Introduction to Pyrrolidone and Caprolactam Chemistry

Abstract

Pyrrolidones and caprolactams are important structural components of solvents, surfactants, polymers, natural products, and pharmaceuticals. This chapter provides an introduction to the structure, conformation, physical properties and reactivity of pyrrolidones and caprolactams. It begins with an overview of the nomenclature of lactams since there are several systems of nomenclature in practice, plus common names and various syncretisms. Next, the structures of pyrrolidone and caprolactam are discussed, starting with the X-ray crystal structures of pyrrolidone, N-methylpyrrolidone (NMP) and caprolactam. The conformational flexibility and ring strain of the two ring systems are also covered.Physical properties, such as dipole moments, the enthalpies of formation, vaporization and fusion, boiling points and melting points, are described. An attempt is made to put the properties of pyrrolidones and caprolactams into context with those of other lactams, amides and even lactones and cyclic ketones. Brønsted and Lewis basicity, acidity, hydrogen bonding and solubility are covered.Finally, a brief description of the basic reactivity of pyrrolidones and caprolactams is given. Topics covered are N-, O-, and α-C-alkylation, hydrolysis, reactions with organometallics, reduction, oxidation, and ring-opening polymerization. The intent is to give a concise physical organic perspective on reactivity (and stability) more than an extended treatise on synthetic elaborations. Definition and Nomenclature of LactamsLactams are cyclic amides in which both the carbonyl carbon and nitrogen atom of the amide group are part of a ring. The name, lactam, is a portmanteau of lactone (cyclic ester) and amide.Nomenclature of lactams follows a variety of conventions (Figure 1 and Table 1). The International Union of Pure and Applied Chemistry (IUPAC) recommends naming lactams as heterocyclic pseudoketones (IUPAC method 1) or by substituting lactam for the

Effect of water content on the homogeneous catalytic process of N-vinyl pyrrolidone synthesis from acetylene

“…Another issue encountered with the conventional acetylene method for synthesizing NVP is that the reactant 2-pyrrolidone is prone to undergoing a ring opening reaction in the presence of strong alkali hydroxide, leading to catalyst deactivation. In addition, the deprotonation process of 2-pyrrolidone produces water, which accelerates the ring opening of 2-pyrrolidone, 7–10 thereby accelerating the loss of catalyst deactivation. The ring-opening process of 2-pyrrolidone is shown in eqn (4), yielding potassium γ-aminobutyrate.As a result, the method of directly using KOH as a catalyst was quickly abandoned, and subsequent development employed a two-step process to achieve the synthesis of NVP.…”