Extrusion Reaction Research Articles

Synthesis of Regular Ladder-Type Fluorenylidene-Xanthene Oligomers via Nucleophilic Aromatic Substitution Reaction.

Fluorenylidene-xanthene and related polycyclic systems are typical examples of bistricyclic aromatic enes (BAEs); however, polycyclic systems of fluorenylidene-xanthene are relatively scarce. Here we synthesized a series of novel ladder-type polycyclic systems containing fluorenylidene-xanthene units, differing from the classic Barton's two-fold extrusion reaction. In the new synthetic scheme, the very popular Suzuki reaction was first used to couple the corresponding precursors, then a catalyst-free nucleophilic aromatic substitution reaction between Ar-F and Ar-OH groups in the backbone afforded ladder-type O-heteroarenes. Moreover, the new synthetic strategy is also suitable for the synthesis of other heterocyclic and polycyclic aromatic hydrocarbons. Some of these products showed reversible mechanochromism properties.

Fluorinated natural rubber with enhanced strength and excellent resistance to ozone, organic solvent, and acid and alkali via in situ reactive melt extrusion

Natural rubber (NR), as a green and renewable industrial raw material, is applied in many fields. However, the relatively weak resistance originated from its unsaturated backbone structure restricts the further application in some harsh conditions. To incorporate the excellent resistance feature of the fluorinated components into NR, fluorinated natural rubber (FNR) was prepared with dodecafluoroheptyl methacrylate (DFHMA) via in situ melt extrusion reaction. The results indicated that fluorinated reaction of NR mainly happened at the α-H of double bond in backbone chain and that styrene could promote fluorination and increase the size of fluorinated side chain. The vulcanized FNR (VFNR) exhibited wonderful mechanical performance, remarkable hydrophobicity, and excellent resistance to ozone, organic solvent, acid and alkali. The water contact angles of VFNR increased from 89 ° to 104 °and the ozone aging cracking time of VFNR increased by one time longer than that of VNR. The swelling degree of VFNR in the full synthetic engine oil is only two-thirds that of VNR, and the retention of tensile strength after immersion in HCl, H2SO4, and NaOH solution was elevated by 13 %, 11 %, and 5 % compared to those of VNR, respectively. This work presents a simple and eco-friendly method to prepare the fluorinated natural rubber facilitating the industrial fabrication of green and high-performance NR via melt extrusion.

Dearomative Intramolecular Diels-Alder/Sulfur Extrusion Reaction of Thiophenes with Alkynes Using peri-Substituted Naphthalene as a Tether.

Dearomative intramolecular Diels-Alder/sulfur extrusion reaction of thiophenes with alkynes successfully afforded fluoranthenes in moderate to excellent yields. The proximity of both reactive sites fixed at the peri-position of naphthalene would play an important role in the progress of this reaction. Tri(o-tolyl)phosphine effectively suppressed the side reactions as a sulfur scavenger.

Arene extrusion as an approach to reductive elimination at boron: implication of carbene-ligated haloborylene as a transient reactive intermediate.

Herein, we report boron-centered arene extrusion reactions to afford putative cyclic(alkyl)(amino) carbene (CAAC)-ligated chloroborylene and bromoborylene intermediates. The borylene precursors, chloro-boranorbornadiene (ClB(C6Me6), 2Cl) and bromo-boranorbornadiene (BrB(C6Me6), 2Br) were synthesized through the reaction of the corresponding 1-halo-2,3,4,5-tetramethylborole dimer (XBC4Me4)2 (X = Cl, 1Cl; X = Br, 1Br) with 2-butyne. Treatment of 2Cl with CAACs resulted in the release of di-coordinate chloro-borylene (CAAC)BCl from hexamethylbenzene (C6Me6) at room temperature. In contrast, the reaction of 2Br with CAAC led to the formation of a boronium species [(CAAC)BC6Me6]+Br- (7) at room temperature. Heating 7 in toluene promoted the release of di-coordinate bromo-borylene (CAAC)BBr as a transient species. Surprisingly, heating 7 in dichloromethane resulted in the C-H activation of hexamethylbenzene. The conversion of a CAAC-stabilized bromo-borepin to a borylene, a boron-centered retro Büchner reaction, was also investigated.

