Chemical synthesis
Chemical synthesis is a fundamental process in chemistry where two or more substances interact to form a new compound, often represented by the equation A + B = AB. It typically involves breaking existing atomic bonds, allowing new bonds to form between different elements. This technique is crucial in laboratories, where scientists strategically plan their reactions to create desired products, commonly seen in total synthesis, which aims to produce organic compounds independently from their natural sources. A notable application of this is the synthesis of vitamin B12, which can be manufactured as a dietary supplement.
Chemical synthesis also plays a role in natural processes, such as photosynthesis, where plants convert sunlight into energy, producing oxygen essential for aerobic life. Natural synthesis reactions, referred to as biosynthesis, are catalyzed by enzymes, enabling organisms to convert food into energy and synthesize necessary compounds, like amino acids. The biomedical field has seen significant advancements through chemical synthesis, exemplified by the total synthesis of the cancer drug taxol in the 1990s, which addressed the unsustainable sourcing from the Pacific yew tree. This highlights the importance of chemical synthesis, not only in improving human health but also in ensuring the sustainability of resources.
Chemical synthesis
Chemical synthesis refers to a chemical reaction in which two or more substances are combined to create a new substance. This can be represented by the generic chemical equation A + B = AB. Whenever scientists refer to chemical synthesis in a laboratory, they are usually referring to the deliberate combination of one or more substances, though other forms of chemical synthesis also exist. One example of chemical synthesis is the combination of sulfur and iron to form iron sulfide, a compound that exists in several different forms, including FeS2 and Fe3S4. Similarly, combining chlorine gas and potassium results in the end product potassium chloride (KCl).
Brief History
Gases were a major area of focus during the eighteenth century. During this time, scientists such as English chemist and philosopher Joseph Priestley (1733–1804) and Swedish chemist Carl Wilhelm Scheele (1742–86) helped identify oxygen gas for the first time. Their insights helped steer science toward a more formal understanding of how different elemental gases could bond and mix with other ones. French chemist Antoine-Laurent Lavoisier (1743–94) helped describe how quantifiable measurements correlated with a chemical process, and his Traité élémentaire de chimie (1789; Elementary Treatise on Chemistry, 1790), widely regarded as the first modern chemistry textbook, contained a list of thirty-three proposed elements that could not be broken down into simpler substances.
However, it was the birth of John Dalton’s atomic theory that really helped provide answers for why certain chemical reactions occur the way they do. In the early nineteenth century, Dalton (1766–1844) proposed the then-radical idea that all matter is composed of atoms, which he described as being extremely small in size, indivisible, and uniquely identified with the element they came from. Dalton also stated that it was because of chemical reactions that atoms could be rearranged to form an entirely new substance.
Overview
Chemical compounds consist of atoms of different elements that have been bonded together through chemical means. For chemical synthesis to occur, any existing bonds between atoms need to become broken so that they can form new bonds with different atoms. When scientists perform chemical synthesis in a laboratory, they usually start with the end product in mind and work backward until they determine the most easily manipulated or readily available compounds that will react to form the desired product.
Perhaps the most well-known type of chemical synthesis reaction is total synthesis, in which the goal is to create an organic compound without help from the original biological system. A good example of this would be the production of vitamin B12. Individuals who lack vitamin B12 in their diets can take them as supplements in order to increase the quality of their health. These supplements are reverse engineered from naturally occurring biological products and created without help from the original source.
Photosynthesis, the process that plants use to convert sunlight to energy, is another example of chemical synthesis. All plant cells contain organelles known as chloroplasts, within each of which are small, membrane-enclosed structures called thylakoids. This is where the energy absorbed from sunlight triggers a series of chemical reactions that result in the production of adenosine triphosphate (ATP) and reduced nicotinamide adenine dinucleotide phosphate (NADPH), which provide chemical energy to the plant. If not for photosynthesis, plants would not produce oxygen, which would make it impossible for organisms that are reliant on aerobic respiration to survive.
Naturally occurring synthesis reactions are called biosynthesis. These reactions are typically catalyzed by enzymes, which are large biological molecules, usually proteins, that help speed up chemical reactions in organisms. Biosynthesis reactions ensure that living organisms are able to convert their food into energy and help them function as a whole. Amino acid synthesis is the biological process that creates amino acids with the help of different compounds. The process typically begins once the organism has obtained energy from an outside source, such as food. Not every organism has the ability to synthesize all the amino acids they need. For instance, humans and other mammals can only synthesize about ten of the twenty standard amino acids that are necessary for life; they must acquire the rest through diet or other means.
One example of successful chemical synthesis in the biomedical industry occurred in the early 1990s. In 1966, researchers isolated a drug called taxol (later paclitaxel) from the Pacific yew tree. After development and clinical trials, the drug was approved by the US Food and Drug Administration (FDA) in 1992 to treat various types of cancer. However, the increasing scarcity of the Pacific yew made long-term, large-scale production of the drug impractical. Numerous research teams began attempting to synthesize taxol. By 1994, two groups, one led by Robert A. Holton at Florida State University and one by K. C. Nicolaou at the Scripps Research Institute, had successfully achieved total synthesis of taxol, thus reducing the cost of production and ending the dependence on a dwindling natural resource.
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