Chemo unit 6

• Aldehyde


  Functional group is a carbonyl group (C=O) bonded to a hydrogen atom
• Methanal (formaldehyde)


  Carbonyl group is bonded to two hydrogen atoms
• Aldehyde


  Carbonyl group is bonded to one hydrogen atom and one carbon atom
• Ketone


  Functional group is a carbonyl group bonded to two carbon atoms
• IUPAC nomenclature for aldehydes and ketones


  1. Select the longest chain of carbon atoms that contains the functional group as the parent alkane

  2. For aldehydes, change the suffix -e of the parent alkane to -al

  3. The suffix "-al" indicates the functional group -CHO

  4. For ketones, use the suffix -one to replace the terminal -e in the corresponding alkane name

  5. The suffix '-one' indicates the functional group -RCOR'
• For aldehydes, the carbonyl group can only appear at the end of the parent chain and numbering starts with that group as carbon-1, its position is unambiguous
• For ketones, the position of the functional group must be indicated in the name of higher ketones
• Polarity of carbonyl group


  Oxygen is more electronegative than carbon, so the C=O bond is polar with oxygen bearing a partial negative charge and carbon bearing a partial positive charge
• Aldehydes and ketones


  They are polar compounds and interact in the liquid state by dipole-dipole interactions
• Aldehydes and ketones have higher boiling points than non-polar compounds with comparable molecular weight
• Low-molecular-weight aldehydes and ketones are more soluble in water than non-polar compounds of comparable molecular weight due to hydrogen bonding with water molecules
• Contents of Carboxylic Acids section


  • Structure and Nomenclature of Carboxylic acids
  • Physical Properties of Carboxylic acids
  • Chemical Properties of Carboxylic acids
  • Preparation of Carboxylic acids
  • Fatty Acids
  • Uses of Carboxylic acids
• Carboxylic acid


  Organic compound characterized by the presence of a carboxyl functional group (COOH)
• Saturated monocarboxylic acid


  General formula is R-COOH, where R is hydrogen or an alkyl group for aliphatic acids, or a phenyl (aryl) group for aromatic acids
• Dicarboxylic acid


  Carboxylic acid containing two carboxyl groups in its structure
• Tricarboxylic acid


  Carboxylic acid containing three carboxyl groups in its structure
• Common names of some monocarboxylic acids


  • Derived from Latin names indicating the first original natural source
• Common naming of branched chain and substituted carboxylic acids


  Named as derivatives of straight chain carboxylic acids, with position of side chain or substituents indicated by Greek letters α, β, γ, δ
• Common and IUPAC names of some dicarboxylic acids


  • Dicarboxylic acids also have common names based on their sources
• Aromatic carboxylic acid


  Compound with a carboxyl group directly attached to an aromatic ring, the simplest is benzoic acid
• IUPAC naming of straight chain monocarboxylic acids


  Replace the terminal "-e" of the corresponding alkane name with "-oic acid", named as alkanoic acids
• IUPAC naming of branched chain and substituted monocarboxylic acids


  Derived from the longest carbon chain containing the carboxyl group, with position of substituents indicated by Arabic numerals
• IUPAC naming of dicarboxylic acids


  Named as alkanedioic acids, obtained by replacing the suffix "-e" in the name of the corresponding alkane with "-dioic acid"
• IUPAC naming of aromatic carboxylic acids


  Named as benzenecarboxylic acids, with position of substituents indicated using Arabic numerals
• Lower aliphatic carboxylic acids up to 9 carbon atoms are liquids, higher members are colourless waxy solids
• Odors of lower aliphatic carboxylic acids progress from sharp and irritating to distinctly unpleasant
• Carboxylic acids have higher melting and boiling points than hydrocarbons and oxygen-containing organic compounds of comparable size and shape due to strong intermolecular attractive forces
• Hydrogen bonding in carboxylic acids


  The hydroxyl group of one carboxylic acid molecule acts as a proton donor toward the carbonyl oxygen of a second, forming two hydrogen bonds
• Carboxylic acids of four carbon atoms or fewer are miscible with water in all proportions
• In aqueous solution, carboxylic acids ionize partially and an equilibrium exists between the ionized and un-ionized forms
• Reaction of carboxylic acids with metals


  1. Carboxylic acids react with active metals to give metal carboxylate salts and hydrogen gas

  2. The salts are named by writing the name of the metal first, followed by the name of the acid replacing the ending -ic acid by -ate