N‐Heterocyclic Carbene Mediated Sulfur Extrusion of Disulfides

AbstractThe sulfur extrusion from organic disulfides is a highly useful reaction recognised for the first time over 40 years ago. Unfortunately, it is mainly performed by aminophosphines, such as hexamethylphosphorus triamine, which is known to be very carcinogenic. This limits the application of the extrusion reaction especially for the synthesis of pharmaceutical products. We have developed a new method, using N‐heterocyclic carbenes (NHCs), generated from the corresponding stable imidazolium salts in combination with a base to transform a broad scope of benzylic disulfides to thioethers. In addition disulfide containing esters as well as cystine undergo this reaction.

Dinaphthooxepine Bisimide Undergoes Oxygen Extrusion Reaction upon Electron Injection at Room Temperature

We report the synthesis and properties of a dinaphthooxepine bisimide (DNOBI), a nonplanar perylene bisimide (PBI) analogue with an inserted oxygen atom. A DNOBI underwent an oxygen-extrusion reaction smoothly upon electron injection at room temperature, affording PBI in good yield. Studies on the reaction mechanism suggest that the injection of two electrons triggers the isomerization of DNOBI to dinaphthooxanorcaradiene bisimide, which is a key step in inducing the oxygen-extrusion reaction.

Chalcogen-doped, (seco)-hexabenzocoronene-based nanographenes: synthesis, properties, and chalcogen extrusion conversion.

A series of chalcogen-doped nanographenes (NGs) and their oxides are described. Their molecular design is conceptually based on the insertion of different chalcogens into the hexa-peri-hexabenzocoronene (HBC) backbone. All the NGs adopt nonplanar conformations, which would show better solubility compared to planar HBC. Except for the oxygen-doped, saddle-shaped NG, the insertion of large chalcogens like sulfur and selenium leads to a seco-HBC-based, helical geometry. All the three-dimensional structures are unambiguously confirmed by single-crystal X-ray diffractometry. Their photophysical properties including UV-vis absorption, fluorescence, chiroptical, charge distribution, and orbital gaps are investigated experimentally or theoretically. The properties of each structure are significantly affected by the doped chalcogen and its related oxidative state. Notably, upon heating or adding an acid, the selenium-doped NG or its oxide undergoes a selenium extrusion reaction to afford seco-HBC or HBC quantitatively, which can be treated as precursors of hydrocarbon HBCs.

Machine learning analysis of dynamic‐dependent bond formation in trajectories with consecutive transition states

AbstractDynamic motion often controls selectivity in reactions featuring two consecutive potential‐energy transition states. Here we report density functional theory (DFT)‐based direct dynamics trajectories and machine learning classification analysis for cyclopentadienone dimerization and a N2 extrusion reaction leading to semibullvalene. These reactions have consecutive transition states, and there is dynamic selectivity that determines which of two possible C‐C bonds is formed after the first transition state. For cyclopentadienone dimerization with a bispericyclic first transition state, machine learning analysis using transition‐state based features provided >90% trajectory classification accuracy, but only using AdaBoost and random forest algorithms. Many other relatively sophisticated machine learning algorithms showed poor accuracy despite the obvious motion responsible for selectivity. Feature importance analysis confirmed that the sigmatropic rearrangement vibrational motion in the bispericyclic transition state provides prediction of which of the second C‐C bonds is dynamically formed. For the reaction leading to semibullvalene, machine learning analysis provides solid accuracy for classifying trajectories and predicting which C‐C bond is formed and which C‐C bond is broken immediately after N2 ejection. Like the cyclopentadienone dimerization reaction, machine learning feature importance analysis showed that the sigmatropic rearrangement vibrational motion in the N2 extrusion transition state determines which C‐C bond is formed and which is broken. Surprisingly, machine learning struggles to predict which trajectories undergo a subsequent [3,3] sigmatropic rearrangement process, which isomerizes equivalent forms of semibullvalene.

