Unsaturated Substances Research Articles

Chemoselective reductive coupling of α, β-unsaturated esters and nitroarenes for sustainable synthesis of β-amino acid esters by a hierarchically porous cobalt nanocatalyst

Chemoselective reductive coupling of α, β-unsaturated esters and nitroarenes for sustainable synthesis of β-amino acid esters by a hierarchically porous cobalt nanocatalyst

Effect of extrusion-spheronization granulation and manganese loading on catalytic ozonation of petrochemical wastewater.

The petrochemical secondary effluent (PSE) is typical refractory wastewater derived from the petrochemical industries, which requires advanced treatment due to the strict environmental protection policies. Catalytic ozonation is one of the most widely used advanced oxidation technologies in wastewater treatment because of its high mineralization rate, in which the alumina-based catalyst usually plays an important role. Extrusion-spheronization is a promising technique for the preparation of alumina spheres because the synthesized alumina particles have high sphericity, high specific surface aera and narrow particle size distribution. In this paper, two kinds of alumina-based catalysts (catalyst A: manganese nitrate added after alumina granulation and catalyst B: manganese nitrate added into alumina powder before granulation) were prepared by the extrusion-spheronization method and used for PSE treatment by catalytic ozonation. The prepared alumina samples were characterized by Brunauer-Emmett-Teller (BET) method, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM), while the wastewater samples were analyzed for Total organic carbon (TOC), UV254 and fluorescence spectroscopy. Results showed that manganese was uniformly distributed in both catalysts, and the specific surface area of two catalysts was 318.36 m2/g and 354.95 m2/g, respectively. Catalytic ozonation experiments were repeated nine times with each catalyst under the same conditions. The TOC removal rates for catalysts A and B in the first run were 48.88% and 49.06%, respectively, then it dropped to 28.05% for catalyst A but remained 47.81% for catalyst B after using for nine times. This implied that the long-term performance of catalyst B would be more stable than catalyst A. Similar result were found in three-dimensional fluorescence analysis. UV254 results indicated that the removal efficiency of aromatic and unsaturated substances by catalyst B was higher than catalyst A. A possible explanation is that the active component manganese oxide formed a catalyst skeleton in catalyst B, which makes it hard to dissolve. Effect of extrusion-spheronization granulation and manganese loading on advanced oxidant treatment of petrochemical wastewater.

Temperature Rise Increases the Bioavailability of Marine Synechococcus-Derived Dissolved Organic Matter.

Synechococcus is one group of main primary producers and plays a key role in oceanic carbon fixation and transformation. To explore how the temperature rise affects the bioavailability of Synechococcus-derived dissolved organic matter (SOM) and whether this effect would be altered by the involvement of heterotrophic bacteria, we compared the optical and molecular properties of the SOM of axenic Synechococcus sp. PCC7002 culture (Syn) to that with associated heterotrophic bacteria (SynB) under 15, 18, and 21°C growth temperatures at exponential and decay growth phases. Our results showed that the temperature rise increased the bioavailability of the SOM of both Syn and SynB cultures by lowering the proportion of the hydrogen-poor and double-bond structure-rich humus-like components and highly unsaturated substances, as indicated by the increase of spectral slope ratio (SR) and biological index (BIX) and decrease of humification index (HIX). Moreover, the involvement of heterotrophic bacteria modified the Synechococcus-derived SOM, together with its intracellular dissolved organic matter (DOM) excludes, lowering the SOM bioavailability. Our results indicated that the warming in climate change scenario may enhance the bioavailability of the Synechococcus-derived SOM although it may be tempered by the involvement of heterotrophic bacteria, providing an insight for preservation of the organic carbon pool in global oceans.

A novel strategy to simultaneously enhance bio-oil yield and nutrient recovery in sequential hydrothermal liquefaction of high protein microalgae

