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Agenda Today
• Lesson on Naming and Structure of:
– Alcohols
– Ethers
– Thiols
• Practice Problems
1.4 Alcohols, Ethers and Thiols
Hydrocarbon Derivatives
Alcohols, Ethers and Thiols
• An alcohol contains the
hydroxyl (-OH) functional
group
ethanol
• An ether contains an oxygen
atom between two carbon
atoms in a chain
methoxyethane
• A thiol contains the sulfhydryl
(-SH) functional group
ethanethiol
dimethyl ether
Question???
• Which has a higher melting point? Methane
or methanol???
Question???
• Which is more soluble in water? Methanol or
ethanol??
• Why are alcohols very useful as solvents?
Naming Alcohols
•The hydroxyl group can also be attached to an
aromatic hydrocarbon.
•Phenol: An organic compound that has a
hydroxyl group bonded to a benzene ring.
**In a case where benzene has multiple hydroxyl
groups, benzene is used as the root word.
More Cyclic Alcohol Examples:
Alcohols Containing More Than
One Functional Group:
• In some cases, a different functional group
takes precedence over the alcohol. In
these cases, the –OH group is treated as a
substituent, called hydroxy.
• This applies later with carboxylic acids,
aldehydes, ketones, etc.
Naming Alcohols with
other Functional Groups
• Later, when we begin naming other types of
compounds such as aldehydes, ketones, and
carboxylic acids; it will be necessary to name the (-OH)
group as a branch.
• In this case, the hydroxyprefix is used.
• When there is a multiple bond in the chain, the –OH
group takes precedence (ex. Pent-4-ene-1-ol)
Ethers
• Are organic compounds containing an
oxygen atom between two carbons atoms
in a hydrocarbon chain.
Naming Ethers
• Identify the two alkyl groups in the chain.
• Write the prefix of the shorter alkyl chain, then the suffix –
oxy, followed by the complete name of the longer alkyl
chain (alkane name).
• A number is required to indicate the carbon in which the
oxygen is attached to in the longer chain for chains 3
carbons and greater.
• An alternate naming system is to use the names of the two
hydrocarbon chains, in alphabetical order, followed by the
word “ether”.
Examples of Ethers
IUPAC Convention
Alternate Method
Ethoxybutane
Ethyl butyl ether
Ethoxyethane
Diethyl ether
2-methoxypropane
Methyl propan-2-yl ether
Textbook method
Intermolecular Forces in Ethers
• Ethers lack the hydroxyl group that alcohols have,
preventing them from having any type of hydrogen
bonding.
• However, the C-O bond is polar, thus, ether molecules
are somewhat polar, just not as polar as alcohols.
• The intermolecular forces in ethers are stronger than
those in alkanes but weaker than those in alcohols.
• The C-O bond also allows dissolving of polar substances
while the C-H bond allows the dissolving of non-polar
substances.
Uses of Ethers
• Ethers were once used as anesthetics to
eliminate pain during medical procedures.
• Due to its flammability and volatile
behaviours, it has largely been reduced in the
medical field.
• Currently, the majority of its uses comes as a
solvent for fats and oils.
Thiols
• Are organic compounds that contain a sulfhydryl
group (–SH).
• Cause compounds to be more polar in nature.
• Commonly have a strong odour (garlic, skunk).
• Are often added to natural gas (methane) to make
leaks easier to detect.
• To name thiols, add thiol to the ending of the
alkane name.
HSCH3 methanethiol
Practice Questions
• Page 34 #1, 2
• Page 39 #1, 2