Definition: Alkanols, also known as alcohols, are organic compounds containing oxygen (O), carbon (C), and hydrogen (H) atoms.

Functional Group

• The functional group of alkanols is the –OH (hydroxyl group).

Naming Alkanols

Alkanols are named by replacing the –e in the corresponding alkane name with –anol. Here are the names based on the number of carbon atoms:

• 1 carbon atom: Methanol
• 2 carbon atoms: Ethanol
• 3 carbon atoms: Propanol
• 4 carbon atoms: Butanol
• 5 carbon atoms: Pentanol
• 6 carbon atoms: Hexanol
• 7 carbon atoms: Heptanol
• 8 carbon atoms: Octanol
• 9 carbon atoms: Nonanol
• 10 carbon atoms: Decanol

General Formula

• The general formula for alkanols is CnH₂n+1OH.

Example Calculations:

• For 2 carbon atoms:
  n=2n = 2n=2 → C2H(2×2)+1OH=C2H5OH
• For 4 carbon atoms:
  n=4n = 4n=4 → C4H(2×4)+1OH=C4H9OH
• For 10 carbon atoms:
  n=10n = 10n=10 → C10H(2×10)+1OH=C10H21OH

Molecular and Condensed Formulae

• Methanol: Molecular formula is CH₃OH; condensed formula is CH₃OH.
• Ethanol: Molecular formula is C₂H₅OH; condensed formula is CH₃CH₂OH.
• Propanol: Molecular formula is C₃H₇OH; condensed formula is CH₃(CH₂)₂OH.
• Butanol: Molecular formula is C₄H₉OH; condensed formula is CH₃(CH₂)₃OH.
• Pentanol: Molecular formula is C₅H₁₁OH; condensed formula is CH₃(CH₂)₄OH.
• Hexanol: Molecular formula is C₆H₁₃OH; condensed formula is CH₃(CH₂)₅OH.
• Heptanol: Molecular formula is C₇H₁₅OH; condensed formula is CH₃(CH₂)₆OH.
• Octanol: Molecular formula is C₈H₁₇OH; condensed formula is CH₃(CH₂)₇OH.
• Nonanol: Molecular formula is C₉H₁₉OH; condensed formula is CH₃(CH₂)₈OH.
• Decanol: Molecular formula is C₁₀H₂₁OH; condensed formula is CH₃(CH₂)₉OH.

Structural Formulae

• Structural formulae show how atoms are bonded in the molecule.

Skeletal Formulae

• Skeletal formulae use zigzag lines to represent bonds. Carbon atoms are implied at points where lines meet.

Classification of Alkanols

1. Primary Alkanol
   • The hydroxyl group (-OH) is attached to a carbon atom bonded to only one other carbon atom.
   • Example: Ethanol (C₂H₅OH)
2. Secondary Alkanol
   • The hydroxyl group is bonded to a carbon atom that is connected to two other carbon atoms.
   • Example: Isopropanol (C₃H₇OH)
3. Tertiary Alkanol
   • The hydroxyl group is bonded to a carbon atom that is connected to three other carbon atoms.
   • Example: Tert-butanol (C₄H₉OH)

Preparation of Ethanol

Indigenous Method

• Ethanol (locally known as kachaso) is prepared by mixing maize bran with sugar solution or fruit juices.
• The mixture is fermented for 3-5 days, then distilled to obtain ethanol.
• During distillation, ethanol boils faster than water, allowing it to be collected as a gas that condenses in a cooler.

Industrial Methods

1. Fermentation of Sugar by Yeast
   • Sugars (like glucose) are mixed with yeast, which contains the enzyme zymase.
   • The mixture is kept at room temperature for about 3-4 days.
   • The reaction produces ethanol and carbon dioxide: 

C6H12O6 (aq)→yeast 2C2H5OH (aq)+2CO2 (g)

The resulting ethanol is often purified through fractional distillation.

1. Hydration of Ethene
   • Ethanol can also be produced by reacting ethene with steam in the presence of a catalyst like phosphoric acid (H₃PO₄): 

C2H4 (g)+H2O (l)→H3PO4      C2H5OH (l)

• This reaction is exothermic and occurs at approximately 300ºC, and it is reversible.

Physical Properties of Alkanols

1. Solubility
   • Alkanols are soluble in water, with solubility decreasing as molecular mass increases.
2. Melting and Boiling Points
   • These points increase with molecular size due to stronger intermolecular forces. Alkanols have higher boiling points than hydrocarbons of similar carbon numbers due to hydrogen bonding.
3. Density
   • Density increases with molecular mass due to stronger intermolecular forces, which bring molecules closer together.
4. Viscosity
   • Viscosity increases with molecular size as stronger intermolecular forces make molecules stick together.
5. Volatility
   • Alkanols are volatile liquids, with volatility decreasing as molecular size increases due to increased intermolecular forces requiring more energy for evaporation.

Chemical Properties/Reactions of Alkanols

1. Combustion
   • Alkanols burn in oxygen to produce carbon dioxide and water.
   • Example: C2H5OH(l)+3O2(g)→2CO2(g)+3H2O(l)
2. Reaction with Alkali Metals
   • Alkanols react with alkali metals to form alkanoxides and hydrogen gas.
   • Example: 2C2H5OH(l)+2Na(s)→2C2H5ONa(aq)+H2(g)
3. Oxidation to Alkanoic Acids
   • Alkanols can be oxidized to alkanoic acids using oxidizing agents or atmospheric oxygen.
   • a. Using oxidizing agents (e.g., potassium dichromate): 

C2​H5​OH(l)+[O]…K2​Cr2​O7​​……2CH3​COOH(aq)

• b. Oxidation by atmospheric oxygen (e.g., ethanol turning to ethanoic acid when exposed to air).

1. Dehydration to Form Alkenes
   • Alkanols can be dehydrated by concentrated sulfuric acid to produce alkenes.
   • Example

C2​H5​OH(l)Conc…….. H2​SO4​​C2​H4​(g)+H2​O(l)

1. Esterification
   • Alkanols react with alkanoic acids to form esters and water in a process known as esterification.
   • Example: 

C2​H5​OH(l)+CH3​COOH(l)→CH3​COOC2​H5​(aq)+H2​O(l)

Uses of Ethanol

1. Solvent: Used in various industrial processes.
2. Manufacturing: Essential in making varnishes, inks, glues, and paints.
3. Fuel: Used in cars, either blended with gasoline or as a standalone fuel.
4. Beverages: Main ingredient in alcoholic drinks like wine and spirits.
5. Cosmetics: Utilized in deodorants and perfumes due to its evaporation properties.
6. Antiseptic: Effective in specified concentrations for disinfecting.
7. Health Benefits: Moderate consumption may protect against heart diseases and improve blood factors.

Dangers of Excessive Consumption of Alcoholic Drinks

1. Addiction: Leads to alcoholism, affecting physical and emotional health.
2. Cancer Risks: Increases the likelihood of liver, mouth, and esophagus cancers.
3. Cardiac Problems: Associated with high blood pressure, heart failure, and stroke.
4. Pregnancy Issues: Can result in miscarriages.
5. Mental Health: May lead to suicidal tendencies or serious injuries.
6. Risky Behaviors: Influences dangerous sexual behaviors, leading to STIs.
7. Job Loss: Contributes to unemployment and poverty.
8. Liver Damage: Can cause liver cirrhosis over time.