As primary resources become increasingly scarce with global population growth, valorizing industrial side streams is essential. In Estonia, oil shale ash-the country's most abundant industrial waste-offers a promising source of calcium and magnesium for producing snow and ice-melting agents. Conventional deicers, such as sodium chloride, pose severe environmental and infrastructural risks due to corrosion and ecological damage. Acetate-based deicers are less corrosive and more environmentally friendly, but their production typically depends on dolomitic lime, which requires mining and processing. Oil shale ash is already generated as a by-product of energy production, eliminating the need for additional extraction and reducing environmental impact. This study evaluated three synthesis methods: (1) conventional solution chemistry with magnetic stirring, (2) ultrasonic-assisted reaction, and (3) solvent-free mechanochemistry. Optimal conditions for solution-based synthesis-80 degrees C for 136 min with 3.4 equivalents of acetic acid-yielded over 96 % for both calcium and magnesium. Ultrasonic-assisted reactions achieved comparable yields (>92 %) but required longer times. Mechanochemistry proved most resource-efficient: a 5-minute milling with only one equivalent of acetic acid produced 78 % calcium and 67 % magnesium, while 30 min yielded 87 % and 72 %, respectively. The resulting salts were characterized for freezing point, effective temperature, and composition. Impurities such as gypsum and iron were detected, likely influencing ice-melting performance. Overall, mechanochemistry emerged as a rapid, sustainable method for producing acetate-based deicers with minimal reactant use, highlighting oil shale ash's potential as a valuable resource for winter road maintenance.

Capillary electrophoresis is a robust and versatile analytical method, particularly known for its precision and speed in separating anionic species. Its ability to maintain high resolution despite the presence of various organic and inorganic additives makes it ideal for verifying the efficiency of various industrial processes.One such process is the analysis of kerogen, which is an organic fraction found in Estonian oil shale known as kukersite. Kukersite was historically utilized for energy production, but now it is being reimagined as a sustainable source for high-value chemicals. Through controlled kerogen oxidation, it is possible to produce a range of essential dicarboxylic acids, including succinic, glutaric, adipic, and sebacic acids. These acids are vital precursors for the manufacturing of advanced materials, polymers, and plasticizers.Several capillary electrophoretic methods have been developed in the past to analyze dicarboxylic acids, but they either failed to separate the acids fully or other anionic compounds co-eluted during analysis. This study sought to overcome these limitations by optimizing various parameters to achieve a high-resolution separation of dicarboxylic acids and other anionic compounds in oxidized kerogen samples. The resulting method not only assisted in the evaluation of the oxidation process’ effectiveness but also provided a scalable framework for adapting capillary electrophoresis to complex anionic mixtures across various industrial sectors.

Derivatization of the kerogen backbone changes its chemical reactivity profile. In this study, kukersite kerogen was methylated with dimethyl carbonate. The substance was analyzed before and after processing by Fourier transform infrared spectroscopy, 13C cross-polarization/magic angle spinning nuclear magnetic resonance spectroscopy, and elemental analysis. It was observed that kukersite kerogen can be readily methylated with dimethyl carbonate. Based on mass balance and the Lille-Blokker model, an average of 19 methyl groups were added to the kerogen unit. It was concluded that about half of the hydroxyl groups in Estonian kukersite kerogen are “free” and accessible to methylation.

