Rearrangement Of Double Bond Research Articles

Selective catalytic conversion of model olefin and diolefin compounds of waste plastic pyrolysis oil: Insights for light olefin production and coke minimization

The primary challenges in ex-situ catalytic pyrolysis of plastic waste to produce light olefins lie in the selective conversion of larger olefins and diolefins downstream of the pyrolyzer. Hence, the catalytic cracking mechanism of plastic pyrolysis oil was explored using an α-olefin (1-decene) and a diolefin (1,9-decadiene) model compounds over an HZSM-5 zeolite-based catalyst in a fixed-bed reactor. Key objectives were to elucidate the reaction pathways for light olefin production, aromatization, and coke formation in catalytic cracking of larger olefins and diolefins. The investigation explored the impact of HZSM-5 steam treatment severity, contact time (∼58–226 ms), and reaction temperature (250–450 °C) on product yields. The severity of steam treatment was found to increase the 1-decene isomerization rate while decreasing the cracking rate and conversion of 1-decene to C3-4 light olefins. In the catalytic cracking of 1-decene, major product types included olefins (linear and nonlinear) and a few naphthenes, while in the case of 1,9-decadiene catalytic cracking, non-linear olefins were absent, with abundant naphthenes followed by lighter diolefins and C3-5 linear olefins. Temperature and contact time variations revealed that the catalytic cracking of 1-decene initiated with double bond rearrangement isomerization, progressing to skeletal isomerization, and intensified cracking reactions producing light C3-4 olefins. Conversely, in the catalytic cracking of 1,9-decadiene, cyclization was the primary reaction pathway, followed by β-scission, resulting in lighter conjugated dienes and light linear olefins. Thermal gravimetric analysis (TGA) of spent catalysts confirmed a higher coke amount generated during 1,9-decadiene cracking compared to 1-decene cracking, indicating that diene compounds serve as precursors for significant coke formation in plastic pyrolysis oil. These insights provide valuable understanding for catalytic upgrading of pyrolysis oil from polyolefin pyrolysis.

Boron-Catalyzed C1 Copolymerization of Arsonium and Sulfoxonium Ylides toward Unrepresented Structures and Fluorescence Properties.

The first synthesis of well-defined poly(methylene-co-1,1-diphenylpropenenylene) (C1-co-C1'), equivalent to poly(ethylene-co-diphenylbutadiene) copolymers was accomplished by C1 copolymerization of novel diphenylpropenyl triphenyl arsonium ylides (Ph2AY) and dimethylsulfoxonium methylide (Me2SY) using B-thexylborepane as initiator. All polymerization conditions, including feed ratio, temperature, and reaction time, were optimized. A series of photoluminescent poly(ethylene-co-diphenylbutadiene)s were synthesized at different feed ratios, opening a new synthetic horizon for poly(ethylene-co-disubstitutedbutadiene) copolymers. Notably, a new C1 segment, arising from a double bond rearrangement, was confirmed by NMR, resulting in an unprecedented two-monomer three-structure random terpolymer. An unexpected red-shift phenomenon in the fluorescence spectra was observed with increasing the ratio of Ph2AY in the copolymer. This shift is attributed to the aggregation of diphenylbutadiene segment, similar to through-space conjugation (TSC), likely induced by a decrease in the crystallinity of copolymers. Furthermore, another disubstituted allylic triphenyl arsonium ylides, (E)-2-phenylbutenyl triphenyl arsonium ylide (MePhAY) was also synthesized and investigated. These additional compounds expand the knowledge and the potential applications of such copolymerization techniques in advanced materials.

