Organic Synthesis

• Analysing organic synethsis


  Type of reaction - addition reactions are more sustainable than substitution or elimination reactions as there are no waste products. Reagents - renewable reagents with few safety concerns are preferred.

  By-products - less harmful by-products are favoured as there would be fewer safety and environmental concerns. If the by-products can be used in another industry, the process is more sustainable. Conditions - choose the reaction with the most energy efficient and safe conditions.
• Alkanes

  Combustion

  Free radical substitution with Br2, Cl2 and UV light (forms haloalkanes)

  Thermal Cracking: 750 degrees (forms short chain alkenes and alkanes)

  Catalytic Cracking: zeolite catalyst, 500 degrees, (forms aromatic compounds and branched alkenes)
• Alkenes

  Electrophilic addition:

  Steam (high pressure and temp) and concentrated acid catalyst-forms alcohols

  Hydrogen halides (forms haloalkanes) or halogens (forms dihaloalkanes)

  Hydrogen and nickel catalyst at 200degrees (forms alkanes)

  
  

  Oxidation with H+ /MnO4 - (forms diols)

  
  

  Addition polymerisation (forms polymers)

  
  

  Combustion
• Haloalkanes

  Nucleophilic substitution:

  Warm NaOH (forms alcohols)

  Reaction with ammonia and heat (forms primary amines)

  Reaction with ethanolic KCN and heat (forms nitriles)

  Elimination:

  Hot ethanolic KOH (forms alkenes)
• Alcohols

  • Combustion
  • Nucleophilic substitution with hydrogen halides, sulfur dichloride oxide or phosphorus(III) halides (forms haloalkanes)
  • Ethanol + sodium (forms sodium ethoxide and hydrogen gas)
  • Oxidation with H+ /Cr2O7 2- (forms carbonyls and carboxylic acids)
  • Dehydration using an acid catalyst at 180degrees (forms alkenes)
  • Esterification with carboxylic acids (c. acid catalyst or acyl chlorides/acid anhydride)
• Aldehydes


  • Oxidation with H+ /Cr2O7 2- or tollen and fehling reagent (forms carboxylic acids)
  • Reduction using NaBH4 or LiAlH4 (forms primary alcohols)
  • Nucleophilic addition with KCN and HCl (forms hydroxynitriles)
• Ketones


  • Reduction using NaBH4 or LiAlH4 (forms secondary alcohols)
  • Nucleophilic addition with KCN and HCl (forms hydroxynitriles)
• Carboxylic Acids

  • Reaction with metals, alkalis or carbonates (forms a salt and inorganic products)
  • Esterification with alcohols and c.H2SO4
  • Reduction with LiAlH4 (forms alcohols)
  • Reaction with SOCl2 (forms acyl chlorides, sulfur dioxide and hydrochloric acid)
  • Reaction with phosphorus(V) chloride or phosphorus(III) chloride (forms acyl chlorides)
  • Oxidation of methanoic acid using Fehling’s or Tollens’ (forms carbon dioxide and water)
  • Oxidation of ethanedioic acid using acidified potassium manganate(VII) (forms water and carbon dioxide)
• Esters 


  • Acid hydrolysis (forms a carboxylic acid and an alcohol)
  • Alkali hydrolysis (forms a carboxylate salt and an alcohol)
• Amines 


  • Reaction with acids (forms a salt)
  • Nucleophillic addition-elimination with acyl chloride or acid anhydride to make amide
• Nitriles 


  • Acid hydrolysis (forms a carboxylic acid and a salt)
  • Alkali hydrolysis (forms a carboxylate salt and ammonia)
  • Hydrogenation with H2, nickel catalyst or LiAlH4 200degrees to make amine
• Arenes 


  • Electrophilic substitution:
  • Halogen (forms chlorobenzene with Cl2 and bromobenzene with Br2 )
  • Nitration (forms nitrobenzene) c.H2SO4 and c.HNO3 to create NO2+ electrophile at 50degrees
  • Friedel-Crafts acylation and alkylation- acyl chloride or acid anhydride- AlCl3 catalyst
  • Oxidation of a side chain (forms benzoic acid)
  • Hydrogenation (forms cyclohexane)
• Phenol


  • Reactions with strong bases (not acidic enough to react with carbonates)
  • Reaction with sodium (forms sodium phenoxide and hydrogen gas)
  • Reaction with diazonium salts (forms azo compounds) Electrophilic substitution:
  • Nitration using HNO3 (forms nitrophenol)
  • Bromination using Br2 (forms bromophenol)
• Acyl chloride 


  • Hydrolysis with water (forms carboxylic acids and HCl)
  • Hydrolysis with sodium hydroxide (forms a carboxylate salt and water)
  • Esterification with alcohols or phenol
  • Reaction with ammonia (forms an amide and HCl)
  • Reactions with primary amines (forms an N-substituted amide)
• Amides 


  • Acid hydrolysis (forms a carboxylic acid and ammonium ions)
  • Alkali hydrolysis (forms a carboxylate salt and ammonia or an amine)
  • Reduction using LiAlH4 (forms a primary amine)