2 An alcohol contains A hydroxyl group (—OH) attached to a carbon chain.
3 Alcohols are classified By the number of alkyl groups attached to the carbon bonded to the hydroxyl. As primary (1°), secondary (2°), or tertiary (3°). Primary (1º) Secondary (2º) Tertiary (3º) 1 group 2 groups 3 groups H CH 3 CH 3 | | | CH 3 —C—OH CH 3 —C—OH CH 3 —C—OH | | | H H CH 3 Classification of Alcohols
5 Naming Alcohols The names of alcohols In the IUPAC system replace -e of alkane name with - ol. that are common names use the name of the alkyl group followed by alcohol. FormulaIUPACCommon Name CH 4 methane CH 3 ─OH methanol methyl alcohol CH 3 ─CH 3 ethane CH 3 ─CH 2 ─OH ethanol ethyl alcohol
6 More Names of Alcohols In IUPAC names for longer carbon chains, the chain is numbered from the end nearest the ─OH group. CH 3 ─CH 2 ─CH 2 ─OH propan-1-ol OH │ CH 3 ─CH─CH 2 ─CH 3 butan-2-ol CH 3 OH │ CH 3 ─CH─CH 2 ─CH 2 ─CH─CH 3 5-methyl hexan-2-ol 6 5 4 3 2 1
11 Boiling Points of Alcohols Alcohols Contain a strongly electronegative O in the OH groups. Form hydrogen bonds between alcohol molecules. Have higher boiling points than alkanes and ethers of similar mass.
12 Solubility of Alcohols in Water Alcohols are more soluble in water than alkanes because the oxygen atom hydrogen bonds with water. Alcohols with 1-4 C atoms are soluble, but alcohols with 5 or more C atoms are not.
13 Comparing Solubility and Boiling Points CompoundMolarBoiling Soluble Mass Point (°C) in Water? Alkane CH 3 ─CH 2 ─CH 3 44-42 No Ether CH 3 ─O─CH 3 46-23 Yes Alcohol CH 3 ─CH 2 ─OH 46 78 Yes
14 Learning Check Which compound would be more soluble in water? Explain. ethanol or 2-pentanol
16 Combustion of Alcohols Combustion is the reaction of an alcohol with O 2 to produce CO 2 and H 2 O. 2CH 3 OH + 3O 2 2CO 2 + 4H 2 O + Heat
17 Dehydration of an alcohol occurs When heated with an acid catalyst. With the loss of —H and —OH from adjacent carbon atoms. H OH | | H +, heat H—C—C—H H—C=C—H + H 2 O | | H H H H alcohol alkene Dehydration of Alcohols
18 Learning Check Write the equations for the reactions when 2-propanol undergoes: 1. combustion 2. dehydration
19 Oxidation and Reduction In the oxidation of an organic compound There is an increase in the number of C—O bonds. There is a loss of H. In the reduction of an organic compound There is an decrease in the number of C—O bonds. There is a gain of H.
21 Oxidation of Ethanol in the Body In the body, Ethanol is oxidized by enzymes in the liver. Aldehyde product impairs coordination. O ║ ║ CH 3 ─CH 2 ─OH CH 3 ─C─H CH 3 ─C─OH Ethanol acetaldehyde acetic acid 2CO 2 + H 2 O
22 Ethanol Acts as a depressant. Kills or disables more people than any other drug. Is metabolized at a rate of 12-15 mg/dL per hour by a social drinker. Is metabolized at a rate of 30 mg/dL per hour by an alcoholic. Ethanol CH 3 ─CH 2 ─OH