Kinetik und Mechanismus der Anlagerung von Propylenoxid an Diäthylamin unter Ausschluß protonenaktiver Verbindungen

Abstract

ZUSAMMENFASSUNG :Die Anlagerung von Propylenoxid an Diathylamin in Substanz wurde kinetisch untersucht. Die Reaktion verlauft autokatalytisch -die OH-Gruppe des entstandenen Aminoalkohols katalysiert die weitere Addition von Epoxid an das Amin. Polyiitherbildung wird nicht beobachtet. Beide Reaktionspartner reagieren nach erster Ordnung. Unter Berucksichtigung der bei der Abreaktion auftretenden Volumenkontraktion wurden die Geschwindigkeitskonstanten der spontanen und der autokatalytischen Reaktion sowohl nach dem differentiellen als auch nach dem integrierten Zeitgesetz ermittelt. Die experimentelle Aktivierungsenergie der Startreaktion betriigt 17,2 f 0,3 kcal/Mol, die der katalysierten Umsetzung 13,L f 0,3 kcal/Mol. Beide Reaktionen verlaufen bimolekular ; im Falle der autokatalytischen Reaktion sind dem geschwindigkeitsbestimmenden Schritt Assoziatgleichgewichte zwischen Epoxid und Aminoalkohol vorgelagert. SUMMARY :The kinetics of the addition of propylene oxide to diethylamine in bulk was investigated. The reaction is autocatalytic -the alcoholic group of the resulting aminoalcohol catalyses the further addition of epoxide to amine. Formation of polyether could not be observed. Experiments have proved a fist order in propylene oxide and diethylamine. The rates of reaction were determined according to the rate equations in differential and integrated forms, considering the contraction of volume in the course of reaction. The activation energy has been found to be 17.2 f 0.3 kcal/mole of the spontaneous reaction and 13.1 0.3 kcal/mole of the catalytic reaction, respectively. Both reactions are bimolecular ; equilibrium reactions between propylene oxide and aminoalcohol precede the autocatalytic reac tion.

The kinetics of propylene oxide reaction with certain alkylamino alcohols in the presence of basic catalysts

“…The strongly negative entropy of activation may be a further indication of a termolecular reaction of propylene oxide with amino alcohols in the presence of basic catalysts. Our calculated values are close to those known in the literature [7,8,11].…”

“…Moreover the rates of ring opening of propylene oxide with dibutylamine in DMSO-benzene mixtures were studied by Kakiuchi, Iijima, and Horie [7]. The kinetics of the addition of propylene oxide to diethylamine without any catalyst were investigated by Tiltscher [8]. It was found that the reaction exhibits second-order kinetics.…”

Reactions of trithiocyanuric acid with oxiranes. II. Kinetics and mechanism of reactions

“…The syntheses were carried out with a large excess of oxirane in DMF solution and in the presence of triethylamine (TEA) as the catalyst. To our knowledge the compositions of reaction products of trithiocyanuric acid with oxiranes and the courses of these reactions have not been reported so far, which is in contrast to reactions of oxiranes with other compounds containing active hydrogen atoms such as alcohols,2–7 phenols,8 thiols,9–11 carboxylic acids,12–16 amines,17–20 amides,21, 22 or imides 23…”

Detailed chemomechanistic sensitivity study on the alkoxylation of fatty amines

“…Two categories of pathways to explain the autocatalysis and the initial ring opening are postulated in the literature. These mechanisms describe either the intermediate steps by a (concerted) ter‐molecular step, or via an ionic intermediate step 14,16–18 . The main differences between these pathways are the way the protons are transported between the reactant the epoxide and the products.…”

“…The main differences between these pathways are the way the protons are transported between the reactant the epoxide and the products. Herein, proton migration is either facilitated using a carrier species 12,16,19,20 or by internal rearrangement via an ionic state 17,18 …”