Organic Chemistry Saturated 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: CH 4 - 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:

Saturated Hydrocarbons –Formulas: For each carbon that is added in an alkane, there are two more hydrogen atoms in the compound. A CH 2 group is added from one compound in the series to the next. CH 3 – (CH 2 ) m – CH 3 –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: CH 3 An alkane substituent is an alkyl group. A chain with one or more substituent is branched.

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. “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 O 2 to make CO 2 and H 2 O. 2C 4 H O 2  8CO H 2 O

Combustion Reactions Write the balanced equation for the combustion of propane: C 3 H 8 +  1. Write O 2 on the left 2. Write CO 2 and H 2 O on the right. 3. Balance. O2O2 CO 2 + H2OH2O 53 4

Substitution Reactions In substitution reactions, hydrogen atoms are replaced by different atoms. CH 4 + Cl 2 CH 3 Cl + HCl The hv represents ultraviolet radiation. hv

Dehydrogenation Reactions In a dehydrogenation reaction, hydrogen atoms are removed and a double or triple bond forms. CH 3 CH 3 + H 2 Cr 2 O °C CC H HH H

Unsaturated Hydrocarbons Alkenes have double bonds. –Naming: add “-ene” –Example: “ethene” CC H HH 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 H CCC HH HHH C H HH H

Unsaturated Hydrocarbons Alkynes have triple bonds. –Naming: add “-yne” –Example: C 2 H 2 “ethyne” CH

Unsaturated Hydrocarbons In addition reactions, atoms are added across a double or triple bond. –Hydrogenation is an addition reaction. H 2 is added. –Halogenation is an addition reaction. A halogen (group 7A) is added. + H 2 CH 3 CH 2 CH 3 Pt Catalyst + Br 2

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 (C 6 H 6 ). C C CC C C H HH 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

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

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 NameCommon Name 1, 2-dichlorobenzeneo-dichlorobenzene 1, 3-dichlorobenzenem-dichlorobenzene 1, 4-dichlorobenzenep-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.

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.

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.

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 CH 3 CH 2 CH 3

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 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 H H O C o C H H HO H + C H H H OC 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