Organic Chemistry

Organic ChemistryChemical compounds fall into one of two categories:

Organic compoundsInorganic compounds

Organic compounds can be found naturally or they can be synthesized, but they all contain C and a few other elements.There are far more organic compounds than inorganic compounds.

Organic Compounds

fuelscarbohydrates, fats, proteinsvitaminspenicillin, sulfa drugs

plasticscotton, silk, woolrubberDNAibuprofen, aspirin, morphine

Organic chemistry is part of our everyday lives!

Properties of Organic Compounds

usually molecular (contain non-metals bonded with covalent bonds)low melting pointsnonpolar (insoluble, or only slightly soluble, in water)very stable (not reactive)

Carbon

Carbon forms 4 covalent bonds, i.e., it will share electrons with 4 other elements.Prefixes are used in the name to indicate how many carbons are in the compound.

Carbon Prefixes

1C meth-

2C eth-

3C prop-

4C but-

5C pent-

6C hex-

7C hept-

8C oct-

9C non-

10C dec-

Memory Aid

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Descent.

Naming Alkanes

Alkanes

Alkanes are hydrocarbons (consisting of only C and H) that only contain single bonds.Start with the Prefix that matches the number of carbonsAlkanes have the ending –ane in their name.

CH4

Draw the structural formula

– C– HH

HI

IH

One carbon is meth + “ane” ending

So this is Methane

C2H6

Draw the structural formula

– C–C– HH

HI

IH

HI

IH

Two carbons is eth + “ane” ending

So this is Ethane

May also be drawn as CH3-CH3

C3H8

Structural formula:

– C–C–C–HH

HI

IH

HI

IH

HI

IH

Three carbons is prop + “ane” ending

So this is Propane

May also be drawn as

CH3-CH2-CH3

C4H10

There are two possible structural formulas:

– C–C–C–C– HH

HI

IH

HI

IH

HI

IH

IH

HI

May also be drawn as CH3-CH2-CH2-CH3

This is n-butane because it is a straight chain

OR

– C–C–C–

H-

H

HI

IH

HIC|

IH

HI

IH

H

-H

This is 2-methyl propane because there is a methyl side group off of the 2nd carbon in the propane chain.

Isomersare compounds that have the same molecular formula, but different structural formulas.Isomers usually have different chemical and physical properties as well.We must have some way of specifying which form of butane we are talking about.

Normal Alkanes

Alkanes that have a continuous chain of carbons are called normal alkanes.The first isomer of butane is a normal alkane and is sometimes referred to as n-butane.

Branched AlkanesThe second isomer has a branch off the second carbon.These branches are referred to as alkyl groups.The name of the alkyl group is determined by the prefix according to the number of carbons and the ending “-yl”The branch in this case would be called methyl

Rules for Naming Alkanes1. Count the carbons of the

longest continuous chain. This will be the prefix. Add –ane to it.

2. Name the alkyl groups attached to the main chain. If there are two or more of the same name, use the counting prefixes (di, tri, etc.)

Rules for Naming Alkanes, cont’d

3. Number the carbons, starting with the carbon closest to the branch.

4. List the alkyl groups first, in alphabetical order, using a number to indicate which carbon it branches from.

This would be called 2-methyl propane

– C–C–C–

H-

H

HI

IH

HIC|

IH

HI

IH

H

-H

This is a short-hand way of writing the same formula:

CH3–CH–CH3

CH3

|