Amines, Cycloaliphatic

Abstract

Cycloaliphatic amines are comprised of a cyclic hydrocarbon structural component and an amine functional group external to that ring. Included in an extended cycloaliphatic amine definition are aminomethyl cycloaliphatics. Although some cycloaliphatic amine and diamine products have direct end use applications, their major function is as low cost organic intermediates sold as moderate volume specification products. For simple primary amines directly bonded to a cycloalkane by a single \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}${{\rm{C}}{\relbar \kern-5pt{\relbar}\kern-7pt{\relbar}}{\rm{N}}}$\end{document} bond to a secondary carbon the homologous series consists of cyclopropylamine, C 3 H 7 N; cyclobutylamine, C 4 H 9 N; cyclopentylamine, C 5 H 11 N; cyclohexylamine, C 6 H 13 N; cycloheptylamine, C 7 H 15 N; cyclooctylamine, C 8 H 17 N; and cyclododecylamine, C 12 H 25 N. Up through C 8 each is a colorless liquid at room temperature. There are numerous cycloaliphatic diamines. Cycloaliphatic amines are strong bases with chemistry similar to that of simpler primary, secondary, or tertiary amines. Salt formation with Brønsted and Lewis acids and exhaustive alkylation to form quaternary ammonium cations are part of the rich derivatization chemistry of these amines. Primary cycloaliphatic amines react with phosgene to form isocyanates. Cycloaliphatic diamines react with dicarboxylic acids or their chlorides, dianhydrides, diisocyanates and di‐ (or poly‐) epoxides as comonomers to form high molecular weight polyamides, polyimides, polyureas, and epoxies. Cycloaliphatic amine synthesis routes may be described as distinct synthetic methods, though practice often combines, or hybridizes, the steps. Among them are amination of cycloalkanols, reductive amination of cyclic ketones, ring reduction of cycloalkenylamines, and others. Larger volume cycloaliphatic amines and diamines are cyclohexylamine, isophoronediamine, methylenedi(cyclohexylamine), 3,3′‐dimethylmethylene/di(cyclohexylamine), dicyclohexylamine, dimethylcyclohexylamine, and 1,2‐cyclohexanediamine. Shipment of these liquid products is by nitrogen‐blanketed tank truck or tank car. Cycloaliphatic amines and diamines are extreme lung, skin, and eye irritatants. Before a 1/1/70 FDA ban (rescission proposed in early 1990), cyclamate noncaloric sweeteners were the major derivatives driving cyclohexylamine production. Cyclohexylamine condensed with mercaptobenzothiazole produces the large volume moderate rubber accelerator N ‐cyclohexyl‐2‐benzothiazolesulfenamide. 1,3‐Dicyclohexylcarbodiimide is an important peptide‐condensing agent and analytical reagent. trans ‐1,2‐Cyclohexanediamine is derivatized, then hydrolyzed to the tetraacetate and sold as a chelating agent. Methylenedi‐(cyclohexylisocyanate) (MDCHI, Desmodur W) is the dominant derivative of MDCHA and is used in light‐stable urethanes. Isophoronediisocyanate made by phosgenation of IPD competes effectively in this same polyurethane market, predominantly coatings, and is the major commercial application of isophoronediamine. A representative agrochemical application of cycloaliphatic amines is the crabgrass and weed control agent Siduron 1‐(2‐methylcyclohexyl)‐3‐phenylurea. Others are herbicides, Cycloate, used for sugar beets, and Hexazinone.