scholarly journals Biobased Aldehydes from Fatty Epoxides Through Thermal Cleavage of β-Hydroxy Hydroperoxides

2020 ◽  
Author(s):  
Thomas De Dios Miguel ◽  
Nam Duc Vu ◽  
Marc Lemaire ◽  
Nicolas Duguet
Keyword(s):  
Methyl Oleate ◽  
Ring Opening ◽  
Tungstic Acid ◽  
Flow Conditions ◽  
Large Excess ◽  
Molybdenum Catalysts ◽  
Thermal Cleavage ◽  
Optimized Conditions ◽  
C Nmr

The ring-opening of epoxidized methyl oleate by aqueous H<sub>2</sub>O<sub>2</sub> has been studied using tungsten and molybdenum catalysts to form the corresponding fatty b-hydroxy hydroperoxides. It was found that tungstic acid and phosphostungstic acid gave the highest selectivities (92-93%) towards the formation of the desired products, thus limiting the formation of the corresponding fatty 1,2-diols. The optimized conditions were applied to a range of fatty epoxides to give the corresponding fatty b-hydroxy hydroperoxides with 30-80% isolated yields (8 examples). These species were fully characterized by <sup>1</sup>H and <sup>13</sup>C NMR, HPLC-HRMS and their stability was studied by DSC. The thermal cleavage of the b-hydroxy hydroperoxide derived from methyl oleate was studied both in batch and flow conditions. It was found that the thermal cleavage in flow conditions gave the highest selectivity towards the formation of aldehydes with limited amounts of byproducts. The aldehydes were both formed with 68% GC yield and nonanal and methyl 9-oxononanoate were isolated with 57 and 55% yield, respectively. Advantageously, the overall process does not require large excess of H<sub>2</sub>O<sub>2</sub> and only generates water as a byproduct.

scholarly journals Biobased Aldehydes from Fatty Epoxides Through Thermal Cleavage of β-Hydroxy Hydroperoxides

2020 ◽  
Author(s):  
Thomas De Dios Miguel ◽  
Nam Duc Vu ◽  
Marc Lemaire ◽  
Nicolas Duguet
Keyword(s):  
Methyl Oleate ◽  
Ring Opening ◽  
Tungstic Acid ◽  
Flow Conditions ◽  
Large Excess ◽  
Molybdenum Catalysts ◽  
Thermal Cleavage ◽  
Optimized Conditions ◽  
C Nmr

The ring-opening of epoxidized methyl oleate by aqueous H<sub>2</sub>O<sub>2</sub> has been studied using tungsten and molybdenum catalysts to form the corresponding fatty b-hydroxy hydroperoxides. It was found that tungstic acid and phosphostungstic acid gave the highest selectivities (92-93%) towards the formation of the desired products, thus limiting the formation of the corresponding fatty 1,2-diols. The optimized conditions were applied to a range of fatty epoxides to give the corresponding fatty b-hydroxy hydroperoxides with 30-80% isolated yields (8 examples). These species were fully characterized by <sup>1</sup>H and <sup>13</sup>C NMR, HPLC-HRMS and their stability was studied by DSC. The thermal cleavage of the b-hydroxy hydroperoxide derived from methyl oleate was studied both in batch and flow conditions. It was found that the thermal cleavage in flow conditions gave the highest selectivity towards the formation of aldehydes with limited amounts of byproducts. The aldehydes were both formed with 68% GC yield and nonanal and methyl 9-oxononanoate were isolated with 57 and 55% yield, respectively. Advantageously, the overall process does not require large excess of H<sub>2</sub>O<sub>2</sub> and only generates water as a byproduct.

scholarly journals Biobased Aldehydes from Fatty Epoxides Through Thermal Cleavage of β-Hydroxy Hydroperoxides

2020 ◽  
Author(s):  
Thomas De Dios Miguel ◽  
Nam Duc Vu ◽  
Marc Lemaire ◽  
Nicolas Duguet
Keyword(s):  
Methyl Oleate ◽  
Ring Opening ◽  
Tungstic Acid ◽  
Flow Conditions ◽  
Large Excess ◽  
Molybdenum Catalysts ◽  
Thermal Cleavage ◽  
Optimized Conditions ◽  
C Nmr

