Carboxylic acids + esters

• What is the functional group of a carboxylic acid?

  • COOH (C=O and C-OH)
• How do you name carboxylic acids?

  By using the suffix -oic acid
• Are carboxylic acids soluble in water? Why?

  Yes, because the acid group can form hydrogen bonds with water molecules
• What are the intermolecular forces in carboxylic acids?

  Hydrogen bonds in solid state, which are very strong
• What are esters formed from?

  Carboxylic acids and alcohols
• What is the general formula for esters?

  RCOOR’ (C=O, C-O-C)
• How do you name esters?

  Start with the alcohol group that has replaced the hydrogen, then the acid part
• Write an equation for the reaction of ethanoic acid with propan-1-ol.

  CH3COOH + CH3CH2CH2OH → CH3COOCH2CH2CH3 + H2O
• What characteristic physical properties do esters have?

  Esters are volatile and have pleasant fruity smells
• What are some uses of esters?

  Flavourings, perfumes, solvents, and plasticisers
• How could you distinguish carboxylic acids from other -OH containing compounds?

  Add NaHCO3; acids will produce sodium salt, water, and carbon dioxide
• Write an equation for the reaction of ethanoic acid with NaOH.

  CH3COOH + NaOH → H2O + CH3COO-Na+
• Write an equation for the reaction of ethanoic acid with Na2CO3.

  2CH3COOH + Na2CO3 → 2CH3COO-Na+ + H2O + CO2
• Write an equation for the reaction of ethanoic acid with calcium oxide.

  2CH3COOH + CaO → (CH3COO)2Ca + H2O
• What catalyst is needed for the formation of esters from alcohols and carboxylic acids?

  Concentrated strong acid, e.g., H2SO4
• What catalyst is needed for the hydrolysis of esters?

  Dilute strong acid, e.g., H2SO4
• What is an alternative method of hydrolysis?

  Base hydrolysis
• What are the advantages of base hydrolysis?

  Reaction goes to completion due to neutralisation by base
• What are carboxylic acid derivatives?

  Molecules that have the acyl group as part of their structure
• Name two acid derivatives and give their functional groups.

  Acyl chlorides: RCOCl; Acid anhydrides: RCOOCR / (RCO)2O
• How do you form an acyl chloride?

  React carboxylic acids with SOCl2
• Draw the mechanism for the acylation of a nucleophile by an acid derivative.

  Mechanism involves:

  • Nucleophile attacks the carbonyl carbon
  • Formation of a tetrahedral intermediate
  • Collapse of the intermediate to form the acylated product and regenerate the leaving group

  
• What are oxylic acid derivatives?

  Molecules that have the acyl group as part of their structure, formed from carboxylic acids
• Name two acid derivatives and their functional groups.

  • Acyl chlorides: RCOCl
  • Acid anhydrides: RCOOCR / (RCO)2O
• How do you form an acyl chloride?

  By reacting carboxylic acids with SOCl2
• What is the mechanism for the acylation of a nucleophile by an acid derivative?

  • The nucleophile attacks the carbonyl carbon
  • A tetrahedral intermediate forms
  • The leaving group departs, forming the product

  
• What are the products when ammonia is the nucleophile in the acylation of acyl chlorides or acid anhydrides?

  An amide is formed
• Write the equation for the reaction of ethanoyl chloride and ammonia.

  CH3COCl + 2NH3 → CH3CONH2 + NH4Cl
• What is the mechanism for the reaction of ethanoyl chloride and ammonia?

  • Nucleophilic attack by ammonia
  • Formation of a tetrahedral intermediate
  • Departure of chloride ion
  • Formation of amide
• What are the products when a primary amine is the nucleophile in the acylation of acyl chlorides or acid anhydrides?

  An N-substituted amide is formed
• Write the equation for the reaction of ethanoyl chloride and methylamine.

  CH3COCl + CH3NH2 → CH3CONHCH3 + CH3NH3Cl
• What is the mechanism for the reaction of ethanoyl chloride and methylamine?

  • Nucleophilic attack by methylamine
  • Formation of a tetrahedral intermediate
  • Departure of chloride ion
  • Formation of N-substituted amide
• What are the products when an alcohol is the nucleophile in the acylation of acyl chlorides or acid anhydrides?

  An ester is formed
• Write the equation for the reaction of ethanoyl chloride and ethanol.

  CH3COCl + CH3CH2OH → CH3COOCH2CH3 + HCl
• What is the mechanism for the reaction of ethanoyl chloride and ethanol?

  • Nucleophilic attack by ethanol
  • Formation of a tetrahedral intermediate
  • Departure of chloride ion
  • Formation of ester
• What are the products when water is the nucleophile in the acylation of acyl chlorides or acid anhydrides?

  A carboxylic acid is formed
• What is the name of the reaction when acyl chlorides or acid anhydrides react with water as a nucleophile?

  Hydrolysis
• Write the equation for the reaction of ethanoyl chloride and water.

  CH3COCl + H2O → CH3COOH + HCl
• What is the mechanism for the reaction of ethanoyl chloride and water?

  • Nucleophilic attack by water
  • Formation of a tetrahedral intermediate
  • Departure of chloride ion
  • Formation of carboxylic acid