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In stereochemistry, an epimer is one of a pair of diastereomers. [1] The two epimers have opposite configuration at only one stereogenic center out of at least two. [2] All other stereogenic centers in the molecules are the same in each. Epimerization is the interconversion of one epimer to the other epimer.
The "AXE method" of electron counting is commonly used when applying the VSEPR theory. The electron pairs around a central atom are represented by a formula AX m E n, where A represents the central atom and always has an implied subscript one. Each X represents a ligand (an atom bonded to A). Each E represents a lone pair of electrons on the ...
Traditionally, double bond stereochemistry was described as either cis (Latin, on this side) or trans (Latin, across), in reference to the relative position of substituents on either side of a double bond. A simple example of cis–trans isomerism is the 1,2-disubstituted ethenes, like the dichloroethene (C 2 H 2 Cl 2) isomers shown below. [7]
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.
One of the first such racemates studied, by Pasteur in 1853, forms from a 1:2 mixture of the bis ammonium salt of (+)-tartaric acid and the bis ammonium salt of (−)-malic acid in water. Re-investigated in 2008, [ 9 ] the crystals formed are dumbbell -shape with the central part consisting of ammonium (+)-bitartrate, whereas the outer parts ...
Meet Copper, an 8-year-old beagle who was recently adopted by PETA staffers Katherine Sullivan and Daniel Paden ahead of their first holiday as newlyweds.
A molecule may contain any number of stereocenters and any number of double bonds, and each usually gives rise to two possible isomers. A molecule with an integer n describing the number of stereocenters will usually have 2 n stereoisomers, and 2 n−1 diastereomers each having an associated pair of enantiomers.
Millions of Americans should prepare for an Arctic blast that will blanket much of the country in below-freezing temperatures over the next several days. Frigid conditions are expected over a ...