The ring-opening of epoxidized methyl oleate by aqueous H<sub>2</sub>O<sub>2</sub> has been studied using tungsten and molybdenum catalysts to form the corresponding fatty b-hydroxy hydroperoxides. It was found that tungstic acid and phosphostungstic acid gave the highest selectivities (92-93%) towards the formation of the desired products, thus limiting the formation of the corresponding fatty 1,2-diols. The optimized conditions were applied to a range of fatty epoxides to give the corresponding fatty b-hydroxy hydroperoxides with 30-80% isolated yields (8 examples). These species were fully characterized by <sup>1</sup>H and <sup>13</sup>C NMR, HPLC-HRMS and their stability was studied by DSC. The thermal cleavage of the b-hydroxy hydroperoxide derived from methyl oleate was studied both in batch and flow conditions. It was found that the thermal cleavage in flow conditions gave the highest selectivity towards the formation of aldehydes with limited amounts of byproducts. The aldehydes were both formed with 68% GC yield and nonanal and methyl 9-oxononanoate were isolated with 57 and 55% yield, respectively. Advantageously, the overall process does not require large excess of H<sub>2</sub>O<sub>2</sub> and only generates water as a byproduct.

The rhodium(II)-catalyzed aziridination of olefins with {[(4-nitrophenyl)sulfonyl]imino}phenyl-lambda3-iodane

1998 ◽  
Vol 76 (6) ◽  
pp. 738-750 ◽  
Author(s):  
Paul Müller ◽  
Corine Baud ◽  
Yvan Jacquier
Keyword(s):  
Ring Opening ◽  
Experimental Results ◽  
Large Excess ◽  
Rhodium Catalysis ◽  
Nitrene Transfer ◽  
One Step ◽  
Optimized Conditions ◽  
Step Mechanism

The aziridination of olefins with {(4-nitrophenylsulfonyl)imino}phenyl-lambda3-iodane, NsN==IPh (1c), in the presence of [Rh2(OAc)4] proceeds in yields of up to 85% when the olefin is used in large excess. Under optimized conditions, styrene (4a) is aziridinated with 1 equiv. of NsN==IPh (1c) in 64% yield with 2 mol% of catalyst. The aziridines derived from electron-rich olefins undergo ring-opening under the conditions of the aziridination and afford rearrangement products or pyrrolidines. The aziridination is sterospecific with 1,2-dialkyl- and 1,2-arylalkyl-disubstituted olefins, but nonstereospecific with stilbene.The rho -value for aziridination of substituted styrenes is -0.61. No ring-opened products are observed upon aziridination of vinylcyclopropanes. In the presence of chiral RhII catalysts, the aziridination is enantioselective, affording an ee of 73% with cis- β -methylstyrene (4k) and Pirrungs [Rh2{(R)-(-)-bnp}4] catalyst. The experimental results are consistent with a one-step mechanism for transfer of the nitrenoid moiety from the catalyst to the olefin.Key words: aziridination, nitrene transfer, rhodium catalysis.

Stereoretentive Olefin Metathesis: A New Avenue for the Synthesis of All-cis Poly(p-phenylene vinylene)s and Stereo­defined Polyalkenamers

Synlett ◽  
2021 ◽  
Author(s):  
Quentin Michaudel ◽  
Samuel J. Kempel ◽  
Ting-Wei Hsu
Keyword(s):  
Olefin Metathesis ◽  
Ring Opening ◽  
Diblock Copolymers ◽  
Catalyst Design ◽  
Phenylene Vinylene ◽  
Grand Challenge ◽  
Ru Catalyst ◽  
Unique Reaction ◽  
Photochemical Isomerization ◽  
Optimized Conditions

AbstractOlefin metathesis has tremendously impacted all fields of synthetic chemistry. However, the control of the olefin stereochemistry during this process remains a grand challenge. Recent innovations in catalyst design have permitted control of the stereochemistry of the olefin product. Here, we discuss the development of stereoretentive olefin metathesis, with an emphasis on the synthesis of stereodefined polyalkenamers through ring-opening metathesis polymerization (ROMP). We then present our application of this unique reaction manifold to the preparation of all-cis poly(p-phenylene vinylene)s (PPVs). A dithiolate Ru catalyst was found to deliver perfect cis selectivity for the polymerization of a paracyclophane diene monomer. By using optimized conditions, all-cis PPVs with narrow dispersities and predictable molar masses were obtained by varying the ratio of monomer to catalyst. The high chain fidelity of the stereoretentive ROMP with a paracyclophane diene monomer enabled the preparation of well-defined diblock copolymers with a norbornene co-monomer. Photochemical isomerization of all-cis to all-trans PPVs was effected with both homopolymers and diblock copolymers. This process was shown to be selective for the PPV block, and resulted in changes in optical properties, polymer size, and solubility. Stereoretentive ROMP provides a promising platform for synthesizing polymers with unique properties, including photoresponsive all-cis PPVs with living characteristics.1 Introduction2 Synthetic Applications of Stereoretentive Olefin Metathesis3 Stereocontrol of Polyalkenamers through Stereoretentive ROMP4 Stereoretentive ROMP To Access All-cis Poly(p-phenylene vinylene)s5 Conclusion

scholarly journals Parylene-Coated Polytetrafluoroethylene-Membrane-Based Portable Urea Sensor for Real-Time Monitoring of Urea in Peritoneal Dialysate