Boron‐Catalyzed C1 Copolymerization of Arsonium and Sulfoxonium Ylides toward Unrepresented Structures and Fluorescence Properties

AbstractThe first synthesis of well‐defined poly(methylene‐co‐1,1‐diphenylpropenenylene) (C1‐co‐C1’), equivalent to poly(ethylene‐co‐diphenylbutadiene) copolymers was accomplished by C1 copolymerization of novel diphenylpropenyl triphenyl arsonium ylides (Ph2AY) and dimethylsulfoxonium methylide (Me2SY) using B‐thexylborepane as initiator. All polymerization conditions, including feed ratio, temperature, and reaction time, were optimized. A series of photoluminescent poly(ethylene‐co‐diphenylbutadiene)s were synthesized at different feed ratios, opening a new synthetic horizon for poly(ethylene‐co‐disubstitutedbutadiene) copolymers. Notably, a new C1 segment, arising from a double bond rearrangement, was confirmed by NMR, resulting in an unprecedented two‐monomer three‐structure random terpolymer. An unexpected red‐shift phenomenon in the fluorescence spectra was observed with increasing the ratio of Ph2AY in the copolymer. This shift is attributed to the aggregation of diphenylbutadiene segment, similar to through‐space conjugation (TSC), likely induced by a decrease in the crystallinity of copolymers. Furthermore, another disubstituted allylic triphenyl arsonium ylides, (E)‐2‐phenylbutenyl triphenyl arsonium ylide (MePhAY) was also synthesized and investigated. These additional compounds expand the knowledge and the potential applications of such copolymerization techniques in advanced materials.

Rare Caulamidine Hexacyclic Alkaloids from the Marine Ascidian Polyandrocarpa sp.

Two new caulamidines C (2) and D (4) and three isocaulamidines B, C, and D (1, 3, and 5) along with the known compound caulamidine B (6) were isolated from the marine ascidian Polyandrocarpa sp. Their structures were elucidated by analysis of nuclear magnetic resonance (NMR) and electronic circular dichroism (ECD) data. Isocaulamidines have an altered pattern of N-methyl substitution (N-15 vs N-13 in the caulamidines) with a concomitant double-bond rearrangement to provide a new C-14/N-13 imine functionality. Caulamidine C (2) and isocaulamidine C (3) are the first members of this alkaloid family with two chlorine substituents in the core 6H-2,6-naphthyridine ring system.

Optical Fiber Grating-Prism Fabrication by Imprint Patterning of Ionic-Liquid-Based Resist.

We present a method of microstructure fabrication on the tip of the optical fiber using a UV soft-imprint process of polymerizable ionic liquid-based optical resist. Ionic liquid with two UV-sensitive vinylbenzyl groups in the structure was diluted in non-hazardous propylene glycol (PG) to obtain liquid material for imprinting. No additional organic solvent was required. The impact of propylene glycol amount and exposure dose on optical and mechanical properties was investigated. The final procedure of the UV imprint on the optical fiber tip was developed, including the mold preparation, setup building, UV exposure and post-laser cure. As the IL-containing vinylbenzyl groups can also be polymerized by the radical rearrangement of double bonds through thermal heating, the influence of the addition of 1-2% BHT polymerization inhibitor was verified. As a result, we present the fabricated diffraction gratings and the optical fiber spectrometer component-grism (grating-prism), which allows obtaining a dispersion spectrum at the output of an optical in line with the optical fiber long axis, as the main component in an optical fiber spectrometer. The process is very simple due to the fact that its optimization already starts in the process of molecule design, which is part of the trend of sustainable technologies. The final material can be designed by the tailoring of the anion and/or cation molecule, which in turn can lead to a more efficient fabrication procedure and additional functionalities of the final structure.

An integrated five-step continuous flow synthesis of 2-(1-cyclohexenyl)ethylamine: a key intermediate for morphinans

A continuous flow synthesis of 2-(1-cyclohexenyl)ethylamine started from cyclohexanone was developed through telescoping Grignard reaction and chlorination, telescoping amination and double bond rearrangement, and hydrazinolysis.

Assessment of Ex Vivo Antioxidative Potential of Murine HDL in Atherosclerosis.

