Organic ChemistryChemistry of Carbon

Objectives

To define what constitutes an “organic compound”

To describe why organic compounds are important and give some examples of them

To be able to name simple unbranched organic compounds with single bonds

To identify and draw isomers of organic molecules

To be able to name more complex, branching organic compounds with single bonds

What are Organic Compounds?

Carbon containing molecules

Many organic molecules are made by living things, but not all

Examples of Organic Compounds

Hydrocarbons

Molecules composed entirely of Carbon and Hydrogen

Methane, Propane, Benzene, Octane, Ethylene (Ethyne), Acetylene (Ethyne)

Fossil fuels...

Examples of Organic Compounds

Lipids

Fats, waxes, sterols, fat soluble vitamins, triglycerides, diglycerides, etc.

Store energy in body, form cell membranes, hormones...

Examples of Organic Compounds

Carbohydrates

Carbon, Hydrogen and Oxygen in specific ratios

Sugars, starches, cellulose, chitin

Examples of Organic Compounds

Polymers (large molecules of repeating structural units)

Proteins and Nucleic Acids

Vinyl, nylon, plastics...

Alkanes

Simple, saturated hydrocarbons (all single bonds)

Each carbon bonded to four atoms

tetrahedral geometry around carbons

Naming Alkanes

C atoms

Word Root

Name Structure Formula

1 Meth- Methane CH4 CH4

2 Eth- Ethane CH3-CH3 C2H6

3 Prop- Propane CH3-CH2-CH3 C3H8

4 But- Butane CH3-(CH2)2-CH3 C4H10

5 Pent- Pentane CH3-(CH2)3-CH3 C5H12

6 Hex- Hexane CH3-(CH2)4-CH3 C6H14

7 Hept- Heptane CH3-(CH2)5-CH3 C7H16

8 Oct- Octane CH3-(CH2)6-CH3 C8H18

9 Non- Nonane CH3-(CH2)7-CH3 C9H20

10 Dec- Decane CH3-(CH2)8-CH3 C10H22

Try naming these molecules

CH3 - CH2 - CH2 - CH2 - CH2 - CH3

Hexane

CH3 - CH3

Ethane

CH3 - CH2 - CH3

Propane

Alkanes can be BRANCHED

Butane C4H10

n-butane (normal butane), is unbranched, C4H10

isobutane (an isomer of n-butane) is branched, C4H10

isomerism = two molecules have same atoms but different bonds

Alkanes can be BRANCHED

Pentane C5H12

n-pentane (normal pentane), is unbranched, C5H12

We can make isomers of n-pentane, with branches, but still C5H12

Can you think of another isomer of pentane?

Draw three structural isomers of heptane

Naming Branched Alkanes

Step 1: Find longest continuous chain of carbons. In this case, you have a chain of 8 - so primary name

of molecule is Octane

Naming Branched Alkanes

Redrawn to show longest chain (8 carbons)

STEP 2 - Count from beginning of longest chain to carbon where branch occurs (in this case, count 4 carbons, not 5)

Naming Branched Alkanes

STEP 3 - Count the carbons on the branch

In this case, there are 2 carbons on the branch

The branch is called a substituent

There are rules for naming substituents based on # of Cs in them

Naming Branched Alkanes

STEP 4 - Name the substituent

1 carbon = methyl

2 carbons = ethyl

3 carbons = propyl

In this case, our substituent is called ethyl because it has 2 carbons

Naming Branched Alkanes

STEP 5 - Name the molecule

since our substituent is on the 4th Carbon

We call this molecule 4-ethyloctane

What if there is more than one branch?

3, 4 - diethyloctane

What if there is more than one branch?

3, 4, 5 - trimethyloctane

Naming Branched Alkanes

6-ethyl-2-methyl-octane

list substituents in alphabetical order

Name this molecule

5-ethyl-3-methyl-heptane

3-ethyl-5-methyl-heptane is equally correct

remember to list substituents in alphabetical order

Name this molecule (this is hard!)

3-ethyl-2,2,3-trimethyl-heptane

Practice Time!

Work on 2 worksheets

Check key (with me)

Finish as homework (I will scan key and put on website)