pKa Values

Name and Structure

Typical pKa Value

Alcohol Hydronium Ion, ROH2+

-3.5

Hydronium Ion, H3O+

-1.7

Carboxylic Acid, RCO2H

4-5

ß-Diketone, beta diketone

~9

Phenol, ArOH

10

Alkylammonium Ion, RNH3+

10-11

Thiol, RSH

10-11

ß-Ketoester, beta keto ester

11

Water, H2O

15.7

Amide, Acetamide with methyl H bolded

15-19

Alcohol, ROH

16-18

Aldehyde/Ketone α-Hydrogen, Ketone with alpha H bolded

18-20

Ester α-Hydrogen, Ester with methyl bolded

23-25

Alkyne, RCCH

25

Hydrogen, H2

35

Amine, Ammonia, RNH2 , NH3

~40

Alkene, H2C=CH2

44

Alkane, RH

51


Dr. Peggy Kline | Physical Science Department | Santa Monica College | last updated 2/17/09