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E–Z configuration, or the E–Z convention, is the IUPAC preferred method of describing the absolute stereochemistry of double bonds in organic chemistry. It is an extension of cis–trans isomer notation (which only describes relative stereochemistry) that can be used to describe double bonds having two, three or four substituents. E and Z ...
The key article setting out the CIP sequence rules was published in 1966, [5] and was followed by further refinements, [6] before it was incorporated into the rules of the International Union of Pure and Applied Chemistry (IUPAC), the official body that defines organic nomenclature, in 1974.
In chemical nomenclature, the IUPAC nomenclature of organic chemistry is a method of naming organic chemical compounds as recommended [1] [2] by the International Union of Pure and Applied Chemistry (IUPAC). It is published in the Nomenclature of Organic Chemistry (informally called the Blue Book). [3]
The Geneva Nomenclature of 1892 was created as a result of many other meetings in the past, the first of which was established in 1860 by August Kekulé. Another entity called the International Association of Chemical Societies (IACS) existed, and on 1911, gave vital propositions the new one should address: [ 2 ]
Stereochemistry, a subdiscipline of chemistry, studies the spatial arrangement of atoms that form the structure of molecules and their manipulation. [1] The study of stereochemistry focuses on the relationships between stereoisomers, which are defined as having the same molecular formula and sequence of bonded atoms (constitution) but differing in the geometric positioning of the atoms in space.
In chemical nomenclature, a descriptor is a notational prefix placed before the systematic substance name, which describes the configuration or the stereochemistry of the molecule. [1] Some of the listed descriptors should not be used in publications, as they no longer accurately correspond with the recommendations of the IUPAC.
Clockwise rotation of the light traveling toward the viewer is labeled (+) enantiomer. Its mirror-image is labeled (−). The (+) and (−) isomers have been also termed d-and l-(for dextrorotatory and levorotatory); but, naming with d-and l-is easy to confuse with D - and L - labeling and is therefore discouraged by IUPAC. [13]
The IUPAC standard designations E and Z are unambiguous in all cases, and therefore are especially useful for tri- and tetrasubstituted alkenes to avoid any confusion about which groups are being identified as cis or trans to each other. Z (from the German zusammen) means "together". E (from the German entgegen) means "opposed" in the sense of ...