pKa values and gas-phase acidities of superacid molecul
pKa values and gas-phase acidities of superacid molecul pKa values and gas-phase acidities of superacid molecul
67 4NO 2 C 6 H 4 SO 2 NHTos 10.04 68 4-Cl-3-NO 2 -C 6 H 3 SO 2 NHTos 9.71 69 4-NO 2 -C 6 H 4 C(=O)NHTf 9.49 70 4-NO 2-C 6H 4SO 2NHSO 2C 6H 4-4-Cl 9.17 71 TosOH 8.6 72 (4-NO 2-C 6H 4SO 2) 2NH 8.32 73 1-C 10 H 7 SO 3 H 8.02 74 C 6H 5CHTf 2 7.85 75 4-Cl-C 6 H 4 SO 3 H 7.3 76 3-NO 2-C 6H 4SO 3H 6.78 77 4-NO 2 -C 6 H 4 SO 3 H 6.73 78 4-MeO-C 6 H 4 C(=NTf)NHTf 6.54 79 4-Me-C 6H 4C(=NTf)NHTf 6.32 80 TosNHTf 6.30 81 C 6 H 5 C(=NTf)NHTf 6.17 82 C 6 H 5 SO 2 NHTf 6.02 83 4-F-C 6 H 4 C(=NTf)NHTf 5.79 84 4-Cl-C 6 H 4 C(=NTf)NHTf 5.69 85 2,4,6-(SO 2 F) 3 -Phenol 5.66 86 4-Cl-C 6 H 4 SO 2 NHTf 5.47 87 4-Cl-C 6H 4SO(=NTf)NHTos 5.27 88 4-NO 2-C 6H 4C(=NTf)NHTf 5.13 89 2,4,6-Tf 3-Phenol 4.93 90 4-NO 2 -C 6 H 4 SO 2 NHTf 4.52 91 4-Cl-C 6H 4SO(=NTf)NHSO 2C 6H 4-4-Cl 4.47 92 2,3,5-tricyanocyclopentadiene 4.16 93 4-Cl-C 6H 4SO(=NTf)NHSO 2C 6H 4-4-NO 2 3.75 1.06 0.73 1.05 0.46 0.53 0.23 2.3 0.56 1.73 1.21 0.23 0.19 1.04 0.54 0.53 0.51 0.51 0.44 1.28 0.75 0.36 0.77 0.53 0.38 0.41 1.25 1.3 0.25 0.50 0.59 0.26 0.83 1.64 0.64 0.71 0.05 0.87 1.10 1.15 0.31 0.74 0.50 0.23 0.23 0.05 0.62 0.5 0.16 0.35 1.11 0.47 1.37 1.25 0.42 0.59 1.20 1.1 H 2 SO 4 pK a ca 8 19 1,2-Dichloroethane • Advantages of 1,2-DCE: • Very low basicity (B' = 40), low anion-solvating ability → strong superacids are measurable • pK auto unmeasurably high • Reasonably inert and stable, readily available, widely used, dissolves also many ionic compounds well • Transparent in UV down to 230 nm • Limitations: • ~Low polarity (ε = 10) • Ion-pair acidities 20 10
1,2-DCE acidity scale • The most acidic equilibrium acidity scale in a constantcomposition medium • Relative acidities • Not easy to anchor • Some values available in literature, but are doubtful A. Kütt et al J. Org. Chem. 2011, 76, 391 No Acid pK a(DCE) Directly measured ΔpK ip values in DCE a pK 1 Picric acid 0.0 2 HCl -0.4 0.73 0.71 1.48 0.36 3 2,3,4,6-(CF 3) 5-C 6H-CH(CN) 2 -0.7 1.09 0.77 0.74 4 4-NO 2-C 6H 4SO 2NHTos c -1.5 2.08 1.00 0.28 1.78 5 HNO 3 -1.7 1.01 6 4-NO 2-C 6H 4SO 2NHSO 2C 6H 4-4-Cl -2.4 1.13 0.88 0.08 7 H 2SO 4 -2.5 0.24 0.12 1.26 8 C 6(CF 3) 5CH(CN) 2 -2.6 1.02 1.02 1.05 9 (4-NO 2-C 6H 4-SO 2) 2NH -3.7 1.48 0.47 10 3-NO 2-4-Cl-C 6H 3SO 2NHSO 2C 6H 4-4-NO 2 -4.1 0.80 0.36 11 (3-NO 2-4-Cl-C 6H 3SO 2) 2NH -4.5 1.35 0.93 0.39 12 HBr -4.9 0.62 0.19 13 