Ensuring material supply security requires greater utilization of local resources, including the valorization of oil shale kerogen into value-added chemicals instead of its conventional use for energy production. This study investigated nitric acid (HNO3) oxidation as a direct route for the conversion of kukersite oil shale kerogen into aliphatic dicarboxylic acids (DCAs). Oxidation experiments were conducted under atmospheric and pressurized conditions to evaluate the effects of temperature, reaction time, HNO3 concentration and amount, pressure, and reactor material on DCA yield and product distribution. Elevated pressures (10–15 bar) enabled DCA yields of ∼30% within short reaction times (30–40 min) at 130–140 °C. Temperature and HNO3 concentration were identified as the primary factors governing DCA yield once a sufficient oxidant amount was present. Elevated pressure increased reaction rates through greater availability of reactive species. Reaction conditions influenced product distribution, with harsher conditions promoting the formation of shorter-chain DCAs (C4–C6), while milder conditions favored longer-chain DCAs (C7–C11). High yields were achieved using 30 wt% nitric acid, indicating that higher concentrations provide limited benefit relative to increased oxidant consumption and safety considerations. These findings demonstrate a viable and scalable route for the valorization of kukersite kerogen into chemical intermediates and provide the experimental basis for the development of the Kerox process.

To promote the transition towards a greener and more efficient chemical industry, new starting materials are needed to produce basic chemicals. Using available resources in a new and efficient way contributes towards mitigating global shortages of particular high-priority chemicals. To address this issue, the low-temperature oxidation of organic matter in different oil shales (OSs) was studied. Oxidation has proven to be an effective way to transform the organic matter in oil shale to value-added products, mainly dicarboxylic acids (DCAs). As this procedure has been effectively implemented on Estonian oil shale, it was expanded to oil shales of different geological origin in an innovative way—by using microwave-assisted oxidation. This paper presents the preliminary mapping of DCA production potential of oil shales from Estonia, the USA, Brazil, Jordan, Kazakhstan, and Syria by using microwave-assisted oxidation. Due to variations in the organic matter structure, the results were presented in relation to total organic carbon (TOC) content. To remove the possible effect of carbonate minerals, one set of the samples was demineralized using formic acid. The preliminary results showed that the proposed method was applicable to different oil shale types, despite not being optimized for individual samples—the reaction was carried out under standard conditions. All samples exhibited a carbon conversion of over 70

The increasing need for sustainable valorization of fossil-based and waste-derived materials has gained interest in converting complex organic matrices such as kerogen into valuable chemicals. This study explores a two-step oxidative strategy to decompose and valorize kerogen-rich oil shale, aiming to develop a locally based source of aliphatic dicarboxylic acids (DCAs). The method combines air oxidation with subsequent nitric acid treatment to enable selective breakdown of the organic structure under milder conditions. Air oxidation was conducted at 165–175 °C using 1% KOH as an alkaline promoter and 40 bar oxygen pressure (or alternatively 185 °C at 30 bar), targeting 30–40% carbon conversion. The resulting material was then subjected to nitric acid oxidation using an 8% HNO3 solution. This approach yielded up to 23% DCAs, with pre-oxidation allowing a twofold reduction in acid dosage while maintaining efficiency. However, two-step oxidation was still accompanied by substantial degradation of the structure, resulting in elevated CO2 formation, highlighting the need to balance conversion and carbon retention. The process offers a possible route for transforming solid fossil residues into useful chemical precursors and supports the advancement of regionally sourced, sustainable DCA production from unconventional raw materials.

The Lille-Blokker model of the chemical structure of kukersite oil shale provides a good basis for developing methods for its direct conversion into new materials and basic organic chemicals. The model of its structure may be considered a complex organic "macromolecule". Existing information on the chemical treatment of kukersite kerogen by hydrogenation, halogenation, alkylation, sulfonation, chloromethylation, oxidation, etc., is critically reviewed, and different options for bulk kukersite conversion are discussed. So far, the direct conversion approach has only been applied to the oxidation of kukersite to obtain dicarboxylic acids. In this paper, a chemical reactivity map of kukersite kerogen is presented, highlighting possible pathways for its transformation. This study aims to demonstrate that, within the context of expanding research on unconventional resources, kerogen can serve as a focal point in materials-oriented science.

4-formyl phenols with electron donating groups in ortho-position react with active alkyl halides in three directions: Williamson reaction up to 48%, aromatic substitution of the formyl group up to 36%, and addition to the ortho-position with dearomatization of the ring up to 10%. The ratio of the products depends on the substituents in the benzene ring and the used alkali and additives.