Grafting of poly(lactic acid) by cyclodextrin extrusion reaction and its foaming properties

Grafting of poly(lactic acid) by cyclodextrin extrusion reaction and its foaming properties

Intersubunit and intrasubunit interactions driving the MukBEF ATPase

MukBEF, a structural maintenance of chromosome-like protein complex consisting of an ATPase, MukB, and two interacting subunits, MukE and MukF, functions as the bacterial condensin. It is likely that MukBEF compacts DNA via an ATP hydrolysis–dependent DNA loop–extrusion reaction similar to that demonstrated for the yeast structural maintenance of chromosome proteins condensin and cohesin. MukB also interacts with the ParC subunit of the cellular chromosomal decatenase topoisomerase IV, an interaction that is required for proper chromosome condensation and segregation in Escherichia coli, although it suppresses the MukB ATPase activity. Other structural determinants and interactions that regulate the ATPase activity of MukBEF are not clear. Here, we have investigated the MukBEF ATPase activity, identifying intersubunit and intrasubunit interactions by protein–protein crosslinking and site-specific mutagenesis. We show that interactions between the hinge of MukB and its neck region are essential for the ATPase activity, that the ParC subunit of topoisomerase IV inhibits the MukB ATPase by preventing this interaction, that MukE interaction with DNA is likely essential for viability, and that interactions between MukF and the MukB neck region are necessary for ATPase activity and viability.

Dinitrogen extrusion from diazene in organic synthesis

Radical-mediated reactions have many advantages in the construction of complex molecular scaffolds by forging chemical bonds of high challenge. Diazenes, including 1,1-diazenes and 1,2-diazenes, can generate biradical species via nitrogen extrusion under thermal or photochemical conditions. The superior reactivity of the generated biradical enables various types of synthetic transformations with excellent chemoselectivity and has been applied to the complex natural products synthesis. In this mini-review, the modes of reaction are summarized and discussed, namely ring contraction via nitrogen deletion, homo or hetero-dimerization, trimethylenemethane (TMM)-diyl cycloaddition. Applications of these classes of reactions in complex natural product synthesis are illustrated. Last but not least, the current state, future directions, and opportunities for dinitrogen extrusion reaction from diazenes are highlighted and discussed.

Production of process flavorings from methionine, thiamine with d-xylose or dextrose by direct extrusion: Physical properties and volatile profiles.

The conventional method to produce process flavoring is non-continuous, time consuming, and generates a high volume of effluent. This research aimed to evaluate the use of methionine, thiamine, and reducing sugars to develop process flavorings by direct extrusion, as a potential alternative to the conventional method. The mixed substrates consisted of methionine: d-xylose (MX), methionine: dextrose (MD), thiamine: d-xylose (TX), and thiamine: dextrose (TD) at 80:20 w/w. Three barrel temperatures of the extruder were controlled at 65, 80, and 50°C, respectively, a screw speed of 30rpm and feed rate at 3 kg/hr. Appearance, pH, odor, and taste description of the product from each mixture were determined. Volatile compounds, possibly occurred from the Maillard reaction during the extrusion were analyzed by gas chromatography-mass spectrometry. The products exhibited different levels of meaty odor and bitter taste. Those obtained from MD showed the highest L* (lightness, 85.37) and frequency for just-about-right in terms of taste (33.33%) and odor (60.00%). Products from MX and MD presented the highest frequency for intense taste, and higher frequency for color compared to TX and TD. More volatile compounds were detected from the use of methionine than from thiamine. The key meaty odor compounds such as dimethyl disulfide, dimethyl trisulfide, methional, and methanethiol were found in the samples from MX and MD, while only dimethyl disulfide was detected in the mixture of TX and TD. Finally, the results demonstrated that direct extrusion reaction from methionine and d-xylose or dextrose is a highly efficient method to produce meaty process flavorings. PRACTICAL APPLICATION: The manuscript describes the production of process flavorings that exhibited meaty flavors by extrusion process. Physical properties, volatile profiles, and sensory evaluation of the products from methionine, thiamine, d-xylose, and glucose were evaluated. The extruded products from methionine and dextrose exhibited acceptable color, taste, and odor and presented many volatiles compounds contributing to meaty flavors. The results revealed the high potential to use a direct extrusion process with very low effluent, compared to the conventional method, to produce meaty flavors for industrial application.

