Quinones are small redox-active molecules that are able to form intra- and intermolecular interactions both in the solid state and in solution. On the basis of 6-amino-substituted pyrido- and pyrimido-[1,2-a]benzimidazole-8,9-diones, weak interactions were investigated by single-crystal X-ray and ¹H NMR spectroscopy methods. Crystallization of quinone derivatives containing a -NH-CH₂- fragment led to the formation of both chiral and achiral crystals. The presence of two forms with (endo form) and without (exo form) an intramolecular hydrogen bond was experimentally detected by X-ray crystallography analysis and variable-temperature (VT) ¹H NMR experiments in the cases of isopentylamino- and benzylamino-substituted derivatives. Interestingly, the exo form dominates both in the solid state and in solution.

In this work, reactions between 6,7-dichloropyrido[1,2-a]benzimidazole-8,9-diones with different benzohydrazides were studied. Nucleophilic substitution at C(6) was followed by isomerization and led to α-hydroxy-p-quinone imine derivatives. Synthesized compounds represent a combination of several structural motifs: a benzimidazole core fused with α-hydroxy-p-quinone imine, which contains a benzamide fragment. X-ray crystallography analysis revealed the formation of dimers linked through OH···O interactions and stabilization of the imine form by strong intramolecular NH···N hydrogen bonds. The protonation/deprotonation processes were investigated in a solution using UV–Vis spectroscopy and a ¹H NMR titration experiment. Additionally, the electrochemical properties of 6,7-dichloropyrido[1,2-a]benzimidazole-8,9-dione and its α-hydroxy-p-quinone imine derivative as cathode materials were investigated in acidic and neutral environments using cyclic voltammetry measurements. Cathode material based on 6,7-dichloropyrido[1,2-a]benzimidazole-8,9-dione could act as a potentially effective active electrode in aqueous electrolyte batteries; however, further optimization is required.

The present research assesses the potential of rapeseed oil soapstock for producing lecithin and its application in the food industry in the context of the circular economy and bioeconomy. The theoretical part summarizes information on the types of lecithin and its production technologies and functional properties, while the empirical part combines semi-structured interviews with 30 experts and company representatives (in Latvia and abroad) and a laboratory experiment with rapeseed soapstock samples. The data provided by the experts were analyzed using descriptive statistics and thematic analysis, while the soapstock samples were tested for dry matter, lipid content, and lecithin and acid oil yield using the techniques of n-hexane Soxhlet extraction and fractionation with cold acetone. The experts’ ratings showed that rapeseed lecithin is technologically competitive with soybean and sunflower lecithin, especially to produce bread, flour confectionery, as well as oil and fat, thereby providing good emulsification capability, texture improvement, and stabilization. The highest potential for the introduction of rapeseed lecithin has been identified in the oil and fat, bread and flour confectionery segments, but wider use is currently hampered by high production costs and lower market visibility. This research demonstrated the practical possibility of isolating lecithin from rapeseed oil soapstock. The laboratory experiment revealed that it is possible to obtain lecithin from rapeseed soapstock in amounts of 1.4–5.2% of the total weight of soapstock (6.2–23.5% of dry matter), which confirmed the usability of rapeseed soapstock as a raw material for lecithin production. The results confirm that the use of rapeseed oil soapstock to produce lecithin can reduce the amount of industrial waste and increase resource efficiency, thus reducing dependence on imported soybean lecithin. Rapeseed lecithin can be found as a sustainable alternative to soybean and sunflower lecithin with potential for oil and fat and bread production.