Must Know pKa Values

HI / I⁻ -10

H2SO4 / HSO4⁻ -9

HBr / Br⁻ -9

HCl / Cl⁻ -7

H3O+ / H2O -1.7

HF / F⁻ +3

Protonated nitrile (R-C≡N-H+) / nitrile (R-C≡N) -10

Protonated ketone or aldehyde / ketone or aldehyde -5 to -10

Protonated ester / ester -4

Protonated carboxylic acid / carboxylic acid -2

MeCOOH / MeCOO⁻ (acetic acid) 4.76

PhNH3+ / PhNH2 (anilinium) 4.6

H2S / HS⁻ 7

NH4+ / NH3 9.2

R3NH+ / R3N (protonated trialkylamine) 10-11

PhOH / PhO⁻ (phenol) 9.95

RCH2NO2 (nitroalkane) 10

Acetoacetate: H3C-CO-CH2-CO-OR 11

Malonate diester: RO-CO-CH2-CO-OR 13

Ketone (R-CO-CH3, alpha H) 16

Ketone (R-CO-R, alpha H) 19-20

Nitrile alpha H (R-CH2-C≡N) 25

Ester alpha H (R-CO-OR) 25

Amide alpha H (R-CO-NR1R2) 26

MeOH / MeO⁻ 15

H2O / HO⁻ 15.7

RCH2OH / RCH2O⁻ (primary alcohol) 16

R1R2CHOH / R1R2CHO⁻ (secondary alcohol) 16.5

R3COH / R3CO⁻ (tertiary alcohol) 17

RCONH2 / RCONH⁻ (amide N-H) 17

ROH / RO⁻ (general alcohol) 15-17

H2 / H⁻ 35

NH3 / NH2⁻ 38

i-Pr2NH / LDA 38

CH4 / CH3⁻ 48

isobutane / (CH3)3C⁻ 51