Molybdenum disulfide (MoS2): A novel activator of peracetic acid for the degradation of sulfonamide antibiotics

Sulfonamide antibiotics (SAs) are typical antibiotics and have attracted increasing concerns about their wide occurrence in environment as well as potential risk for human health. In this study, we applied a novel advanced oxidation process in SAs degradation by combining molybdenum sulfide and peracetic acid (MoS2/PAA). Reactive oxygen species (ROS) including HO●, CH3C(O)O●, CH3C(O)OO●, and 1O2 were generated from PAA by MoS2 activation and contributed to SAs degradation. The effects of initial pH, the dosages of PAA and MoS2, and humic acid for SAs degradation were further evaluated by selecting sulfamethoxazole (SMX) as a target SA in the MoS2/PAA process. Results suggested that the optimum pH for SMX removal was 3, where the degradation efficiency of SMX was higher than 80% after reaction for 15 min. Increasing PAA (0.075–0.45 mM) or MoS2 (0.1–0.4 g/L) dosages facilitated the SMX degradation, while the presence of humic acids retarded the SMX removal. This MoS2/PAA process also showed good efficiencies in removing other SAs including sulfaguanidine, sulfamonomethoxine and sulfamerazine. Their possible degradation pathways were proposed based on the products identification and DFT calculation, showing that apart from the oxidation of amine groups to nitro groups in SAs, MoS2/PAA induced SO2 extrusion reaction for SAs that contained six-membered heterocyclic moieties.

Using twin screw extrusion reaction (TSER) to produce thermoplastic polyurethane (TPU): Tunable, stoichiometric and eco‐friendly

TPU and flame‐retardant TPU (FR‐TPU) were prepared through a polyaddition reaction with polytetramethylene ether glycol (PTMEG) and 4,4′‐methylene‐bisphenyl‐isocyanate (MDI) by reactive extruding. 1,4‐Butanediol (BDO) and diethyl bis(2‐hydroxyethyl) amino methyl phosphonate (DBAMP) were used as the chain extender in different ratios, respectively, to obtain TPU and flame‐retardant TPU (FR‐TPU)with adjusted molecular weight and mechanical properties. The resulting TPU and FR‐TPU were characterized by FTIR, DSC, TGA, and NMR. A kinetic model based on the data from extrusion process was used to depict the polymerization of TPU. These reactions carried out without any solvent and the residual water showed that the polymerization with BDO could be achieved in 20 minutes, instead, that with DBAMP in 55 minutes while with a similar molecular weight. These results point out that Twin Screw Extrusion Reaction (TSER) is a suitable and convenient way to produce a variety of polymers.

PdII insertion-triggered meso-carbon extrusion of N-fused pentaphyrin to form N-fused sapphyrin PdII complexes.

meso-Carbon extrusion of N-fused [22]pentaphyrin(1.1.1.1.1) occurred upon its PdII complexation, giving N-fused [22]pentaphyrin (1.1.1.1.0) ([22]sapphyrin) PdII complexes 5 and 6 as 22π aromatic compounds. Oxidation of 5 with DDQ and Sc(OTf)3 gave directly C-N linked dimer 7.

Dinaphthothiepine Bisimide and Its Sulfoxide: Soluble Precursors for Perylene Bisimide.

