Chapter 4. Formation of cyclic derivatives
Chapter Summary: For compounds containing two or more functional groups such as OH, NH and SH in close proximity (1,2-, 1,3- or 1,4-positions in an alkyl chain or in the ortho-position of an aromatic ring), cyclic derivatives forming at the expense of two such groups are quite common. In the course of such derivatisations, new 5-, 6- or even 7-membered rings having stable configurations can be formed in the molecule under study. As a result, the above-mentioned polar groups are protected and the derivatives possess increased volatility, good chromatographic properties and sometimes show mass spectra that can be more efficiently used for structure determination and quantitative determination of the derivatised compounds.