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In chemistry, a precursor is a compound that participates in a chemical reaction that produces another compound. In biochemistry , the term "precursor" often refers more specifically to a chemical compound preceding another in a metabolic pathway , such as a protein precursor .
Drug precursors, also referred to as precursor chemicals or simply precursors, are substances used to manufacture illicit drugs. Most precursors also have legitimate commercial uses and are legally used in a wide variety of industrial processes and consumer products, such as medicines, flavourings, and fragrances.
In chemistry, a precursor is a compound that contributes in a chemical reaction and produces another compound, or a chemical substance that gives rise to another more significant chemical product. Since several years metal-organic compounds are widely used as molecular precursors for the chemical vapor deposition process (MOCVD).
Atomic layer deposition (ALD) is a thin-film deposition technique based on the sequential use of a gas-phase chemical process; it is a subclass of chemical vapour deposition. The majority of ALD reactions use two chemicals called precursors (also called "reactants"). These precursors react with the surface of a material one at a time in a ...
Hybrid physical-chemical vapor deposition (HPCVD) – This process involves both chemical decomposition of precursor gas and vaporization of a solid source. Metalorganic chemical vapor deposition (MOCVD) – This CVD process is based on metalorganic precursors.
Organic Synthesis requires many steps to separate and purify products. Depending on the chemical state of the product to be isolated, different techniques are required. For liquid products, a very common separation technique is liquid–liquid extraction and for solid products, filtration (gravity or vacuum) can be used. [15] [16]
Precursor (chemistry), a compound that participates in the chemical reaction that produces another compound; Precursor (physics), a phenomenon of wave propagation in dispersive media; Precursor in the course of a disease, a state preceding a particular stage in that course; Precursor cell (biology), a unipotent stem cell
Schedule 1 is divided into Part A substances, which are chemicals that can be used directly as weapons, and Part B which are precursors useful in the manufacture of chemical weapons. Examples are mustard and nerve agents, and substances which are solely used as precursor chemicals in their manufacture.