The synthesis and properties of dinaphtho[1,8-bc:1',8'-ef]thiepine bisimide (DNTBI) and its oxides are described. Their molecular design is conceptually based on the insertion of a sulfur atom into the perylene bisimide (PBI) core. These sulfur-inserted PBI derivatives adopt nonplanar structures, which significantly increases their solubility in common organic solvents. Upon electron injection, light irradiation, or heating, DNTBI and its sulfoxides undergo sulfur extrusion reactions to furnish PBI. The photoinduced and thermal sulfur extrusion reactions proceed almost quantitatively. This unique reactivity enabled the fabrication of a high-performance solution-processed n-type organic field-effect transistor with an electron mobility of up to 0.41 cm2 V-1 s-1.

Preparation and Properties of Nylon 6,6 Grafted Graphene Composites.

Nylon 6,6 composite fiber containing grafted graphene (nylon 6,6-g-graphene) was prepared by nylon and graphene grafted with acyl chloride (graphene-COCl) through extrusion reaction. Graphene-COCl was prepared through acid-treated reacting, graphene with thionyl chloride functional group. The chemical structure of nylon 6,6-g-graphene obtained using reactive extrusion technique was characterized using Fourier transform infrared spectrometer. It was found that this kind of composite fiber has the characteristics of less amount of graphene and excellent mechanical properties and has certain application prospects. Nylon 6,6-g-graphene dispersed evenly in the Nylon composite. But pristine graphene exhibited aggregate structure when composite was produced by pristine graphene through reactive extrusion. The composite reinforcement was increased obviously with the increase content of grafted graphene. After examined, the nylon/nylon 6,6-g-graphene with a certain content grafted graphene composite exhibited high level of reinforcement, and mechanical properties were improved.

Synthesis of fully substituted pyrazoles from pyridinium 1,4-zwitterionic thiolates and hydrazonoyl chlorides via a [[3 + 3] - 1] pathway.

A novel and practical protocol for the synthesis of fully substituted pyrazoles from pyridinium 1,4-zwitterionic thiolates and hydrazonoyl chlorides in excellent yields under mild conditions is described. The transformation proceeds via an unusual [[3 + 3] - 1] pathway, which involves a formal [3 + 3] cascade cyclization followed by a spontaneous ring-contraction/sulfur extrusion reaction from 4H-1,3,4-thiadiazine intermediates.

Reactive extrusion mechanism, mechanical and tribological behavior of fiber reinforced polyamide 66 with added carbodiimide

In this study, the reactive extrusion mechanism of fiber-reinforced polyamide 66 materials with added carbodiimide was clarified, and the mechanical and tribological properties of the materials were evaluated. Increasing the molecular weight of resin is one of the methods that has been proposed to improve the wear resistance and toughness of fiber-reinforced materials. This study proposes a reactive extrusion method using poly-carbodiimide compounds. The effects of the feeding position of the poly-carbodiimide compounds in the twin screw extruder, type of carbodiimide compounds, and proportion of carbodiimide compounds on the extrusion reaction and static mechanical properties were elucidated. The toughness of the glass fiber-reinforced polyamide 66 was improved by the increase in molecular weight of the polyamide 66 related to the addition of the carbodiimide compounds. The wear resistance properties were significantly improved by the addition of carbodiimide compounds for both glass fiber-reinforced polyamide 66 and aramid fiber-reinforced polyamide 66 materials. In addition, a synergistic improvement in the toughness was also observed with the addition of both carbodiimide compounds and a maleic anhydride modified olefin polymer to the glass fiber-reinforced polyamide 66 material. The results of this study will be beneficial for improving the mechanical and tribological properties of extruded resins.

Switchable Ring-Contractive Extrusion Reactions of 2,5-Dihydro-1,4,5-thiadiazepine S-Oxides: Entries to Pyridazines or Pyrazoles

Switchable ring-contractive extrusion reactions of 2,5-dihydro-1,4,5-thiadiazepine S-oxides are described, which allow expedient access to pyridazines under thermal conditions or pyrazoles under Lewis acid-mediated conditions.