This chapter provides details on a simple and reproducible method used to determine the capacity of murine HDL to prevent the oxidation of LDL . The principle of the method is based on the rearrangement of double bonds of polyunsaturated fatty acids that occurs during the oxidation of human LDL , which generates a sigmoidal curve. The shape and length of the curve is modified in the presence of HDL , and such modifications are easily quantifiable by measuring the absorbance of conjugated dienes at 234nm. The general technique described herein may be applied to evaluate the effect of HDL obtained from different experimental murine models of atherosclerosis.

Lipid peroxidation and oxidative modification of proteins in tick-borne encephalitis and ixodic tick-borne borreliosis

BACKGROUND: In the South Ural region of Russia, the group of ITTB and TBE occupies the leading rank positions in the structure of infections that are ecologically associated with ixodic ticks. At the present stage, studies aimed at studying non-specific pathological biochemical processes that determine the degree of oxidative damage to cell membranes and organelle membranes, the reactivity of the body, its reserve-adaptive potential under the influence of a number of endogenous and exogenous factors are becoming particularly relevant. One of the most significant metabolic processes of this kind is the free radical oxidation of lipids and the oxidative modification of proteins.
 AIMS: To give a clinical and epidemiological characteristic and to study the role of oxidative stress in the pathogenesis of various clinical forms of tick-borne infections in an endemic region (on the example of the Chelyabinsk region).
 MATERIAL AND METHODS: The study was conducted at the clinical base of the Department of Infectious Diseases of the Southern State Medical University in the MAUZ GKB No. 8 in Chelyabinsk. The study randomly included 105 patients with tick-borne encephalitis, ixodic tick-borne borreliosis and mixed infection who were hospitalized in the hospital in the period from May to October 20182019. The diagnosis was verified by standard immunological methods (ELISA). Modern molecular genetic methods (PCR-RV) were used in the etiological diagnosis of ICD. Material for the study: leukocyte fraction and blood serum. The content of carbonyl products of oxidative modification of proteins was estimated by their reaction with 2.4-dinitrophenylhydrazine, followed by spectrophotometric registration of the interaction products-dinitrophenylhydrazones. When determining the content of primary and secondary products of lipid peroxidation, a method based on the phenomenon of rearrangement of double bonds into diene conjugates during the peroxidation of polyunsaturated fatty acids was used. Statistical processing of the obtained results was carried out by standard methods of nonparametric statistics using the Statistica 8.0 for Windows software package.
 RESULTS: In the structure of infections transmitted by ixodic ticks, ixodic tick-borne borreliosis was most often registered (50.5%), tick-borne encephalitis was observed in 44.8% of cases, mixed infection ― in 4.7%. Borrelia miyamotoi DNA was detected by PCR-RV in 8.6% of biological samples (blood serum, leukocyte fraction). When analyzing the results of oxidative modification of proteins and lipid peroxidation, a reliable picture of oxidative stress is observed, which is more pronounced in patients with ixodic tick-borne borreliosis.
 CONCLUSION: The revealed changes in the study of oxidative stress in patients with tick-borne encephalitis and ixodic tick-borne borreliosis not only indicate the prospects of developing new approaches to the pathogenetic therapy of tick-borne infections, providing for the use of antioxidants in complex therapy, but also suggest a greater effectiveness of direct-acting lipophilic antioxidants that limit diene conjugation, and thereby prevent the accumulation of secondary cytotoxic products of lipid peroxidation.

Derivatization of Soyasapogenol A through Microbial Transformation for Potential Anti-inflammatory Food Supplements.