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4560 ◽  
Author(s):  
Park ◽  
Kim ◽  
Kim ◽  
Pyun ◽  
Sung
Keyword(s):  
Electrode System ◽  
Optimum Concentration ◽  
Artificial Kidney ◽  
Optimum Number ◽  
Flow Conditions ◽  
Flow Rates ◽  
Peritoneal Dialysate ◽  
Amine Functionalized ◽  
Fast Flow ◽  
Optimized Conditions

A portable urea sensor for use in fast flow conditions was fabricated using porous polytetrafluoroethylene (PTFE) membranes coated with amine-functionalized parylene, parylene-A, by vapor deposition. The urea-hydrolyzing enzyme urease was immobilized on the parylene-A-coated PTFE membranes using glutaraldehyde. The urease-immobilized membranes were assembled in a polydimethylsiloxane (PDMS) fluidic chamber, and a screen-printed carbon three-electrode system was used for electrochemical measurements. The success of urease immobilization was confirmed using scanning electron microscopy, and fourier-transform infrared spectroscopy. The optimum concentration of urease for immobilization on the parylene-A-coated PTFE membranes was determined to be 48 mg/mL, and the optimum number of membranes in the PDMS chamber was found to be eight. Using these optimized conditions, we fabricated the urea biosensor and monitored urea samples under various flow rates ranging from 0.5 to 10 mL/min in the flow condition using chronoamperometry. To test the applicability of the sensor for physiological samples, we used it for monitoring urea concentration in the waste peritoneal dialysate of a patient with chronic renal failure, at a flow rate of 0.5 mL/min. This developed urea biosensor is considered applicable for (portable) applications, such as artificial kidney systems and portable dialysis systems.

scholarly journals New way of anionic ring-opening copolymerization of β-butyrolactone and ε-caprolactone: determination of the reaction course

2020 ◽  
Vol 27 (12) ◽  
Author(s):  
Zbigniew Grobelny ◽  
Justyna Jurek-Suliga ◽  
Sylwia Golba
Keyword(s):  
Ring Opening ◽  
Chemical Structure ◽  
Side Reactions ◽  
Complexing Agent ◽  
Critical Approach ◽  
Anionic Ring ◽  
Tetrahydrofuran Solution ◽  
End Group ◽  
C Nmr

Abstract Poly(ε-caprolactone)-block-poly(β-butyrolactone) copolymers were prepared in two-step synthesis. Firstly, poly(ε-caprolactone) (PCL) was obtained by anionic ring-opening polymerization of CL initiated with anhydrous KOH activated 12-crown-4 cation complexing agent. Reaction was carried out in tetrahydrofuran solution and argon atmosphere at room temperature. Then, β-butyrolactone (BL) and 18-crown-6 were added to the system, resulting in PCL-block-PBL copolymer, which contains after methylation hydroxyl starting group and methyl ester end group. The main product was contaminated with PCL and PBL homopolymers formed in a side reactions. 13C NMR technique was used for determination of chemical structure of polymers obtained. The course of the studied processes was proposed. MALDI-TOF technique was used to reveal the macromolecules’ architecture where several series were found. The identified series shown that mainly copolymeric macromolecules were formed with scare contribution of homopolymeric polybutyrolactone with trans-crotonate starting groups and polycaprolactone, which is congruent with the proposed reaction mechanism. Moreover, critical approach concerning previously reported PCL-block-PBL copolymer synthesis by use of NaH as initiator was also presented.

