Organic Chemistry The Chemistry of Carbon

Why call it Organic? Fewer than 200 years ago, it was thought that only living organisms could synthesize carbon compounds. So, they called carbon compounds “organic”

How can carbon form 4 bonds? Carbon is in the 4 th group on the periodic table. This means carbon has 4 valence electrons. Carbon will want to bond with 4 other atoms to achieve the octet rule.

Hydrocarbons Hydrocarbons – any molecule that contains only hydrogen and carbon Simple Hydrocarbons Methane and Ethane

Fats are Hydrocarbons

Group 1: Alkanes Alkanes are hydrocarbons made of single bonds only. Draw Methane Draw Ethane Draw Propane Draw Butane

Branched Alkanes – Each branch is called a SUBSTITUENT.

Naming Branched Alkanes Find the longest chain of carbons. (8 – Octane)

Naming Branched Alkanes Number the longest chain starting with the end that will give substituents the smallest numbers.

Naming Branched Alkanes To name these substituents, start with the number. Add a dash. Add the type of substituent (drop the –ane ending and add the –yl ending) 4-methyl, 4-ethyl, 5-propyl

Naming Branched Alkanes Add prefixes to indicate that the same substituent appeared more than once. If there were two methyl groups on carbon 4, we would put 4,4 dimethyl

Naming Branched Alkanes List substituents in alphabetical order (ignore prefixes di, tri, tetra) Combine all parts and use proper punctuation. Write the entire name without any spaces. Use commas to separate numbers and hyphens to separate numbers and words.

4-ethyl-4-methyl-5-propyloctance

You Try!

4-ethyl-2-methylhexane

Group 2: Alkenes Alkenes are hydrocarbons that contain one or more double bonds. The rules for naming is mostly the same, except for… –We drop the ending –ane and use –ene. –We use numbers to indicate the position of the double bond.

1-butene2-butene 3,3-dimethyl-1-butene4-methyl-2-pentene

Group 3: Alkynes Alkynes are hydrocarbons that contain one or more triple bonds. The same rules apply with alkenes and alkynes. The only difference is that you drop the –ene ending and add –yne.

Isomers Isomers - compounds that have the same molecular formula, but have different structures. Example: –C 4 H 10

Stereoisomers Stereoisomers are molecules in which the atoms are joined in the same order, but the positions of the atoms in space are different.

Cis-Trans Isomers Molecules with double bonds prevent rotating with respect to each other. Because of this lack of rotation, the groups on either side of the double bond can have different orientations.

Cis-Trans Isomers Cis Configuration –Similar groups are on the same side of the double bond.

Cis-Trans Isomers Trans Configuration –Similar groups are on opposite sides of the double bond.

Cis-Trans Significance Cis-Trans configurations have different physical and chemical properties.

Enantiomers Enantiomers – Optical Isomers –Enantiomers have identical physical properties, but behave differently when they react. –Enantiomers have asymmetric carbons.

Why are some enantiomers more effective as medicines? Substrates and enzymes must fit correctly (like puzzle pieces) for the enzyme to function correctly. Certain enantiomers work better than their mirror image.

Cyclic Hydrocarbons Clycloalkane –Contains only single bonds

Aromatic Hydrocarbons An aromatic compound contains a benzene ring.