Functional Groups and pKa Values

Aldehyde

Structure: R-CH=O (Carbonyl group bonded to a hydrogen and an R group)

Ketone

Structure: R-C(=O)-R (Carbonyl group bonded to two carbon groups)

Carboxylic Acid

Structure: R-COOH (Carbonyl group bonded to an OH group)

Ester

Structure: R-COO-R' (Carbonyl group bonded to an OR group)

Ether

Structure: R-O-R' (Oxygen atom bonded to two carbon groups)

Alcohol

Structure: R-OH (Hydroxyl group bonded to a carbon)

Amine

Structure: R-NH2 / R-NH-R' / R-N(R')R'' (Nitrogen bonded to alkyl or aryl groups)

Amide

Structure: R-C(=O)-NR2 (Carbonyl group bonded to a nitrogen atom)

Alkene

Structure: C=C (Carbon-carbon double bond)

Alkyne

Structure: C≡C (Carbon-carbon triple bond)

Alkane

Structure: C-C (Saturated hydrocarbons with single bonds)

Thiol

Structure: R-SH (Sulfhydryl group bonded to a carbon)

Acid Chloride

Structure: R-COCl (Carbonyl group bonded to a chlorine atom)

Anhydride

Structure: R-C(=O)-O-C(=O)-R' (Two acyl groups bonded to the same oxygen atom)

Epoxide

Structure: Three-membered cyclic ether ring containing an oxygen atom

Nitrile

Structure: R-C≡N (Carbon triple-bonded to a nitrogen atom)

Peroxide

Structure: R-O-O-R or R-COO-OH (Contains a single oxygen-oxygen bond)

pKa of Protonated Carbonyl

-7

pKa of Hydronium / Protonated Alcohol

0

pKa of Carboxylic Acid

5

pKa of Proton between two carbonyls

10

pKa of Phenol

10

pKa of Protonated Amine

10

pKa of Amide

15

pKa of Alcohol

16

pKa of Water

16

pKa of Alpha Proton (adjacent to carbonyl)

20

pKa of Terminal Alkyne

25

pKa of Amine

35

pKa of Aryl / Vinyl Proton

40

pKa of Alkane

50

pKa of Hydroiodic Acid (HI)

-10

pKa of Hydrobromic Acid (HBr)

-8

pKa of Hydrochloric Acid (HCl)

-7

pKa of Sulfuric Acid

-3

pKa of Nitric Acid

0

pKa of Carbocations

-3

pKa of Hydrofluoric Acid (HF)

3

pKa of Hydrogen Nitride (HN3)

5

pKa of Hydrogen Cyanide (HCN)

9