Epoxidation of Methyl Oleate and Subsequent Ring-Opening Catalyzed by Lipase from Candida sp. 99-125

2017 ◽  
Vol 120 (2) ◽  
pp. 1700257 ◽  
Author(s):  
Niuniu Lv ◽  
Wei He ◽  
Zheng Fang ◽  
Qin Sun ◽  
Chuanhong Qiu ◽  
...  
Keyword(s):  
Methyl Oleate ◽  
Ring Opening ◽  
Candida Sp

scholarly journals Synthesis of New Imidazolidine and Tetrahydropyrimidine Derivatives

2014 ◽  
Vol 2014 ◽  
pp. 1-4 ◽  
Author(s):  
Hamid Beyzaei ◽  
Reza Aryan ◽  
Zahra Keshtegar
Keyword(s):  
Ring Opening ◽  
Reaction Times ◽  
Reaction Conditions ◽  
Ir Spectrometry ◽  
H Nmr ◽  
Chemical Structures ◽  
Thioamide Group ◽  
Solvent Free Conditions ◽  
Ft Ir ◽  
C Nmr

Synthesis of new imidazolidine and tetrahydropyrimidine derivatives 3a, b and 4a–c as cyclic 1,3-diamines under two reaction conditions (A and B) is described. Under reaction conditions-A, a suspension of (E)-2-cyano-2-(oxazolidin-2-ylidene)ethanethioamide 1 (1 eq.) and diaminoalkanes 2a–e (2 eq.) in absolute ethanol is heated under reflux for 16–22 h to afford 3a, b and 4a–c. Alternatively, under reaction conditions-B, a solution of thioamide 1 (1 eq.) in diaminoalkanes 2a–e (3 eq.) is stirred under solvent-free conditions at room temperature for 3 days to give desired products. Reaction conditions-A for having higher yields, shorter reaction times, and required less diamines is more effective than reaction conditions-B. Oxazolidine ring opening is observed by reacting compound 1 with all of the diamines 2a–e, but the thioamide group only reacts with nonbulky diamines 2a, b. The chemical structures of novel compounds were confirmed by 1H NMR, 13C NMR, elemental analysis, and FT-IR spectrometry.

2,5-Bridged 1-Carba-arachno-pentaborane(10) Derivatives – Intermediates on the Way to Pentaalkyl-1,5-dicarba-closo-pentaboranes(5)

2015 ◽  
Vol 70 (10) ◽  
pp. 741-745 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Hans-Joerg Schanz
Keyword(s):  
Nmr Spectroscopy ◽  
Low Temperature ◽  
Thermal Degradation ◽  
Dft Calculations ◽  
Large Excess ◽  
Thermally Induced ◽  
Independent Synthesis ◽  
Induced Decomposition ◽  
C Nmr

AbstractStimulated by a report from (R. Köster, G. Benedikt, M. A. Grassberger, Liebigs Ann. Chem. 1968, 719, 187.) on a carbaborane, for which the structure of 2,3,4,5,-tetraethlyl-1-methyl-2,5-μ-(ethyl-1′,1′-diyl)-1-carba-arachno-pentaborane(10) 1 was proposed, an independent synthesis was developed. Diethyl(ethynyl)borane was generated in situ in the presence of a large excess of “Et2B–H” (hydride bath) by ethynyl/H exchange, using ethynyl(trioctyl)tin to react in a mixture with diethyl(vinyl)borane at low temperature. Hydroboration and Et2B–H-catalysed condensation afforded 1, as shown by 11B, 13C NMR spectroscopy and DFT calculations. Thermal degradation of 1 gave 2,3,4-triethyl-1,5-dimethyl-1,5-dicarba-closo-pentaborane(5), whereas the pentaethyl-1,5-dicarba-closo-pentaborane(5) resulted from thermally induced decomposition of other suitably substituted arachno carbaboranes.

scholarly journals An Efficient and Mild Method for the Synthesis and Hydrazinolysis ofN-Glyoxylamino Acid Esters

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Ayman El-Faham ◽  
Zainab Al Marhoon ◽  
Ahmed Abdel-Megeed ◽  
Mohamed Siddiqui
Keyword(s):  
Hydrazine Hydrate ◽  
Good Yield ◽  
Acid Ester ◽  
Ring Opening ◽  
Acid Hydrazide ◽  
Type Reaction ◽  
H Nmr ◽  
Elemental Microanalysis ◽  
Acid Esters ◽  
C Nmr

N-Glyoxylamino acid ester derivatives were synthesized via the ring opening ofN-acetylisatin using moderate conditions. During the hydrazinolysis ofN-glyoxylamino acid ester derivatives with hydrazine hydrate (80%) in methanol, unexpected reduction of theα-keto group occurred to affordN-acylamino acid hydrazide derivatives in good yield (80–90%) (Wolff-Kishner type reaction). All the synthesized compounds were characterized by1H NMR,13C NMR, and elemental microanalysis.

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