10. Alcohols and phenols – classification, isomerism. Chemical properties – acid base properties, esterification, oxidation of alcohols and phenols. Reactions of the aromatic ring, dehydration, formation of chelates. Biological oxidation of alcohols (methanol, ethanol, 1,2-ethandiol, glycerol). Esters of phosphoric acid and esters of nitric acid – biological significance. Thioalcohols - definition and chemical properties. Coenzyme A, thioesters.

Alcohols and phenols

• Alcohols, phenols, and ethers are important classes of organic compounds with distinct structural features, properties, and applications.
• 1. Structural Characteristics:
• Alcohols contain a hydroxyl (-OH) group attached to a saturated carbon atom.
• Phenols feature a hydroxyl group (-OH) directly bonded to an aromatic ring.
• Ethers consist of two alkyl or aryl groups bonded to an oxygen atom.
• 2. Properties:
• Ethers have lower boiling points compared to alcohols due to the absence of hydrogen bonding.
• Alcohols and phenols are generally soluble in organic solvents but insoluble in water.
• Alcohols exhibit basic properties due to the presence of the hydroxyl group.
• Some ethers, like diethyl ether, have narcotic effects and are used as general anaesthetics.

Structure and nomenclature.

• 1. Alcohols:
• Structure:
• Contain a hydroxyl group (OH) bonded to a saturated carbon atom.
• The carbon atom with the OH group is sp³ hybridized.
• They can have one, two, or three OH groups per molecule, classified as monohydric, dihydric, or trihydric alcohols, respectively.

• Nomenclature:
• IUPAC system:
• Identify the longest carbon chain containing the OH group as the parent chain.
• Change the "-ane" suffix of the corresponding alkane to "-ol".
• Number the carbon chain to give the carbon with the OH group the lowest possible number.
• Use numbers to indicate the positions of other substituents.
• Example: CH3-CH2-CH2-OH is named butan-1-ol (1 refers to the position of the OH group).
• Common system:
• Name the alkyl group attached to the OH group and add the word "alcohol".
• Example: CH3-CH2-CH2-OH is named propyl alcohol.
• 2. Phenols:
• Structure:
• Contain a hydroxyl group (OH) directly bonded to a benzene ring.
• The carbon atom attached to the OH group is sp² hybridized.
• Can have additional substituents on the benzene ring.
• Nomenclature:

• IUPAC system:
• Use "hydroxy-" as a prefix before the name of the benzene ring (benzene becomes "benzene").
• Number the carbon atoms on the ring to give the OH group the lowest possible number (if there are other substituents).
• Indicate the positions of other substituents with numbers.
• Example: HO-C6H5 is named phenol, and Cl-C6H4-OH (Cl at position 2) is named 2-chlorophenol.
• Common system:
• Use the term "phenol" and add the names or positions of any substituents on the ring.
• Example: Cl-C6H4-OH can also be called chlorophenol.