Stereospecific thermal rearrangement of the four labile isomers of retinal. Activation parameters and FT-IR data

Zhu, Yun; Ganapathy, Srinivasan; Liu, Robert S. H.

doi:10.1021/jo00030a015

Cited by 21 publications

(11 citation statements)

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“…The XRD pattern of PAC was displayed in Figure S5a (Supporting Information), and no obvious peak except the broad peak of (002) diffraction was observed, indicative of amorphous nature. Figure d exhibits FT‐IR measurement results, in which the ν(CC) and ν(CO) vibration signals appear at ≈1635 and ≈1275 cm −1 , respectively . In the spectrum of SbOC/C composite, an extra medium intensity band lying at ≈599 cm −1 is attributable to ν(SbOC) vibration, verifying a strong oxygen–bond interaction between antimony and carbon .…”

Section: Resultsmentioning

confidence: 89%

Dual Functions of Potassium Antimony(III)‐Tartrate in Tuning Antimony/Carbon Composites for Long‐Life Na‐Ion Batteries

Zhang

Hou

et al. 2018

Adv Funct Materials

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Antimony holds a high-specific capacity as a promising anode material for Na-ion batteries (SIBs) and much research is focused on solving the poor cycling stability issue associated with its large volume expansion during alloying/dealloying processes. Here, self-thermal-reduction method is successfully applied to prepare antimony/carbon rods (Sb/C rods) utilizing potassium antimony(III)tartrate (C 8 H 10 O 15 Sb 2 K 2 ) as a dual source of carbon matrix and metallic antimony. According to theory calculations and experiment results, the formation process is explicitly explored as follows: C 8 H 10 O 15 Sb 2 K 2 → Sb 2 O 3 /C → Sb 2 O 3 / Sb/C → Sb/C rods. Notably, organic ligands in C 8 H 10 O 15 Sb 2 K 2 can be gradually turned into amorphous carbon with simultaneous reduction of Sb 3+ to metal Sb. Moreover, potassium chloride acts as an activator and a template during the course of carbonization, and synchronous reduction is introduced. Consequently, an antimony/carbon electrode material denoted as SbOC/C is formed, exhibiting a unique dual-carbon-modified structure and extensive SbOC bridge bonds that give rise to outstanding cycling performance and rate capacity. Specifically, the capacity is maintained at 404 mA h g −1 with 89% retention after 700 cycles at 500 mA g −1 . The low-cost, self-thermal-reduction method and excellent electrode performances of electrode material make it attractive for large-scale energy storage systems.

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Section: Resultsmentioning

confidence: 89%

Dual Functions of Potassium Antimony(III)‐Tartrate in Tuning Antimony/Carbon Composites for Long‐Life Na‐Ion Batteries

Zhang

Hou

et al. 2018

Adv Funct Materials

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“…Previous reports have established that the interconversion between the cis -1,3-dienone and 2 H -pyran by oxa-6π electrocyclization/retro-electrocyclization is facile; 9 however, the studies suggest that equilibrium favors the closed form only when the pyran contains sterically demanding substitutents, 10 or is part of a bicyclic system, 11 and is therefore substrate dependent. However, trans -1,3-dienone is unreactive unless it can be smoothly isomerized to the cis isomer.…”

Section: Resultsmentioning

confidence: 99%

No Acid Required: 4π and 6π Electrocyclization Reactions of Dienyl Diketones for the Synthesis of Cyclopentenones and 2H-Pyrans

2014

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The 1,6-conjugate addition of nucleophiles to dienyl diketones produces either cyclopentenone or 2H-pyran products with high selectivity through either Nazarov (4π) or 6π electrocyclization, respectively. The outcome of the reaction is dependent upon the nature of the nucleophile used. Nucleophiles that are anionic or easily deprotonated exclusively produce cyclopentenones via Nazarov cyclization, whereas the neutral nucleophile DABCO promotes 6π cyclization to afford 2H-pyrans. Experimental evidence is presented for both retro-4π and -6π electrocyclization in these systems, lending support to the bifurcated mechanistic hypothesis proposed for these cyclizations.

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“…Among initial products are characteristically significant amounts of products with retention of all or part of the hindered geometry present in the starting material. In fact, the preferred direction of isomerization appears, unexpectedly, not to be dictated by release of steric strain but simply iso-merizing at the bond (13,14) closest to the electron withdrawing end group. Thus, for all isomers containing the 134s geometry, the corresponding 13trans isomer was invariably formed as the major product (57-100% among all products).…”

Section: Direct Irraditionmentioning

confidence: 97%

Photoisomerization of Sixteen Isomers of Retinal. Initial Product Distribution in Direct and Sensitized Irradiation. Photochemistry of Polyenes 31*

Ganapathy

Liu

1992

Photochem & Photobiology

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Abstract— Initial product distributions of all 16 geometric isomers of retinal in hexane solutions have been determined. With direct irradiation, the product ratios are characterized by a preference for isomerization at the 13,14‐bond. In particular, all isomers containing the 13‐cis geometry give the corresponding 13‐trans isomer as the major product. Preference for one‐photon‐one‐bond isomerization was also noted, although a substantial amount of the all‐trans isomer was detected for all poly‐cis, 13‐trans isomers. In sensitized irradiation, the initial mixture shows extensive one‐photon‐two(or multiple)‐bond isomerization to the corresponding unhindered isomers. In cases of hindered isomers, multiple‐bond isomerized products are dominant. The different results are accountable by the different shapes of the excited state potential curves for singlet and triplet states.

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Stereospecific thermal rearrangement of the four labile isomers of retinal. Activation parameters and FT-IR data

Cited by 21 publications

References 0 publications

Dual Functions of Potassium Antimony(III)‐Tartrate in Tuning Antimony/Carbon Composites for Long‐Life Na‐Ion Batteries

Dual Functions of Potassium Antimony(III)‐Tartrate in Tuning Antimony/Carbon Composites for Long‐Life Na‐Ion Batteries

No Acid Required: 4π and 6π Electrocyclization Reactions of Dienyl Diketones for the Synthesis of Cyclopentenones and 2H-Pyrans

Photoisomerization of Sixteen Isomers of Retinal. Initial Product Distribution in Direct and Sensitized Irradiation. Photochemistry of Polyenes 31*

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