• Bio-oil yield increased from 16% to 28.65% in SEQ-HTL with SII-AP recycling. • 33–53% C in SII-AP were recovered and transferred into SII-Oil and SII-Char. • Maillard, Michael addition and acylation reactions were key pathways of bio-oil increase. • Replacing medium nutrients with SI-AP was feasible for fungal-algal cultivation. Advances in sequential hydrothermal liquefaction (SEQ-HTL, or two-step HTL) is limited by its low bio-oil production and enormous aqueous phase (AP) byproduct. The objective of this study was to integrate AP recirculation and fungal-microalgal cultivation with the SEQ-HTL to simultaneously improve bio-oil yield, energy recovery, and nutrient recovery. Specifically, AP from the first step (SI-AP) of SEQ-HTL was used to culture microalgae and fungi for nutrient recovery, and AP from the second step (SII-AP) was recycled four times as reaction solvent to enhance bio-oil yield. Interestingly, the SI-AP showed excellent biodegradability, and the complementary cultivation of fungi and algae has tremendous potential to recover nutrients. For example, 0.96 g/L fungi biomass and 87.71% chemical oxygen demand (COD) removal rate were obtained by fungi cultivation in SI-AP, and 1.35 g/L biomass and 63.80% ammonia nitrogen (NH 4 -N) removal rate were received by microalgae cultivation in SI-AP. The difference of dissolved organic matter in SI-AP and the AP from conventional HTL (HTL-AP, inhibited microalgae significantly) pointed out unsaturated substances and lignins/carboxylic-rich alicyclic molecules substances might be the primary factor inhibiting microalgae growth. During SII-AP recirculation, the yields of bio-oil (SII-Oil) and hydrochar (SII-Char) increased from 16.00% to 28.65% and 2.93% to 5.66%. 32.96–53.08% C and 15.93–24.00% N in SII-AP were recovered and transferred into SII-Oil and SII-Char. A series of characterizations showed that the increased bio-oil formation was mainly the transformation of amines, glycerol, alcohols, acetic acid, and amino acid fragments from the AP into the oil phase via Maillard reaction, Michael addition reaction and acylation. Overall, the novel strategy could improve the economic feasibility of processing high-protein microalgae biomass using the SEQ-HTL technique and is promising to the industrial applications of microalgae.

APLICAÇÕES E IMPLICAÇÕES DO OZÔNIO NA INDÚSTRIA, AMBIENTE E SAÚDE

OZONE APPLICATIONS AND IMPLICATIONS FOR INDUSTRY, ENVIRONMENT, AND HEALTH. Stratospheric ozone is an efficient filter for ultraviolet radiation, which damages organisms’ lives exposed to sunlight. In the troposphere, ozone is essential to oxidate volatile organic compounds, but its effects are harmful to animals and plants, particularly humans. The high reactivity of ozone with some organic compounds makes it a promising agent for several applications, such as microbiological control and the medical field. However, their contact with surfaces containing unsaturated substances and other compounds can result in the formation of products that are harmful to human health or distort the organoleptic and structural properties of food. The results available in the literature are often divergent as to their safety and economic viability. Despite this, there are many cases of dermatological applications, and as sanitizing agents in several environments. Antiviral and bactericide properties were that guided the expansion of ozone application in the current coronavirus pandemic (COVID-19). However, more studies should be carried out to comprove its effectiveness, considering possible damages resulting from these applications.

Theoretical insights on boron reducing agent for the reduction of carbonyl compounds.

In this perspective, we present computational progress in the reduction of carbonyl compounds using boron reducing agents, such as L·BH3, HBcat, HBpin, and 9-BBN. For the catalytic reduction reactions, establishing a catalytic mechanism will provide an important theoretical basis for the improvement of a more efficient combination of reducing agents and catalysts. Current computational studies reveal that the mechanisms of reactions are different due to the various combinations of electrophilic boron reducing agents and catalysts (transition-metal catalyst, main group metal catalysts, and metal-free frustrated Lewis pair). We discuss the role of boron reducing agents on the efficiency of reactions and believe that possible Lewis acid-base interaction between Bδ+, Mδ+ and Oδ-, Hδ- existing in boron reducing agent, unsaturated substances, and catalyst should be considered fully. A tentative outlook on future opportunities of this research field is proposed.

Chemical Composition and Biological Activities of Essential Oils from the Fruits of Cuminum cyminum L. and Ammodaucus leucotrichus L. (Apiaceae)

