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A meso compound or meso isomer is an optically inactive isomer in a set of stereoisomers, at least two of which are optically active. [1] [2] This means that despite containing two or more stereocenters, the molecule is not chiral. A meso compound is superposable on its mirror image (not to be confused with superimposable, as any two objects ...
In stereochemistry, diastereomers (sometimes called diastereoisomers) are a type of stereoisomer. [1] Diastereomers are defined as non-mirror image, non-identical stereoisomers. Hence, they occur when two or more stereoisomers of a compound have different configurations at one or more (but not all) of the equivalent (related) stereocenters and ...
2,3-Butanediamines can be prepared by hydrolyzing 2-ethoxy-4,5-dihydro-4,5-dimethylimidazole with barium hydroxide. [4] Alternative, it is produced by reduction of dimethylglyoxime with lithium aluminium hydride. [5] The meso and the d,l diastereomers can be separated by fractional crystallization of the hydrochlorides.
These include meso compounds, cis–trans isomers, E-Z isomers, and non-enantiomeric optical isomers. Diastereomers seldom have the same physical properties. In the example shown below, the meso form of tartaric acid forms a diastereomeric pair with both levo- and dextro-tartaric acids, which form an enantiomeric pair.
Of the three stereoisomers, two are enantiomers (levo- and dextro-2,3-butanediol) and one is a meso compound. [ 1 ] [ 2 ] The enantiomeric pair have (2 R , 3 R ) and (2 S , 3 S ) configurations at carbons 2 and 3, while the meso compound has configuration (2 R , 3 S ) or, equivalently, (2 S , 3 R ).
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.
1,2-Diphenyl-1,2-ethylenediamine, DPEN, is an organic compound with the formula H 2 NCHPhCHPhNH 2, where Ph is phenyl (C 6 H 5). DPEN exists as three stereoisomers: meso and two enantiomers S,S- and R,R-. The chiral diastereomers are used in asymmetric hydrogenation. Both diastereomers are bidentate ligands. [1]
It is an important tool in the production of optically active compounds, including drugs. [3] Another term with the same meaning is optical resolution . The use of chiral resolution to obtain enantiomerically pure compounds has the disadvantage of necessarily discarding at least half of the starting racemic mixture.