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Superacids and Their Applications in Chemistry: A Comprehensive Overview

Explore the definitions of gas-phase acidity and basicity, connections between gas-phase and solution acidity, and the role of Lewis acids and bases in chemistry. Delve into the acidity of various compounds and the significance of superacids. Learn about the Yagupolskii Principle, carborane anions, and milestones in acid strength measurements. Discover the potential applications of superstrong acids in industries like petrochemical refining, organic synthesis, and catalysis. Unveil the requirements and benefits of using superacids for various chemical processes.

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Superacids and Their Applications in Chemistry: A Comprehensive Overview

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  1. Superhapetest kodukeemianiIlmar KoppelTartu Ülikool

  2. Definition of Gas-Phase Acidity and Basicity

  3. Connection Between Gas-Phase Acidity and Acidity in Solution

  4. Lewis Acids and Bases A + D:  AD e.g.: HF: + BF3 HBF4 HF: + SbF5 HSbF6 HSO3F + SbF5 “Magic acid”

  5. Strong Neutral Acids & Weak Anionic Bases - the common knowledge • Strong and Highly Polarizable Electron-Acceptor Substituents • Extensive Resonance Stabilization of the Anion / Delocalization of Negative Charge • Coplanarity of the Anion • Aromaticity and Antiaromaticity

  6. Acidity of various acids composed of hydrogen H22+ H2+ H3+  H·  H2 - 70 100 312 400 (acidity, kcal/mol)

  7. Superacids by ‘Brute Force’

  8. Superacids by ‘Brute Force’

  9. Superacids by ‘Brute Force’

  10. Acidity Scale in Water • CH4 ~ 55 ? • MeOH 15.5 • PhOH 10.0 • H(H2O) 9.7 • NH4+ 9.3 • (CF3)3COH 5.4 • PyH+ 5.2 • AcOH 4.7 • HF 3.4 • H2SO4 -3 • HCl -7 • HBr -9  -11 • HI -11 • CF3SO3H, HClO4 -1  -14 !!??

  11. Effect of Solvation pKa (H2O)PA Py 5.4 224 NH3 9.3 207  = 5.5  = -17 Cl- -7 (?) 333 (CF3)3CO- 5.4 330  = 16.8  = -3 NH3 9.3 207 O2NCH2- 9.3 360  = 0  = 153

  12. A Few Milestones of DGacid CH4 408.5 NH3 396.1 H2 394.2 C6H6 390.1 MeOH 374.0 HF 365.7 SiH4 363.8 PH3 360.7 LiH 351.1 H2S 344.8 MeCOOH 341.7 PhOH 342.3 PhCOOH 331.7 HONO 330.4 HCl 328.0 (CF3)3CH 326.8 HNO3 317.8 HBr 318.8 Ho 312.5 HI 308.9 Tf2CH2 301.5 H2SO4 302.2 CF3SO3H 299.5 Tf3CH 289.0 (C4F9SO2)2NH 284.1 zeolites 290-255

  13. Koppel et al., JACS, 2000, 122, 5114-5124 DFT B3LYP/6-311+G**

  14. Yagupolskii Principle

  15. Yagupolskii Principle

  16. Yagupolskii Principle pKa(DMSO) GP 16.3 DpKa=14.1 DpKa=25 8.0 3.2 Koppel et al.,J.Chem.Soc. Perkin 2 2001, 230-234

  17. Generalization of Yagupolskii Principle Why only =NSO2CF3 substitution? • =NX1 • =CX1X2 • =PX1X2X3 • =SX1X2X3X4 • =ClX1X2X3X4X5 X = SO2F, SO2CF3, CN, etc. Koppel et al., JACS, 2002, 124, 5594-5600

  18. Generalization of Yagupolskii Principle 1091 Acidifying Effects of Different Yagupolskii-Type Substituents on the Acidity of CH3C(=X)H (B3LYP/6-311+G**) Koppel et al., JACS, 2002, 124, 5594-5600

  19. New Paradigm for Design of Superstrong Acids - Weak Anionic Bases:Carborane Anions • No  Electrons • No “Loose” Lone Electron Pairs • 3-Dimensional -Aromaticity • Extensive Delocalization of Negative Charge • Pseudo-Icosahedral Symmetry

  20. Carboranes • The strongest acids • The least coordinating anions The 1-carba-closo-dodecaborate anion CB11H12–: Koppel et al., JACS, 2000, 122, 5114-5121

  21. Carborane anion CB11H12–: The Distribution of Negative Charge

  22. Carboranes: The Site of Protonation CB11H12–: On B12

  23. Carborane anion CB11F12–: The Distribution of Negative Charge 1068 Times stronger than H2SO4

  24. Carboranes: The Site of Protonation CB11F12–: On substituents

  25. Carborane acids: the Acidity (DFT B3LYP 6-31+G*) and Site of Protonation

  26. Carborane acids: the Acidity (PM3 and HF 3-21G*) and Site of Protonation Acid protonation sitePM3 HF 3-21G* DHacidDHacid CB11H12HB12292260 CB11H11FH 7-8-12266248 CB11H6F6H 7-8-12246234 CB11H6Cl6H Cl12Cl7261237 CB11H6Br6H Br12Br7222236 CB11H6(CN)6H (CN)12263262 CB11H6(CF3)6H (CF3)12(CF3)7221 — CB11H6(SO2CF3)6H Tf12Tf7260 — CB11F12H F12F7229211 CB11Cl12H Cl12Cl7247222 CB11(CN)12H(CN)12241 — CB11(CF3)12H (CF3)12(CF3)7197 — CB11(SO2CF3)12H Tf12Tf7255 —

  27. Carborane Anions CB11(CF3)12– The acid CB11(CF3)12H is expected to have DGacid < 200 kcal/mol That is: 1080 times stronger than H2SO4!

