Differential Scanning Calorimetry (DSC) as a Tool for Probing the Reactivity of Polyynes Relevant to Hexadehydro-Diels–Alder (HDDA) Cascades

Woods, Brian P.; Hoye, Thomas R.

doi:10.1021/ol503162k

Cited by 20 publications

(6 citation statements)

References 28 publications

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“…It is worth noting that the Δ H m of LMPA-5 with BMI loading exhibited a higher value compared with that without BMI loading, ranging from 9.5 to 16.5 J g –1 . This result hinted that the higher Δ H m value may be involved in the overlap of the endothermic process between the retro-DA reaction and melting of the polymer. − Based on the results reported in the literature, − the endothermic value of the retro-DA reaction is in the broad range of 6.2–32.5 J g –1 . In addition, the T g and T d5 of LMPA-5 with BMI loading exhibited slightly higher values than those of LMPA-5 without BMI loading, thanks to the formation of a more robust molecular structure by DA trace cross-linked networks.…”

Section: Resultsmentioning

confidence: 81%

Synthesis and Characterization of Low-Melting-Point Polyamides with Trace Thermoreversible Cross-Linked Networks

Chen

Huang

Lee

et al. 2021

Ind. Eng. Chem. Res.

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In this study, we synthesized low-melting-point polyamides (LMPAs, T m ≈ 145 °C), which were composed of εcaprolactam, hexamethylenediamine, adipic acid, 1,10-decanedicarboxylic acid, and 2,5-furandicarboxylic acid. The LMPA materials with temperature-triggered reversible cross-linking were prepared by adding various bismaleimide (BMI) loadings (0, 0.1, 0.5, and 1.0 wt %), and their thermal and mechanical properties were obviously better than those of pure LMPA without BMI loading. According to rheological studies, the temperaturetriggered reversible cross-linking (i.e., Diels−Alder reaction) described above occurs at a temperature range of 150−160 °C. In addition, the rheological activation energy of LMPAs with crosslinked networks was significantly higher than that of LMPA without cross-linked networks (298.6 vs 77.7 J kg −1 K −1 , respectively). For mechanical properties, the yield strength of LMPAs with BMI loading (29.1−36.5 MPa) was higher than that of LMPA without BMI loading (19.1 MPa), which was improved by about 50%. As a method of developing LMPA materials with high performance, this is the first report of LMPA materials with temperaturetriggered reversible cross-linking.

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Section: Resultsmentioning

confidence: 81%

Synthesis and Characterization of Low-Melting-Point Polyamides with Trace Thermoreversible Cross-Linked Networks

Chen

Huang

Lee

et al. 2021

Ind. Eng. Chem. Res.

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“…To identify the key structural features necessary to stabilize these ketenimine salts, we used differential scanning calorimetry (DSC), a well-established tool for the characterization of small molecule thermal behavior 7 to perform structure exothermic relationships with our synthesized ketenimine salts and a wellknown coupling reagent EDC, which is sold and distributed as the hydrochloric acid ammonium salt. During our analysis, we encountered very subtle exothermic events and much more defined endothermic maxima; so, we decided to compare our ketenimine salts and EDC in regard to their maximum heat flow temperature.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Three-Component Approach to Pyridine-Stabilized Ketenimines for the Synthesis of Diverse Heterocycles

2019

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Ketenimines are versatile synthetic intermediates capable of performing novel transformations in organic synthesis. They are normally generated in situ due to their inherent instability and high level of reactivity. Herein, we report pyridine-stabilized ketenimine zwitterionic salts, which are prepared through click chemistry from readily accessible alkynes and sulfonyl azides. To demonstrate their synonymous reactivity to ketenimines, these salts have been utilized in a cascade sequence to access highly functionalized quinolines including the core structures of an antiprotozoal agent and the potent topoisomerase inhibitor Tas-103.

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“…All of the salts prepared in this study appear to be thermally stable at room temperature. However, we looked for evidence of exothermic events when heated in the solid state by differential scanning calorimetry (DSC) analysis. , This behavior was also dependent on aryl electronic effects and counteranion identity. Analogous to light stability, iodonium salts with PF 6 counteranions appeared less thermally stable than those with OTs counteranions as evidenced by exothermic onset peaks at lower temperature (compare 22 -PF 6 vs 22 -OTs or 14 -PF 6 vs 14 -OTs Figure ).…”

Section: Results and Discussionmentioning

confidence: 99%

Unsymmetrical Aryl(2,4,6-trimethoxyphenyl)iodonium Salts: One-Pot Synthesis, Scope, Stability, and Synthetic Studies

et al. 2016

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Diaryliodonium salts have recently attracted significant attention as metal-free-arylation reagents in organic synthesis, and efficient access to these salts is critical for advancement of their use in reaction discovery and development. The trimethoxybenzene-derived auxiliary is a promising component of unsymmetrical variants, yet access remains limited. Here, a one-pot synthesis of aryl(2,4,6-trimethoxyphenyl)iodonium salts from aryl iodides, m-CPBA, p-toluenesulfonic acid, and trimethoxybenzene is described. Optimization of the reaction conditions for this one-pot synthesis was enabled by the method of multivariate analysis. The reaction is fast (<1 h), provides a high yield of product (>85% average), and has broad substrate scope (>25 examples) including elaborate aryl iodides. The utility of these reagents is demonstrated in moderate to high yielding arylation reactions with C-, N-, O-, and S-nucleophiles including the synthesis of a liquid crystal molecule.

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Differential Scanning Calorimetry (DSC) as a Tool for Probing the Reactivity of Polyynes Relevant to Hexadehydro-Diels–Alder (HDDA) Cascades

Cited by 20 publications

References 28 publications

Synthesis and Characterization of Low-Melting-Point Polyamides with Trace Thermoreversible Cross-Linked Networks

Synthesis and Characterization of Low-Melting-Point Polyamides with Trace Thermoreversible Cross-Linked Networks

Three-Component Approach to Pyridine-Stabilized Ketenimines for the Synthesis of Diverse Heterocycles

Unsymmetrical Aryl(2,4,6-trimethoxyphenyl)iodonium Salts: One-Pot Synthesis, Scope, Stability, and Synthetic Studies

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