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
|