Synthesis and anticorrosive activity of <i>tert</i>-amines containing cycloacetal or <i>gem</i>-dichlorocyclopropane fragments and quaternary ammonium salts on their basis

Abstract

Objectives. The work set out to synthesize tertiary amines comprising derivatives of morpholine and piperidine containing a 1,3-dioxolane or gem-dichlorocyclopropane fragment, as well as quaternary ammonium salts based on them. In order to determine the process conditions (duration and temperature of the reaction) under which the maximum possible yield of the target quaternary ammonium salts is achieved, the effect of the halide structure on the yield of tert-amines and their subsequent salts was evaluated. The study also aimed to establish the structural and spatial structure of the obtained carbo- and heterocyclic amines and salts based on them, as well as to evaluate the anticorrosive properties of the obtained products in a hydrogen sulfide medium. Methods. The target compounds, such as tertiary amines and quaternary ammonium salts (QAS), were obtained by classical methods of organic synthesis consisting of alkylation and condensation of the corresponding amines of various structures. Preparation of QAS was carried out using a microwave system for organic synthesis via microwave activation on a Sineo device (China). The qualitative and quantitative composition of the reaction masses was determined using gas–liquid chromatography (Crystal 2000 hardware and software complex), while mass spectroscopy was carried out on a Chromatec-Crystal 5000M device with a NIST 2012 database). A Bruker AM-500 device having operating frequencies of 500 and 125 MHz was used to perform nuclear magnetic resonance spectroscopy. Results. Tertiary amines containing a cycloacetal or gem-dichlorocyclopropane fragment were obtained under thermal heating conditions. By carrying out their condensation in excess halides using microwave radiation, new quaternary ammonium salts were synthesized with a yield close to quantitative. Anticorrosive activity was estimated for the obtained cyclic compounds. 4-Allyl-4-[2-(1,3-dioxolan-2-yl)-ethyl]morpholinium chloride was determined to have the maximum protective effect in a hydrogen sulfide medium with a protection level of 91 %. Conclusions. Tertiary amines containing a cycloacetal or gem-dichlorocyclopropane fragment were obtained under the proposed conditions. Such substances are in demand as intermediates in the synthesis of quaternary ammonium salts having anticorrosive activity.

Keywords

• alkylation
• microwave radiation
• quaternary ammonium salt
• corrosion