Alcohols and Flammability

• Flammability was a method to determine the alcohol content in distilled beverages.
• To test, gunpowder was mixed with the beverage.
• If the gunpowder ignited, the beverage was "100 percent proof," containing at least 57% alcohol by volume.
• Modern containers list the proof based on ethanol percentage.
• Flambé is a cooking technique that uses the flammability of ethanol.
• Methanol and ethanol are commercially valuable alcohols.
• Methanol can be made from methane, or was originally created by heating wood without air
• Ethanol is made by fermenting sugars from plants or by an addition reaction of ethene.
• Ethanol is legally consumed in Canada but is toxic in large quantities.

Alcohols

• Alcohols have the hydroxyl group (-OH).
• Alcohols are classified based on the number of carbon atoms bonded to the carbon atom attached to the hydroxyl group.
• Butanol's isomers have different properties based on their molecular arrangement.
• Primary alcohol: The hydroxyl group is bonded to a terminal carbon atom, like butan-1-ol.
• Secondary alcohol: The hydroxyl group is bonded to a carbon atom attached to two other carbon atoms, like butan-2-ol.
• Tertiary alcohol: The hydroxyl group is bonded to a carbon atom attached to three alkyl groups, like 2-methylpropan-2-ol.
• The presence of the electronegative oxygen atom in the -OH group affects a molecule's polarity.
• The C-O bond is more polar than the C-H bond.
• Alcohols are polar molecules.

Naming and Drawing Alcohols

• IUPAC naming replaces the final -e of the parent hydrocarbon with -ol.
• The name includes the carbon atom number to which the hydroxyl group is attached.
• The chain is numbered to give the hydroxyl group the lowest possible number.
• Propan-1-ol is a solvent, while propan-2-ol (isopropyl alcohol) is rubbing alcohol.
• Both propanol isomers are toxic if ingested.
• Polyalcohols contain multiple -OH groups and use suffixes like -diol or -triol.
• Ethane-1,2-diol (ethylene glycol) is used as antifreeze.
• Propane-1,2,3-triol (glycerol/glycerine) is used in pharmaceutical preparations due to its low toxicity and water solubility.
• Cyclic alcohols follow similar naming conventions, adding -ol to the root name of the cyclic hydrocarbon.
• The -OH group takes precedence in numbering cyclic hydrocarbons, as seen in 2,2-dimethylcyclohexanol.
• Aromatic alcohols have a bonded -OH group to an aromatic hydrocarbon, with phenol being the simplest.
• Benzene-1,2-diol is an example of a benzene ring with two -OH groups.
• In some cases, the -OH group is treated as a hydroxyl substituent if another functional group takes precedence like in carboxylic acids.

Naming Alcohols Steps

• Identify the longest carbon chain or ring.
• Use the suffix -ol for one -OH group or -diol/-triol for multiple.
• Number the parent chain to give the -OH group the lowest possible number.
• Identify other substituents and their locations.
• Count carbon atoms bonded to the -OH group to identify the alcohol type.

Properties of Alcohols

• Alcohols have higher boiling points than alkanes due to strong dipole-dipole forces and hydrogen bonding.
• Hydrogen bonding occurs between the hydroxyl groups of adjacent molecules.
• Alcohols with shorter carbon chains are more soluble in water.
• The -OH group increases polarity and solubility in water.
• Larger carbon chains reduce solubility in water.
• Alcohols can dissolve both polar and non-polar substances, making them useful as solvents.

Reactions Involving Alcohols

• Alkenes react with water to produce alcohols through hydration.
• Sulfuric acid catalyzes the formation of butan-2-ol from but-1-ene and water, following Markovnikov's rule.
• Methanol is produced by combining carbon monoxide with hydrogen gas at high temperature and pressure, using a catalyst.
• Ethanol is traditionally prepared by fermenting an aqueous sugar solution with yeast in the absence of oxygen.
• Alcohols undergo combustion, producing carbon dioxide and water.
• The reverse of alcohol production is dehydration reactions.
• Alkenes and water are formed from alcohol with a sulfuric acid catalyst.

Alcohol Reactions - Addition and Dehydration

• Markovnikov’s rule determines that a hydrogen atom will bond to the carbon atom that is already bonded to the greatest number of hydrogen atoms.
• During a dehydration reaction, a water molecule is removed from an alcohol to form an alkene.

Ethers

• Ethers contain an oxygen atom bonded between two carbon atoms within a chain.
• Condensation reactions synthesize ethers from alcohols, producing water.
• Boiling points of ethers are slightly higher than similar-sized alkanes but lower than alcohols.
• Ethers cannot form hydrogen bonds but are somewhat polar due to the C-O bond.
• Ethers are useful solvents that dissolve polar and less polar substances.

Naming Ethers

• The IUPAC method adds -oxy to the smaller hydrocarbon group bonded to the larger alkane group.
• A common alternative nomenclature uses the names of the two hydrocarbon groups followed by "ether".

Thiols

• Thiols contain the sulfhydryl functional group (-SH).
• Thiols have strong odors and may contribute to the smell of garlic.
• Thiols are added to natural gas for leak detection.
• Hydrogen peroxide can neutralize thiol odors by forming odorless disulfide compounds.
• To name thiols, add the suffix -thiol to the alkane name.