Organic compounds three-dimensional

Spectrometric Analysis. Remarkable developments ia mass spectrometry (ms) and nuclear magnetic resonance methods (nmr), eg, secondary ion mass spectrometry (sims), plasma desorption (pd), thermospray (tsp), two or three dimensional nmr, high resolution nmr of soHds, give useful stmcture analysis information (131). Because nmr analysis of or N-labeled amino acids enables determiaation of amino acids without isolation from organic samples, and without destroyiag the sample, amino acid metaboHsm can be dynamically analy2ed (132). Proteia metaboHsm and biosynthesis of many important metaboUtes have been studied by this method. Preparative methods for labeled compounds have been reviewed (133). 

So far we have emphasized structure in terms of electron bookkeeping. We now turn our attention to molecular geometry and will see how we can begin to connect the three-dimensional shape of a molecule to its Lewis formula. Table 1.6 lists some simple compounds illustrating the geometries that will be seen most often in our study of organic chemistry. 

In the previous chapters, we discussed electron distrihution in organic molecules. In this chapter, we discuss the three-dimensional stracture of organic compounds. The structure may be such that stereoisomerism is possible. Stereoisomers are compounds made up of the same atoms bonded by the same sequence of bonds but having different three-dimensional stracmres which are not interchangeable. These three-dimensional structures are called configurations. 

A lattice is a three-dimensional array, and there are eight systems known. Inorganic substances are usually defined by one crystal system by the so-called radius-ratio rule [22], but organic compounds often have the capability of existing in more than one crystal form, a phenomenon referred to as polymorphism. 

Molecular structure determines the gross activity of an organic compound, as it is responsible for the molecular volume, water solubility, vapor pressure, density, and electrical charge of the compound. The three-dimensional structure of an organic... 

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