Download Alcohols

ALCOHOLS
ALCOHOLS
• ALCOHOLS ARE A FAMILY OF ORGANIC COMPOUNDS THAT HAVE A HYDROXYL (-OH) GROUP
ATTACHED TO A CARBON ATOM.
• ALCOHOLS ARE VERY DIFFERENT FROM INORGANIC BASES. IN ALCOHOLS, THE HYDROXYL
GROUP IS ATTACHED TO A CARBON BY A COVALENT BOND; THIS IS DIFFERENT FROM THE
HYDROXIDE ION (OH-) WHICH IS A NEGATIVELY CHARGED PARTICLE FOUND IN BASES. IN
BASES, THE HYDROXIDE ION IS HELD TO A POSITIVE ION BY AN A IONIC BOND.
• ALCOHOLS HAVE THE GENERAL FORMULA CnH 2n+ 1OH
CLASSIFICATION OF ALCOHOLS
• ALCOHOLS ARE CLASSIFIED AS PRIMARY, SECONDARY OR TERTIARY, DEPENDING ON WHETHER
THE CARBON THAT HAS THE –OH GROUP IS BONDED TO ONE, TWO OR THREE OTHER CARBONS,
RESPECTIVELY.
PRIMARY
SECONDARY
TERTIARY
NAMING ALCOHOLS
1. NAME THE PARENT COMPOUND.
FIND THE LONGEST CHAIN THAT HAS THE HYDROXYL SUBSTITUENT ATTACHED. NAME THE CHAIN
ACCORDING TO THE NUMBER OF CARBON ATOMS AND CHANGE THE ENDING TO “OL”.
2. NUMBER THE CARBON ATOMS N THE MAIN CHAIN, STARTING AT THE END NEARER THE HYDROXYL
GROUP.
3. WRITE THE NAME BY PLACING THE NUMBER THAT LOCATES THE HYDROXYL GROUP IMMEDIATELY
BEFORE THE PARENT COMPOUND NAME.
4. WRITE THE NAMES OF ANY SUBSTITUENTS AND THEIR POSITIONS, LISTING THEM ALPHABETICALLY.
ALCOHOLS
• IDENTIFY THE FOLLOWING COMPOUNDS AS PRIMARY, SECONDARY OR TERTIARY.
ALCOHOLS
• NAME THE FOLLOWING COMPOUNDS:
ALCOHOLS
• WRITE THE STRUCTURAL FORMULA FOR THE FOLLOWING COMPOUNDS
4-METHYL-4-HEPTANOL
3-ETHYL-4-METHYL-2-HEXANOL
PROPERTIES OF ALCOHOLS
• ALCOHOLS ARE MUCH MORE POLAR THAN HYDROCARBONS BECAUSE OF THE ELECTRONEGATIVE
OXYGEN ATOM IN THE –OH GROUP.
• BECAUSE OF THIS POLARITY, HYDROGEN BONDING OCCURS IN ALCOHOLS AND BECAUSE OF THE
STRONGER INTERMOLECULAR FORCES, ALCOHOLS HAVE HIGHER BOILING POINTS THAN THEIR RELATED
ALKANES.
• BECAUSE OF THE POLAR –OH GROUP, ALCOHOLS CAN FORM HYDROGEN BONDS WITH WATER. AS A
RESULT, ALCOHOLS ARE MORE SOLUBLE IN WATER THAN ALKANES OF COMPARABLE MOLAR MASS. FOR
EXAMPLE, ETHANOL, THE ALCOHOL PRESENT IN ALCOHOLIC DRINKS, IS SOLUBLE IN WATER. HOWEVER,
AS THE HYDROCARBON CHAIN BECOMES LONGER, THE SOLUBILITY OF ALCOHOLS IN WATER
DECREASES.
REACTIONS OF ALCOHOLS- COMBUSTION
REACTIONS OF ALCOHOLS-OXIDATION
OXIDATION
• ALCOHOLS CAN REACT WITH OXIDIZING AGENTS SUCH AS POTASSIUM PERMANGANATE
OR POTASSIUM DICHROMATE.
• WHEN WRITING THESE REACTIONS, THE OXIDIZING AGENT IS SHOWN AS +[O] ABOVE THE
ARROW.
• THE PRODUCT OBTAINED WILL DEPEND ON WHETHER THE ALCOHOL IS PRIMARY,
SECONDARY, OR TERTIARY.
OXIDATION-PRIMARY ALCOHOLS
PRIMARY ALCOHOLS ARE OXIDIZED IN A TWO STEP REACTION.
1. MILD OXIDATION YIELDS AN ALDEHYDE.
2. FURTHER OXIDATION YIELDS A CARBOXYLIC ACID.
THE H FROM THE –OH AND AN H FROM THE CARBON BEARING THE –OH ARE REMOVED. CONSEQUENTLY, A
DOUBLE BOND FORMS BETWEEN THE CARBON AND THE OXYGEN.
OXIDATION OF PRIMARY ALCOHOLS
OXIDATION OF PRIMARY ALCOHOLS
OXIDATION OF PRIMARY ALCOHOLS
OXIDATION OF PRIMARY ALCOHOLS
• REMEMBER:
OXIDATION OF SECONDARY ALCOHOLS
• OXIDATION OF SECONDARY ALCOHOLS YIELDS A KETONE.
• KETONES CAN NOT BE FURTHER OXIDIZED.
• AS IN PRIMARY ALCOHOLS, THE H FROM THE –OH AND AN H FROM THE CARBON BEARING THE
–OH ARE REMOVED, AND A DOUBLE BOND FORMS BETWEEN THE CARBON AND OXYGEN
ATOMS.
OXIDATION OF TERTIARY ALCOHOLS
• TERTIARY ALCOHOLS DO NOT OXIDIZE.
OXIDATION OF ALCOHOLS
• POTASSIUM DICHROMATE IS AN ORANGE SOLUTION. AS THE ALCOHOL IS OXIDIZED, THE
CHROMIUM BECOMES REDUCED AND THE SOLUTION TURNS GREEN.
• HOWEVER, IN TERTIARY ALCOHOLS, SINCE THERE IS NO OXIDATION, THE SOLUTION STAYS
ORANGE.
OXIDATION OF ALCOHOLS