24936-44-5Relevant academic research and scientific papers
The ionic liquid microphase enhances the catalytic activity of Pd nanoparticles supported by a metal-organic framework
Peng, Li,Zhang, Jianling,Yang, Shuliang,Han, Buxing,Sang, Xinxin,Liu, Chengcheng,Yang, Guanying
, p. 4178 - 4182 (2015)
Here we demonstrate the utilization of the ionic liquid (IL) microphase for enhancing the catalytic activities of the metal nanoparticles supported on a MOF. The IL microphase offers an excellent environment for stabilizing metal nanoparticles. A new heterogeneous catalyst Pd/IL/MOF is developed, which combines the advantages of highly dispersed small Pd nanoparticles, the IL microphase and a porous MOF. The as-synthesized Pd/IL/MOF catalysts have shown high catalytic activity and reusability for selective hydrogenation under mild conditions.
Visible Light Photoinitiated Metal-Free Living Cationic Polymerization of 4-Methoxystyrene
Perkowski, Andrew J.,You, Wei,Nicewicz, David A.
, p. 7580 - 7583 (2015)
Metal-free, visible light-initiated, living cationic polymerization of 4-methoxystyrene using 2,4,6-tri(p-tolyl)pyrylium tetrafluoroborate and methanol is demonstrated. Molecular weight and dispersity are controlled by the concentration of methanol. Initial mechanistic analysis suggests that methanol likely serves to regulate propagation of the cation chain end via reversible chain transfer in a manner analogous to reversible addition-fragmentation chain transfer polymerization.
Fast and Regioselective Polymerization of para-Alkoxystyrene by Palladium Catalysts for Precision Production of High-Molecular-Weight Polystyrene Derivatives
Liao, Guangfu,Xiao, Zefan,Chen, Xiaolin,Du, Cheng,Zhong, Liu,Cheung, Chi Shing,Gao, Haiyang
, p. 256 - 266 (2020)
Polymerization of polar vinyl monomers by a coordination-insertion approach is a topic of fundamental importance to the field of polymer synthesis. Herein, we initially report the coordination-insertion polymerization of para-alkoxystyrene (pAOS) monomers by the dibenzobarrelene-based α-diimine palladium catalysts. The unprecedented polymerization characteristics including rapid initiation, fast chain growth, controlled chain transfer, and high-molecular-weight polymer with a narrow distribution (Mw > 1000 kg/mol, PDI 1.32) reflected previously unrecognized aspects of palladium-catalyzed pAOS polymerization. Chain-end analysis and characterization of palladium intermediates showed that the pAOS monomer was rapidly inserted into the primary palladium species in a full 1,2-regioselectivity, and the chain transfer took place by monomer-assisted β-H abstraction at high monomer concentrations. The resultant polymers showed improved mechanical properties and thermal stabilities and were also attractive candidates of hydrophilic styrenic resin.
Efficient synthesis of styrene derivatives through ethenolysis of renewable propenylbenzenes
Avenda?o Villarreal, Jesus A.,Delolo, Fábio G.,Granato, Artur V.,dos Santos, Eduardo N.
, (2021)
Functionalized styrenes were obtained by the ethenolysis of renewable 1-propenylbenzenes in a very efficient synthetic pathway. Some of the products are valuable food & flavor ingredients (4-vinylguaiacol) or locust pheromone (4-vinylanisole). The catalysts employed were ruthenium-alkylidene complexes bearing a N-heterocyclic carbene as a ligand, which bulkiness proved to be important for the catalysis output. The judicious choice the reaction conditions was critical to enable near quantitative yields under mild conditions in short reaction times. More strikingly, the catalyst load could be reduced to 0.01 mol%, keeping good conversion and selectivity.
Fabrication of photoactive self-assembled ultra-thin films from diazoresin and poly(4-vinylphenol) via H-bonding
Cao,Chen,Yang,Cao
, p. 305 - 307 (2001)
Using a self-assembly technique, a type of photoactive multilayer film was successfully fabricated from diazoresin (DR) and poly(4-vinylphenol) (PVPh) followed by UV irradiation. The driving force of the self-assembly was confirmed to be the H-bonding interaction between the diazonium group (-N2 +) of DR and the phenolic hydroxy group (-Ph-OH) of PVPh. A linkage conversion from an H-bond to a covalent bond takes place following the decomposition of the -N2 + group when the multilayer film undergoes UV irradiation. As a result, the stability of the film towards etching by polar solvents increases dramatically.