4-NO 2-C 6H 4SO 2CH(CN) 2 -5.1 1.03 0.80 14 2,4,6-(SO 2F) 3-Phenol -5.9 1.33 15 2,4,6-Tf 3-Phenol d -6.4 0.64 16 CH(CN) 3 -6.5 0.94 0.42 1.14 1.12 17 4-Cl-C 6H 4SO(=NTf)NHTos -6.8 0.33 0.65 0.51 0.05 18 NH 2-TCNP e -6.8 0.24 0.20 19 2,3,5-tricyanocyclopentadiene -7.0 20 Pentacyanophenol -7.6 0.67 0.84 21 4-Cl-C 6H 4SO(=NTf)NHSO 2C 6H 4-4-Cl -7.6 1.77 1.56 22 HI -7.7 1.64 1.00 0.98 1.13 23 4-NO 2-C 6H 4SO 2NHTf -7.8 1.10 0.93 1.04 1.01 0.81 24 Me-TCNP -8.6 0.96 0.90 0.09 25 3,4-(MeO) 2-C 6H 3-TCNP -8.7 0.13 1.42 -0.02 26 4-MeO-C 6H 4-TCNP -8.7 0.12 0.12 27 C(CN) 2=C(CN)OH -8.8 0.46 0.24 0.28 1.61 28 4-Cl-C 6H 4SO(=NTf)NHSO 2C 6H 4-NO 2 -8.9 0.22 0.59 0.74 29 2,4-(NO 2) 2-C 6H 3SO 2OH -8.9 0.67 0.06 0.59 30 C 6F 5CH(Tf) 2 -9.0 0.60 0.52 31 HB(CN)(CF 3) 3 -9.3 0.47 0.44 1.33 0.13 32 Ph-TCNP -9.4 1.56 1.62 0.83 1.57 33 HBF 4 -10.3 1.23 1.06 34 FSO 2OH -10.5 0.26 1.34 001 21 1,2-DCE acidity scale 2,4-(NO 2) 2-C 6H 3SO 2OH H N 45 [C(CN) 2=C(CN)] 2NH -11.8 46 3,5-(CF 3) 5-C 6H 3-TCNP -11.8 29 -8.9 30 C 6F 5CH(Tf) 2 -9.0 31 HB(CN)(CF 3) 3 -9.3 32 Ph-TCNP -9.4 33 HBF 4 -10.3 34 FSO 2OH -10.5 35 3-CF 3-C 6H 4-TCNP -10.5 36 H-TCNP -10.7 37 [C 6H 5SO(=NTf)] 2NH -11.1 38 [(C 2F 5)2PO] 2NH -11.3 39 2,4,6-(NO 2) 3-C 6H 2SO 2OH -11.3 40 [C(CN) 2=C(CN)] 2CH 2 -11.4 41 TfOH -11.4 42 C 6H 5SO(=NTf)NHTf -11.5 43 TfCH(CN) 2 -11.6 44 Br-TCNP -11.8 + N P N 48 4-Cl-C 6H 4SO(=NTf)NHTf -12.1 47 Tf 2NH -11.9 N 49 Cl-TCNP -12.1 • Ion pair acidities • Counter-ion: • Aqueous pK a (H 0 ) values down to -10 .. -15 50 (C 3F 7SO 2) 2NH -12.2 51 (C 4F 9SO 2) 2NH -12.2 52 CN-CH 2-TCNP -12.3 53 (C 2F 5SO 2) 2NH -12.3 54 CF 3-TCNP -12.7 55 HClO 4 -13.0 56 CF 2(CF 2SO 2) 2NH -13.1 57 4-NO 2-C 6H 4SO(=NTf)NHTf -13.1 58 HB(CN) 4 -13.3 59 (FSO 2) 3CH -13.6 60 Tf 2CH(CN) -14.9 61 2,3,4,5-tetracyanocyclopentadiene -15.1 62 CN-TCNP -15.3 63 Tf 3CH f -16.4 64 CF 3SO(=NTf)NHTf f -18 0.67 0.06 0.59 0.60 0.52 0.47 0.44 1.33 0.13 1.56 1.62 0.83 1.57 1.23 1.06 0.26 1.34 0.01 0.21 0.60 0.22 0.58 0.73 0.78 0.46 0.84 0.84 0.89 0.91 0.29 0.28 0.44 0.21 0.10 0.12 0.47 0.04 0.07 0.09 0.49 0.40 0.32 0.47 0.36 0.21 0.45 0.19 0.30 0.31 1.06 0.06 0.69 0.20 0.25 0.01 0.10 0.10 0.19 0.15 0.13 0.27 0.10 0.02 1.05 1.06 0.72 0.19 0.19 0.44 1.76 1.92 2.16 1.46 1.73 0.22 0.40 0.21 0.23 0.36 0.47 0.67 0.40 0.21 0.44 0.46 0.80 0.80 1.04 0.40 0.11 0.56 0.89 0.86 1.29 0.63 1.04 0.07 0.42 0.77 0.73 0.75 0.93 0.93 0.96 0.43 22 0.29 11
- Page 4 and 5: What is a superacid? • Superacidi
