394 research outputs found
Rhodium-Catalyzed Cascade Annulative Coupling of 3,5-Diarylisoxazoles with Alkynes
A rhodium-catalyzed cascade annulative coupling of 3,5-diarylisoxazoles with three equivalents of an alkyne proceeds smoothly in the presence of a Cu(II) oxidant, where the sequential construction of isoquinoline and naphtho[1,8- bc ]pyran frameworks connected by a biaryl linkage is achieved by a single operation. Most of the obtained polycyclic compounds exhibit visible fluorescence in both the solution and the solid state. The hexaphenylated isoquinoline-naphthopyran conjugate (R = Ph) as a representative product shows a green emission which can be turned off by making an isoquinolinium salt with an acid. The emission is also reversibly turned on by treatment with a base.Noguchi T., Nishii Y., Miura M.. Rhodium-Catalyzed Cascade Annulative Coupling of 3,5-Diarylisoxazoles with Alkynes. Synthesis (Germany) 51, 258 (2019); https://doi.org/10.1055/s-0037-1610376
Materials Processing Characteristics of a 2kW Class High Power Density Direct Diode Laser System(Physics, Processes, Instruments & Measurements)
Measurement of Secondary Products During Oxidation Reactions of Terpenes and Ozone Based on the PTR-MS Analysis: Effects of Coexistent Carbonyl Compounds
Continuous measurements using proton transfer reaction mass spectrometry (PTR-MS) can be used to describe the production processes of secondary products during ozone induced oxidation of terpenes. Terpenes are emitted from woody building materials, and ozone is generated from ozone air purifiers and copy machines in indoor environments. Carbonyl compounds (CCs) are emitted by human activities such as smoking and drinking alcohol. Moreover, CCs are generated during ozone oxidation of terpenes. Therefore, coexistent CCs should affect the ozone oxidation. This study has focused on the measurement of secondary products during the ozone oxidation of terpenes based on the use of PTR-MS analysis and effects of coexistent CCs on oxidized products. Experiments were performed in a fluoroplastic bag containing α-pinene or limonene as terpenes, ozone and acetaldehyde or formaldehyde as coexistent CCs adjusted to predetermined concentrations. Continuous measurements by PTR-MS were conducted after mixing of terpenes, ozone and CCs, and time changes of volatile organic compounds (VOCs) concentrations were monitored. Results showed that, high-molecular weight intermediates disappeared gradually with elapsed time, though the production of high-molecular weight intermediates was observed at the beginning. This phenomenon suggested that the ozone oxidation of terpenes generated ultrafine particles. Coexistent CCs affected the ozone oxidation of α-pinene more than limonene
2,7-Bis(4-acetylphenoxy)naphthalene
The title compound, C26H20O4, has an asymmetrical conformation at 193 K. The 4-acetylphenyl groups are twisted away from the the naphthalene ring system, with one benzene ring turned towards the 1-position of the naphthalene ring and the other benzene ring turned towards the 6-position. The interplanar angles between the mean planes of the benzene rings and the naphthalene ring system are 68.71 (6) and 74.01 (6)°. The structure displays C—H⋯O hydrogen bonding and π–π stacking interactions [centroid–centroid and interplanar distances are 3.5938 (9) and 3.517 Å, respectively]
High speed welding of thin steel plates with high power and high power density diode laser system
Gravitational Kaluza-Klein Modes in Warped Superstring Compactification
The Kaluza-Klein (KK) modes of graviton are studied in the IIB superstring
compactification where the warped geometry is realized at the
Klebanov-Strassler (KS) throat. Knowledge of the metric of the KS throat
enables us to determine their wave functions with good accuracy, without any
further specification of the rest of Calabi-Yau space, owing to the
localization of the KK modes. Mass spectrum and couplings to the four
dimensional fields are computed for some type of the KK modes, and compared to
those of the well-known Randall-Sundrum model. We find that the properties of
the KK modes of the two models are very different in both the masses and the
couplings, and thus they are distinguishable from each other experimentally.Comment: 13 pages, Table 2 replaced, the related discussion modifie
Welding and Forming of Steel Plates with Diode Laser(Physics, Processes, Instruments & Measurements)
Rhodium-catalyzed annulative coupling of isothiazoles with alkynes through n-s bond cleavage
A Rh(III)-catalyzed annulative coupling of 3,5-diarylisothiazoles and alkynes is reported. The N–S bond in the isothi-azole ring acts as an internal oxidant to regenerate the Rh(III) species in combination with an external Cu(II) oxidant, and the corre-sponding 1:2 coupling products are obtained. The remarkable difference in the reaction outcome between isothiazoles and the relevant isoxazoles has been investigated by DFT calculations, revealing that the relative stability of the enolate intermediates dictates the product selectivity.Mihara G., Noguchi T., Nishii Y., et al. Rhodium-catalyzed annulative coupling of isothiazoles with alkynes through n-s bond cleavage. Organic Letters. 22(2), 661-665, (2020), 17 January 2020; ©2020 American Chemical Society. https://doi.org/10.1021/acs.orglett.9b04437
New 60-cm Radio Survey Telescope with the Sideband-Separating SIS Receiver for the 200 GHz Band
We have upgraded the 60-cm radio survey telescope located in Nobeyama, Japan.
We developed a new waveguide-type sideband-separating SIS mixer for the
telescope, which enables the simultaneous detection of distinct molecular
emission lines both in the upper and lower sidebands. Over the RF frequency
range of 205-240 GHz, the single-sideband receiver noise temperatures of the
new mixer are 40-100 K for the 4.0-8.0 GHz IF frequency band. The image
rejection ratios are greater than 10 dB over the same range. For the dual IF
signals obtained by the receiver, we have developed two sets of acousto-optical
spectrometers and a telescope control system. Using the new telescope system,
we successfully detected the 12CO (J=2-1) and 13CO (J=2-1) emission lines
simultaneously toward Orion KL in 2005 March. Using the waveguide-type
sideband-separating SIS mixer for the 200 GHz band, we have initiated the first
simultaneous 12CO (J=2-1) and 13CO (J=2-1) survey of the galactic plane as well
as large-scale mapping observations of nearby molecular clouds.Comment: 15 pages, 15 figures, Accepted for publication in PASJ, version with
high resolution figures is available via
http://www.nro.nao.ac.jp/~nakajima/vst1_2sb.pd
- …