Properties of Functional Groups

Alkanes

1. Contain only C and H

2. C atoms are sp3 hybridized (tetrahedral, can be distorted by strain)

3. rotation around C-C single bond occurs freely (except in ring systems)

Alkenes

1. Contain only C and H

2. C atoms in double bond sp2 (trigonal planar)

3. C atoms not in double bond sp3 hybridized

4. double bond is planar and cant rotate

Conjugated Alkenes

1. Contain only C and H

2. C atoms in double bonds sp2 (trigonal planar)

3. Pi orbitals of conjugated double bonds interact allowing pi electrons to delocalize (creates more complex pi molecular orbitals)

4. double bonds are planar and cant rotate. single bonds between double bond can rotate

Alkynes

1. C atoms in triple bond sp (linear)

2. Triple bond cant rotate, but entire alkyne can rotate like a cylinder

Aromatic compounds

1. Completely conjugated rings of pi electron systems with extra stability

2. Ring systems are flat

3. C atoms in ring are sp2

4. All C-C bond lengths identical

5. Pi electrons delocalized around the ring system

Alcohols

1. Contain the hydroxy group (-OH)

2. O atom is sp3 hybridized

3. Alcohols are weakly acidic (pKa ~10-15)

4. R-O-H can donate or accept H-bonds

5. C-O bond is polar

Ethers

1. O atom is sp3 hybridized

2. C-O bonds are polarized

3. C-O bond slightly shorter than C-C bond

4. The C-O bond rotates freely

Thiols, Sulfides, Sulfoxides, Sulfones

1. Thiols (R-SH) and thioethers (R-S-R) are comparable to alcohols and ethers, but S is larger & more polarizable

2. Thioethers can be oxidized to sulfoxides and sulfones

   1. S atom has tetrahedral electron geometry in both

Amines

1. N atom is sp3 but inversion occurs

2. Amines are basic

3. C-N bond is polarized

4. Different classes based on carbon substituents

5. Amines can donate and accept H-bonds

Aldehydes and Ketones

1. Contain a polar carbonyl group

2. C and O atom in carbonyl sp2 (trigonal planar)

   1. lone pairs in hybridized atomic orbitals

3. Carbonyl group contains 1 sigma and 1 pi bond

4. Carbonyl group is planar and rotation is restricted

Carboxylic Acid Derivatives

1. Carboxylic acids are acidic (pKa ~4-6)

2. Carboxylic acids form strong H-bonds (a stable dimer forms)

3. The C=O bond doesn’t rotate, but the C-O bond does

4. Esters (R’=alkyl, aryl, etc)

Amides

1. Lone pair on N delocalized into carbonyl stem

2. C-N bond is short and has partial double bond character and limited rotation

Compounds w/ Nitro Groups

1. Planar group. Central N is sp2 hybridized and N-O bonds

2. Must include formal charges when drawing the bonding of the NO2 group

3. Can be conjugated with alkenes or aromatic rings