Fields in Chemistry

Synthetic Chemistry

Chemists seek to relate the properties of all substances, both natural and man-made, to their detailed chemical composition, including the atomic arrangements of all the chemical components. Chemists want to do this not only for existing substances but also for new substances that do not yet exist. For instance medicinal chemists make new substances as potential cures for disease. Understanding how the properties of substances are related to their molecular structures helps chemists and chemical engineers design new molecules that have the desired properties, allows them to develop or invent new types of transformations for carrying out the syntheses, and assists them as they design ways to manufacture and process the new substances.

Chemists want to understand not only the substances and transformations that occur in the natural world, but also those others that are permitted by natural laws. Consequently, the field involves both discovery and creation. Chemists want to discover the components of the chemical universe—from atoms and molecules, to materials, devices, living cells, and whole organisms. However, chemical scientists consider not just the components of the chemical universe that already exist; they also consider the unknown molecules and substances and interactions that could exist. 

Thus there is a field of synthetic chemistry, in which new molecules and substances and chemical transformations are created, rather than discovered in nature. 

New chemical compounds—consisting of new molecules—are being created at the rate of more than one million each year. 

Many reactions of great commercial importance can proceed by more than one reaction path; which means there exists competing reactions. Competing reactions convert the starting material to something other than the desired products.  The study of the detailed processes of reaction mechanisms make it possible to choose reaction conditions favouring one path over another, thereby giving maximum amounts of desired products and minimum amounts of undesired products. The study of reaction mechanisms is also complicated by the reversibility of most reactions (the tendency of the reaction products to revert to the starting materials) 

The chemical universe is filled with transformations, both natural and invented. A chemical transformation can occur when molecules collide with sufficient energy.  We apply them in manufacturing, we admire them in biological chemistry, but we do not yet know enough about their details.  There are still big gaps in our understanding of the molecular details of chemical and biochemical reactions.  With understanding, when we have it, will come greatly improved methods for synthesis and manufacturing.  

Many intermediates along the path of a reaction cannot be directly observed with current instrumental technology 

Whereas the detailed molecular structures involved throughout the entire procession from starting materials through the transition states to products in a chemical reaction are so far not directly observable, there are certain classical ways in which reaction mechanisms are effectively deduced 

Evidence on the mechanism of reactions can also come from examining the exact molecular geometry of the overall process, its stereochemistry 

Biomimetic Synthesis

An interesting observation has been that some of the highly complex synthesis processes using traditional approaches become easy and efficient through biomimetic synthesis. Biomimetic synthesis typically refers to syntheses that mimic biological synthesis processed in living organisms.  

ex. Bones, teeth, pearls, shells, diatoms, and spider silk are special tissues in living organisms.  Because of the unique formation process, these biominerals often have special structures distinct from inorganic structures existing outside living organisms. These structures give these biominerals unique and interesting properties. Their formation reaction is controlled in a sophisticated manner by bio-macromolecules. Understanding the mechanisms of biomineralization can be useful to guide biomimetic syntheses of new functional materials. The ultimate goal is to develop synthesis techniques and processes that can lead to the creation of new materials with similar (or better/improved) properties of naturally existing biological materials.

Enzymes can selectively bind a particular molecule out of the mixture of substances in the cell, then hold it in such a way that the geometry of the enzyme-substrate complex determines what happens next in a sequence of chemical reactions. For example, in an enzyme-substrate complex the reaction may take place at a particular part of a molecule even if that is not the most chemically reactive site—in contrast to normal synthetic chemistry, where changes take place at the reactive functional groups. New procedures increasingly involve the formation of well-defined molecular complexes between substrate and catalyst, or substrate and reagent, that may allow chemists to overcome the classical domination of selectivity by the reactivity of functional groups. 

There is another approach that is increasingly part of synthesis: the use of enzymes as catalysts. This approach is strengthened by the new ability of chemists and molecular biologists to modify enzymes and change their properties. There is also interest in the use of artificial enzymes for this purpose, either those that are enzyme-like but are not proteins, or those that are proteins but based on antibodies. 

Spontaneous self-assembly of the chemical components 

Medicines today operate mainly by binding to various biological molecules, but they don't carry out catalyzed reactions in the body. If we fully understand enzymes well enough to be able to make new catalysts of similar effectiveness, such artificial enzymes could be an exciting class of molecular machines and medicines. They could destroy undesirable species or toxins, or promote the formation of materials that are present in insufficient quantities due to some diseases.