A possibility of use of the Michael addition reaction of the A,B-ring fragment enolate to sulfoxide 2­-(S)-­[(4­-methylphenyl)sulfinyl]-­2­-cyclopenten-1­-one for constructing the main skeleton of 9,11-secosterols was studied. The reaction was conducted with the racemic or the enantiomerically enriched sulfoxide as the acceptor, affording a mixture of five or three main diastereomers, respectively. It was shown that the diastereoselectivity of that addition reaction is relatively low and does not afford a competitive new route for the total synthesis of secosterols.

The aerobic ring-opening oxidation of cyclopropanols catalyzed by copper complexes was systematically investigated, with a focus on the effect of nitrogen ligands on the distribution of oxidation products. This study led to the development of a new synthesis of beta-aminoketones and beta-enaminones from cyclopropanols, where product specificity is tuned through ligand and solvent selection. beta-Aminoketones were prepared in 34-99% yields by copper(II) acetate-catalyzed aerobic oxidation of cyclopropanols in the presence of nucleophilic secondary aliphatic amines. In contrast, bipyridine-ligated copper catalysts resulted in the generation of beta-enaminones in 36-86% yields, presumably via the Kornblum-DeLaMare rearrangement of intermediate 1,2-dioxolanes.

A possibility of use of the Michael addition reaction of the A,Bring fragment enolate to sulfoxide 2(S)[(4methyl phenyl)sulfinyl]2cyclopenten1one for constructing the main skeleton of 9,11secosterols was studied. The reaction was conducted with the racemic or the enantiomerically enriched sulfoxide as the acceptor, affording a mixture of five or three main diastereomers, respectively. It was shown that the diastereoselectivity of that addition reaction is relatively low and does not afford a competitive new route for the total synthesis of secosterols.

The application of Michael addition to the construction of the carbon skeleton of 9,11-secosterols has been investigated using the following Michael acceptor - sulfone 2-[(4-methylphenyl)sulfonyl]cyclopent-2-en-1-one, where the addition product was isolated in good yield and as a mixture of two diastereomers. Also, the diastereomers were separable by crystallization, and, based on NMR spectroscopic data, the relative configuration of the formed stereocentres of the isolated diastereomer matched the 9,11-secosterol found in nature. This study can be exploited to create a total synthesis scheme for 9,11-secosterols.

The organic matter in oil shale (kerogen) contains vast potential as its structure is rich in easily convertible and versatile building blocks. Due to the complex structure of kerogen, simplifications are often used in order to obtain any information about the mechanism of its processing. This paper presents an approximate two-stage kinetic model which has been constructed to describe the wet air oxidation (WAO) process of the kerogen of Estonian kukersite oil shale, i.e. an alternative oil shale treatment process. The results obtained highlight the basic mechanisms of oil shale oxidation by molecular oxygen in water into different products. These outcomes add to the already existing knowledge on the structure of kerogen and validate it. The composed two-stage reaction formula outlines a fast reaction period which describes the dissolution of organic material, followed by a slower oxidation of dissolved substances. The attained high dissolution rate of kukersite kerogen illustrates the potential for recovering feedstock chemicals. The rate constants found remained independent of the oxygen-to-carbon ratio and good agreement was observed between calculated kinetic curves and experimental values.

Alkylation of resorcinol and methyl-substituted resorcinols and its methyl ethers with alkyl bromides in water and anhydrous organic solvents led to mono- and/or dialkylated resorcinols and alkyl cyclohexendiones, depending on the structure of the starting substrates and reaction conditions. Selective di-alkylation was achieved in both, aqueous and anhydrous conditions, up to 76% yield. Resorcinol monomethyl ethers behaved similarly to phenols, giving in dry organic solvents predominantly ortho -substituted products, and a mixture of ortho- and para-substituted products together with resorcinol ethers in aqueous solution. The alkylation of 2,4,6-trimethyl resorcinol monomethyl ether showed selective 2 C-alkylation in 53% yield. 2-Methyl resorcinol with electrophiles in excess afforded in tetra-alkylation up to 72% yield.