Hydrodistilled volatile oils obtained from the fruits of Cuminum cyminum L. and Ammodaucus leucotrichus L., cultivated in Morocco, were analyzed by GC/FID and GC/MS. Twenty-one compounds repre- senting 98.7 % of the oil were identified for the C. cyminum L. species. The main components of the oil were: γ- terpinen-7-al (37.2 %), cuminaldehyde (29.1 %), γ-terpinene (10.0 %), β-pinene (7.1 %) and p-cymene (6.1 %). For the Ammodaucus leucotrichus L. species, there were 21 identified compounds, representing 98.4 % of the total oil. The major constituents were perrilla aldehyde (78.2 %) and limonene (9.5 %). Isolated essential oils were tested for radical-scavenging ability using the stable DPPH radical and the ABTS radical, for reducing power ability with a test based on the reduction of ferric cations, and for lipid peroxidation inhibitory ability using β- carotene bleaching assay. The two oils showed a particularly interesting profile concerning oxidation of the fatty unsaturated substances. The antimicrobial activity of the essential oils was individually evaluated against representatives of Gram-positive and Gram-negative bacteria using the agar diffusion method. The most sensi- tive microorganisms are: Enterococcus faecalis, Salmonella sp, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Staphylococcus epidermis, Citrobacter freundii and Escherichia coli.

STUDY OF THE INFLUENCE OF BUCKWHEAT FLOUR AND FLAX SEEDS ON CONSUMPTION PROPERTIES OF LONG-STORED BAKERY PRODUCTS

Rusk and ring-shaped bakery products relate to the group of long-stored ones. For today it is urgent to use ingredients that give products functional properties in food technologies. The important source of food fibers, full-value protein, unsaturated fatty acids, mineral substances and vitamins are grain and oil-bearing crops. Buckwheat and flax seeds are separated among them due to the valuable chemical composition and positive effect on the human organism. The aim of the work was to establish the influence of buckwheat flour and flax seeds on the technological process course and quality of long-stored bakery products. Buckwheat flour of green and dark buckwheat of TM “Organic-Eco-Product” (Ukraine) is used in the rusk technology. For producing ring-shaped products (ring-shaped crackers), gold flax seeds were used. Research results testify that good quality parameters of bread for producing rusks from it, were achieved at dosing green buckwheat seeds as 20 % and dark ones as 15 % instead of the flour mass. It has been established, that rusks with adding green buckwheat flour have quality parameters, corresponding to requirements of normative documents. It has been proven, that it is not expedient to use dark buckwheat flour in the rusk technology, because ready products have the increased water share and soaking index. It is connected with the influence of the operation of hydrothermal processing of grains that dark buckwheat flour is produced of, its high water-absorbing and water-retaining capacities. For the technology of ring-shaped crackers, enriched with flax seeds, it is recommended to dose flax seeds as 15 % of the flour mass. At such dosage bakery products got the highest number of points by the complex quality parameter and corresponded to requirements of normative documents.

A first-principles study on the hydrogenation of acetone on HxMoO3 surface

Hydrogenation of acetone on the (010) surface of hydrogen molybdenum bronzes was investigated by density functional theory (DFT) calculations with periodic slab models. The formation of H-bond between the carbonyl oxygen of acetone and the terminal OH group of the surface leads to a stable adsorption of acetone. The effect of hydrogen concentration in the bronzes on the hydrogenation of acetone was systematically investigated, indicating the hydrogenation reaction is a one-step concerted and exothermic process regardless of the hydrogen contents in the bronzes surface. The 8H surface with increased H-content shows a significantly exothermic reaction process and exhibits the smallest kinetic barrier compared with 4H or 6H surfaces. Additionally, the selectivity for hydrogenation acetone could increase owing the absence of CC bond activation. The findings in this study can help with designing of high-efficient and low-cost metal oxide catalysts for hydrogenation of unsaturated substances.

Using NMR to study changes in the characteristic constituents of stored rice

Abstract This study investigated constituent differences between stored and fresh rice using multidimensional solution-state nuclear magnetic resonance (NMR) spectroscopy. Fourier transform infrared (FTIR) spectroscopy and gas chromatography–mass spectrometry (GC-MS) was also used to determine constituent changes during storage. Signal variations in alkyl, alkoxy, acyl, hydroxyl, amine, and amino groups revealed hydrolysis of neutral fats and phospholipids to free fatty acids or lower esters. Signals from double bonds showed changes in unsaturated substances, such as glycerides and phospholipids, which correspond to a phenomenon exposed by GC-MS detection, that is, a reduction in polyunsaturated fatty acids occurs on storage. Moreover, the hydrolysis or oxidation of unstable lipids result in a conversion from fresh to aging rice with respect to the development of disagreeable flavors. Results from this study can both aid in our understanding and further the research into the progression and phenomenon of aging rice.