- Page 6 and 7: Solvent • As low basicity as poss
- Page 8 and 9: UV-Vis ΔpK a measurement Compound
- Page 12 and 13: Important aspects for superacids
- Page 14 and 15: Fluorine • Highly electronegative
- Page 16 and 17: 250 256 255.5 HSbF 6 250.8 HAuF 6 2
1,2-DCE acidity<br />
scale<br />
• The most acidic<br />
equilibrium acidity<br />
scale in a constantcomposition<br />
medium<br />
• Relative <strong>acidities</strong><br />
• Not easy to anchor<br />
• Some <strong>values</strong><br />
available in<br />
literature, but<br />
are doubtful<br />
A. Kütt et al J. Org. Chem.<br />
2011, 76, 391<br />
No Acid pK a(DCE) Directly measured ΔpK ip <strong>values</strong> in DCE a pK<br />
1 Picric acid 0.0<br />
2 HCl -0.4 0.73 0.71<br />
1.48 0.36<br />
3 2,3,4,6-(CF 3) 5-C 6H-CH(CN) 2 -0.7<br />
1.09<br />
0.77 0.74<br />
4 4-NO 2-C 6H 4SO 2NHTos c -1.5<br />
2.08 1.00<br />
0.28 1.78<br />
5 HNO 3 -1.7<br />
1.01<br />
6 4-NO 2-C 6H 4SO 2NHSO 2C 6H 4-4-Cl -2.4 1.13<br />
0.88 0.08<br />
7 H 2SO 4 -2.5<br />
0.24<br />
0.12 1.26<br />
8 C 6(CF 3) 5CH(CN) 2 -2.6<br />
1.02 1.02 1.05<br />
9 (4-NO 2-C 6H 4-SO 2) 2NH -3.7 1.48<br />
0.47<br />
10 3-NO 2-4-Cl-C 6H 3SO 2NHSO 2C 6H 4-4-NO 2 -4.1<br />
0.80<br />
0.36<br />
11 (3-NO 2-4-Cl-C 6H 3SO 2) 2NH -4.5 1.35<br />
0.93<br />
0.39<br />
12 HBr -4.9<br />
0.62<br />
0.19<br />
13 4-NO 2-C 6H 4SO 2CH(CN) 2 -5.1 1.03<br />
0.80<br />
14 2,4,6-(SO 2F) 3-Phenol -5.9 1.33<br />
15 2,4,6-Tf 3-Phenol d -6.4 0.64<br />
16 CH(CN) 3 -6.5 0.94<br />
0.42 1.14 1.12<br />
17 4-Cl-C 6H 4SO(=NTf)NHTos -6.8 0.33 0.65<br />
0.51 0.05<br />
18 NH 2-TCNP e -6.8<br />
0.24<br />
0.20<br />
19 2,3,5-tricyanocyclopentadiene -7.0<br />
20 Pentacyanophenol -7.6 0.67 0.84<br />
21 4-Cl-C 6H 4SO(=NTf)NHSO 2C 6H 4-4-Cl -7.6 1.77<br />
1.56<br />
22 HI -7.7<br />
1.64<br />
1.00<br />
0.98 1.13<br />
23 4-NO 2-C 6H 4SO 2NHTf -7.8 1.10 0.93<br />
1.04 1.01<br />
0.81<br />
24 Me-TCNP -8.6<br />
0.96<br />
0.90<br />
0.09<br />
25 3,4-(MeO) 2-C 6H 3-TCNP -8.7 0.13 1.42<br />
-0.02<br />
26 4-MeO-C 6H 4-TCNP -8.7<br />
0.12<br />
0.12<br />
27 C(CN) 2=C(CN)OH -8.8<br />
0.46 0.24<br />
0.28 1.61<br />
28 4-Cl-C 6H 4SO(=NTf)NHSO 2C 6H 4-NO 2 -8.9 0.22<br />
0.59<br />
0.74<br />
29 2,4-(NO 2) 2-C 6H 3SO 2OH -8.9 0.67<br />
0.06<br />
0.59<br />
30 C 6F 5CH(Tf) 2 -9.0<br />
0.60<br />
0.52<br />
31 HB(CN)(CF 3) 3 -9.3 0.47 0.44<br />
1.33 0.13<br />
32 Ph-TCNP -9.4 1.56 1.62<br />
0.83 1.57<br />
33 HBF 4 -10.3<br />
1.23<br />