The structure of kukersite organic matter has been a matter of scientific investigation and disputes over a hundred years. When considering the publications on the subject the authors of the current article concluded that the structure of kukersite is well described by a model proposed independently by ulo Lille and Peter Blokker at the beginning of this millennium. This model characterizes the behaviour of kukersite in thermal processing and predicts the behaviour of oil shale kerogen in oxidation and other chemical transformations. The structural model may serve as a basis for new technologies for oil shale processing in order to get valuable chemicals directly from it.

Electrochemical hydroxylation of arenes by trifluoroacetic acid provides a straightforward access to aryl oxygen compounds under the mild and environmental benign reaction conditions. Harmful and pollutant stoichiometric amounts of oxidation reagents and the use of metal-catalysts can be avoided. Herein, we present a novel method for the synthesis of hydroxylated products from electron-rich arenes that was achieved by the implementation of a continuous-flow setup. The continuous nature of the process allowed to fine-tune the reactions conditions in order to prevent the decomposition of the sensitive products expanding the reaction scope beyond electron-poor and neutral arenes that were previously reported in the batch processes. Thus, synthetically valuable hydroxylated arenes were obtained in good yields with the residence time just over a minute. In order to demonstrate the reliability and the efficiency of the electrochemical flow setup, a scale up experiment was also performed.

Oxidation has been a long sought-after alternative to classical thermal processing of oil shale, in order to obtain valuable raw materials for the chemical industry. A number of different methods have been applied, but thus far, one of the most effective ways to transform oil shale to value added products, such as aliphatic terminal dicarboxylic acids, is oxidation with nitric acid. In order to obtain insight into the reactivity of oil shale in nitric acid, a study focusing on the kinetics and behavior of oil shale particles during oxidative leaching was performed. To that end, the particle size distribution, surface area, and carbon content were measured during the leaching process in addition to the amount of total residual solids. Determining the carbon content of the solid residue was proposed as a simple measure of the reaction progress, based on the hypothesis that all carbon measured by elemental analysis correspond to organic carbon since inorganic carbon is present as carbonate in the starting material and would have dissolved under the acidic conditions. To our surprise, the solid residue had a significant amount of organic carbon in the form of calcium oxalate mineral. Thus, measuring carbon content in the solid residue could provide only an indirect measure of the overall oxidation degree provided that the amount of oxalates was known. In general, the results revealed that the total solid residue amounts to between 20% and 34% of the initial values after 24 h of the reaction, while the total carbon content ranges from 4% to 14% of the starting values. These results show that we were able to extract around 90% of the organic carbon present in the solid phase.

The asymmetric oxidation of a key intermediate for 9,11-secosterol synthesis, 2-[(4-methylphenyl)thio]-2-cyclopenten-1-one 2 with a Ti(iPrO)4/(+)-DET/TBHP complex was studied. The kinetic resolution of racemic 2-[(4-methylphenyl)sulfinyl]- 2-cyclopenten-1-one 1 by oxidation with the same Ti-complex was also carried out. In both cases enantioenriched 2-(S)-[(4-methylphenyl)sulfinyl]-2-cyclopenten-1-one 1 was obtained in satisfactory yields and sufficient enantiomeric purity for further enantioenrichment by recrystallization. The obtained results afford simple access to the D-ring precursor of 9,11-secosterols.

The Front Cover demonstrates that electrochemistry in continuous flow is so convenient and reliable that even kids could do it. Electrochemical hydroxylation of sensitive electron-rich arenes was achieved by the implementation of a flow setup. Our goal is to motivate organic chemists, who tend to be quite conservative, to apply the modern techniques in their everyday research and explore new reaction pathways. Cover artwork by Alina Andreyenka. More information can be found in the Research Article by M. Ošeka et al.