CHEM301 F10 CA4 - CHEM 301 Fall 2010 Dr Ruder Class...

CHEM 301, Fall 2010 Dr. Ruder
Class Activity 4
Nomenclature of Alkanes
How do we name organic compounds?
Model 1: Straight Chain Alkanes
# Carbons Prefix Name Structure
1 Meth Methane CH
4
2 Eth Ethane CH
3
CH
3
3 Prop Propane CH
3
CH
2
CH
3
4 But Butane CH
3
CH
2
CH
2
CH
3
5 Pent Pentane CH
3
CH
2
CH
2
CH
2
CH
3
6 Hex Hexane CH
3
CH
2
CH
2
CH
2
CH
2
CH
3
7 Hept Heptane CH
3
CH
2
CH
2
CH
2
CH
2
CH
2
CH
3
8 Oct Octane CH
3
CH
2
CH
2
CH
2
CH
2
CH
2
CH
2
CH
3
9 Non Nonane CH
3
CH
2
CH
2
CH
2
CH
2
CH
2
CH
2
CH
2
CH
3
10 Dec Decane CH
3
CH
2
CH
2
CH
2
CH
2
CH
2
CH
2
CH
2
CH
2
CH
3
Questions:
1. Based on the information in Table 1, how is the prefix modified to name a straight
chain alkane?
2. The prefix dodec means twelve carbons. Give the name of the corresponding alkane
and draw the structure.
Model 2: Branched Alkanes
- Note that a dash separates a number and a letter in a name.
Structure Parent
Chain
#C in
parent
Substituent #C in
substituent
Name
A propane 3 methyl 1 2-methylpropane
B 2-methylbutane
C pentane 5 ethyl 2
D 3-methylhexane
Questions:
3 . For compound A in Model 2.
(a). How many carbons are in the parent chain? Circle the parent chain.
(b). How many carbons are in the substituent? Put a box around the substituent.
(c). Number the carbons in the parent chain consecutively.
(d). Why is there a number 2 in front of the methyl in the name?
4. Complete the table for B, C and D.

CHEM 301, Fall 2010 Dr. Ruder
5. (a). For compound B in Model 2, number the carbons in the parent chain
consecutively.
(b). Does your numbering scheme agree with the name given?
(c). If not, renumber the chain so the numbering agrees with the name.
(d). The name for compound B is 2-methylbutane, not 3-methylbutane. What
conclusion can you make for numbering substituents?
6 . (a). For compound D, circle the parent chain. Does the parent have six carbons?
(b). If not circle a chain with six continuous carbons.
(c). The parent name for compound D is 3-methylhexane not 2-ethylpentane. What
conclusion can you make about choosing the parent chain?