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In chemistry, isomers are molecules or polyatomic ions with identical molecular formula – that is, the same number of atoms of each element – but distinct arrangements of atoms in space. [1] Isomerism refers to the existence or possibility of isomers. Isomers do not necessarily share similar chemical or physical properties.
Two compounds that are enantiomers of each other have the same physical properties, except for the direction in which they rotate polarized light and how they interact with different enantiomers of other compounds. As a result, different enantiomers of a compound may have substantially different biological effects.
In chemistry, a structural isomer (or constitutional isomer in the IUPAC nomenclature [1]) of a compound is another compound whose molecule has the same number of atoms of each element, but with logically distinct [clarification needed] bonds between them. [2] [3] The term metamer was formerly used for the same concept. [4]
Diastereomers are distinct molecular configurations that are a broader category. [3] They usually differ in physical characteristics as well as chemical properties. If two molecules with more than one chiral centre differ in one or more (but not all) centres, they are diastereomers. All stereoisomers that are not enantiomers are diastereomers.
As polarized light passes through a chiral molecule, the plane of polarization, when viewed along the axis toward the source, will be rotated clockwise (to the right) or anticlockwise (to the left). A right handed rotation is dextrorotary (d); that to the left is levorotary (l). The d- and l-isomers are the same compound but are called enantiomers.
Prototropic tautomers are sets of isomeric protonation states with the same empirical formula and total charge. Tautomerizations are catalyzed by: [ 4 ] bases , involving a series of steps: deprotonation, formation of a delocalized anion (e.g., an enolate ), and protonation at a different position of the anion; and
In organic chemistry, two molecules are valence isomers when they are constitutional isomers that can interconvert through pericyclic reactions. [ 1 ] [ 2 ] Benzene
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]