1679-47-6Relevant articles and documents
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Marvel,Brace
, p. 1775 (1948)
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Extension of the Eschenmoser sulfide contraction/iminoester cyclization method to the synthesis of tolyporphin chromophore
Minehan, Thomas G.,Kishi, Yoshito
, p. 6811 - 6814 (1997)
Tolyporphin chromophore 2 has been synthesized by performing a double-retroaldol/oxidation sequence on an octahydroporphyrin precursor 18 prepared by using the Eschenmoser sulfide-contraction/iminoester-condensation method.
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Bianchi et al.
, p. 107,109,110 (1977)
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Poosner,Loomis
, p. 892 (1972)
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Esterification and ketalization of levulinic acid with desilicated zeolite β and pseudo-homogeneous model for reaction kinetics
Umrigar, Vaishali,Chakraborty, Mousumi,Parikh, Parimal
, p. 299 - 308 (2019)
To maximize the production of esters (E), keto (K) and keto-ester (KE) by esterification and ketalization of levulinic acid (LA) has been reacted using diols such as 1,2-propane diol (PDOL),1,2-ethane diol (EDOL), and 1,2,3-propane triol or glycerol (TRIOL) with desilicated Hβ. This work aims to assess the conversion and selectivity for the production of esters using conventional and microwave-irradiated (MWI) reactors. Catalysts characterizations were performed using NH3-temperature programme desorption, Brunauer, Emmett and Teller surface area (BET), Barrett, Joyner, and Halenda (BJH), scanning electron microscope, transmission electron microscope, and dynamic light scattering. Operating parameters such as reaction temperature (170–180°C), reaction time (20–80?min), feed composition (LA:PDOL/EDOL/TRIOL, 1:8/10/12), and microwave energy (300–500 watt) have been systematically investigated. Note that 99–100% conversion was achieved with the product selectivity of E (40%), K (30%), and KE (30%) with1,2-EDOL; E (56%), K (2%), and KE (17%) with 1,2-PDOL; E (69%), K(0%), and KE (22%) with TRIOL using D-Hβ as a solid catalyst in an MWI reactor. Reaction paths and kinetics were studied using pseudo-homogeneous (PH) model.
Cobalt-Mediated Switchable Catalysis for the One-Pot Synthesis of Cyclic Polymers
Lam, Jacky W. Y.,Liao, Can,Tang, Ben Zhong,Wang, Xianhong,Wang, Yong,Xie, Xiaolin,Zhao, Yajun,Zhou, Xingping,Zhu, Shuaishuai
, p. 16974 - 16979 (2021)
A cobalt salen pentenoate complex [salen=(R,R)-N,N′-bis(3,5-di-tertbutylsalicylidene)-1,2-cyclohexanediamine] is rationally designed as the catalyst for the ring-opening copolymerization (ROCOP) of epoxides/anhydrides/CO2. Via migratory insertion of carbon monoxide (CO) into the Co?O bonds, the ROCOP-active species α-alkene-ω-O-CoIII(salen) can be rapidly and quantitatively transformed into α-alkene-ω-O2C-CoIII(salen) telechelic linear precursors. Upon dilution of reaction mixtures, the homolytic cleavage of Co?C bonds induced by visible light generates α-alkene acyl radicals that spontaneously undergo intramolecular radical addition to afford organocobalt-functionalized cyclic polyesters and CO2-based polycarbonates with excellent regioselectivity. The cyclic products can either react with radical scavengers to generate metal-free cyclic polymers or serve as photo-initiators for organometallic-mediated radical polymerization (OMRP) to produce tadpole-shaped copolymers.
Selective hydrogenolysis of 2-furancarboxylic acid to 5-hydroxyvaleric acid derivatives over supported platinum catalysts
Asano, Takehiro,Takagi, Hiroshi,Nakagawa, Yoshinao,Tamura, Masazumi,Tomishige, Keiichi
, p. 6133 - 6145 (2019/11/20)
The conversion of 2-furancarboxylic acid (FCA), which is produced by oxidation of furfural, to 5-hydroxyvaleric acid (5-HVA) and its ester/lactone derivatives with H2 was investigated. Monometallic Pt catalysts were effective, and other noble metals were not effective due to the formation of ring-hydrogenation products. Supports and solvents had a small effect on the performance; however, Pt/Al2O3 was the best catalyst and short chain alcohols such as methanol were better solvents. The optimum reaction temperature was about 373 K, and at higher temperature the catalyst was drastically deactivated by deposition of organic materials on the catalyst. The highest yield of target products (5-HVA, δ-valerolactone (DVL), and methyl 5-hydroxyvalerate) was 62%, mainly obtained as methyl 5-hydroxyvalerate (55% yield). The byproducts were mainly ring-hydrogenation compounds (tetrahydrofuran-2-carboxylic acid and its ester) and undetected ones (loss of carbon balance). The catalyst was gradually deactivated during reuses even at a reaction temperature of 373 K; however, the catalytic activity was recovered by calcination at 573 K. The reactions of various related substrates were carried out, and it was found that the O-C bond in the O-CC structure (1,2,3-position of the furan ring) is dissociated before CC hydrogenation while the presence and position of the carboxyl group (or methoxy carbonyl group) much affect the reactivity.