For the optimum use of soyasaponins isolated from soybean cake and to explore the potential anti-inflammatory agents from pentacyclic triterpenes as natural food supplements, microbial transformation of soyasapogenol A was carried out. Four strains of microbes, including Bacillus megaterium CGMCC 1.1741, Penicillium griseofulvum CICC 40293, Bacillus subtilis ATCC 6633, and Streptomyces griseus ATCC 13273, showed robust catalytic capacity to the substrate. Preparative biotransformation and column chromatographic purification led to the isolation of 10 novel and 1 reported metabolites. The structure elucidation was performed using 1D/2D NMR and HR-ESI-MS analytical method. Several novel tailoring reactions, such as allyl oxidation, C-C double bond rearrangement, hydroxylation, dehydrogenation, and glycosylation, were observed in the biotransformation. In the follow-up bioassay, most of the metabolites exhibited low cytotoxicity and potent inhibitory activity against the production of nitric oxide (NO) in RAW 264.7 cells stimulated by lipopolysaccharide. Especially compound 6 (3-oxo-11α,21β,22β,24-tetrahydroxy-olean-12-ene) showed comparable activity to the positive control of quercetin with an IC50 value of 16.70 μM. These findings provided an experimental approach to achieve the derivatization of natural aglycons in soybeans through microbial transformation for developing potent anti-inflammatory food supplements.

Spirocyclizative Remote Arylcarboxylation of Nonactivated Arenes with CO 2 via Visible-Light-Induced Reductive Dearomatization

Spirocyclizative Remote Arylcarboxylation of Nonactivated Arenes with CO ₂ via Visible-Light-Induced Reductive Dearomatization

Preparation of 2-phospholene oxides by the isomerization of 3-phospholene oxides.

A series of 1-substituted-3-methyl-2-phospholene oxides was prepared from the corresponding 3-phospholene oxides by double bond rearrangement. The 2-phospholene oxides could be obtained by heating the 3-phospholene oxides in methanesulfonic acid, or via the formation of cyclic chlorophosphonium salts. Whereas mixtures of the 2- and 3-phospholene oxides formed, when the isomerization of 3-phospholene oxides was attempted under thermal conditions, or in the presence of a base. The mechanisms of the various double bond migration pathways were elucidated by quantum chemical calculations.

Evolution in the formation of graphene nanocapsules from coal tar pitch

It has recently been reported that coal tar pitch (CTP) can be utilised as raw material for the production of graphene nanocapsules (GNCs) because it is formed by a great quantity of aromatic organic compounds (which promote the rearrangement of double bonds by a process of polymerisation). Due to the importance of graphene and the search for a non-expensive methodology to produce it, this work used CTP to synthesise GNCs using an in situ activation technique at low temperatures and evaluating the effect of the working temperature on the formation of such nanostructures. In other words, analysing the form of the particle as the temperature rises from 600 to 900 °C. As result of the experimentation, powders were obtained and analysed by the techniques of X-Ray Diffraction, Raman Spectroscopy and Microscopy, employing Field Emission Scanning Electron Microscopy by normal mode as well as by Scanning Transmission Electron Microscopy and a High-Resolution Scanning Electron Microscopy. The results show that working with temperatures between 800 and 850 °C promotes the production of GNCs, considering that their size reduces as the working temperature rises.

Synthesis of Bis-Cycloborate Olefin and Butatriene Derivatives through the Reduction of Alkynyl-Bridged Diboryl Compounds.

A series of bis-cycloborate olefin and butatriene derivatives were synthesized from alkynyl-bridged diboryl compounds using a simple reduction strategy. In the reduction route of 1,2-bis[2-(dimesitylboranyl)phenyl]ethyne (1), bis-cycloborate olefin (4) to diborate-bridged stilbene (5) can be obtained selectively by varying the reaction temperature. In addition, a thermal isomerization from 4 to 5 was found as a result of the rearrangement of double bonds. The generality of this reaction was further verified in similar reduction reactions. In the direduction of 1,2-bis[8-(dimesitylboranyl)naphthalen-1-yl]ethyne (2), the bis-cycloborate olefin (6) was isolated in high yield and demonstrated no thermal isomerization. In the two-electron reduction of 1,8-bis{[2-(dimesitylboranyl)phenyl]ethynyl}naphthalene (3), the bis-cycloborate butatriene (7) was obtained unexpectedly because of the departure of the naphthyl group. When using Na as the reductant and diethyl ether as the solvent, 1,2-bis[( Z)-2-(dimesitylboranyl)benzylidene]-1,2-dihydroacenaphthylene (8) was isolated after adding 1 or 2 drops of H2O to the reduction reaction filtrates. Meanwhile, the related mechanisms for radical cyclization, thermal isomerization, and formation of bis-cycloborate butatriene were also discussed.

