Synthesis and properties of fatty imidazolines and their N‐(2‐aminoethyl) derivatives

Abstract

Cationic high molecular weight surfactants hold promise as water repellents for soil for water harvesting. Specifically, the products of the reaction of 2 moles of fatty acids with 1 mole of diethylenetriamine were investigated. Optimum conditions for the formation of imidazolines as well as the open-chain N-(2-aminoethyl) derivatives, i.e., the diamides, were determined. Saturated fatty acids, pelargonic through behenic, oleic acid, elaidic acid as well as tallow, tallow fatty acids, and hydrogenated tallow fatty acids, were converted in 6 hr at 150 C to form the diamides. The fatty imidazolines were synthesized by cyclizing the diamides at 150 C for 2 hr under reduced pressure in a 92% yield. The crude imidazolines were purified by crystallization. The fatty imidazolines were readily hydrolyzed at the C=N bond of the imidazoline ring with water or dilute alcohol. The resulting diamides, RCON(CH 2CH 2NH 2)CH 2CH2NHCOR, were also purified by crystallization. Water repellency of these compounds was evaluated by contact angle measurements and percolation tests. The surface properties of these series of compounds are determined by four parameters. The open-chain diamides are more hydrophobic than the analogous imidazolines, and hydrophobicity increases with increasing molecular weight of derivatives of saturated fatty acids. Oleic acid derivatives are far more hydrophilic than the saturated acid derivatives or the analogous elaidic acid derivatives. The latter are more hydrophilic than stearic derivatives.

Thermal reactions of fatty acids with diethylene triamine

“…Thus, the primary amine is more reactive than the secondary amine in that the 1,3-diamides 5 are the main reaction products. Traditionally, formation of imidazoline compounds 7 from the 1,3-diamides 5 requires severe reaction conditions (high temperature and vacuum or long reaction times) (3,8,9). In the present work, when a highly dilute solution of 1 and 2 was used, amide formation took place with the more reactive secondary amine position, and the reaction proceeded probably by way of 1,2-diamides 6 (Scheme 1), which led to the imidazoline compounds 8 in good yield under mild reaction conditions.…”

“…Even though no structural evidence is given, the preparation of compounds 3 and 4 is still claimed in recent patents (6,7). Other researchers have reported that the reaction of DETA with fatty acids does not take place in a 1:1 molar ratio; hence fatty acid monoamides 3 and the related imidazoline derivatives 4 are unlikely (3,4,8). Additionally, discrepancies exist in the literature over the mechanism of the reaction, in particular the relative reactivities of the primary and secondary amines (3,4,8,9).…”

“…Other researchers have reported that the reaction of DETA with fatty acids does not take place in a 1:1 molar ratio; hence fatty acid monoamides 3 and the related imidazoline derivatives 4 are unlikely (3,4,8). Additionally, discrepancies exist in the literature over the mechanism of the reaction, in particular the relative reactivities of the primary and secondary amines (3,4,8,9). To clarify the mechanism of this important thermal acylation reaction and to prepare fatty amides or imidazoline compounds that contain a free primary amine group, we have studied the reaction of fatty acids 1 and DETA 2, and report here the results of our studies.…”

“…Industrially, imidazolines are prepared in a thermal reaction between diethylene triamine (DETA) with fatty acids, triglycerides, or methyl esters of fatty acids (3,4). However, the literature of this fatty acid-DETA reaction is contradictory.…”

Influence of vacuum on kinetic of low quality rapeseed oil amidation by aminoethylethanolamine

“…Researchers [28] found out that tertiary amine content reduced on 5-8 % wt. in 18 months when stored in a closed container.…”