Carboxylic Acids and Derivatives, and Nitrogen Compounds

Introduction

• Presenter: Chris Harris from Alley Chemistry
• Topics: Carboxylic acids, derivatives (e.g., esters), and nitrogen compounds (Topic 18 & 19)
• Context: Cambridge International Examination (CIE) specification

Carboxylic Acids

Properties

• Contain carboxyl functional group (COOH)
• Composed of carbonyl group (C=O) and hydroxyl group (OH)
• Named by finding the longest carbon chain and adding "-oic acid"
• Weak acids, dissociate partially in water
• React with carbonates to form CO2, and with bases to form salts

Formation

• From primary alcohols and aldehydes via oxidation using oxidizing agents (e.g., potassium dichromate)
• From nitriles via hydrolysis

Reactions

• With Carbonates: Form CO2, H2O, and a salt
• With Bases: Form salts
• With Metals (e.g., Mg): Form hydrogen gas and salt
• With Ammonia: Form ammonium salts

Derivatives of Carboxylic Acids

Esters

• Formed by reacting carboxylic acids with alcohols using a sulfuric acid catalyst
• General reaction: Carboxylic acid + Alcohol → Ester + Water
• Hydrolysis (Acid or Base) can break esters back into carboxylic acids and alcohols
  • Acid Hydrolysis: Uses dilute acid
  • Base Hydrolysis: Uses dilute base, forms carboxylate ion

Uses of Esters

• Perfumes and food flavorings due to sweet smell
• Solvents in adhesives and glues
• Plasticizers in polymers

Reduction of Carboxylic Acids

• Carboxylic acids can be reduced to alcohols using lithium aluminum hydride (LiAlH4)

Nitrogen Compounds

Aliphatic Amines

• Made by reacting halogenoalkanes with excess ammonia
• Mechanism involves nucleophilic substitution

Nitriles

• Formed by reacting halogenoalkanes with cyanide ions (e.g., in potassium cyanide)
• Reaction follows nucleophilic substitution to extend carbon chain

Hydroxy Nitriles

• Formed by reaction of carbonyl compounds with cyanide ions via nucleophilic addition
• Produce hydroxy nitriles (contain OH and CN groups)
• Can use KCN dissolved in acidic solution or HCN directly

Notes on Reactions

• Many reactions are revisits from previous topics (e.g., nucleophilic substitution, reactions with carbonyls)
• Concepts of equilibrium, acid-base reactions, and optical isomerism are relevant

Additional Resources

• Full range of CIE-related videos available on Ally Chemistry YouTube channel
• PowerPoint slides available for purchase

Conclusion

• Topics covered highlight key reactions and properties of carboxylic acids, derivatives, and nitrogen compounds.