PROPERTIES OF ORGANIC COMPOUNDS

• Boiling point


  Breaking away from the attractive forces that hold particles together
• Melting point


  Breaking away from the attractive forces that hold particles together
• Ionic solids


  • Held to the crystal lattice by very strong interionic forces, have higher melting point
• Molecular solids


  • Held by relatively weaker intermolecular forces of attraction (IMFA) or Van der Waal's forces, have lower melting point
• Dipole-dipole interaction


  Stronger type of intermolecular force that holds polar molecules together
• Compounds exhibiting dipole-dipole interaction

  • Carbonyl compounds (aldehydes and ketones)
  • Acid derivatives (acid halides)
  • Ethers
• Hydrogen bonding


  Particularly strong type of dipole-dipole interaction present when H is bonded to F, O or N
• Organic compounds exhibiting hydrogen bonding

  • Carboxylic acids
  • Alcohols
  • Amines
• London dispersion forces (LDF)


  General type of intermolecular interaction that operates in all atoms and molecules, gets stronger with increasing molecular size
• Melting and boiling point order of functional groups

  • Organic salts
  • RCOOH
  • ROH
  • RNH2, RCOR, RCOZ
  • ROR
  • HCs
• Factors affecting boiling point and melting point

  • Molecular size - Higher molecular weight increases boiling and melting point
  • Branching - More branching decreases boiling and melting point
  • Polarity - Higher polarity increases boiling and melting point
  • Molecular symmetry - Symmetrical molecules have lower boiling point
  • Intramolecular H-bonding - Decreases boiling and melting point
• Solubility


  Depends on the ability of the solute to interact effectively with the solvent molecules
• Solubility in water order

  • RCOOH
  • ROH
  • RNH2
  • RCHO
  • RCOR
  • ROR
  • HCs
• Factors affecting solubility


  • Nature of solute
  • Carbon chain length - Longer chain decreases solubility
  • Branching - More branching increases solubility
  • Tendency to form intramolecular H-bond - Decreases solubility
• Reaction mechanism


  Step-by-step description of how a reaction takes place at the atomic molecular level
• Reagent


  The attacking species in a chemical reaction
• Substrate


  The species being attacked or acted upon in a chemical reaction
• Radical reactions


  Involve symmetrical bond breaking and bond formation, can be homolytic or homogenic
• Polar reactions


  Involve unsymmetrical bond breaking and bond formation, can be heterolytic or heterogenic
• Polar functional groups


  Cause polar reactions, where carbon acquires a partial positive or negative charge
• Nucleophile


  Nucleus loving or electron rich
• Electrophile


  Electron loving, usually electrically neutral or electron deficient
• Acid-base reaction or Neutralization

  1. OH + H+ → R-OH2 → H2O + R+
• Addition reactions


  Two reactants added together to form a single product
• Elimination reactions


  Opposite of addition reaction
• Substitution reactions


  Two reactants exchange parts to give new products
• Rearrangement reactions


  Single reactant undergoes reorganization of bonds and atoms to yield an isomeric product
• Redox reactions


  Reduction - bond formation to an atom less EN than C, removal of O or addition of H

  Oxidation - bond formation to an atom more EN than C, addition of O and removal of H
• Reaction coordinate diagram


  Tracks the free energy of a set of chemical species as they undergo one or more elementary reactions
• Transition state


  Partially formed & broken bonds, represent the highest energy structures involved in a reaction, unstable and can't be isolated
• Intermediate


  Fully formed bonds, molecules that exist momentarily in the course of a reaction, have higher energy than reactants and products, but more stable than transition states
• Exergonic reaction


  Releases energy, decreases free energy
• Endergonic reaction


  Requires energy, increases free energy
• Gibbs standard free energy change (ΔG°)


  Energy change that occurs during a chemical reaction
• Enthalpy (ΔH°)


  The heat given off or absorbed during a reaction, if negative, bonds in products are stronger than those of the reactants
• Entropy (ΔS°)


  Measure of freedom of motion