1. Handout: Hydrocarbons: IUPAC names
Naming Hydrocarbons (nomenclature)
Handout: Hydrocarbons: IUPAC names

2. Drawing structures: it’s all good
2-butene
This is called the “condensed structure”
On a test, choose a method that shows all Hs
CH3CH=CHCH3
Using brackets can also shorten some formulas: CH3(CH2)4CH3 vs. CH3CH2CH2CH2CH2CH3

3. Background: formulas for HCs
Alkanes= CnH2n+2, enes= CnH2n, ynes= CnH2n-2
Remember enes, then think of what would happen if bond was single or triple instead.
Provides some useful information (e.g. for compositional analysis, or to check work)
Cannot always tell hydrocarbon type based on numbers (e.g. propyne vs. propadiene)
Q - how many hydrogens in each of these:
6 carbon alkane
Alkene: C22H 14 44
8 (2x5 - 2 = )

4. Naming: common vs. IUPAC
Common names used in the 1800’s are still used for some compounds today:
Acetone
Formic acid
Acetylene
The International Union of Pure and Applied Chemistry (IUPAC) was established in 1900s
Frequent revisions to nomenclature
Systematic method allows an infinite number of compounds to be named given a few rules

5. Basic names of hydrocarbons
Hydrocarbon names are based on: 1) class 2) # of C, 3) side chain type and 4) position
1) name will end in -ane, -ene, or -yne
2) the number of carbons is given by a “Prefix”
1 meth- 2 eth prop- 4 but pent hex hept- 8 oct non dec-
Actually, all end in a, but a is dropped when next to a vowel. E.g. a 6 C alkene is hexene
Q - What names would be given to these:
7C, 9C alkane
2C, 4C alkyne
1C, 3C alkene
heptane, nonane
ethyne, butyne
does not exist, propene

6. Mnemonic for first four prefixes
Monkeys
Eat
Peeled
Bananas
First four prefixes
Meth-
Eth-
Prop-
But-

7. ? Other prefixes Decade Decimal Decathalon Pent- Oct- Dec-
Hex-, Hept-, Non-

8. Numbering carbons 1-pentene Q- draw pentene A- Where’s the bond?
We number C atoms
Thus, naming compounds with multiple bonds is more complex than previously indicated
Only if 2+ possibilities exist, are #s needed
Always give double bond the lowest number
Q - Name these
C2H4
2-butene
Ethene
3-nonyne

9. Multiple multiple bonds
2,3-heptadiene
2,4,6-nonatriyne
Give 1st bond (1st point of difference) lowest #
include di, tri, tetra, penta, etc. before ene/yne
Comma between #s, hyphen between #-letter
You do not need to know ene + yne
CH3CH2CH2CH=C=CH2
2-butyne
1,2,4-pentatriene
1,2-hexadiene

10. Cyclic structures Cyclic structures are circular Have “cyclo” in name
Benzene is not a cyclic structure
cyclopentane
Q- Draw these (note: carbons in a double bond should be consecutive- 1 and 2, 5 and 6, etc.):
cyclobutene 1,3-cyclopentadiene cyclopropane

11. Naming side chains Names are made up of: side chains, root3
Names are made up of: side chains, root
2,3-dimethylpentane
Root is the longest possible HC chain
Must contain multiple bonds if present
Add -yl to get name of side chain
Common side chains include:
CH3- methyl CH3CH2- ethyl
CH3CH2CH2- propyl (CH3)2CH- isopropyl
“iso” (branched) is not an IUPAC convention
Br- (bromo), Cl- (chloro), F- (fluoro), I- (iodo)

12. Naming side chains
Example: use the rules on the bottom of handout to name the following structure
Rule 1: choose the correct ending
ene

13. Naming side chains
Rule 2: longest carbon chain
ene

14. Naming side chains Rule 3: attach prefix (according to # of C) ene
1-hexene

15. Naming side chains
Rule 4: Assign numbers to each carbon
1-hexene

16. Naming side chains Rule 4: Assign numbers to each carbon 1-hexene

17. Naming side chains Rule 5: Determine name for side chains 1-hexene
ethyl
methyl
methyl
Rule 5: Determine name for side chains
1-hexene
1-hexene

18. Naming side chains Rule 6: attach name of branches
ethyl
methyl
methyl
Rule 6: attach name of branches
2-ethyl-4-methyl-4-methyl-1-hexene
1-hexene

19. Naming side chains Rule 7: list alphabetically
ethyl
methyl
methyl
Rule 7: list alphabetically
2-ethyl-4-methyl-4-methyl-1-hexene
1-hexene

20. Naming side chains Rule 8,9: group similar branches
ethyl
methyl
methyl
Rule 8,9: group similar branches
2-ethyl-4-methyl-4-methyl-1-hexene
1-hexene

21. Naming side chains Rule 8,9: group similar branches
ethyl
methyl
methyl
Rule 8,9: group similar branches
2-ethyl-4,4-dimethyl-1-hexene

22. Naming side chains Try PE 1 on pg. 1019 (answer to a is wrong)
3-methylhexane
4-ethyl-2,3-dimethylheptane
5-ethyl-2,4,6-trimethyloctane

23. Naming side chains Name the structures below 3-ethyl-2-methylpentane
3-ethyl-1,5,5-trimethylcyclohexene

24. More practice
4-bromo-7-methyl-2-nonene
2,5-dibromo-6-chloro-1,3-cycloheptadiene
5-fluoro-7,7-dimethyl-2,4-octadiene
Pg # 24.5, 24.6, 24.7, 24.14, 24.15
Ignore e)

25. Pg. 1049
Recall, the exceptions to organic compounds are oxides of carbon, carbonates, bicarbonates, cyanides.
b) is an oxide, d) bicarbonate, e) carbonate
This is a straight chain molecule as all carbons are consecutive.
none are possible: a) one too few Hs (should be CH3CH2CH3), b) one H too many (should be CH2=CHCH2CH3), c) one H too many (should be CH3CH=CHCH2CH3).

26. 24.15 2,2-dimethyloctane 1,3-dimethylcyclopentane
1,1-diethylcyclohexane
6-ethyl-5-isopropyl-7-methyl-1-octene

27. Aromatic nomenclature
There are 2 naming methods
Numbering carbons
ortho, meta, para (stomp)
1,2-dimethylbenzene
orthodimethylbenzene ST
Ortho
Meta
1,3-dimethylbenzene
metadimethylbenzene
Para
Benzene is very stable (does not generally undergo addition)
1,4-dimethylbenzene
paradimethylbenzene

28. For more lessons, visit www.chalkbored.com
More practice
Build a molecule that can be named according to the rules that we have talked about. Make it challenging.
Place your model at a vacant lab station.
On a scrap piece of paper write the following: 1) your station number, 2) the structure of your molecule, 3) the name of the structure. Give this to your teacher.
Rotate through the stations, drawing the structures and determining their names. At the end of the class students will reveal the answer with an explanation.
For more lessons, visit