an equilibrium reaction to give the acetate ion and − + HA A + H the hydronium ion. Key: Hydrogen is white, oxygen is red, carbon is gray. Lines are chemical bonds. K is defined, subject to certain conditions, as a where [HA], [A−] and [H+] are equilibrium concentrations of the reactants. The term acid dissociation constant is also used for pKa, which is equal to −log 10 Ka. The term pKb is used in relation to bases, though pKb has faded from modern use due to the easy relationship available between the strength of an acid and the strength of its conjugate base. Though discussions of this topic typically assume water as the solvent, particularly at introductory levels, the Brønsted–Lowry acid-base theory is versatile enough that acidic behavior can now be characterized even in non-aqueous solutions. The value of pK indicates the strength of an acid: the larger the value the weaker the acid. In aqueous a solution, simple acids are partially dissociated to an appreciable extent in in the pH range pK ± 2. The a actual extent of the dissociation can be calculated if the acid concentration and pH are known. -
Unit 9 Neutralization Titrations-Ii
Estimations Based On Kinetic and Acid-Base UNIT 9 NEUTRALIZATION TITRATIONS-II Equilibria Studies Structure 9.1 Introduction Objectives 9.2 Non-aqueous Titrations 9.3 Role of Solvents in Acid-Base Reactions 9.4 Solvent Systems 9.5 Importance of Dielectric Constant 9.6 Hammett’s Acidity Functions 9.7 Titrants and End Point Detection 9.8 Some Applications 9.9 Summary 9.10 Terminal Questions 9.11 Answers 9.1 INTRODUCTION In the last unit you have learnt about the neutralization titrations in aqueous medium. I hope you know that water is poorly dissociated. But that does not prevent water to dissolve many of the electrolytes. Quantitative methods of analysis have been developed by these sort of rapid ionic reactions. It is economical and easier to handle aqueous solutions leading to the wide use of aqueous solution for analysis. But in many instances it is seen that non-aqueous ionizing solvents are advantageous in case of acidimetry and alkalimetry. This is specially true for cases where compounds cannot be titrated in an aqueous medium. In this unit I am going to introduce you to the non-aqueous titrations, the purpose of a particular solvent in specific reactions and also the various solvent systems. Have you heard about the term “dielectric constant”? Well in this unit you will also learn about its importance. After discussing Hammett’s acidity functions, titrants, end point detection, I will also bring to your notice certain applications for such titrations. This unit will help you to learn about the different aspects of nonaqueous neutralisation titrations which are utilised in analytical chemistry. -
WB Jensen, the Lewis Acid-Base Concepts (1980)
1 W. B. Jensen, The Lewis Acid-Base Concepts (1980) Most of this chapter is concerned with the Lewis definition, its more recent explanation in terms of molecular orbitals, & its application to inorganic chemistry. 2 6-1-1 History 3 6-2 Major Acid-Base Concepts 6-2-1 Arrhenius Concept Arrhenius received 1903 Nobel Prize in chemistry for this theory, Arrhenius acids form hydrogen ions (now frequently called hydronium or oxonium + ions, H3O ) in aqueous solution, Arrhenius bases form hydroxide ions in aqueous solution. 4 This explanation works well in aqueous solution, but it is inadequate for nonaqueous solutions & for gas & solid phase reactions in which H+ & OH- may not exist. Definition by Br∅nsted & Lewis are more appro- priate for general rule. 5 6-2-2 Br∅nsted-Lowry concept In 1923, Br∅nsted-Lowry defined an acid as a species with a tendency to lose a hydrogen ion & a base as a species with a tendency to gain a hydrogen ion. This definition expanded the Arrhenius list of acids & bases to include the gaseous HCl & NH3. 6 This definition also introduced the concept of conjugate acids & bases, differing only in the presence or absence of a proton, & described all reactions as occurring between a stronger acid & base to form a weaker acid & base. 7 Na + NH3 8 6-2-3 Solvent System Concept The solvent system definition applies to any solvent that can dissociate into a cation & an anion (autodissociation), where the cation resulting from autodissociation is the acid & the anion is the base. Solutes that increase the conc of the cation of the solvent are considered acids & solutes that increase the conc of the anion are considered bases. -
George Andrew Olah Across Conventional Lines
GENERAL ARTICLE George Andrew Olah Across Conventional Lines Ripudaman Malhotra, Thomas Mathew and G K Surya Prakash Hungarian born American chemist, George Andrew Olah was aprolific researcher. The central theme of his career was the 12 pursuit of structure and mechanisms in chemistry, particu- larly focused on electron-deficient intermediates. He leaves behind a large body of work comprising almost 1500 papers and twenty books for the scientific community. Some selected works have been published in three aptly entitled volumes, 3 Across Conventional Lines. There is no way to capture the many contributions of Olah in a short essay. For this appreciation, we have chosen to high- 1 light some of those contributions that to our mind represent Ripudaman Malhotra, a student of Prof. Olah, is a asignificant advance to the state of knowledge. retired chemist who spent his entire career at SRI International working mostly Organofluorine Chemistry on energy-related issues. He co-authored the book on Early on in his career, while still in Hungary, Olah began studying global energy – A Cubic Mile organofluorine compounds. Olah’s interest in fluorinated com- of Oil. pounds was piqued by the theoretical ramifications of a strong 2 Thomas Mathew, a senior C-F bond. Thus, whereas chloromethanol immediately decom- scientist at the Loker Hydrocarbon Research poses into formaldehyde and HCl, he reasoned that the stronger Institute, has been a close C-F bond might render fluoromethanol stable. He succeeded in associate of Prof. Olah over preparing fluoromethanol by the reduction of ethyl flouorofor- two decades. 3 mate with lithium aluminum hydride [1].