University of Tartu Faculty of Physics and Chemistry Institute of Chemical Physics Superhapetest...

University of TartuFaculty of Physics and Chemistry

Institute of Chemical Physics

Superhapetest kodukeemiani

Ilmar KoppelTartu Ülikool



Definition of Gas-Phase Acidity and Basicity

:B + H+ BH+H

G = -RTlnK

PA = H

A- + H+ AHH

G

G



Connection Between Gas-Phase Acidity and

Acidity in Solution

Ag- + Hg

+Gg

AHg

o

Gso= -RTlnKa =

Gg + Gg sA-

+ Gg sH+

- Gg sAH

As- + Hs

+Gs

AHs

o

Gg s Gg s Gg s

o=



Lewis Acids and Bases

A + D: AD

e.g.:HF: + BF3 HBF4

HF: + SbF5 HSbF6

HSO3F + SbF5 “Magic acid”



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



Acidity of various acids composed of hydrogen

H22+ H2

+ H3+ H· H2

- 70 100 312 400(acidity, kcal/mol)



Superacids by ‘Brute Force’

NO2

NO2

CH3

O2N

CH3

NO2O2N

O2N

NO2

NO2

NH2

NO2

NO2

NO2O2N

O2N

(CF3SO2)3CH

H CN

CNNC

CNNC




CH C CH

2

CH C CH

2




H

SO2CF3

SO2CF3CF3SO2



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 !!??



Effect of Solvation

pKa (H2O) PA

Py 5.4 224NH3 9.3 207

= 5.5 = -17 Cl- -7 (?) 333(CF3)3CO- 5.4 330

= 16.8 = -3NH3 9.3 207

O2NCH2- 9.3 360

= 0 = 153



A Few Milestones of Gacid

CH4 408.5 NH3

396.1H2394.2 C6H6 390.1

MeOH 374.0 HF 365.7SiH4 363.8 PH3 360.7

LiH 351.1 H2S 344.8

MeCOOH 341.7 PhOH 342.3PhCOOH 331.7 HONO 330.4HCl 328.0 (CF3)3CH 326.8

HNO3 317.8 HBr 318.8

Ho312.5 HI 308.9Tf2CH2 301.5 H2SO4 302.2

CF3SO3H 299.5 Tf3CH 289.0

(C4F9SO2)2NH 284.1

zeolites 290-255



HF362

TaF5

94HTaF6 268

PF5

85HPF6 277

SO3

71FSO3H291

BF3

74HBF4 288

SbF5

106HSbF6 256

H2O383

Cl2O7

90HClO4

293

SO3

82H2SO4

301

N2O5

69HNO3 314

H2S2O7

274

SO3

27H2S3O10

261SO3

13

HS2O6F269

SO3

22HS3O9F257

SO3

12HS4O12F249

SO3

8

CF3H 365

SO3

72

CF3SO3H293

SO3

21

AlBr3

57

P2O5

80

HPO3

303

CO2

53

CF3S2O6H272

CF3CO2H312

HCl324

SO3

37

ClSO3H287

AlCl367

HAlCl4257

HBr315

HAlBr4

258

SO3

95CH4

408

CH3SO3H313

Koppel et al., JACS, 2000, 122, 5114-5124

DFT B3LYP/6-311+G**



Yagupolskii Principle

S

O

O

F3C NH2 + O Z

R1

R2

S

O

O

F3C N Z

R1

R2

-H2O

R C

H

O

; S

O

O

R (SO2F, SO2CF3, etc.) P O

R1

R2

R3

;




S

N

N

OHF3C

S

S

CF3

CF3

NS

CF3

O

NS

F3CO

O O

N NSS

CF3

O

O

F3CO

O




Koppel et al.,J.Chem.Soc. Perkin 2 2001, 230-234

pKa(DMSO) GP

16.3

8.0

3.2

pKa=14.1

pKa=25



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



Generalization of Yagupolskii PrincipleAcidifying Effects of Different Yagupolskii-

Type Substituents on the Acidity of CH3C(=X)H (B3LYP/6-311+G**)X G G=O 357.2 0.0=NH 366.4 -9.2=CH2 379.6 -22.4=PH3 357.7 -0.5=SH4 346.6 10.6=ClH5 298.4 58.8=NCN 331.1 26.1=NSO2F 316.4 40.8=C(CN)2 321.1 36.1=C(SO2F)2 299.9 57.3=P(CN)3 281.0 76.2=P(SO2F)3 233.5 123.7=S(CN)4 234.9 122.3

Koppel et al., JACS, 2002, 124, 5594-5600

1091



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



Carboranes The strongest acids The least coordinating anions

The 1-carba-closo-dodecaborate anion CB11H12

–:

