pKas

Hydrobromic Acid
HBr
-9
Hydrochloric Acid
HCl
-8
Picric Acid
(NO2)3C6H2OH
0
Hydrofluoric Acid
HF
3.2
Acetic Acid
HCO2CH3
4.75
Benzoic Acid
PhCo2H
4.25
Hydrazoic Acid
HN3
4.7
Cyanic Acid
HCN
9.1
Thiophenol
PhSH
6.5
Ammonium
NH4+
9.2
Phenol
PhOH
10.0
trifluoroethanol
F3CCh2OH
12.4
Amide
Ch3CoNH2
15.1
methanol
15.5
water
H20
15.75
Alkane Chain Length
Decreases acidity in solution (makes it harder to solvate)
Electrowithdrawing group
Increase Acidity by stabilizing the anion
Ketones
20
thiols
about 10
esters, nitriles, sulfones
~25
Alcohols
16-18
Adenine
[image]
Thymine
[image]
Guanine
[image]
Cytosine
[image]
Uracil
[image]
Toluene
C6H5CH3
37
ethers
~20
E vs. Z acids
Acids prefer the Z-form by about 5 kcal/mol
Carbocation Stability
More substituted carbons more stable cation because of electron donating methyls and hyperconjugation/resonance
Carbanions
Stability affected by Electronegativity, delocatiolization of charge
Activation Energy -> half life
3 5 10 15 20 30
3->17E-12s
5->4.8E-10s
10->2E-6s
15->0.0084s
20->35s
30->6916 days
Radicals
More substituted carbons also more stable radicals
Equilibrium Constants and Free Energy Difference
0
-1.36
-2.72
-4.08
0 -> K = 1 50% each
-1.36 -> K = 10 90% 10%
-2.72 -> K = 100 99% 1%
-4.08 -> K = 1000 99.9% 0.1%
Thorpe-Ingold Effect
Gem-dimethyl Effect
Increasing size of substituents of tetrahedral center increases reaction rate between other two and decreases the angle
Anomeric Effect
Explains why OCH3 prefers axial when in a heterocycle, and why hydrogen peroxide is at 120
Inductive Effect
Withdrawing Electrons through sigma bonds to the more electronegative group
Field Effect
polarization through charges that interact through space
Hybridization Formula
cos @ = -1/m
sp^m
Electronegativity
1/2(Ionization Potential + Electron Affinity)
Hill Plot
log ([SL]/[S]) vs. log [L]

expect 1 but if slope greater than one hints at cooperativity

Benensi-Hildebrand Plot
Double Reciprocal
1/[Fraction of S] vs. 1/[L]
Scatchard Plot
calculates affinity constant of ligand with protein
R lnKa =
(with heat capacity)
-dH/T + CplnT + (dS-dCp)
dielectric constant
Measured by the shielding a solvent gives when put between a capacitor by opposing the E-field
Kirkwood Factor
Related to the Bell Equation and Dielectric Constant

e-1/2e+1

delta-d
Solubility
Hildebrand

“Cohesive Energy Density”

d^2 = dH(vap) – RT/molar volume

Kosover Z-Scale (Z)
Reichardt Scale (Et)
From Absorption Spectra of salts

The more polar the solvent the higher the frequency of light needed to go from ion pair to two radicals

Y Scale
Winstein and Grunwald
Used rates of solvolysis of t-Bu chloride
log ky/k0 = mY

m – substrate specificity
Y = solvent scale and also related to Et
k0 based off 80% aquaous ethanol (20% water)

Why Water is weird
1) Temperature of max density higher than melting point
2)thermal expansion 1/V(dV/dT) is negative from -20 to 4
3) Bulk Modulus Kappa= -VdP/dV
has minimum at 46 C
4)Cp pretty much constant from 0-100 but changes a lot at low temperatures
18-crown-6
K+
15-crown-5
Na+
Crown Ethers and Macrocycles pioneered by:
Cram, Lehn, Petersen
spherands
[image]
Rebek
Kemp’s Triacid to bind DNA bases
Hamilton
Cyclophane like things to make bind adenine
Zimmerman
Molecular Tweezers
3 aromatic portions with acid moeity to bind
Secondary vs. Primary H-bonding
Primary worth 7.5
Secondary worth 2.5
Cyclophanes
Diederich
evolved from Pedersens crown ethers
Had solubilizing Ammonium Groups
alpha-effect
larger anions not as well solvated, originally thought to be lone-pair lone-pair repulsions
Hammett Equation
log Kx/Ko = sigmax * rho
a positive sigma -> electron withdrawing
negative -> electron donating
?>1, the reaction is more sensitive to substituents than benzoic acid and negative charge is built during the reaction.
0?=0, no sensitivity to substituents, and no charge is built.
?<0, the reaction builds positive charge.
Swain-Scott Equation
log (k/ko) = sn
n = nucleophilicity
s = substrate specificity
Grunwald-Winstein Equation
log(k/ko) = mY

Y is solvent scale
m is sensitivity of substrate

based of solvolysis of t-butyl chloride in 80% aqueous ethanol

alpha-carbonyl effect on Sn2
has to be in the same plane with p orbital of carbonyl and siqma star LUMO
x

Hi!
I'm Larry

Hi there, would you like to get such a paper? How about receiving a customized one?

Check it out