Synthesis of Dihydrooxepino[3,2-c]Pyrazoles via Claisen Rearrangement and Ring-Closing Metathesis from 4-Allyloxy-1H-pyrazoles.

Synthesis of novel pyrazole-fused heterocycles, i.e., dihydro-1H- or 2H-oxepino[3,2-c]pyrazoles (6 or 7) from 4-allyloxy-1H-pyrazoles (1) via combination of Claisen rearrangement and ring-closing metathesis (RCM) has been achieved. A suitable catalyst for the RCM of 5-allyl-4-allyloxy-1H-pyrazoles (4) was proved to be the Grubbs second generation catalyst (Grubbs2nd) to give the predicted RCM product at room temperature in three hours. The same reactions of the regioisomer, 3-allyl-4-allyloxy-1H-pyrazoles (5), also proceeded to give the corresponding RCM products. On the other hand, microwave aided RCM at 140 °C on both of 4 and 5 afforded mixtures of isomeric products with double bond rearrangement from normal RCM products in spite of remarkable reduction of the reaction time to 10 min.

Biotransformation of 20(S)-protopanaxatriol by Mucor racemosus and the anti-cancer activities of some products.

To produce new derivatives of 20(S)-protopanaxatriol by fungal biotransformation. Biotransformation of 20(S)-protopanaxatriol (1) by Mucor racemosus AS 3.205 afforded six products. Their structures were elucidated on the basis of extensive spectroscopic analyses. M. racemosus could selectively catalyze dehydrogenation at C-12 and further hydroxylation at C-7, C-11, and C-15, as well as rearrangement of double bond at C-26. Two of these new compounds exhibited potent inhibitory activity against SH-SY5Y and HepG2 cell lines. Biotransformation by M. racemosus AS 3.205 was an effective approach to produce new derivatives of 20(S)-protopanaxatriol.

RNAi construct of a cytochrome P450 gene CYP82D109 blocks an early step in the biosynthesis of hemigossypolone and gossypol in transgenic cotton plants

Naturally occurring terpenoid aldehydes from cotton, such as hemigossypol, gossypol, hemigossypolone, and the heliocides, are important components of disease and herbivory resistance in cotton. These terpenoids are predominantly found in the glands. Differential screening identified a cytochrome P450 cDNA clone (CYP82D109) from a Gossypium hirsutum cultivar that hybridized to mRNA from glanded cotton but not glandless cotton. Both the D genome cotton Gossypium raimondii and A genome cotton Gossypium arboreum possessed three additional paralogs of the gene. G. hirsutum was transformed with a RNAi construct specific to this gene family and eight transgenic plants were generated stemming from at least five independent transformation events. HPLC analysis showed that RNAi plants, when compared to wild-type Coker 312 (WT) plants, had a 90% reduction in hemigossypolone and heliocides levels, and a 70% reduction in gossypol levels in the terminal leaves, respectively. Analysis of volatile terpenes by GC–MS established presence of an additional terpene (MW: 218) from the RNAi leaf extracts. The 1H and 13C NMR spectroscopic analyses showed this compound was δ-cadinen-2-one. Double bond rearrangement of this compound gives 7-hydroxycalamenene, a lacinilene C pathway intermediate. δ-Cadinen-2-one could be derived from δ-cadinene via a yet to be identified intermediate, δ-cadinen-2-ol. The RNAi construct of CYP82D109 blocks the synthesis of desoxyhemigossypol and increases the induction of lacinilene C pathway, showing that these pathways are interconnected. Lacinilene C precursors are not constitutively expressed in cotton leaves, and blocking the gossypol pathway by the RNAi construct resulted in a greater induction of the lacinilene C pathway compounds when challenged by pathogens.