Koppel et al., JACS, 2000, 122, 5114-5121



Carborane anion CB11H12–: The

Distribution of Negative Charge



Carboranes: The Site of Protonation

CB11H12–: On B12



Carborane anion CB11F12–: The

Distribution of Negative Charge

1068 Times stronger than H2SO4



Carboranes: The Site of Protonation

CB11F12–: On substituents



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

Species protonation sitea Hacidc,d Gacid

c,d

CB11H12–

CB11H12H B12 267.8 260.4CB11H12H 7-8-12 264.8 257.6CB11H12H 2-7-8 259.1 252.1CB11H12H 2-3-7 259.9 252.6CB11H11F

–

CB11H11FH F12 247.0 241.5CB11H11FH 7-8-12 258.8 251.9CB11H6F6

–

CB11H6F6H F12 F7 234.3 226.8

CB11H6F6H 7-8-12 237.6 231.0CB11F12

–

CB11F12H F12 F7 216.7 209.2

CB11F12H 7-8-12 215.0 208.5 a The site of protonation for the protonated forms. X-Y-Z denotesstructure, protonated on the surface in the center of the trianglespecified by X, Y and Z; AX

BY denotes structure protonated onsubstituent A in the position X and giving hydrogen bond tosubstituent B in position Y. c Values at 298 K. d Hacid values (H)and Gacid values (G) given in kcal/mol (1 cal = 4.184 J). Thevalid estimates are the nonitalicized values corresponding to themost stable protonated forms.



Carborane acids: the Acidity (PM3 and HF 3-21G*) and Site of Protonation

Acid protonation site PM3 HF 3-21G*

Hacid Hacid

CB11H12H B12 292 260

CB11H11FH 7-8-12 266 248

CB11H6F6H 7-8-12 246 234

CB11H6Cl6H Cl12Cl7 261 237

CB11H6Br6H Br12Br7 222 236

CB11H6(CN)6H (CN)12 263 262

CB11H6(CF3)6H (CF3)12(CF3)7 221 —

CB11H6(SO2CF3)6H Tf12Tf7 260 —

CB11F12H F12F7 229 211

CB11Cl12H Cl12Cl7 247 222

CB11(CN)12H (CN)12 241 —

CB11(CF3)12H (CF3)12(CF3)7 197 —

CB11(SO2CF3)12H Tf12Tf7 255 —



Carborane Anions

The acid CB11(CF3)12H is expected to have Gacid < 200 kcal/mol

That is: 1080 times stronger than H2SO4!

CB11(CF3)12–



Acidities of Carborane Acids



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 likeLi+, Ti4+, Et4N+, Zr4+, RE3+,

imidazolonium (e.g. emimi), etc.



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




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




Petrochemical refining and cracking of fuel (zeolites)

Organic synthesis Reusable water-stable

catalysts Oligomerization of olefins,

epoxides, ethers, etc. Enantioselective synthesis

Continued ...




Organic synthesis Diels-Alder reactions Electrophilic Aromatic

Substitutions Friedel-Crafts reactions

Ionic liquidsN N R2R1 + · A-



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



Elements of an Electrochemical Cell



Lead/Acid Battery

Charge: Discharge:

Anode: PbSO4+2e-+2H+ Pb+H2SO4 Anode: Pb+H2SO4 PbSO4+2e-+2H+

Cathode: PbSO4+SO42--2e- Pb(SO4)2 Cathode: Pb2+2H2SO4

Pb(SO4)2+2H2O Pb(SO4)2+2H2O PbO2+2H2SO4 Pb(SO4)2+2e-+2H+ PbSO4+H2SO4

Overall: Pb+PbO2+2H2SO4 2PbSO4+2H2O E0=2.04V



Fuel Cells



Fuel Cells Timeline



Fuel Cells



Planar Solid Oxide Fuel Cell



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



Fuel Cells that Use Proton Conduction



Polymer-Electrolyte Fuel Cells



Conducting Polymer



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



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



Charge and Discharge of a Li-ion Battery



Lithium-Ion Secondary Battery




Cathode: LiNiO2

LiCoO2

LiMn2O4

Anode: Li-metal C(graphite, amorphous carbon, etc)

Electrolyte: high conductivityelectrochemical stabilitythermal stabilitynon-toxiclow-costnon-coordinatinganion“free” Li+ cation




Solvent high D, high polaritylow viscosityunflammablenon-toxic, env. friendly, etc.MeCN, PC, EC, PC+DEC,PC+MeCN, etc.

Separator polyethylenepolypropylene

Some electrolytes:

LiPF6, LiBF4, LiClO4,

LiSO3CF3, LiN(SO2CF3)2

LiN(SO2C4F9)2, LiC(SO2CF3)3



LiCoO2 Type layered Rocksalt Structure



A Double-Layer Supercapacitor

Electrodes: Nanostructured Carbon, pore sizes tailored for cations and anions

Electrolyte: as in case of Li-ion batteries

Hybrides: battery plus supercapacitor



RE Triflates in Organic Synthesis

University of Tartu Faculty of Physics and Chemistry Institute of Chemical Physics Superhapetest...

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