Organic Synthesis

• Organic synthesis is the process of creating organic compounds from simpler substances through a series of chemical reactions.
• It involves the manipulation of functional groups to increase the complexity of the molecule.

Steps in Organic Synthesis

• There are typically six steps involved: retrosynthesis, reaction, purification, separation, identification, and analysis.
• Retrosynthesis involves working backwards from the desired end product to determine the reactants and reactions needed.
• The reaction stage is where the reactants undergo one or more chemical reactions to produce the desired product and possibly some undesired by-products.
• Purification is the process of isolating the desired product from the reaction mixture, which often involves techniques like recrystallisation or distillation.
• The separation stage involves separating the desired substance from undesired by-products using techniques like filtration or chromatography.
• Identification entails comparing the produced compound with known substances to confirm its identity.
• Analysis refers to using various tests to determine the purity of the final product.

Types of Synthesis

• Total synthesis refers to the creation of a complex molecule from simple, commercially available precursors in the laboratory.
• In semi-synthesis or partial chemical synthesis, natural precursors (e.g., plant or microbial metabolites) are chemically modified to result in a more complex molecule.
• In multi-step synthesis, multiple reactions occur in a sequence. Each step can also yield other products, necessitating purification after each stage.

Instrumental Analysis

• Instrumental analysis is used not only in the final analysis stage of organic synthesis, but also at multiple stages to monitor the progress of reactions.
• Relevant techniques include mass spectrometry (MS), which can provide information about molecular weight and structure, and nuclear magnetic resonance (NMR), which can provide detailed information about the structure and environment of atoms in a molecule.
• Other useful techniques include infrared (IR) spectroscopy, which provides information about functional groups present, and ultraviolet-visible (UV-Vis) spectroscopy, which gives information on electronic transitions in a molecule.
• Analytical techniques can also provide quantitative information, such as the concentration of a compound in a solution (UV-Vis spectroscopy) or the relative amounts of different isotopes in a sample (isotope-ratio mass spectrometry, or IRMS).
• Instrumental analysis can also point to the presence of impurities in a sample, which may indicate a need for further purification or changes in the reaction process.

Remember, gaining understanding of these principles is crucial not just for Organic Chemistry, but also for a variety of other disciplines, including forensic science, drug discovery, environmental science, and materials science.