Chapter 9Organic Chemistry

John Singer,

Jackson Community College

Chemistry for Changing Times,

Thirteenth Edition

Lecture Outlines

© 2013 Pearson Education, Inc.

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Organic Chemistry

Organic chemistry is defined as the chemistry of hydrocarbons and their derivatives. Of tens of millions of known chemical compounds, over 95% are compounds of carbon.

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The Unique Carbon Atom

Carbon is unique in that carbon atoms can bond to each other to form long chains and rings.

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Hydrocarbons

Hydrocarbons are the simplest organic compounds. As their name implies, they are composed entirely of carbon and hydrogen.

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Alkanes

Alkanes are hydrocarbons that contain only single bonds. Because all carbon-to-carbon bonds are single bonds, alkanes are often called saturated hydrocarbons.

The simplest hydrocarbon is methane (CH4).

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The general formula of alkanes is CnH2n+2.

Alkanes

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The names of alkanes begin with a prefix denoting the number of carbon atoms followed by the suffix –ane.

Alkanes

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Ball-and-stick and space-filling models can be used to represent organic compounds.

Alkanes

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Condensed structural formulas are often used to represent organic compounds. In condensed structural formulas, C to H bond lines are omitted and the formulas are written in the following manner:

propane: CH3CH2CH3

Alkanes

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The alkanes represent a homologous series that differs by the number of –CH2– groups. Members of a homologous series exhibit properties that vary in a regular and predictable manner.

Alkanes

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Isomerism: Isomers are compounds with the same molecular formula, but different structural formulas.

Alkanes

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Alkanes

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Cyclic Hydrocarbons

Cyclic hydrocarbons are ring compounds. The simplest cyclic hydrocarbon is cyclopropane.

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The names of cyclic hydrocarbons begin with the prefix cyclo- followed by the name of the alkane with the same number of carbon atoms.

Cyclic Hydrocarbons

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Unsaturated Hydrocarbons

Alkenes are hydrocarbons that contain a carbon-to-carbon double bond. Their general formula is CnH2n. Their names begin with a prefix denoting the number of carbon atoms followed by the suffix –ene.

Ethylene is the simplest alkene.

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Alkynes are hydrocarbons that contain a carbon-to-carbon triple bond. Their general formula is CnH2n-2. Their names begin with a prefix denoting the number of carbon atoms followed by the suffix –yne.

Ethyne (acetylene) is the simplest alkyne.

Unsaturated Hydrocarbons

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Both alkenes and alkynes are unsaturated hydrocarbons. A saturated hydrocarbon has the maximum number of hydrogen atoms attached to each carbon and no double or triple bonds. Unsaturated hydrocarbons can undergo an addition reaction, such as that seen on the right here.

Unsaturated Hydrocarbons

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Aromatic Hydrocarbons: Benzene and Relatives

Benzene is a unique organic compound in that it is a very stable six-carbon ring. Aromatic hydrocarbons contain a benzene ring or have properties similar to those of benzene.

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Aromatic Hydrocarbons: Benzene and Relatives

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Aromatic Hydrocarbons: Benzene and Relatives

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Chlorinated Hydrocarbons

When chlorine is substituted for one or more hydrogen atoms of a hydrocarbon, a chlorinated hydrocarbon is formed. Chlorinated hydrocarbons have many useful properties.

Dichloromethane is used as a solvent and paint remover.

Trichloromethane (chloroform) is also a solvent and at one time was used as an anesthetic. It is now considered hazardous.

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Chlorofluorocarbons

Carbon compounds with both chlorine and fluorine are known as chlorofluorocarbons (CFCs).

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Functional Groups

Functional groups are atoms or groups of atoms that are attached to, or part of, the hydrocarbon skeletons and give the compounds characteristic chemical and physical properties. Double and triple bonds, as well as halogen substituents, are examples of functional groups.

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Functional Groups

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Alkyl Groups

Alkyl groups are derived from the alkanes.

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Alcohols

Alcohols contain the hydroxyl (-OH) functional group.

Examples include:

Methanol CH3OH

Ethanol CH3CH2OH

1-propanol CH3CH2CH2OH

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Methanol

Methanol or methyl alcohol is sometimes called wood alcohol. It is an important solvent, automotive fuel additive, and possible fuel replacement.

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Ethanol

Ethanol or ethyl alcohol is also known as grain alcohol. It is the alcohol of alcoholic beverages. It is also an additive to automotive fuel and is being considered as a gasoline replacement.

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Toxicity of Alcohols

All alcohols are toxic. Methanol, for instance, is oxidized to formaldehyde by liver enzymes. Formaldehyde is a poison and can cause blindness or death.

Even ethanol is toxic. The effects of drinking ethanol are due to its toxicity. Drunk driving, alcoholism, and fetal alcohol syndrome are all effects due to the toxicity of ethanol.

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Ethanol

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Multifunctional Alcohols

Some alcohols contain more than one hydroxyl group.

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Phenols

Phenols are aromatic compounds with the hydroxyl group attached to the aromatic ring. The presence of the aromatic ring alters the properties of the hydroxyl group. Phenols do not act as alcohols, but as acids. Phenols are an effective antiseptic.

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Ethers

Ethers are compounds with two alkyl groups bonded to the same oxygen.

General formula: ROR or ROR’

CH3CH2OCH2CH3 is diethyl ether.

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Ethers

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Aldehydes and Ketones

Aldehydes and ketones are two families of organic compounds that contain the carbonyl (C=O) functional group.

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Aldehydes and Ketones

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Carboxylic Acids

Organic acids contain the carboxyl (COOH) functional group.

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When a carboxyl group is attached directly to a benzene ring, the compound is called benzoic acid.

Carboxylic Acids

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Esters

Esters are formed by replacing the hydrogen of a carboxylic acid with the alkyl group of an alcohol or phenol.

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Esters generally have a pleasant odor.

Esters

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Esters are named by stating the name of the alcohol part first followed by the root name of the acid.  Drop the –e and add the suffix –oate.

For example:  Methyl butanoate

Esters

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Amines and Amides

Amines are derivatives of ammonia. When one or more hydrogen of ammonia is replaced by an alkyl group, an amine is the result. Like ammonia, amines tend to be basic and have similar odors.

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Aniline has an amine functional group attached to a benzene ring.

Amines and Amides

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Amines and Amides

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Amides have nitrogen bonded to a carbonyl carbon.

The amino acids of proteins are linked by amide linkages.

Amines and Amides

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Heterocyclic CompoundsHeterocyclic compounds are rings that contain atoms other than carbon as part of the ring. Most organic heterocyclic compounds contain nitrogen, oxygen, or sulfur.

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Alkaloids

Alkaloids are amines that occur naturally in plants, bacteria, fungi and animals. Many have physiological effects. Morphine, caffeine, nicotine, and cocaine are alkaloids. So are the bases pyrimidine and purine.