Qualitative organic analysis: An efficient, safer, and economical approach to preliminary tests and functional group analysis

摘要

Qualitative organic analysis of an unknown compound is an integral part of the university chemistry laboratory curriculum. This type of training is essential as students learn to approach a problem systematically and to interpret the results logically. However, considerable quantities of waste are generated by using conventional methods of analysis. This waste is a complex mixture of compounds, difficult to segregate or reuse, and its commercial disposal incurs a huge expense. Many thousands of undergraduate and postgraduate students study chemistry each year, and, at a rough estimate, each student produces about 225 g/year of the waste while performing qualitative organic analysis. Perturbed by these facts, we have made a concerted effort to reduce the quantities of waste generated and to replace the commonly used procedure by spot tests. The reagents used in the spot tests are the same as in the conventional analysis and are relatively inexpensive and easily available, in contrast to complex and expensive reagents mentioned for the spot tests in the literature. In the present work, spot tests have been developed for the detection of nitrogen and sulfur, Baeyer's test for unsaturation, and the functional groups present in carbohydrates, carboxylic acids, phenols, alcohols, esters, aldehydes, ketones, aromatic nitro compounds, aromatic amides, and primary, secondary, and tertiary aromatic amines. The modified scheme is simple, eco-friendly, and energy- and time-efficient.