Download Drawing Organic Structures Functional Groups Constitutional Isomers

DRAWING ORGANIC STRUCTURES
FUNCTIONAL GROUPS
CONSTITUTIONAL ISOMERS
Dr. Sheppard
CHEM 2411
Spring 2015
Klein (2nd ed.) sections 2.1 – 2.6, 4.3
Draw Lewis 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
Molecular Representations
• Example: isopropyl alcohol (C3H80)
• Lewis structure
• Show all bonds, atoms, lone pairs
• Partially condensed/Condensed structure
• Omit some bonds (C─C, C─H, O─H, N─H)
• Often omit lone pairs
• Not the same as a molecular formula
• Skeletal structure/Bond-line 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 structures
Name
Acetone
Butane
1-Butene
Cyclohexane
Benzene
Lewis structure
Condensed structure
Line-angle drawing
Lone Pairs on Line-angle Drawings
• Formal charges must be shown
• Lone pairs may be omitted, and can be determined from
structure
Lone Pairs on Line-angle Drawings
Interpreting Line-angle Structures
• What is the molecular formula for the following:
• What is the molecular formula for adrenaline?
• What is the molecular formula for thalidomide?
Molecular Representations
• Which Lewis structure is correct?
Molecular Representations
• Draw partially condensed and line-angle structures for this
condensed structure: (CH3)3CCH2COCHCH2
• How many hydrogens on each carbon atom?
3D Organic Structures
• Remember, carbons are tetrahedral
• Use dashes and wedges to show 3D structure
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
O
• Aldehyde: RCHO
CH3CH2
• Ketone: RCOR'
C H
O
CH3
C CH3
Carboxylic acids and their derivatives
• Carboxylic Acid: RCOOH
O
C OH
O
• Acid Chloride: RCOCl
C Cl
O
• Ester: RCOOR' (RCO2R’)
C OCH
3
O
• Amide: RCONH2
• Acid Anhydride: RCO2COR
C NH
2
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 (PO42-)
• Thiol (R─SH)
• Sulfides (R─S─R)
• Sulfoxides (S=O)
• Thioester (RCOSR)
Functional Groups
• Identify the functional group(s) present in the following
molecules.
OH
(a)
O
(e)
(b)
H N
O
(f)
(c)
O
O
O
(d)
NH2
(g)
OH
OH
Functional Groups
• Identify the functional groups present in thalidomide:
• Draw as many structures as you can with the molecular
formula C4H8O2. Identify the functional groups present in
each structure.
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
Constitutional Isomers
Constitutional Isomers
• Are the following pairs of molecules constitutional
isomers, the same molecule, or neither?
(a)
(b)
(c)
(d)