Detection limit in the (pX,X) technique—A novel method for trace element analysis

The (pX, X) technique is a very reliable tool for trace element analysis when large amounts of a neighboring element are present. This paper describes the experimentally determined detection limits of some available sources of GaAs, Ge and Zr, to evaluate the utility of this technique. The theoretical detection limits calculated with a computer program are also described.     

Total synthesis of tylonolide,an aglycone of tylosin

The total synthesis of tyionolide, a 16-membered-ring aglycone of a macrolide antibiotic, tyiosin, has been accomplished by coupling two segments of C1-C10 and C11-C17 portions, which are stereospecifically derived from D-glucose.     

Synthesis of high‐performance polyurethanes with rigid 5‐6‐5‐fused ring system in the main chain from naturally occurring myo‐inositol

A bisketal of myo‐inositol was used as a diol‐type monomer for synthesis of polyurethanes. The monomer was obtained by treatment of myo‐inositol with 1,1‐dimethoxycyclohexane in the presence of p‐toluenesulfonic acid as a catalyst. The ketalization resulted in the formation of a 5‐6‐5‐fused ring system, which endowed the diol‐type monomer with high rigidity. The diol readily reacted with diisocyanate to give the corresponding polyurethane, which exhibited excellent heat resistance due to the rigid 5‐6‐5 system in the main chain. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3956–3963     

A chemical oscillator based on the photoreduction of 2-methyl-1,4-benzoquinone

This study investigated bromate-2-methyl-1,4-benzoquinone photoreaction in a batch reactor, in which the photoreduction of 2-methyl-1,4-benzoquinone plays a vital role in initiating and sustaining the reaction process. Transient oscillatory phenomena are observed over broad reaction conditions, but a phase diagram in the bromate and sulfuric acid concentration plane shows that the nonlinear behavior is more sensitive to the ratio of bromate and acid than their absolute concentrations. Light intensity and the photosensitive substance 2-methyl-1,4-benzoquinone exhibited opposite effects on the induction time of these oscillations, implying that illumination does more than just reduce 2-methyl-benzoquinone. The oscillatory behavior has been qualitatively reproduced with a generic model developed for bromate-aromatic compounds systems.     

In situ removal of carbon contamination from optics in a vacuum ultraviolet and soft X‐ray undulator beamline using oxygen activated by zeroth‐order synchrotron radiation

Carbon contamination of optics is a serious issue in all soft X‐ray beamlines because it decreases the quality of experimental data, such as near‐edge X‐ray absorption fine structure, resonant photoemission and resonant soft X‐ray emission spectra in the carbon K‐edge region. Here an in situ method involving the use of oxygen activated by zeroth‐order synchrotron radiation was used to clean the optics in a vacuum ultraviolet and soft X‐ray undulator beamline, BL‐13A at the Photon Factory in Tsukuba, Japan. The carbon contamination of the optics was removed by exposing them to oxygen at a pressure of 10^?1–10^?4 Pa for 17–20 h and simultaneously irradiating them with zeroth‐order synchrotron radiation. After the cleaning, the decrease in the photon intensity in the carbon K‐edge region reduced to 2–5%. The base pressure of the beamline recovered to 10^?7–10^?8 Pa in one day without baking. The beamline can be used without additional commissioning.     

Rhodium-catalyzed reaction of terminal alkynes with allylamine leading to (E)-3-alkylidene N-heterocycles

Terminal alkynes react with allylamine in the presence of a RhCl(PPh3)3 catalyst to give (E)-3-alkylidene-3,4-dihydro-2H-pyrroles. The products consist of two molecules of alkyne and one molecule of allylamine. Although dimers, trimers, and oligomers of alkynes are also obtained as byproducts, the addition of various ammonium salts to the reaction suppresses such oligomerization, resulting in an increase in product.     

Synthesis and properties of poly(carbonate‐urethane) consisting of alternating carbonate and urethane moieties

Poly(carbonate‐urethane) consisting of alternating carbonate and urethane moieties (poly(HC‐MDI)) was prepared by polyaddition of 4,4′‐diphenylmethane diisocyanate (MDI) and a monocarbonate diol bis(3‐hydroxypropyl)carbonate (HC), prepared by hydrolysis of a six‐membered spiroorthocarbonate 1,5,7,11‐tetraoxa‐spiro[5.5]undecane. The polyaddition proceeds without concomitant side reactions including carbonate exchange reaction and affords the desired poly(carbonate‐urethane). The hydrolysis and thermal behaviors of poly(HC‐MDI) were compared with those of the analogous polyurethane carrying no carbonate structure (poly(ND‐MDI)) prepared from MDI and 1,9‐nonanediol (ND). Although the glass transition behaviors are almost identical, poly(HC‐MDI) is less crystalline than poly(ND‐MDI). Poly(HC‐MDI) is more susceptible to hydrolysis than poly(ND‐MDI) probably due to the higher polarity and the lower crystallinity. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2802–2808, 2006     

GaCl3 Promoted one-step α,α-diethynylation and α,α-diethenylation reactions of silyl enol ethers

In the presence of GaCl₃ and 2,6-di(tert-butyl)-4-methylpyridine, α-monosubstituted silyl enol ethers were α,α-diethynylated with a chlorosilylacetylene in one step. An analogous reaction using a silylacetylene gave α,α-diethenylated ketones.