Organic ChemistrySaturated HydrocarbonsPetroleumReactions of AlkanesUnsaturated HydrocarbonsAromatic Hydrocarbons

AlcoholsAldehydes and KetonesCarboxylic AcidsEstersPolymers

Saturated Hydrocarbons

• Hydrocarbons are molecules of carbon and hydrogen, like methane.

• Methane– Formula: CH4

- When carbon has four bonds, it has a tetrahedral arrangement.

Saturated Hydrocarbons

• Alkanes are hydrocarbons with only single bonds.– A straight-chain alkane has a long chain of

carbons bonded to each other with hydrogen atoms around the outside.

• Example: propane has three carbon atoms and 8 hydrogen atoms:

C C C

H H

HH

H H H

H

Saturated Hydrocarbons

– Formulas: For each carbon that is added in an alkane, there are two more hydrogen atoms in the compound.

• A CH2 group is added from one compound in the series to the next.

CH3 – (CH2) m – CH3

– Memorize the first ten prefixes for naming alkanes: meth, eth, prop, but, pent, hex, hept, oct, non, dec

Saturated Hydrocarbons

• Branched-Chain Alkanes – A substituent is an atom or group that

attaches to a carbon.• Name alkyl groups by removing “-ane” and adding

“-yl”• Methyl group: CH3

• An alkane substituent is an alkyl group.

• A chain with one or more substituent is branched.

CHCCH3

CH3

CH3

CH3

CH2 CH3

Saturated Hydrocarbons

• Naming alkanes with the IUPAC rules.• Step 1. Find the longest continuous

chain of carbons (it doesn’t have to be straight). (Draw a line through these carbons if it’s helpful.) Assign an “alkane” name according to the number of carbons in this chain.

 

Saturated Hydrocarbons

• Step 2. All carbons not in this main chain are “branches” connected to the main chain. Name each branch using the corresponding prefix with a “–yl” ending.1 carbon - “methyl”2 carbons - “ethyl”3 carbons - “propyl”

 

Saturated Hydrocarbons

• Step 3. Number the carbons in the main chain so that the branch(es) have the lowest possible numbers assigned to them. Assign each branch a number corresponding to where it attaches to the main chain.

CHCCH3

CH3

CH3

CH3

CH2 CH3

“2, 2, 3 – trimethyl pentane”

Petroleum

• Petroleum and natural gas were formed from decayed plants over 500 million years old.

• It is called “buried sunshine” because the energy in it originally came from the sun.– Plants used photosynthesis to store energy.

• Petroleum contains hydrocarbons with chains containing 5-25 carbon atoms.

• Natural gas contains methane, ethane, propane and butane.

Combustion Reactions

• In a combustion reaction, a hydrocarbon (or another fuel) reacts with O2 to make CO2 and H2O.

• 2C4H10 + 13O2 8CO2 + 10H2O

Combustion Reactions

• Write the balanced equation for the combustion of propane:

• C3H8 +

• 1. Write O2 on the left

• 2. Write CO2 and H2O on the right.• 3. Balance.

O2 CO2 + H2O5 3 4

Substitution Reactions

• In substitution reactions, hydrogen atoms are replaced by different atoms.

CH4 + Cl2 CH3Cl + HCl• The hv represents ultraviolet radiation.

hv

Dehydrogenation Reactions

• In a dehydrogenation reaction, hydrogen atoms are removed and a double or triple bond forms.

• CH3CH3 + H2

Cr2O3

500 °C C C

H

H H

H

Unsaturated Hydrocarbons

• Alkenes have double bonds.– Naming: add “-ene”– Example: “ethene”

C C

H

H H

H

Unsaturated Hydrocarbons

– Naming alkenes: Name them like alkanes, but use a number to show the location of the double bond.

– Because there’s only one place for the double bond on ethene and propene, you don’t need a number.

– Example: 2-butene

HC C C

H H

H H H

C

H

HH

H

Unsaturated Hydrocarbons

• Alkynes have triple bonds.– Naming: add “-yne”– Example: C2H2 “ethyne”

CHCH

Unsaturated Hydrocarbons

• In addition reactions, atoms are added across a double or triple bond.– Hydrogenation is an addition reaction. H2 is

added.

– Halogenation is an addition reaction. A halogen (group 7A) is added.

