CHS Module 8 Video 1 Alcohols, Phenols, Ethers

Introduction to Organic Chemistry

  • Focus on alcohols, phenols, and ethers.

Alcohols

Definition of Alcohols

  • An alcohol is defined as a compound with an -OH group (hydroxyl group) bonded to a saturated alkane-like carbon.

  • Example: Ethyl alcohol (ethanol) is formed by adding the -OH group to ethane (CH3-CH2-).

Physical Properties of Alcohols

  • Structural similarity to water leads to similar physical properties, notably boiling points due to hydrogen bonding.

  • Boiling Point Comparison:

    • Water: 100°C

    • Ethyl Alcohol: 78.5°C

    • Ethers: -23°C (do not form hydrogen bonds)

    • Propane: -42°C

Polarity and Solubility

  • Alcohols are more polar than hydrocarbons due to the electronegative oxygen atom.

  • Miscibility with Water:

    • Methanol (1 carbon) and Ethanol (2 carbons) are miscible with water (form homogeneous solutions).

    • Alcohols with higher carbon counts become less soluble in water (e.g., heptanol).

Reactions of Alcohols

Dehydration

  • Removal of water when treated with a strong acid, forming an alkene.

  • Example: Tert-butanol dehydrated to form 2-methylpropene.

Oxidation

  • Primary and secondary alcohols oxidize to form carbonyl-containing compounds.

  • Aldehydes formed from oxidizing primary alcohols; ketones from secondary alcohols.

  • Tertiary alcohols do not react with oxidation due to the lack of a hydrogen atom on the bonded carbon.

Phenols

Definition of Phenols

  • A phenol is an -OH group attached to a benzene-like ring.

  • Hydroxybenzene (C6H5OH) is the specific compound known as phenol.

Properties of Phenols

  • Influenced by electronegative oxygen and hydrogen bonding, making them somewhat water-soluble.

  • Higher melting and boiling points than comparable alkylbenzenes but less soluble in water compared to alcohols.

Ethers

Definition of Ethers

  • Ethers contain an oxygen atom bonded between two carbon atoms (alkyl groups).

  • Named by identifying the two organic groups, followed by 'ether' (e.g., dimethyl ether).

Properties of Ethers

  • Do not form hydrogen bonds with one another, resulting in higher boiling points than alkanes but lower than alcohols.

  • Ethers can hydrogen bond with water, making some (e.g., dimethyl ether) water-soluble.

  • Good solvents in reactions requiring polar solvents without -OH groups.

  • Flammability and handling precautions necessary (historical use in operating rooms).

Applications

  • Ethers found in nature, including plant oils and perfumes.

Conclusion

  • Overview of alcohols, phenols, and ethers provided insights into their structures, properties, and chemical behaviors.