organic chemistry
DESCRIPTION
Organic Chemistry. Alcohols Aldehydes and Ketones Carboxylic Acids Esters Polymers. Saturated Hydrocarbons Petroleum Reactions of Alkanes Unsaturated Hydrocarbons Aromatic Hydrocarbons. Saturated Hydrocarbons. - When carbon has four bonds, it has a tetrahedral arrangement. - PowerPoint PPT PresentationTRANSCRIPT
Organic ChemistrySaturated Hydrocarbons
Petroleum
Reactions of Alkanes
Unsaturated Hydrocarbons
Aromatic Hydrocarbons
Alcohols
Aldehydes and Ketones
Carboxylic Acids
Esters
Polymers
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 Name
1, 2-dichlorobenzene o-dichlorobenzene
1, 3-dichlorobenzene m-dichlorobenzene
1, 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-OH
2). Secondary alcohol – two“R” groups attached to the C-OH
3). 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