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421.
Suddapalli Chaitanya Kumar Adolfo Esteban‐Martin Takuro Ideguchi Ming Yan Simon Holzner Theodor W. Hnsch Nathalie Picqu Majid Ebrahim‐Zadeh 《Laser \u0026amp; Photonics Reviews》2014,8(5):L86-L91
A few‐cycle, broadband, singly‐resonant optical parametric oscillator (OPO) for the mid‐infrared based on MgO‐doped periodically‐poled LiNbO3 (MgO:PPLN), synchronously pumped by a 20‐fs Ti:sapphire laser is reported. By using crystal interaction lengths as short as 250 µm, and careful dispersion management of input pump pulses and the OPO resonator, near‐transform‐limited, few‐cycle idler pulses tunable across the mid‐infrared have been generated, with as few as 3.7 optical cycles at 2682 nm. The OPO can be continuously tuned over 2179‐3732 nm (4589‐2680 cm‐1) by cavity delay tuning, providing up to 33 mW of output power at 3723 nm. The idler spectra exhibit stable broadband profiles with bandwidths spanning over 422 nm (FWHM) recorded at 3732 nm. The effect of crystal length on spectral bandwidth and pulse duration is investigated at a fixed wavelength, confirming near‐transform‐limited idler pulses for all grating interaction lengths. By locking the repetition frequency of the pump laser to a radio‐frequency reference, and without active stabilization of the OPO cavity length, an idler power stability better than 1.6% rms over >2.75 hours is obtained when operating at maximum output power, in excellent spatial beam quality with TEM00 mode profile. Photograph shows a multigrating MgO:PPLN crystal used as a nonlinear gain medium in the few‐cycle femtosecond mid‐IR OPO. The visible light is the result of non‐phase‐matched sum‐frequency mixing between the interacting beams. 相似文献
422.
Ali Ramazani Liela Yousefi Ebrahim Ahmadi Ali Souldozi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1459-1464
Protonation of the highly reactive 1:1 intermediates, produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates, by phenols (1-hydroxynaphthalene, 2-hydroxynaphthalene, 4-bromophenol, 2-hydroxybenzaldehyde, and 5-bromo-2-hydroxyben- zaldehyde) leads to vinyltriphenylphosphonium salts, which undergo electrophilic substitution reaction with conjugate base to produce corresponding stabilized phosphorus ylides. Microwave was found to catalyze conversion of the stabilized phosphorus ylides to chromene derivatives in the presence of solid catalysts in solvent-free conditions at microwave power 0.4 KW in 3 min. 相似文献
423.
Ali Ramazani Ebrahim Ahmadi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1455-1457
Microwave was found to catalyze stereoselective conversion of dialkyl 2-(imido-N-yl)-3-(triphenylphosphoranylidene)butanedioates to electron-poor (Z)-N-vinylimides in the presence of iron(II) sulfate powder in solvent-free conditions in 4 min. 相似文献
424.
Ali Ramazani Ebrahim Ahmadi Ali Reza Kazemizadeh Leila Dolatyari Nader Noshiranzadeh Issa Eskandari 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):2419-2422
Abstract Protonation of the highly reactive 1:1 intermediates, produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates by amide derivatives of 2-aminobenzaldehyde in the mixture of acetone-water (3:1) leads to vinyltriphenylphosphonium salts, which undergo a Michael addition reaction with a conjugate base to produce the corresponding stabilized phosphorus ylides. An intramolecular Wittig reaction of the stabilized phosphorus ylide group with the aldehyde group leads to the corresponding dialkyl 1,2-dihydroquinoline-2,3-dicarboxylates. 相似文献
425.
426.
An efficient and direct protocol for the preparation of amidoalkyl naphthols employing a multicomponent, one-pot condensation reaction of β-naphthol, aromatic aldehydes, and amides (acetamide, benzamide, and urea) in the presence of tetrakis(acetonitrile)copper(I) hexafluorophosphate [Cu(CH3CN)4PF6] under solvent-free conditions at 80 °C is described. Good yields, short reaction time, and easy workup are advantages of this procedure. 相似文献
427.
This review highlights the methods used for the synthesis of 3-oxo-N-(pyridin-2-yl)butanamide compounds. The reactivity and synthetic importance are investigated. In this context, recent progress in the synthesis and use of 3-oxo-N-(pyridin-2-yl)butanamide as precursors for heterocyclic compounds is reviewed. The synthetic routes for preparation of 3-oxo-N-(pyridin-2-yl)butanamide are based on the reaction of diketene with aromatic primary amine and reaction of 2-aminopyridine with β-keto-t-butylthioester or ethylacetoacetate. The bibliography includes 73 references. 相似文献
428.
Abbas Ali Esmaeili Hamid VesalipoorRahele Hosseinabadi Alireza Fakhari ZavarehMohammad Ali Naseri Ebrahim Ghiamati 《Tetrahedron letters》2011,52(38):4865-4867
The zwitterions generated from pyridine and dialkyl acetylenedicarboxylate (DAAD) reacted with benzofuran-2,3-diones to form highly substituted spiro pyrido[2,1-b][1,3]oxazines in good to high yields without using a catalyst. 相似文献
429.
430.
Natural gas viscosity is an important parameter in many gas and petroleum engineering calculations.This study presents a new empirical model for quickly calculating the natural gas viscosity.The model was derived from 4089 experimental viscosity data with varieties ranging from 0.01 to 21,and 1 to 3 of pseudo reduced pressure and temperature,respectively.The accuracy of this new empirical correlation has been compared with commonly used empirical models,including Lee et al.,Heidaryan et al.,Carr et al.,and Adel Elsharkawy correlations.The comparison indicates that this new empirical model can predict viscosity of natural gas with average absolute relative deviation percentage AARD (%) of 2.173. 相似文献