Functional Groups

Alkane

non-polar, hydrophobic, lipophilic

chemically stable

tetrahedral

Alkyl Halide (Haloalkane)

hydrophobic, lipophilic

chemically stable

(X = F, Cl, Br, I )

may be displaced by nucleophiles or eliminated by bases.

Alkene

non-polar, hydrophobic, lipophilic

stable

planar

C=C

Alkyne

non-polar, hydrophobic, lipophilic

stable hydrocarbon

linear

Aromatic Hydrocarbon (Arene)

non-polar, hydrophobic, lipophilic

stable

planar ring system

$(4n + 2 e^-)$ delocalized electrons

Aromatic Halide

hydrophobic, lipophilic

stable

polarity depends on the attached halogen

Benzylic Carbon

non-polar, hydrophobic, lipophilic

stable

carbon atom directly attached to an aromatic ring.

Alcohol

polar, hydrophilic

stable

neutral/ high pKa (>14)

Enol

acidic

variable pKa

tautomer of a ketone (less stable)

Phenol/Phenolate

polar, hydrophilic

stable

weakly acidic pKa = 10

Catechol

polar, hydrophilic

weakly acidic pKa = 9.4

2 adjacent OH groups on an aromatic ring

prone to oxidation

Ether (Dialkylether / Arylether)

intermediate polarity

neutral

stable

(diethyl ether and THF can form unstable peroxides)

Epoxide

cyclic ether

intermediate polarity

strained and readily attacked by nucleophiles

Peroxide

intermediate polarity

unstable

reactive with reducing groups

Aldehyde

polar, hydrophilic

electron-withdrawing

prone to oxidation (into COOH)

Ketone

polar, hydrophilic

stable

electron-withdrawing

Carboxylic Acid/Carboxylate

weak acid pKa 5

polar, hydrophilic anion (carboxylate) at pH 7

Benzoic Acid/Benzoate

aromatic carboxylic acid

pKa 4

polar, chemically stable anion (benzoate) at pH $7$.

Ester (if cyclic: Lactone)

electron-withdrawing

intermediate polarity

Carbonate

intermediate polarity

Amide (if cyclic: Lactam)

polar, hydrophilic

neutral

planar geometry

stable

electron-withdrawing

Urea

polar, hydrophilic

neutral

planar

similar properties to an amide

Carbamate (Urethane)

polar, hydrophilic

neutral

amide-like properties

ester-like side hydrolyze more slowly than esters

(Aminium) Amine

polar, hydrophilic

basic pKa 11

free base can oxidize

Aromatic Amine (Arylamine)

polar hydrophilic,

weakly basic pKa 5

stable amine attached to an aromatic ring

Quaternary Amine

polar, hydrophilic

fixed cation

Amidine

polar, hydrophilic

basic pKa 12

planar

Guanidine

polar, hydrophilic

basic pKa 13

planar

Nitro

neutral, stable

strongly electron-withdrawing

Nitrile

neutral, linear, stable

strongly electron-withdrawing

Thiol (Mercaptan)

weakly polar

very weakly acidic pKa 10

forms disulfides in oxidizing environments

Thioether (Sulfide)

weakly polar

stable

forms sulfoxides in oxidizing environments

Disulfide

stable

prefers 90 torsion angle

reduced to thiols or oxidized to sulfonates.

Sulfoxide

polar, stable

S can be chiral

Sulfone

polar, stable

Sulfonic Acid (sulfonate)

polar, hydrophilic, stable

strongly acidic pKa <0

Sulfonamide (Alkylsulfonamide)

polar, hydrophilic, stable

neutral

Aromatic Sulfonamide (Arylsulfonamide)

polar, hydrophilic

weakly acidic pKa 10

electron-withdrawing substituents can lower its pKa

Sulfate Monoester

polar, hydrophilic

strongly acidic pKa <0

Phosphate Monoester

polar, hydrophilic

anion (-1 charge) pka 2

dianion (-2 charge) pka 6