This article needs attention from an expert in Chemistry. The specific problem is: The article is essentially an unsourced essay, and while it is of better quality than most that take this attitude here, it nevertheless stands in defiance of WP:VERIFY (no material here is sky-is-blue to the readers I send) and so fails at being encyclopedic.See the talk page for details. WikiProject Chemistry (or its Portal) may be able to help recruit an expert.(March 2016)
A total synthesisis the complete chemical synthesis of complex organicmolecules from simple, commercially available (petrochemical) or natural precursors. [page needed] Total synthesis may be accomplished either via a linear or convergent approach. In a linear synthesis—often adequate for simple structures—several steps are performed one after another until the molecule is complete; the chemical compounds made in each step are called synthetic intermediates. For more complex molecules, a convergent synthetic approach may be preferable, one that involves individual preparation of several "pieces" (key intermediates), which are then combined to form the desired product.
Each step of a synthesis involves a chemical reaction, and reagents and conditions for each of these reactions must be designed to give an adequate yield of pure product, with as little work as possible.[page needed] A method may already exist in the literature for making one of the early synthetic intermediates, and this method will usually be used rather than an effort to "reinvent the wheel". However, most intermediates are compounds that have never been made before, and these will normally be made using general methods developed by methodology researchers. To be useful, these methods need to give high yields, and to be reliable for a broad range of substrates. For practical applications, additional hurdles include industrial standards of safety and purity.[non-primary source needed]
Methodology research usually involves three main stages: discovery, optimisation, and studies of scope and limitations. The discovery requires extensive knowledge of and experience with chemical reactivities of appropriate reagents.Optimisation is a process in which one or two starting compounds are tested in the reaction under a wide variety of conditions of temperature, solvent, reaction time, etc., until the optimum conditions for product yield and purity are found. Finally, the researcher tries to extend the method to a broad range of different starting materials, to find the scope and limitations. Total syntheses (see above) are sometimes used to showcase the new methodology and demonstrate its value in a real-world application. Such applications involve major industries focused especially on polymers (and plastics) and pharmaceuticals.
Elias James Corey brought a more formal approach to synthesis design, based on retrosynthetic analysis, for which he won the Nobel Prize for Chemistry in 1990. In this approach, the synthesis is planned backwards from the product, using standard rules.[page needed] The steps "breaking down" the parent structure into achievable component parts are shown in a graphical scheme that uses retrosynthetic arrows (drawn as ⇒, which in effect, mean "is made from").
More recently,[when?] and less widely accepted, computer programs have been written for designing a synthesis based on sequences of generic "half-reactions".
^Woodward, R. B.; Cava, M. P.; Ollis, W. D.; Hunger, A.; Daeniker, H. U.; Schenker, K. (1954). "The Total Synthesis of Strychnine". Journal of the American Chemical Society. 76 (18): 4749–4751. doi:10.1021/ja01647a088.[non-primary source needed]
^March, J.; Smith, D. (2001). Advanced Organic Chemistry, 5th ed. New York: Wiley.[page needed]
^Carey, J.S.; Laffan, D.; Thomson, C. & Williams, M.T. (2006). "Analysis of the reactions used for the preparation of drug candidate molecules". Org. Biomol. Chem.(print, online research report)|format= requires |url= (help). 4: 2337–2347. doi:10.1039/B602413K.CS1 maint: Uses authors parameter (link)[non-primary source needed]