Polycationic Salts V [1]. 15N NMR Spectra of Amines, Ammonium Salt Monomers, and Polymers of Styrene Based Trialkylammonium Salts

Vogl, Otto; Rehman, Abdul; Zarras, Peter

doi:10.1007/pl00010313

Cited by 12 publications

(3 citation statements)

References 7 publications

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“…30 ppm relative to the free ligand 6. This is in line with a deshielded quaternary ammonium atom, 39,40 indicating that the nitrogen atom is coordinated to the metal center.…”

Section: ■ Introductionsupporting

confidence: 60%

Study of Precatalyst Degradation Leading to the Discovery of a New Ru⁰ Precatalyst for Hydrogenation and Dehydrogenation

Anaby¹,

Schelwies

Schwaben

et al. 2018

Organometallics

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The complex Ru-MACHO ( 1) is a widely used precatalyst for hydrogenation and dehydrogenation reactions under basic conditions. In an attempt to identify the active catalyst form, 1 was reacted with a strong base. The formation of previously unreported species was observed by NMR and mass spectrometry. This observation indicated that complex 1 quickly degraded under basic conditions when no substrate was present. X-ray crystallography enabled the identification of three complexes as products of this degradation of complex 1. These complexes suggested degradation pathways which included ligand cleavage and reassembly, along with reduction of the ruthenium atom. One of the decomposition products, the Ru 0 complex [Ru(N(CH 2 CH 2 PPh 2 ) 3 )CO] (5), was prepared independently and studied. 5 was found to be active, entirely additivefree, in the acceptorless dehydrogenation of aliphatic alcohols to esters. The hydrogenation of esters catalyzed by 5 was also demonstrated under base-free conditions with methanol as an additive. Protic substrates were shown to add reversibly to complex 5, generating Ru II −hydrido species, thus presenting a rare example of reversible oxidative addition from Ru 0 to Ru II and reductive elimination from Ru II to Ru 0 .

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“…30 ppm relative to the free ligand 6. This is in line with a deshielded quaternary ammonium atom, 39,40 indicating that the nitrogen atom is coordinated to the metal center.…”

Section: ■ Introductionsupporting

confidence: 60%

Study of Precatalyst Degradation Leading to the Discovery of a New Ru⁰ Precatalyst for Hydrogenation and Dehydrogenation

Anaby¹,

Schelwies

Schwaben

et al. 2018

Organometallics

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“…The identification of the 2‐ionene oligomers and side products was accomplished by 15 N NMR spectroscopy. 15 N enrichment of our 2‐ionene compounds was not necessary because of the high solubility of these compounds (O‐1, O‐2, and O‐3) in DI water (10.0 M) 38. TMED exhibits a single peak at −357.9 ppm.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and characterization of polyacrylamide‐grafted sodium alginate copolymeric membranes and their use in pervaporation separation of water and tetrahydrofuran mixtures

Kurkuri

Kumbar

Aminabhavi

2002

J of Applied Polymer Sci

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Polyacrylamide-grafted sodium alginate (PAAm-g-Na-Alg) copolymeric membranes have been prepared, characterized, and used in the pervaporation separation of 10-80 mass % water-containing tetrahydrofuran mixtures. Totally three membranes were prepared: (1) neat Na-Alg with 10 mass % of polyethylene glycol (PEG) and 5 mass % of polyvinyl alcohol (PVA), (2) 46 % grafted PAAm-g-Na-Alg membrane containing 10 mass % of PEG and 5 mass % of PVA, and (3) 93 % grafted PAAm-g-Na-Alg membrane containing 10 mass % of PEG and 5 mass % of PVA. Using the transport data, important parameters like permeation flux, selectivity, pervaporation separation index, swelling index, and diffusion coefficient have been calculated at 30°C. Diffusion coefficients were also calculated from sorption gravimetric data of water-tetrahydrofuran mixtures using Fick's equation. Arrhenius activation parameters for the transport processes were calculated for 10 mass % of water in the feed mixture using flux and diffusion data obtained at 30, 35, and 40°C. The separation selectivity of the membranes ranged between 216 and 591. The highest permeation flux of 0.677 kg/m 2 h was observed for 93% grafted membrane at 80 mass % of water in the feed mixture.

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“…Nonetheless, Olah and co‐workers found that the 17 O nuclei in oxonium ions are generally deshielded compared to those in their parent alcohols and ethers . For nitrogen (observed by 15 N NMR analysis), the result seems to depend on the situation; the nitrogen atom in protonated trimethylamine is deshielded relative to the free base, while the nitrogen atom in tetramethylammonium bromide is shielded relative to trimethylamine …”

Section: Methodsmentioning

confidence: 99%

Spectroscopic Characterization of a [C−F−C]⁺ Fluoronium Ion in Solution

2018

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We report the first spectroscopic evidence for a [C-F-C] fluoronium ion in solution. Extensive NMR studies ( F, H, C) characterize a symmetric cage-like species in which fluorine exhibits substantial covalent bonding to each of the two carbon atoms involved in the three-center interaction. Experimental NMR data comport well with calculated values to lend credence to the structural assignment. As the culminating experiment, a Saunders isotopic perturbation test confirmed the symmetric structure. Congruent with the trend in other types of onium ions, the calculated charge at fluorine moves in a more positive (less negative) direction from the neutral. It is this important trend that explains in part the extraordinary historical difficulty in making theoretical predictions of fluoronium ions come true in solution, and why it takes fluorine captured in a cage to produce, finally, a stable ion and complete the historical arc of the organic halonium ion story.

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Polycationic Salts V [1]. 15N NMR Spectra of Amines, Ammonium Salt Monomers, and Polymers of Styrene Based Trialkylammonium Salts

Cited by 12 publications

References 7 publications

Study of Precatalyst Degradation Leading to the Discovery of a New Ru⁰ Precatalyst for Hydrogenation and Dehydrogenation

Study of Precatalyst Degradation Leading to the Discovery of a New Ru⁰ Precatalyst for Hydrogenation and Dehydrogenation

Synthesis and characterization of polyacrylamide‐grafted sodium alginate copolymeric membranes and their use in pervaporation separation of water and tetrahydrofuran mixtures

Spectroscopic Characterization of a [C−F−C]⁺ Fluoronium Ion in Solution

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Polycationic Salts V [1]. 15N NMR Spectra of Amines, Ammonium Salt Monomers, and Polymers of Styrene Based Trialkylammonium Salts

Cited by 12 publications

References 7 publications

Study of Precatalyst Degradation Leading to the Discovery of a New Ru0 Precatalyst for Hydrogenation and Dehydrogenation

Study of Precatalyst Degradation Leading to the Discovery of a New Ru0 Precatalyst for Hydrogenation and Dehydrogenation

Synthesis and characterization of polyacrylamide‐grafted sodium alginate copolymeric membranes and their use in pervaporation separation of water and tetrahydrofuran mixtures

Spectroscopic Characterization of a [C−F−C]+ Fluoronium Ion in Solution

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Study of Precatalyst Degradation Leading to the Discovery of a New Ru⁰ Precatalyst for Hydrogenation and Dehydrogenation

Study of Precatalyst Degradation Leading to the Discovery of a New Ru⁰ Precatalyst for Hydrogenation and Dehydrogenation

Spectroscopic Characterization of a [C−F−C]⁺ Fluoronium Ion in Solution