+ H2 CH3CH2CH3

Pt Catalyst

+ Br2

CHCH2 CH3

CHCH2 CH3

Aromatic Hydrocarbons

• Aromatic hydrocarbons smell nice, like wintergreen and cinnamon.

• Most aromatic hydrocarbons contain a benzene ring.

• Benzene is a 6-carbon ring with three double bonds (C6H6).

CC

CC

C

C

H

H H

H

H

H

Aromatic Hydrocarbons

• When two or more structures can be drawn for a molecule, resonance occurs.

Aromatic Hydrocarbons

• In reality, there are no double bonds in benzene. The electrons are shared evenly around the ring.

• This is a more accurate way to represent benzene:

Aromatic Hydrocarbons

• Benzene is called a “phenyl” group when it is a side group on an alkane.

– Example: 3-phenylnonane

CH3 CH2 CH CH2 CH2 CH2 CH2 CH2 CH3

Aromatic Hydrocarbons

• Naming benzene with one side group: “Benzene” + “Side group name”– Example: Methylbenzene

Aromatic Hydrocarbons

• Naming benzene with two side groups: Name them like alkanes, but assign one group the #1:– Example: 1,3-dimethyl benzene

CH3

CH3

Aromatic Hydrocarbons• Common names for disubstituted benzenes:

– 1, 2 position is “orotho” (o)– 1, 3 position is “meta” (m)– 1, 4 position is “para” (p)

Systematic Name Common Name1, 2-dichlorobenzene o-dichlorobenzene1, 3-dichlorobenzene m-dichlorobenzene1, 4-dichlorobenzene p-dichlorobenzene

Alcohols

• Functional groups are groups of atoms that are capable of characteristic chemical reactions.– For example, the functional group of a

carboxylic acid is circled below, a COOH group.

– The “R” stands for the “rest” of the molecule.

R C

O

O H

Alcohols

• An alcohol is an organic compound with an “-OH” group.– The “-OH” group is called a hydroxyl group.– There are three kinds of alcohols:

1). Primary alcohol – one “R” group attached to the C-OH2). Secondary alcohol – two“R” groups attached to the C-OH3). Tertiary alcohol – three “R” groups attached to the C-OH

Alcohols

• Primary

• Secondary

• Tertiary

Alcohols

• Naming alcohols: Drop the “e” from the alkane name and “-ol”– Example: Methanol.

CH3 O H

Alcohols

• Properties– Ethanol is produced by fermentation, which

is the digestion of sugar by yeast. Alcoholic beverages such as beer are made by this process.

– Methanol is used to make many materials—plastics, fibers, etc.

Aldehydes and Ketones

• A carbonyl group is a functional group with a group.

• An aldehyde has a carbonyl group, where the carbon is bonded to one or two hydrogen atoms. It has the general formula: RCHO.

C O

Aldehydes and Ketones

• A keytone has a carbonyl group on a carbon that is bonded to two other carbons. General formula: RCOR

Aldehydes and Ketones

• IUPAC Naming:• Aldehydes: alkane name minus “e” plus

“al”:– Methane Methanal

• Keytones: alkane name minus “e” plus “anone.” Write the number of the carbon that has the carbonyl group first:“2-pentanone”

C

O

CH3 CH2CH2 CH3

Carboxylic Acids

• Carboxylic acids have the general formula RCOOH

• They ionize slightly when dissolved in water:

Carboxylic Acids

• IUPAC Naming:• Add “-oic acid”

– “Ethanoic acid”• Carboxylic acids don’t smell good.• Vinegar contains ethanoic acid.

Esters

• Esters• Esters have the general formula RCOOR

Esters

• Esters can be made by a reaction between a carboxylic acid and alcohol.

• Esters smell good, and make the smells in bananas, oranges and other fruits and flowers.

C

H

H

HH OC

o

C

H

H

H O HO H + C

H

H

HOC

o

H

C

H

H

H

“Methyl ethanoate”

Polymers

• Polymers are made from small molecules, called monomers.– Ethene can react with itself, creating an

addition polymer. – This reaction is called an addition reaction.

Many ethene add onto the growinig polymer chain to make a very long molecule.

Polymers

Ethene Growing polymer chain Polyethylene

C C C

H H

H H H

C

H

C

H

H

C C

H

H H

H H H

( )nC C

H

H H

H