Application of ketenes to well-defined polyester synthesis. III. Living anionic polymerization of ethyl(4-methoxyphenyl)ketene—Development of polyester having masked phenol side chain

A novel ketene, ethyl(4-methoxyphenyl)ketene (EMPK), was synthesized by the dehydrochlorination of 2-(4-methoxyphenyl)butanoyl chloride. The anionic polymerizations of EMPK by butyllithium in tetrahydrofuran at −20 °C were carried out with a varying feed ratio to give the corresponding polyesters having predictable molecular weights and narrow molecular weight distributions, quantitatively. The selective formation of the polyester was confirmed by IR analysis, and the reductive degradation of the polymer was supported by lithium–aluminium hydride. The second feed of the monomer (after the first stage of polymerization) resulted in the formation of the polymer with the expectedly increased molecular weight and low polydispersity to strongly support the living mechanism of this polymerization. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1596–1600, 2001     

Determination and perturbation of the electronic potentials of solid catalysts for innovative catalysis

Concerns about energy and the environment are motivating a reexamination of catalytic processes, aiming to achieve more efficient and improved catalysis compatible with sustainability. Designing an active site for such heterogeneous catalytic processes remains a challenge leading to a next level breakthrough. Herein, we discuss a fundamental aspect of heterogeneous catalysis: the chemical potential of electrons in solid catalysts during thermal catalysis, which directly reflects the consequent catalytic reaction rate. The use of electrochemical tools during thermal catalysis allows for the quantitative determination of the ill-defined chemical potentials of solids in operando, whereby the potential–rate relationship can be established. Furthermore, the electrochemical means can also introduce the direct perturbation of catalyst potentials, in turn, perturbing the coverage of adsorbates functioning as poison, promoters, or reactants. We collect selected publications on these aspects, and provide a viewpoint bridging the fields of thermal- and electro-catalysis.

Concerns about energy and the environment are motivating a reexamination of catalytic processes, aiming to achieve more efficient and improved catalysis compatible with sustainability.     

Facile synthesis of 4-substituted butenolides from furan

A variety of 4-substituted butenolides were prepared utilizing 2-acetoxyfuran as a key intermediate which can be easily synthesized by anodic oxidation of furan.     

Stability evaluation of inference methods for optoelectronic fuzzy inference system

System stability of various membership functions and fuzzy control methods are compared by numerical simulations to determine the feasibility of optoelectronic fuzzy inference method. An inverted pendulum is used for the destination system. A Gaussian membership function is better than a triangular one. MIN operations of grade evaluation and modification of consequent membership functions are better than other operations. SUM operation of consequent operation is better than MAX operation.     

Reaction of tri-n-butyltin formate. III. Synthesis of allylic tri-n-butyltin by the reaction of tri-n-butyltin formate with allylic sulfones and sulfides.

Allylic tri-n-butyltins can be prepared easily by the treatment of allylic sulfones or sulfides with tri-n-butyltin formate in refluxing xylene.     

Effect of dual frequency on sonochemical reaction rates

An ultrasonic reactor that combined a standing-wave-type transducer and a horn-type emitter was constructed and the ultrasonic frequency of the standing-wave-type transducer was varied and the sonochemical reaction rates were estimated. The synergy effect was observed below 100 kHz. In order to consider the mechanism of effect of synergy, the acoustic noise, the sonochemical luminescence and the bubble behavior in the reactor were investigated. The frequency spectrum of acoustic noise indicated that the synergy effect came from the increase of number of cavitation bubbles.     

Selective synthesis, structure and oxidation properties of isomeric 1,4-dithiins fused to two benzo[b]thiophenes

Two novel isomers of 1,4-dithiins fused to two benzo[b]thiophenes on both sides were obtained by selective synthetic methods via the corresponding sulfides. The crystal structures of two dithiins were determined by X-ray crystallographic analyses. Examination of oxidation properties of the dithiins showed interesting results by CV measurement. The ESR spectra of chemically oxidized dithiins indicated formation of stable radical cations.     

Anionic alternating copolymerization of 3,4‐dihydrocoumarin and glycidyl ethers: A new approach to polyester synthesis

Anionic copolymerizations of 3,4‐dihydrocoumarin (DHCM) and a series of glycidyl ethers (n‐butyl glycidyl ether, tert‐butyl glycidyl ether, and allyl glycidyl ether) with 2‐ethyl‐4‐methylimidazole as an initiator proceeded in a 1:1 alternating manner to give the corresponding polyesters, whose structures were confirmed by spectroscopic analyses and reductive scission of the ester bonds in the main chain with lithium aluminum hydride, followed by detailed analyses of the resulting fragments. The polyester obtained by the copolymerization of DHCM and allyl glycidyl ether inherited the allyl groups in the side chain, whose applicability to chemical modifications of the polyester was successfully demonstrated by a platinum‐catalyzed hydrosilylation reaction. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4092–4102, 2008     

Inadmissibility of the uncombined two-stage estimator when additional samples are available

Consider the problem of constructing an estimator with a preassigned bound on the risk for a mean of a normal distribution. The paper shows that the usual two-stage estimator is improved on by combined estimators when additional samples taken from distributions with the same mean and different variances are available.