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In stereochemistry, an asymmetric carbon is a carbon atom that is bonded to four different types of atoms or groups of atoms. [1] [2] The four atoms and/or groups attached to the carbon atom can be arranged in space in two different ways that are mirror images of each other, and which lead to so-called left-handed and right-handed versions (stereoisomers) of the same molecule.
There are six substances encompassed under this general name - in fact, there are much more than that. 1,1 dichlorobutane; 1,2 dichlorobutane (2 optical isomers); 1,3 dichlorobutane (2 optical isomers); 1,4 dichlorobutane; 2,2, dichlorobutane; 2,3 dichlorobutane (3 optical isomers); 1,1 dichloro methyl propane (2 optical isomers); 1,2 dichloro methyl propane (2 optical isomers); 1,3 dichloro ...
[2] [3] Stereocenters can exist on chiral or achiral molecules; stereocenters can contain single bonds or double bonds. [1] The number of hypothetical stereoisomers can be predicted by using 2 n, with n being the number of tetrahedral stereocenters; however, exceptions such as meso compounds can reduce the prediction to below the expected 2 n. [4]
Le Bel-van't Hoff rule states that for a structure with n asymmetric carbon atoms, there is a maximum of 2 n different stereoisomers possible. As an example, D-glucose is an aldohexose and has the formula C 6 H 12 O 6. Four of its six carbon atoms are stereogenic, which means D-glucose is one of 2 4 =16 possible stereoisomers. [20] [21]
2,3-Dichlorobutadiene is a chlorinated derivative of butadiene. This colorless liquid is prone to polymerization, more so than 2-chlorobutadiene. It is used to produce specialized neoprene rubbers. It can be prepared by the copper-catalyzed isomerization of dichlorobutynes. Alternatively dehydrochlorination of 2,3,4-trichloro-1-butene: [1]
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.
For esters such as ethyl acetate (CH 3 COOCH 2 CH 3), ethyl formate (HCOOCH 2 CH 3) or dimethyl phthalate that are based on common acids, IUPAC recommends use of these established names, called retained names. The "-oate" changes to "-ate." Some simple examples, named both ways, are shown in the figure above.
[3] As an example, four of the carbon atoms of the aldohexose class of molecules are asymmetric, therefore the Le Bel–Van 't Hoff rule gives a calculation of 2 4 = 16 stereoisomers. This is indeed the case: these chemicals are two enantiomers each of eight different diastereomers : allose , altrose , glucose , mannose , gulose , idose ...