Chapter Twelve chemistry note

·         Alcohols and ethers are two classes of organic compounds that contain an oxygen (O) atom.

·         In an alcohol, the oxygen atom is part of a hydroxyl group (-OH).

·         In an ether, the oxygen atom is attached to two carbon atoms.

·         They both have structures similar to water.

·         One hydrogen atom of water is replaced by an alkyl group in an alcohol and by a benzene ring in a phenol.

·         Naming alcohols:

1.      Name the longest carbon chain containing the –OH group and replace the –e with –ol.

2.      Number the longest chain, starting at the end closest to the –OH group.

3.      Name and number the other substituents relative to the –OH group.

4.      Name a cyclic alcohol as a cycloalkanol.

5.      When the –OH group is attached to a benzene ring, it is named a phenol.

***The –OH is the first when counting.

·         Alcohols are classified by the number of carbon groups attached to the carbon atom bonded to the hydroxyl (-OH) group.

·         A primary alcohol has one alkyl group attached the carbon atom bonded to the –OH.

·         A secondary alcohol has two alkyl groups.

·         A tertiary has three alkyl groups.

·         Thiols are a family of sulfur containing organic compounds that have a thiol (-SH) group. It’s like alcohol except the –SH group replaces the –OH group. These are named by adding thiol to the longest carbon chain.

·         An ether contains an oxygen atom that is attached by single bonds to two carbon groups that are alkyls or aromatic rings. They have a bent structure like water and alcohols.

·         The first four alcohols are soluble in water.

·         Phenol is soluble in water because the hydroxyl group ionizes slightly as a weak acid. In fact, an early name for phenol was carbolic acid.

·         Alcohols burn with oxygen too.

·         During dehydration of alcohol, H- and –OH are removed from adjacent carbon atoms of the same alcohol to produce a water molecule. When alcohol is dehydrated, it turns into an alkene and water.

·         Oxidation means the loss of a hydrogen atom or the addition of oxygen. It occurs when there is an increase in the number of carbon-oxygen bonds.

·         The oxidation of a primary alcohol produces an aldehyde, which contains a double bond between the carbon and the oxygen.

·         Tertiary alcohols do not oxidize readily because there are no hydrogen atoms on the carbon bonded to the –OH group. C-C bonds are usually too strong to oxidize, tertiary alcohols resist oxidation.

·         In an aldehyde, the carbon of the carbonyl group is bonded to at least one hydrogen atom. The group name suffix changes to –al.

·         In a ketone, the carbonyl group is bonded to two alkyl groups or aromatic rings. The group name suffix changes to –one.

·         Naming aldehydes:

1.      Name the longest carbon chain containing the carbonyl group by replacing the –e to –al. No number is needed for the aldehyde because it’s always at the end.

2.      Name and number the substituents on the carbon chain by counting the carbonyl carbon as carbon 1.

·         Naming ketones:

1.      Name the longest carbon chain containing the carbonyl group by replacing the –e in the corresponding alkane name by –one.

2.      Number the main chain starting from the end nearest the carbonyl group.

3.      Name and number any substituents on the carbon chain.

4.      For cyclic ketones, the prefix cyclo is used in front of the ketone name.

·         Aldehydes oxidize readily to carboxylic acids.

·         Molecules are structural isomers when they have had the same molecular formula, but different bonding arrangements.

·         Another group of isomers called steroisomers have identical molecular formulas but are not structural isomers. The atoms are bonded in the same sequence, but differ in the way they are arranged in space.

·         Objects that have nonsuperimposable mirror images are chiral. Left and right shoes are chiral. So if the item is in the mirror it looks exactly the same only in the mirror.

·         A carbon compound is chiral if it has at least one carbon atom bonded to four different atoms or groups. This type of carbon atom is called a chiral carbon because there are two different ways that it can bond to four atoms or groups of atoms. ***Has to be four different bonds***

·         When steroisomers cannot be superimposed, they are called enantiomers.