Taming the beast: fluoromesityl groups induce a dramatic stability enhancement in boroles.

The electron-deficient pentaarylborole 1-(2',4',6'-tris(trifluoromethyl)phenyl)-2,3,4,5-tetraphenylborole (1) has been synthesised with the long-term aim of developing borole-based optoelectronic materials. The bulky 2,4,6-tris(trifluoromethyl)phenyl (FMes) group on the boron atom of 1 significantly improves (>600 times) its air stability relative to its mesityl analogue. Moreover, 1 shows good thermal stability without undergoing the dimerisation or isomerisation reactions reported for some other boroles. A triarylborole analogue (2), belonging to a new class of borole with the 3- and 4-positions of the BC4 ring linked by a -(CH2)3- group, has also been synthesised to elucidate the influence of carbon-bonded substituents on the stability of boroles. Both boroles were prepared through the reaction of Li[FMesBF3] and divinyldilithium reagents, a new and general method for borole syntheses. Compound 2 was found to isomerise through a [1,3]-H shift and double-bond rearrangement to an s-trans-butadienylborane species under highly basic (NaOH) conditions. The increased steric crowding at the boron centre through incorporation of the FMes group does not preclude binding of Lewis bases to either 1 or 2, as demonstrated by their fully reversible binding of pyridine. Interestingly, 1 exhibits a blue-shifted absorption spectrum, as compared with its mesityl analogue, a result contrary to previous understanding of the influence of substituent electronics on the absorption spectra of boroles. Most importantly, these boroles exhibit much greater air-stability than previously reported analogues without sacrificing the strong electron-accepting ability that makes boroles so attractive; indeed, 1 and 2 have very low reduction potentials of -1.52 and -1.69 eV vs. Fc/Fc+, respectively.

Total Synthesis of Rugulovasine A

A concise total synthesis of rugulovasine A is achieved by using Uhle's ketone derivative as the key intermediate, which was synthesized by intramolecular cyclization via metal-halogen exchange. Two different routes to construct a spirocyclic butyrolactone subunit involving a Ru-catalyzed cyclocarbonylation and a special Ru-catalyzed double bond rearrangement were studied.

Cloning and Characterization of an Armillaria gallica cDNA Encoding Protoilludene Synthase, Which Catalyzes the First Committed Step in the Synthesis of Antimicrobial Melleolides

Melleolides and related fungal sesquiterpenoid aryl esters are antimicrobial and cytotoxic natural products derived from cultures of the Homobasidiomycetes genus Armillaria. The initial step in the biosynthesis of all melleolides involves cyclization of the universal sesquiterpene precursor farnesyl diphosphate to produce protoilludene, a reaction catalyzed by protoilludene synthase. We achieved the partial purification of protoilludene synthase from a mycelial culture of Armillaria gallica and found that 6-protoilludene was its exclusive reaction product. Therefore, a further isomerization reaction is necessary to convert the 6–7 double bond into the 7–8 double bond found in melleolides. We expressed an A. gallica protoilludene synthase cDNA in Escherichia coli, and this also led to the exclusive production of 6-protoilludene. Sequence comparison of the isolated sesquiterpene synthase revealed a distant relationship to other fungal terpene synthases. The isolation of the genomic sequence identified the 6-protoilludene synthase to be present as a single copy gene in the genome of A. gallica, possessing an open reading frame interrupted with eight introns.

Efficient Acylation and One-Pot Synthesis of Dehydroandrographolide Succinate on a Large Scale Assisted with Microwave Radiation

A rapid and convenient method for acylation and large-scale synthesis of dehydroandrographolide succinate has been developed under microwave irradiation. It is a one-pot condensation and is compatible with dehydration and rearrangement of double bond in mild reaction conditions with good yield, high purity (up to 99.8%), time-savings, few pollutants and low cost. In addition, a number of acylation derivatives were synthesized under microwave irradiation.