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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 .
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).
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.
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.
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 ...
Schedule 3 substances, in the sense of the Chemical Weapons Convention, are chemicals which have large-scale industrial uses, but are feasible to use as toxic chemical weapons (Part A) or manufacturing precursors (Part B).
A total synthesis refers to the complete chemical synthesis of molecules from simple, natural precursors. [1] Total synthesis is accomplished either via a linear or convergent approach. In a linear synthesis —often adequate for simple structures—several steps are performed sequentially until the molecule is complete; the chemical compounds ...
Schematic representation of the different stages and routes of the sol–gel technology. In this chemical procedure, a "sol" (a colloidal solution) is formed that then gradually evolves towards the formation of a gel-like diphasic system containing both a liquid phase and solid phase whose morphologies range from discrete particles to continuous polymer networks.