Spectral characterization of dissolved organic matter in bio-treated effluent of coking wastewater

Fractionation of dissolved organic matter(DOM) in the bio-treated effluent of coking wastewater was conducted by non-ionic DAX-8 resin and ion exchange resins. Characterization methods included dissolved organic carbon (DOC), UV-visible spectroscopy, three-dimensional fluorescence spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. The results showed that hydrophobic acid (HoA), hydrophilic acid (HiA) and the hydrophilic neutral (HiN) substance were the main components of DOM, accounting for 39.88%, 25.38%, 20.85%, respectively. DOM was mainly composed of single-ring aromatic compounds or conjugated double bond compounds. Based on the UV-visible spectroscopic data(E254/E365=3.89, E445/E665=1.91, SR=0.926), it suggested that organic compounds with low MW(molecular weight) were the main component of hydrophilic substances (HIS) fraction. The hydrophilic acid (HiB) fraction featured as the component with the highest degree of aromatic and the most abundant of unsaturated aromatic substances, according to the results that UV254 accounted for 32%, SUVA=49.94 L·mg-1·cm-1. HoA may contained like-fulvic substances and had the highest degree of humification (E300/E400=2.58). DOM characterization with spectral analysis methods convey messages of the proportions of hydrophilic and hydrophobic substances, the degree of aromatic, molecular weight, chromophore and organic groups, which can be considered as references to determine the characteristics of wastewater.

Electron-beam derived polymeric cryogels

In this study we publish a novel attempt to macroporous, polymeric cryogels (MPCs) by electron-beam (EB) initiated free radical crosslinking polymerization of (meth)acrylates in frozen aqueous media. The EB-process is an environmentally benign fast process (radiation and reaction time about 10–20 min) which allows the initiator-free polymerization of double-bond containing monomers. The MPCs were thoroughly characterized by swelling experiments, SEM, detailed XPS studies, DMA, Hg intrusion porosity and ESEM. The processes during the reaction were studied using ESR experiments. The influences of the reaction parameters like dose, radiation time, freezing conditions, chemical composition and (meth)acrylate concentration on the properties of the MPCs were investigated. The MPCs were synthesized in situ in capillaries or in tubes up to a diameter of 25 mm. The porous structure of the MPCs is mainly controlled by the freezing temperature and the macromonomer/crosslinker concentration and consists of large interconnected pores in the range of 10–70 μm. The crosslinker concentration directly affects the stiffness and the Tg of the materials. The MPCs were successfully modified with poly(allylamine hydrochloride). This straightforward method provides a toolbox for the synthesis of manifold MPCs from various unsaturated substances in large quantities and scale.

Factors Augmenting the Detonability of Energetic Materials

This review is compiled from the experimental results of investigations that were carried out from the 1970s to 2004 in the laboratory and in the Department of Technological Processes Reliability and Safety, which was headed by Professor Boris N. Kondrikov. Sensitization to detonation by the addition of acids, amines or unsaturated substances, by introduction of porosity and by raising the initial temperature is described. All of these factors are examined in the context of the reliability and safety of technological processes.

Multiple Insertion of Unsaturated Molecules into the Zr−N Bonds of [η5:σ-Me2A(C9H6)(C2B10H10)]Zr(NMe2)2 (A = C, Si)

The compounds [η5:σ-Me2A(C9H6)(C2B10H10)]Zr(NMe2)2 (A = C, Si) reacted with CS2, PhCN, CH2CHCN, nBuNCS, and PhNCO to give the mono-, di-, and triinsertion products, depending upon the substrates. These unsaturated substances inserted exclusively into the Zr−N bonds, and the Zr−C(cage) bond remains intact in all reactions. It is believed that the preference of Zr−N over Zr−C(cage) insertion is governed by steric factors. The metal amide compounds also initiated the polymerization of CH2CHCN to produce poly(acrylonitrile) and catalyzed the trimerization of PhNCO. On the other hand, they reacted with methyl methacrylate to afford [{η5:σ-Me2A(C9H6)(C2B10H10)}Zr(OCH3)(μ-OCH3)]2 and CH2C(Me)CONMe2. All insertion products were fully characterized by various spectroscopic data, elemental analyses, and X-ray diffraction studies.

