Abstract  Pyrrole is a planar, aromatic, five-membered heterocycle which provides the fundamental structural subunit for many of the most important biological molecules, such as heme and chlorophyll. Extensive delocalization of the lone pair of nitrogen electrons throughout the system accounts for the lack of basicity and pronounced aromatic character of pyrrole systems. Pyrrole derivatives are often prepared by condensation of amines with carbonyl-containing compounds. Several widely used synthetic reactions that are variations of this procedure are discussed. These include the reaction of an α-aminoketone with β-dicarbonyls (Knorr), the condensation of an α-haloketone with a β-ketoester in the presence of an amine (Hantzsch), and the condensation of a 1,4-diketone with ammonia or a primary amine (Paal-Knorr). Brief descriptions of the preparation and utility of some of the very large number of pyrrole derivatives are provided. These include the hydroxypyrroles, as well as aldehydes, ketones, acids, esters, and various reduced forms, such as pyrrolines and pyrrolidines. Condensed pyrroles with two, three, or four pyrrole nuclei are well known, as are the larger polypyrroles. Polypyrroles form highly stable, flexible films which are electrically conducting. Pyrrolidinones are five-membered nonaromatic cyclic amide systems prepared by the reaction of butyrolactone with ammonia or a primary amine at relatively high temperatures. Several are commercially available and are widely used as intermediates, wetting agents, and solvents with relatively low toxicity. The important monomer 1-vinyl-2-pyrrolidinone is derived from 2-pyrrolidinone.

Abstract  Many industrial processes depend on efficient methods for separating azeotropic, close-boiling, or other low relative volatility mixtures. Ordinary distillation is typically either uneconomical or impossible in these cases. However, by adding specially chosen separating agents, the separation can generally be accomplished. The principal distillation-based techniques employed for separating such mixtures are discussed: extractive or homogeneous azeotropic distillation, where a completely miscible liquid separating agent is added to alter the relative volatilities; heterogeneous azeotropic distillation, where the agent, known as the entrainer, forms one or more azeotropes and causes immiscibility; distillation in the presence of ionic salts that alter the relative volatilities of the components; and pressure-swing distillation, wherein some azeotropes can be circumvented using a series of columns operating at different pressures. Residue curve maps, material balance lines, and column sequences are given for several example systems. Methods for identifying feasible separating agents are also discussed.

Abstract  Lithium, an element of unique physical and chemical properties, is useful in a wide range of applications as the metal, as the lithium ion in inorganic salts, and as the more covalent species in inorganic compounds. The largest uses of lithium compounds are in traditional areas such as the preparation of glass, glass-ceramics, and enamels; in aluminum cell broth; in the preparation of lithium greases; and as polymerization initiators. Lithium compounds are also employed as psychopharmacological agents and in organic synthesis, catalysis, absorption, air conditioning, photographic processing, and in batteries. The use of organic lithium compounds as industrial catalysts and the consumption of various lithium compounds in batteries are the most rapidly expanding markets. The various lithium mineral and brine resources are reviewed along with the processes for lithium extraction and recovery. Manufacturing processes, properties, health and safety factors, and applications for lithium metal and lithium compounds are discussed