1. Drawing Organic Structures Functional Groups Constitutional Isomers
Dr. Sheppard
CHEM 2411
Spring 2015
Klein (2nd ed.) sections 2.1 – 2.6, 4.3

2. Draw Lewis structures…
C2H6
CH4O
C3H6 (contains C=C)
C4H10 (multiple possible answers)

3. More Lewis structures…
CH5N
CHN
HNO3
Remember…
Keep in mind total available valence electrons
Try to minimize formal charges
Patterns for formal charge

4. 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

5. Drawing line-angle structures
Name
Lewis structure
Condensed structure
Line-angle drawing
Acetone
Butane
1-Butene
Cyclohexane
Benzene

6. Lone Pairs on Line-angle Drawings
Formal charges must be shown
Lone pairs may be omitted, and can be determined from structure

7. Lone Pairs on Line-angle Drawings

8. 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?

9. Molecular Representations
Which Lewis structure is correct?

10. Molecular Representations
Draw partially condensed and line-angle structures for this condensed structure: (CH3)3CCH2COCHCH2
How many hydrogens on each carbon atom?

11. 3D Organic Structures Remember, carbons are tetrahedral
Use dashes and wedges to show 3D structure

12. 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

13. 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

14. 2. Compounds containing oxygen
Alcohol: R─OH
Ether: R─O─R'
Carbonyl group: C=O
Aldehyde: RCHO
Ketone: RCOR'

15. Carboxylic acids and their derivatives
Carboxylic Acid: RCOOH
Acid Chloride: RCOCl
Ester: RCOOR' (RCO2R’)
Amide: RCONH2
Acid Anhydride: RCO2COR

16. 3. Compounds containing nitrogen
Amines: RNH2, RNHR', or R3N
Amides: RCONH2, RCONHR, RCONR2
Nitrile: RCN

17. 4. Compounds containing S or P
Phosphates (PO42-)
Thiol (R─SH)
Sulfides (R─S─R)
Sulfoxides (S=O)
Thioester (RCOSR)

19. Functional Groups
Identify the functional group(s) present in the following molecules.

20. 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.

21. 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

22. 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

23. Constitutional Isomers

24. Constitutional Isomers
Are the following pairs of molecules constitutional isomers, the same molecule, or neither?
(a)
(b)
(c)
(d)