1.06<br />
34 FSO 2OH -10.5 0.26 1.34<br />
001<br />
21<br />
1,2-DCE acidity<br />
scale<br />
2,4-(NO 2) 2-C 6H 3SO 2OH<br />
H N<br />
45 [C(CN) 2=C(CN)] 2NH -11.8<br />
46 3,5-(CF 3) 5-C 6H 3-TCNP -11.8<br />
29 -8.9<br />
30 C 6F 5CH(Tf) 2 -9.0<br />
31 HB(CN)(CF 3) 3 -9.3<br />
32 Ph-TCNP -9.4<br />
33 HBF 4 -10.3<br />
34 FSO 2OH -10.5<br />
35 3-CF 3-C 6H 4-TCNP -10.5<br />
36 H-TCNP -10.7<br />
37 [C 6H 5SO(=NTf)] 2NH -11.1<br />
38 [(C 2F 5)2PO] 2NH -11.3<br />
39 2,4,6-(NO 2) 3-C 6H 2SO 2OH -11.3<br />
40 [C(CN) 2=C(CN)] 2CH 2 -11.4<br />
41 TfOH -11.4<br />
42 C 6H 5SO(=NTf)NHTf -11.5<br />
43 TfCH(CN) 2 -11.6<br />
44 Br-TCNP -11.8<br />
+<br />
N P N<br />
48 4-Cl-C 6H 4SO(=NTf)NHTf -12.1<br />
47 Tf 2NH -11.9<br />
N<br />
49 Cl-TCNP -12.1<br />
• Ion pair <strong>acidities</strong><br />
• Counter-ion:<br />
• Aqueous pK a<br />
(H 0<br />
)<br />
<strong>values</strong> down to<br />
-10 .. -15<br />
50 (C 3F 7SO 2) 2NH -12.2<br />
51 (C 4F 9SO 2) 2NH -12.2<br />
52 CN-CH 2-TCNP -12.3<br />
53 (C 2F 5SO 2) 2NH -12.3<br />
54 CF 3-TCNP -12.7<br />
55 HClO 4 -13.0<br />
56 CF 2(CF 2SO 2) 2NH -13.1<br />
57 4-NO 2-C 6H 4SO(=NTf)NHTf -13.1<br />
58 HB(CN) 4 -13.3<br />
59 (FSO 2) 3CH -13.6<br />
60 Tf 2CH(CN) -14.9<br />
61 2,3,4,5-tetracyanocyclopentadiene -15.1<br />
62 CN-TCNP -15.3<br />
63 Tf 3CH f -16.4<br />
64 CF 3SO(=NTf)NHTf f -18<br />
0.67 0.06<br />
0.59<br />
0.60<br />
0.52<br />
0.47 0.44<br />
1.33 0.13<br />
1.56 1.62<br />
0.83 1.57<br />
1.23<br />
1.06<br />
0.26 1.34<br />
0.01<br />
0.21<br />
0.60 0.22<br />
0.58<br />
0.73 0.78 0.46<br />
0.84<br />
0.84<br />
0.89 0.91<br />
0.29<br />
0.28<br />
0.44 0.21<br />
0.10<br />
0.12<br />
0.47<br />
0.04<br />
0.07 0.09 0.49<br />
0.40 0.32 0.47<br />
0.36<br />
0.21 0.45<br />
0.19<br />
0.30 0.31<br />
1.06<br />
0.06<br />
0.69<br />
0.20 0.25<br />
0.01<br />
0.10<br />
0.10<br />
0.19<br />
0.15<br />
0.13<br />
0.27<br />
0.10<br />
0.02<br />
1.05 1.06<br />
0.72<br />
0.19<br />
0.19<br />
0.44<br />
1.76<br />
1.92<br />
2.16<br />
1.46<br />
1.73 0.22<br />
0.40<br />
0.21 0.23<br />
0.36<br />
0.47<br />
0.67<br />
0.40<br />
0.21<br />
0.44<br />
0.46<br />
0.80<br />
0.80 1.04<br />
0.40<br />
0.11<br />
0.56<br />
0.89 0.86<br />
1.29<br />
0.63<br />
1.04<br />
0.07<br />
0.42<br />
0.77<br />
0.73 0.75<br />
0.93<br />
0.93<br />
0.96<br />
0.43<br />
22<br />
0.29<br />
11
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