  28. Acidities of Carborane Acids

  29. Most Used and Highly Perspective Superstrong Acids and Their Salts • Acids H2SO4, HClO4, CF3SO3H (TfOH), FSO3H, HBF4, HB(TfO)3, HSbF6, HPF6, HPF3(CF3)3, HCTf3, HNTf2, HAl[OC(CF3)3]4 HN[O2SOCH(CF3)2]2, derivatives of CB11H13, HAlCl4, HAlBr4, HB(C6F5)4, Acidic Zeolites, etc • And their salts with cations like Li+, Ti4+, Et4N+, Zr4+, RE3+, imidazolonium (e.g. emimi), etc.

  30. Application of Superstrong Acids and Their Salts • “Classical” Primary and Secondary Batteries (lead/acid, Ni/Cd, Fe/Ni, etc) • Fuel Cells • Lithium-Ion Batteries • Electric Double Layer Capacitors

  31. Application of Superstrong Acids and Their Salts Requirements: • High Conductivity • Thermal and Chemical Stability • Electrochemical Stability • Cheap • User- and Environment-Friendly • Non- Corrosive • Non Hygroscopic • Non- Coordinated Li+ • Low viscosity and high dielectric constant of the medium • Not “too large” anions

  32. Application of Superstrong Acids and Their Salts • Petrochemical refining and cracking of fuel (zeolites) • Organic synthesis • Reusable water-stable catalysts • Oligomerization of olefins, epoxides, ethers, etc. • Enantioselective synthesis Continued ...

  33. Application of Superstrong Acids and Their Salts • Organic synthesis • Diels-Alder reactions • Electrophilic Aromatic Substitutions • Friedel-Crafts reactions • Ionic liquids

  34. Spontaneous Proton Transfer in Gas Phase K2O + H+ = K2OH+ G=324.6 ClO4- + H+ = HClO4G=293.3 K2O + HClO4 = K2OH+ ClO4-G=119.4 K2OH+ + ClO4- = K2OH+ ClO4-G=88.0

  35. Elements of an Electrochemical Cell

  36. Lead/Acid Battery

  37. Fuel Cells

  38. Fuel Cells Timeline

  39. Fuel Cells

  40. Planar Solid Oxide Fuel Cell

  41. Fuel Cells • Alkaline (AFC) • Proton Exchange Membrane (PEM, 40-80 °C) • Phosphoric Acid (PAFC, 80 – 100 °C) • Molten Carbonate (MCFC) 650-700ºC • Solid Oxide (SOFC) 900-1000º C • anode: Ni/YSZ (Nickel/Yttrium-stabilized zirconia) • cathode: perovskite type: LaMnO3, La0.8Ca0.2CrO3 • Hybride Cars

  42. Fuel Cells that Use Proton Conduction

  43. Polymer-Electrolyte Fuel Cells

  44. Conducting Polymer

  45. Ford Focus FCV • Fuel Cells • Type: Proton Exchange Membrane (PEM) • Fuel Type: Compressed Hydrogen • Stack Type: Ballard Mark 900 • Voltage: 255v • Fuel Capacity (gls.): 3.1 • Fuel Consumption (Gas Equivalent): 60.0 mpg - City/ 79.0 mpg - Highway • Tank Pressure: 3,600 PSI / 5,000 PSI • Emissions: ZEV

  46. Ford Focus FCV • Electric Motor/Transaxle (Integrated) • Electric Motor: AC Induction • Transaxle: Single Speed • Configuration: Front Wheel Drive • Peak Power: 67 kW (90 hp) • Peak Torque: 190 Nm (140 ft-lbs) • Peak Efficiency: 91% • Traction Inverter Module • Type: 3 Phase Bridge • Max Current: 280 amps • Max/Min Voltage: 420/250 volts • Nominal Voltage: 315 volts • Performance • Range: 100 miles • Acceleration: 0 to 60 in under 14 seconds • Maximum Speed: 80+ mph • Fleet availability: 2004

  47. Charge and Discharge of a Li-ion Battery

  48. Lithium-Ion Secondary Battery

  49. Lithium-Ion Secondary Battery Cathode: LiNiO2 LiCoO2 LiMn2O4 Anode: Li-metal C(graphite, amorphous carbon, etc) Electrolyte: high conductivity electrochemical stability thermal stability non-toxic low-cost non-coordinating anion “free” Li+ cation

  50. Lithium-Ion Secondary Battery Solvent high D, high polarity low viscosity unflammable non-toxic, env. friendly, etc. MeCN, PC, EC, PC+DEC,PC+MeCN, etc. Separator polyethylene polypropylene Some electrolytes: LiPF6, LiBF4, LiClO4, LiSO3CF3, LiN(SO2CF3)2 LiN(SO2C4F9)2, LiC(SO2CF3)3

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