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In chemistry, an activated complex represents a collection of intermediate structures in a chemical reaction when bonds are breaking and forming. The activated complex is an arrangement of atoms in an arbitrary region near the saddle point of a potential energy surface . [ 1 ]
Cyanocuprates undergo S N 2' substitution in the presence of allyl electrophiles and conjugate addition reactions in the presence of enones. Higher-order cyanocuprates (R 2 Cu(CN)Li 2) are formed upon the reaction of two equivalents of organolithium with copper(I) cyanide. These reagents are more reactive towards substitution than the ...
Host–guest chemistry encompasses the idea of molecular recognition and interactions through non-covalent bonding. Non-covalent bonding is critical in maintaining the 3D structure of large molecules, such as proteins and is involved in many biological processes in which large molecules bind specifically but transiently to one another.
Compare the atomic number (Z) of the atoms directly attached to the stereocenter; the group having the atom of higher atomic number Z receives higher priority (i.e. number 1). If there is a tie, the atoms at distance 2 from the stereocenter have to be considered: a list is made for each group of further atoms bonded to the one directly attached ...
PubChem is a database of chemical molecules and their activities against biological assays.The system is maintained by the National Center for Biotechnology Information (NCBI), a component of the National Library of Medicine, which is part of the United States National Institutes of Health (NIH).
Text annotations can serve a variety of functions for both private and public reading and communication practices. In their article "From the Margins to the Center: The Future of Annotation," scholars Joanna Wolfe and Christine Neuwirth identify four primary functions that text annotations commonly serve in the modern era, including: (1)"facilitat[ing] reading and later writing tasks," which ...
Cheminformatics (also known as chemoinformatics) refers to the use of physical chemistry theory with computer and information science techniques—so called "in silico" techniques—in application to a range of descriptive and prescriptive problems in the field of chemistry, including in its applications to biology and related molecular fields.
Most antimony is mined as the sulfide; lower-grade ores are concentrated by froth flotation, while higher-grade ores are heated to 500–600 °C, the temperature at which stibnite melts and separates from the gangue minerals. Antimony can be isolated from the crude antimony sulfide by reduction with scrap iron: [64] Sb 2 S 3 + 3 Fe → 2 Sb + 3 FeS