Enantiomers and chiral molecules

Enantiomers always have the possibility of existing in pairs. We may not always find that nature (or a reaction) has produced a pair of enantiomers, however. In fact, in nature we often find only one enantiomer of the two that are possible. We shall find out later why this is often the case. Typically, when we carry out a chemical reaction, we find that the reaction produces a pair of enantiomers. Again, we will explain later why this occurs. What structural feature must be present for two molecules to exist as enantiomers  

What is the relationship between a chiral molecule and its mirror image  

Classify each of the following objects as to whether it is chiral or achiral  

Working with models is a helpful study technique whenever three-dimensional aspects of chemistry are involved. 

The chirality of molecules can be demonstrated with relatively simple compounds. Consider, for example, 2-butanol  

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As discussed in detail in Ref. 36, for use in optoelectronics only systems crystallizing in non-centrosymmetric crystal lattices are of interest if the use of expensive enantiomers of chiral molecules is to be avoided. This considerably limits the available crystal lattices since most organic achiral molecules crystallize into centrosymmetric space groups. An interesting example of enantioselective inclusion complexation was reported by Gdaniec and coworkers [37]. 

In 1962 the first implicit prediction appeared of a cross-effect between natural and magnetic optical activity, which discriminates between the two enantiomers of chiral molecules [7]. This was followed independently by a prediction of magnetospatial dispersion in noncentrosymmetrical crystalline materials [8]. This cross-effect has been called magnetochiral anisotropy and has since been predicted independently several times more [9-12]. Its existence can be appreciated by expanding the dielectric tensor of a chiral medium subject to a magnetic field to first order in the wave vector k and magnetic field B [8] ... 

The covalent attachment of optically active groups, such as amino acids, to the polymer backbone of polypyrroles and polythiophenes has provided ICPs which have the ability to discriminate between the enantiomers of chiral molecules and ions [29-31]. 

Enantiomers are chiral molecules that are non-superimposable mirror images of each other, and with one exception have identical physical properties. Enantiomers react at the same rate with achiral reagents. 

Consider an ideal gas of 2N molecules, each containing one chiralic center. Initially, we prepare the system in such a way that all the molecules are in one of the enantiomeric forms, say the d enantiomer. We then introduce a catalyst which induces a racemization process in adiabatic conditions. At equilibrium, we obtain N molecules of the d enantiomer and N molecules of the l enantiomer. The entropy change in this spontaneous process is well known ... 

Enantiomers - A chiral molecule and its non-superposable mirror image. The two forms rotate the plane of polarized light by equal amounts in opposite directions. Also called optical isomers. 

Emissivity (e) - Ratio of the radiant flux emitted per unit area to that of an ideal black body atthe same temperature. Also called emittance. [1] Emu - The electromagnetic system of units, based upon the cm, g, and s plus the emu of current (sometimes called the abampere). Enantiomers - A chiral molecule and its non-superposable mirror image. The two forms rotate the plane of polarized light by equal amounts in opposite directions. Also called optical isomers. 

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