Theoretical Study of the Effects of Protonation and Deprotonation on Bond Dissociation Energies of Second-Row Elements: Comparison with First-Row Elements

Ab initio MO calculations indicate that protonation of XHn to XHn+1+ increases bond dissociation energies (BDEs) for homolytic cleavage of CX bonds in CH3XHn, CH3−CH2−XHn, CH2CH−XHn, and CH⋮C−XHn compounds (X = N, O, F, P, S, and Cl). Deprotonation of XHn to XHn-1- (X = C, N, O, Si, P, and S) in saturated species generally results in small decreases in CX BDEs; in unsaturated substances, as a result of resonance, deprotonation yields large increases in the CX BDEs, X = Si being the exception. For adjacent CC bonds, protonation of XHn increases the CC BDEs because it produces larger electronegativity differences between bonded groups; deprotonation decreases the BDEs as a result of resonance effects. Two types of correlation between bond lengths and homolytic BDEs are observed, with second-row elements exhibiting bond length changes to a much lesser extent than first-row ones. Firstly, bond lengths of adjacent CC bonds increase as their BDEs decrease. Secondly, and apparently anomalously, CX bond lengths and homolytic BDEs both increase with protonation of XHn, except with X = P. The increase in BDE together with the increase in bond length is, in part, a result of the focus on homolytic BDEs: heterolytic cleavage of most protonated, and many deprotonated, species is actually preferred, in which case bond lengths generally increase as bond strengths decrease in accordance with the normally accepted trend.

Dibenzoyl peroxide as an initiator of radical polymerizations: Reactions of the benzoyloxy radical with monomers

Experimental methods for comparing the reactivities of unsaturated substances towards the benzoyloxy radical are considered. Results for various monomers are discussed. It is shown that some substances show high reactivity towards the radical although they do not ordinarily give homopolymers or act as comonomers; they include β-methylstyrene, stilbene and related substances, and 1.4-diphenylbuta-1, 3-diene.

Gas chromatographic analysis of metabolites of trees damaged by exhalations

The composition of volatile organic compounds expired by the plant was investigated in dependence on the environment. Using two-step adsorption-concentration, hydrocarbons were preseparated from oxygen-containing compounds present in metabolites. In addition to gaseous samples water excreted by the plant was also analysed for the content of volatile organic compounds. Using gas chromatography differences were found in the content of unsaturated hydrocarbons, aldehydes and other substances in the metabolites of sick and healthy trees. The greatest differences in the composition of metabolites in dependence on the environment were found in Norway spruce (Picea excelsa), and the lowest for birch (Betula verrucosa).

Catalytic hydrogenation of binary and ternary mixtures of unsaturated substances in the liquid phase on platinum

Hydrogenation of olefinic substrates in binary and ternary mixtures using 5% Pt on silica gel as the catalyst was studied in normal conditions in the liquid phase with methanol or cyclohexane or in solvent-free systems. The effect of the solvent concentration on the selectivity of hydrogenation of the unsaturated alcohol-olefin binary mixtures was investigated. In ternary systems of unsaturated substrates, the effect of each of the substrates on the selectivity of hydrogenation of the remaining two substances was examined. Another system was found in which a jump change of the hydrogenation selectivity occurred on the vanishing of the fastest reacting substance.

Applications of Chromium (II) Salts in Preparative Organic Chemistry

The applications of chromium(II) salts to the reduction of alkyl halides, unsaturated systems, epoxides, acyloxyketones, and nitro compounds are reviewed. 1. Chromium(II) Reagents 2. Reduction of Alkyl Halides 3. Reduction of Unsaturated Substances 4. Reduction of Epoxides 5. Reduction of Acyloxyketones 6. Reduction of Nitro Compounds

Use of the sea urchin egg for quick screen testing of the biological activities of substances. I. Influence of fractions of a tobacco smoke condensate on early development.

Discussion and SummaryWe have tested the influence of cigarette-smoke condensates on the fertilized sea urchin egg. Our results show that neither nicotine nor benzo(a)pyrene adducted to ovalbumin showed any effect on early egg development when they were added after fertilization, even though the applied concentrations were many times higher than the substances which occurred in the tested fractions. The egg, however, is very sensitive to fractions containing unsaturated hydrocarbons and other substances. For further subfractionation of these fractions, the sea urchin egg offers a certain advantage, compared with the mammalian system, because it is not sensitive to nicotine or polycyclic hydrocarbons still present in these fractions. If the mammalian system is used, nicotine has to be removed in order to test the toxicity of other substances. Technically this problem cannot easily be solved.Examination of substances to determine their toxic effect on human beings is done mostly with mammals. For certain in...