Alcohols and Phenols

ALCOHOLS AND PHENOLS

Module Overview

  • Instructor: Mr. Jan Clarence Salinas, LPT

  • College of Allied Medical Professions, Angeles University Foundation

Learning Objectives

  • Classify and name alcohols and phenols using classical and IUPAC names.

  • Explain the physical and chemical properties and classification of alcohols.

Topic Outline

Bonding Characteristics of Oxygen in Organic Compounds

  • Oxygen can form either 2 single bonds or 1 double bond.

  • Carbon forms four bonds; Hydrogen forms one bond.

Structural Characteristics of Alcohols

  • Alcohols are organic compounds with an -OH group bonded to a saturated carbon.

  • General formula: R-OH, where R = alkyl group.

IUPAC Nomenclature of Alcohols

  • To name alcohols:

    1. Drop the final -e from the alkane name.

    2. Add -ol as a suffix.

    3. Name the longest carbon chain to which the hydroxyl group is attached.

    4. Number the chain starting at the end nearest the hydroxyl group.

    5. Name and locate any other substituents present.

    6. In cyclic compounds, start numbering the ring at the -OH group.

Properties of Alcohol

Physical Characteristics

  • Alcohols possess both polar (hydroxyl) and nonpolar (alkyl) characteristics.

  • Their physical properties depend on the balance between these characteristics.

  • Alcohols have higher boiling points and greater solubility in water than alkanes of similar molecular mass due to hydrogen bonding.

Classification of Alcohols

  • Primary Alcohols: Hydroxyl-bearing carbon is bonded to one other carbon.

  • Secondary Alcohols: Hydroxyl-bearing carbon is bonded to two other carbons.

  • Tertiary Alcohols: Hydroxyl-bearing carbon is bonded to three other carbons.

Isomerism in Alcohols

  • Positional Isomers: Same carbon skeleton, different locations of the hydroxyl group.

  • Skeletal Isomers: Same functional groups, different connectivity of the carbon skeleton.

Commonly Encountered Alcohols

  • Methanol (Methyl Alcohol):

    • Simplest colorless alcohol, toxic, used as fuel.

  • Ethanol (Ethyl Alcohol):

    • Found in alcoholic beverages; produced via fermentation.

  • Isopropyl Alcohol:

    • Rubbing alcohol; induces vomiting.

  • Ethylene Glycol:

    • Main ingredient for antifreeze; toxic.

  • Propylene Glycol:

    • Non-toxic; used in drugs and food.

  • Glycerol:

    • Used in food and is a biological antifreeze.

Chemical Reactions of Alcohols

  1. Combustion: Produces CO2 and water.

  2. Dehydration: Removal of water components from reactants.

  3. Oxidation: Alcohols lose hydrogen atoms, often producing carbonyl compounds.

  4. Halogenation: Substituting hydroxyl group with a halogen.

PHENOLS

Definition

  • Phenols are organic compounds with an -OH group attached to an aromatic carbon ring (General Formula: Ar-OH).

  • Phenol is the simplest member and used as a common name.

Nomenclature of Phenols

  • Follow similar rules as naming benzene derivatives with substituents. Ring numbering begins at the hydroxyl group.

  • Common derivatives include methylphenols (cresols).

  • For multiple substituents, assign the lowest possible numbers, and list them in alphabetical order.

Properties of Phenols

  • Colorless, flammable, oily at room temperature, slightly soluble in water.

  • Non-dehydrable and oxidizable only with strong agents.

Conclusion

  • Review key points on classification, nomenclature, and common reactions involving alcohols and phenols.

References

  • Stoker, H. Stephen. General Organic and Biological Chemistry. Singapore: Cengage Learning, 7th Edition, 2016.

Page 13 Notes

  • Overview of Alcohols and Phenols

    • Alcohols: Organic compounds containing a hydroxyl (-OH) group.

    • Phenols: Compounds with a hydroxyl group attached to an aromatic carbon.

  • Bonding Characteristics of Oxygen

    • Oxygen can form two single bonds or one double bond.

    • Importance of hydrogen bonding in distinguishing the properties of alcohols from other organic compounds.

  • Differences in Solubility and Boiling Points

    • Alcohols have higher boiling points due to hydrogen bonding compared to alkanes.

    • Solubility in water varies with molecular mass and structure (e.g., primary vs tertiary).