Hydroxyalkylation of Cyclic Imides with Oxiranes. Part II. The Mechanism of Reaction in Presence of Triethylamine

Jacek Lubczak

doi:10.4236/ojpc.2012.22013

Abstract

The mechanism of reaction of cyclic monoimides with oxiranes was established based upon kinetic studies and product analysis. It has been established that the reaction proceeds through initial formation of an adduct of imide and triethylamine. The crucial bond in adduct has ionic character; in non-aqueous solvents it is present as ion pair, while in water the adduct dissociate and free ions are present. The adduct enables the proton transfer from imide to oxirane. The rate determining step is reaction of imide and this adduct. Different values of entropy of transition states obtained from thermodynamic calculations suggest slightly different structure of transition state of rate determining step.

Highlights

IntroductionThe reaction of cyclic monoimides with oxiranes in presence of triethylamine (TEA) leads to N-(hydroxy-alkyl) imides of the general formula (I): CO
The reaction of cyclic monoimides with oxiranes in presence of triethylamine (TEA) leads to N-(hydroxy-alkyl) imides of the general formula (I): CO R NH + R' O N CH2CHOH (I)where R = (-CH2-)2, (-CH2-)3, -Ph R' = -H, -CH3 As it was presented in [1] the reaction follows the rate law (2):V k1 2c1K2c3AH2 c1B 2 (2)where cK, cAH, and cB mean the catalyst, imide groups, and oxirane concentrations, respectively.The process can be considered to have the competitive and consecutive character consistent with reaction of N(hydroxyalkyl)imides, which are the primary products, with oxirane
The crucial bond in adduct has ionic character; in non-aqueous solvents it is present as ion pair, while in water the adduct dissociate and free ions are present

Summary

Introduction

The reaction of cyclic monoimides with oxiranes in presence of triethylamine (TEA) leads to N-(hydroxy-alkyl) imides of the general formula (I): CO. Where R = (-CH2-), (-CH2-)3, -Ph R' = -H, -CH3 As it was presented in [1] the reaction follows the rate law (2):. The process can be considered to have the competitive and consecutive character consistent with reaction of N(hydroxyalkyl)imides, which are the primary products, with oxirane. The rate law describing the reaction of N-(2-hydroxyalkyl)imides with oxiranes obeys another kinetics (first order related to oxirane concentration vs 1/2 for the first step), indicating that the reactions of oxiranes with N-(hydroxyalkyl)imides, which reveals the alcohol character, occur via different mechanism [2,3,4,5,6]. Based upon the rate constants the monoimides were ordered according to lowering reactivity as: PI ≥ SI > GI >HMSI. We propose the mechanism of those reactions based on product analysis, intermediate identification and kinetic measurements

Conductometric Measurements

Cryoscopic Measurements

Mechanism of Reaction

Kinetic Evidences for Proposed Mechanism

Non-Kinetics Evidences

Summary and Conclusions