DRAWING ORGANIC STRUCTURESFUNCTIONAL GROUPSCONSTITUTIONAL ISOMERSDr. ClowerCHEM 2411Spring 2014

McMurry (8th ed.) sections 1.12, 3.1, 3.2

Draw these structures…• C2H6

• CH4O

• C3H6 (contains C=C)

• C4H10 (multiple possible answers)

More Lewis structures…• CH5N

• CHN

• HNO3

• Remember…• Keep in mind total available valence electrons• Try to minimize formal charges• Patterns for formal charge

Drawing Organic Structures• Example: isopropyl alcohol (C3H80)

• Lewis structure• Show all bonds, atoms, lone pairs

• Condensed structure• Omit some bonds (C─C, C─H, O─H, N─H)• Often omit lone pairs

• Skeletal structure/line-angle drawing• Show bond framework as lines• C atoms at intersections of lines (bonds) and end of each line• H atoms bonded to C are not shown• Heteroatoms (atoms other than C and H) are shown

Drawing line-angle structuresName Lewis structure Condensed structure Line-angle drawing

Acetone

Butane

1-Butene

Cyclohexane

Benzene

C C C

O H

H

H

H

H

H

C C C CH

H

H

H

H

H

H

H

H

H

C C C CH

H H H

H

H

H

H

C

CC

C

CC

HHH

H

H

H

H

H

H HH

H

H H

H

HH

H

Interpreting line-angle structures• What is the molecular formula for adrenaline?

• What is the molecular formula for thalidomide?

HO

OH

N

HO

H

N

N

O

O O

O

H

Drawing Organic Structures• Draw Lewis and line-angle structures for this condensed

structure: (CH3)3CCH2COCHCH2

Functional Groups• Collection of atoms at a

site within a molecule with a common bonding pattern

• Reacts in a typical way, generally independent of the rest of the molecule

• Four broad classes• Hydrocarbons• Compounds containing O• Compounds containing N• Compounds containing S

or P

1. Hydrocarbons• Alkane: single bonds, sp3 carbons• Cycloalkane: carbons form a ring• Alkene: double bond, sp2 carbons• Cycloalkene: double bond in ring• Alkyne: triple bond, sp carbons• Aromatic (arene): contains a benzene ring

• Not a hydrocarbon, but related…• Alkyl halide: R─X

• R = any carbon group• X = halogen

2. Compounds containing oxygen• Alcohol: R─OH• Ether: R─O─R'• Carbonyl group: C=O

• Aldehyde: RCHO

• Ketone: RCOR'

CH3CH2 C

O

H

CH3 C

O

CH3

Carboxylic acids and their derivatives• Carboxylic Acid: RCOOH

• Acid Chloride: RCOCl

• Ester: RCOOR' (RCO2R’)

• Amide: RCONH2

• Acid Anhydride: RCO2COR

C

O

OH

C

O

Cl

C

O

OCH3

C

O

NH2

CO

C

O O

3. Compounds containing nitrogen

• Amines: RNH2, RNHR', or R3N

• Amides: RCONH2, RCONHR, RCONR2

• Nitrile: RCN CH3 C N

4. Compounds containing S or P• Phosphates (PO4

2-)

• Thiol (R─SH)

• Sulfides (R─S─R)

• Sulfoxides (S=O)

• Thioester (RCOSR)

Isomers• Isomers have the same molecular formula, but different

arrangements of atoms

• Constitutional isomers • differ in their connectivity

• Stereoisomers• differ in the spatial arrangement/orientation of their atoms

Constitutional Isomers• Molecules with the same molecular formula, but different

connectivity• Same number and kinds of atoms• Differ in which atoms are bonded

• Example: C4H10

• Straight-chain (“normal”) alkane vs. branched-chain alkane

CH3 CH2 CH2 CH3 CH3 CH CH3

CH3

butane isobutane

Constitutional Isomers

Constitutional Isomers• Are the following pairs of molecules constitutional

isomers, the same molecule, or neither?

(a)

(b)

(c)

(d)

CH3 CH2 CH CH3

CH2 CH3

CH3 CH2 CH CH2 CH3

CH3

CH CH2 CH2 CH CH2

CH3

CH2

CH3 CH3CH3CH3

CH3

CH3 C

CH3

CH3

CH2 CH3 CH3 C

CH3

CH2

CH2 CH3

CH3

CH3 CH2 CH2 CH2 CH2 CH3 CH2 CH CH2

CH3 CH3 CH3