Polymers and life

• Why are carboxylic acids only weak: Because the hydrogen ion only partially dissociates
• How do you name carboxylic acids: -Name as alkane

  -Remove 'e'

  -Add 'oic acid
• How is a polyester formed: Diol + Dicarboxylic acid --> polyester + water
• What type of reaction is the reaction between a Diol and a Dicarboxylic acid: Condensation polymerisation
• What is a condensation reaction: Release of a small molecule (HCL/H2O)
• What homologous series are reacted with phenols: Acid anhydrides and Acyl chlorides
• Why are carboxylic acids not used in reactions with phenols: A more vigorous reaction is required
• What is the general formula of a primary amine: R-NH2
• What is the general formula of a secondary amine: R-NH-R
• What is the general formula of a tertiary amine: N-R3
• How to name amines: For below 4 carbons, alkyl first, for 4 carbons and above, alkyl after amine.
• Why does ammonia have similar properties to amines: Amines can act as bases (accept protons) as they can form dative covalent bonds
• Reaction of methyl amine with water: Methylammonium ions and hydroxide
• Why are amine solutions alkali: Due to the presence of Hydroxide ions in the solution
• Reaction of short chained amines with acids: Soluble due to H-bonding
• Reaction of long chained amines with acids: Unsoluble/less soluble because more H-bonding in water has to be broken, is energetically unfavourable.
• Reaction of acyl chlorides and ammonia: Forms a primary amide and HCl
• Why is the reaction of acyl chloride and ammonia a condensation reaction: Because a small molecule (HCl) is produced
• Reaction of an Acyl chloride with a primary amine: -Forms a secondary amide functional group (peptide bond) and HCl

  -Condensation reaction
• Reaction of a diamines and dicarboxylic acids: Forms nylons and water
• What type of reaction is that between diamines and dicarboxylic acids: A condensation polymerisation
• How are nylons formed industrially: -Diamines and dicarboxylic acids

  -Slow
• How are nylons formed in a lab: -Diamines and Diacyl chloride

  -Vigorous so not safe on a large scale
• What catalyst is used in esterification and why: -Concentrated sulphuric acid

  -It is a dehydrating agent, removing water, so shifts equilibrium to the right, forming more of the ester.
• Describe the hydrolysis of esters: Very slow so catalyst is used. Excess water is used as catalyst favours both forward and backwards reactions
• reaction of esters with basic solutions: Soluble ionic salt and alcohol
• What type of reaction is the one between esters and basic solutions: Irreversible reaction therefore the reaction will go to completion
• Reactions of esters with water under acidic conditions: Carboxylic acid + Alcohol
• What type of reaction is the reaction between esters and water under acidic conditions: Acid hydrolysis
• Conditions for hydrolysis of esters: -Strong acid/base

  -Heat under reflux
• Hydrolysis of primary amides under acidic conditions: Carboxylic acid and ammonium ion formed
• Hydrolysis of secondary amides under acidic conditions: Carboxylic acid and R-(N+H3)
• Reaction of amides under moderately conc alkali: Carboxylate ion and R-NH2
• General structure of an amino acid


  H2N-C(R)(H)-COOH
• General structure of an amino acid in alkali solution: Carboxylate ion + water
• General structure of an amino acid in acidic solution: Nitrate salt (H3N+) + water
• What is a feature of a zwitter ion: Its ionic so very soluble in water
• What is a chiral carbon/chiral centre: Carbon has 4 different side groups (entire chain)
• Why are dipeptides/peptides able to polymerise: Due to them being bifunctional
• Describe the hydrolysis of polypeptides: Requires moderately conc acid or alkali. Use enzymes biologically.