Naming Hydrocarbons

Question

Petroleum or crude oil is a mixture of hydrocarbons, which are molecules that contain only carbon and hydrogen. The three simplest families of hydrocarbons are known as the alkanes, alkenes, and alkynes.

Alkanes have the formula CxH2x+2 and end with the suffix “ane.”

Alkenes have the formula CxH2x and end with the suffix “ene.”

Alkynes have the formula CxH2x-2 and end with the suffix “yne.”

The nomenclature of organic compounds (compounds containing carbon) is based on a simple system of prefixes. You are responsible for learning the prefixes for molecules containing up to 10 carbon atoms. The first four prefixes are probably new to you, but you’re familiar with the rest:

Prefixes for Organic Molecules

# of Carbon

Atoms

Prefix

1

Meth

2

Eth

3

Prop

4

But

5

Pent

6

Hex

7

Hept

8

Oct

9

Non

10

Dec

Examples:

1. An alkane with 4 carbons is known as butane and has the formula C4H10. 2. An alkene with 6 carbons is known as hexene and has the formula C6H12. 3. An alkyne with 8 carbons is known as octyne and has the formula C8H14.

4. An alkane containing 50 carbons has the formula C50H102 (you’re not responsible for the name).

5. An alkene containing 26 hydrogens has the formula C13H26 (you’re not responsible for the name).

Answer 1

6. An alkyne with 5 carbons is known as pentyne and has the formula C5H8. 7. An alkane with 9 carbons is known as nonane and has the formula C9H20. 8. An alkene with 3 carbons is known as propene and has the formula C3H6. 9. An alkyne with 10 carbons is known as decyne and has the formula C10H18. 10. An alkane with 7 carbons is known as heptane and has the formula C7H16.