Retentive Solvolysis. Part 12. Mechanism of the Reaction of Optically Active 1-(p-Methoxyphenyl)ethyl Trifluoroacetate with Phenol and Metanol in Benzene and Cyclohexane
Okamoto, Kunio,Takeuchi, Ken'ichi,Inoue,Takeshi
, p. 842 - 848 (1980)
The rate, product distribution, and stereochemical course for the reactions of 0.05-0.1M-1-(p-methoxyphenyl)ethyl trifluoroacetate (1) with methanol and phenol have been investigated in benzene or cyclohexane as solvent at 25.0 deg C.Below 1E-3M-methanol or -phenol the total kinetic order is two overall .The rates are virtually independent of the pyridine used to bind the trifluoroacetic acid produced.The major product from the phenol reaction, 1-(p-methoxyphenyl)ethyl phenyl ether, shows net retention (6-9percent) of configuration along with predominant racemization.In addition, the methyl ether product from the methanol reaction also undergoes net retention (24percent with 0.2M-methanol).The formation of the ethers with net retention of configuration can be accounted for by an intermolecular SNi mechanism.
Fluoride-free Hiyama and copperand amine-free Sonogashira coupling in air in a mixed aqueous medium by a series of PEPPSI[?]-themed precatalysts
Dash, Chandrakanta,Shaikh, Mobin M.,Ghosh, Prasenjit
, p. 1608 - 1618 (2009)
A new series of robust, user-friendly, and highly active PEPPSI-themed (pyridine-enhanced precatalyst preparation, stabilization and initiation) (NHC)PdX2(pyridine)-type (X = Cl, Br) precatalysts of C4-C5 saturated imidazole(1-4) and triazole-based (5 and 6) N-heterocyclic carbenes for the Hiyama and Sonogashira couplings under amenable conditions are reported. Specifically 1-6 efficiently catalyze the fluoride-free Hiyama coupling of aryl halides with PhSi(OMe)3 and CH2=CHSi(OMe)3 in air in the presence of NaOH as a base in a mixed aqueous medium (dioxane/H 2O, 2:1 v/v). Along the same lines, these 1-6 precatalysts also promote the Cu-free and amine-free Sonogashira coupling of aryl bromides and iodides with phenylacetylene in air and in a mixed aqueous medium (DMF/H 2O, 3/1 v/v). The complexes 1-6 were synthesized by the direct reaction of the respective imidazolinium and triazolium halide salts with PdCl2 in pyridine in the presence of K2CO3 as a base. DFT studies on the catalytically relevant palladium(0) (NHC)Pd(pyridine) precursors 1a-6a reveal significant donation from the N-heterocyclic carbene lone pair onto the unfilled σ* orbital of the trans Pd-pyridine bond. This weakens the Pd-bound "throwaway" pyridine ligand, and its dissociation marks the initiation of the catalytic cycle. ( Wiley-VCH Verlag GmbH and Co. KGaA, 69451 Weinheim, Germany, 2009).
Photoredox Catalyzed Sulfonylation of Multisubstituted Allenes with Ru(bpy)3Cl2 or Rhodamine B
Chen, Jingyun,Chen, Shufang,Jiang, Jun,Lu, Qianqian,Shi, Liyang,Xu, Zekun,Yimei, Zhao
supporting information, (2021/11/09)
A highly regio- and stereoselective sulfonylation of allenes was developed that provided direct access to α, β-substituted unsaturated sulfone. By means of visible-light photoredox catalysis, the free radicals produced by p-toluenesulfonic acid reacted with multisubstituted allenes to obtain Markovnikov-type vinyl sulfones with Ru(bpy)3Cl2 or Rhodamine B as photocatalyst. The yield of this reaction could reach up to 91%. A series of unsaturated sulfones would be used for further transformation to some valuable compounds.
Functionalized styrene synthesis via palladium-catalyzed C[sbnd]C cleavage of aryl ketones
Zhang, Xu,Wang, Zhen-Yu,Wang, Xing,Xu, Hui,Dai, Hui-Xiong
, (2022/03/31)
We report herein the synthesis of functionalized styrenes via palladium-catalyzed Suzuki–Miyaura cross-coupling reaction between aryl ketone derivatives and potassium vinyltrifluoroborate. The employment of pyridine-oxazoline ligand was the key to the cleavage of unstrained C[sbnd]C bond. A variety of functional groups and biologically important moleculars were well tolerated. The orthogonal Suzuki–Miyaura coupling demonstrated the synthetic practicability.
Electrochemistry enabled selective vicinal fluorosulfenylation and fluorosulfoxidation of alkenes
Jiang, Yimin,Shi, Zhaojiang,Wu, Jinnan,Wu, Shaofen,Ye, Keyin,Yu, Yi,Yuan, Yaofeng
supporting information, (2021/11/17)
Both sulfur and fluorine play important roles in organic synthesis, the life science, and materials science. The direct incorporation of these elements into organic scaffolds with precise control of the oxidation states of sulfur moieties is of great significance. Herein, we report the highly selective electrochemical vicinal fluorosulfenylation and fluorosulfoxidation reactions of alkenes, which were enabled by the unique ability of electrochemistry to dial in the potentials on demand. Preliminary mechanistic investigations revealed that the fluorosulfenylation reaction proceeded through a radical-polar crossover mechanism involving a key episulfonium ion intermediate. Subsequent electrochemical oxidation of fluorosulfides to fluorosulfoxides were readily achieved under a higher applied potential with the adventitious H2O in the reaction mixture.
