Synthetic routes

Synthetic Routes in Organic Chemistry

Introduction to Synthetic Routes

  • The term synthetic routes refers to the series of reactions used to transform simple organic compounds into more complex ones.
  • An understanding of synthetic routes involves knowing how to manipulate functional groups, perform various organic reactions, and control reaction conditions.
  • The goal is often to achieve the target molecule with high yield and few side effects.

Choosing a Synthetic Route

  • Choosing a synthetic route involves identifying the functional groups present in the starting materials and the product.
  • The route typically involves converting functional groups into other functional groups, and creating or breaking carbon-carbon bonds.
  • Retro-synthesis is the practice of ‘working backwards’ from the target product, considering possible reactions in reverse to decide on an appropriate synthetic route to follow.

Common Organic Reactions in Synthetic Routes

Addition Reactions

  • Addition reactions involve adding two components together to create a larger molecule, often with the formation of a new single bond and the loss of a double bond.
  • Typical examples include the addition of hydrogen (hydrogenation) or water (hydration) to alkenes.

Substitution Reactions

  • In substitution reactions, one atom or group of atoms in a molecule is replaced (substituted) with another.
  • For instance, a halogen atom can be substituted for a hydrogen atom in a hydrocarbon, creating a halogenoalkane.

Elimination Reactions

  • Elimination reactions involve the removal of atoms or groups of atoms from a molecule, producing a smaller molecule in the process.
  • Elimination reactions often result in the formation of a carbon-carbon double bond, as seen in the dehydration of alcohols to form alkenes.

Oxidation and Reduction Reactions

  • In organic chemistry, oxidation typically refers to the loss of hydrogen from a molecule or the addition of oxygen. Notable reactions include the oxidation of alcohols to aldehydes, ketones, or carboxylic acids.
  • Conversely, reduction involves the gain of hydrogen or the loss of oxygen, such as the reduction of a carbonyl group in an aldehyde or ketone to form an alcohol.

Reaction Conditions

  • The conditions under which a reaction occurs can have a significant effect on the products formed.
  • Factors to consider include temperature, pressure, the use of a catalyst, and whether the reaction is carried out in an acidic or basic environment.
  • A good synthetic route will aim to use conditions that are safe, economical, and environmentally friendly, while still achieving the desired product with high yield.

Monitoring Reaction Progress

  • Various techniques can be used to monitor the progress of a reaction and verify the product, including 1H NMR spectroscopy, 13C NMR spectroscopy, IR spectroscopy, and mass spectrometry.

Practical Application of Synthetic Routes

  • Synthetic routes are incredibly important in industrial chemistry, particularly in the production of pharmaceuticals, pesticides, plastics, and other organic materials.
  • These processes often involve complex synthetic routes with numerous stages, requiring careful planning and optimisation to ensure a viable yield of the desired product.