无溶剂高度分散Ni/MCM-41催化剂的制备及其萘加氢性能

分别用机械研磨无溶剂法、添加柠檬酸无溶剂法制备了Ni/MCM-41催化剂,对所制催化剂进行了分析表征,探究其萘加氢反应性能并与常规浸渍法进行了对比。与常规浸渍法相比,机械研磨无溶剂法所制催化剂的物理性质相近,金属镍分散度和萘加氢性能略有提高;添加柠檬酸无溶剂法则显著提升了催化剂的分散度和萘加氢性能,金属镍分散度由6.9%大幅提高至67.9%,萘加氢性能提高了近1倍。通过红外光谱、紫外光谱和热重分析,提出了添加柠檬酸对无溶剂法制备催化剂性能的促进作用机制。     

How to Predict Excited State Geometry by Using Empirical Parameters Obtained from Franck-Condon Analysis of Optical Spectrum

Excited state geometries of molecules can be calculated with highly reliable wavefunction schemes. Most of such schemes, however, are applicable to small molecules and can hardly be viewed as error-free for excited state geometries. In this study, a theoretical approach is presented in which the excited state geometries of molecules can be predicted by using vibrationally resolved experimental absorption spectrum in combination with the theoretical modelling of vibrational pattern based on Franck-Condon approximation. Huang-Rhys factors have been empirically determined and used as input for revealing the structural changes occurring between the ground and the excited state geometries upon photoexcitation. Naphthalene molecule has been chosen as a test case to show the robustness of the proposed theoretical approach. Predicted 1B_2u excited state geometry of the naphthalene has similar but slightly different bond length alternation pattern when compared with the geometries calculated with CIS, B3LYP, and CC2 methods. Excited state geometries of perylene and pyrene molecules are also determined with the presented theoretical approach. This powerful method can be applied to other molecules and specifically to relatively large molecules rather easily as long as vibrationally resolved experimental spectra are available to use.     

On the reactivity of naphthalene and biphenyl dianions: tying up loose ends concerning an SN2‐ET dichotomy in alkylation reactions

Naphthalene and biphenyl dianions are interesting compounds that can be obtained by double reduction of the corresponding arenes in solution with certain alkali metals. These dianions are highly reactive and rather elusive species with very high laying and highly delocalized electrons. They share many aspects of the reactivity of the alkali metal they originated from and consequently behave primarily as strong electron transfer (ET) reagents. We report here kinetic evidence for a different type of reactivity in their alkylation reactions with alkyl fluorides. By using cyclopropylmethyl fluoride (c‐C₃H₅CH₂F) as a very fast radical probe, we were able to settle that this alkylation does not involve the classical electron transfer reaction followed by radical coupling between diffusing radicals, but supports the alternative S_N2 concerted mechanism, discerning thus this mechanistic S_N2‐ET dichotomy. Copyright © 2015 John Wiley & Sons, Ltd.     

Living cationic polymerization of vinyl ethers with a naphthyl group: Decisive effect of the substituted position on naphthalene ring

Living cationic polymerization of a vinyl ether with a naphthyl group [2‐(2‐naphthoxy)ethyl vinyl ether, βNpOVE] was achieved using base‐assisting initiating systems with a Lewis acid. The Et_1.5AlCl_1.5/1,4‐dioxane or ethyl acetate system induced the living cationic polymerization of βNpOVE in toluene at 0 °C. The living nature of this reaction was confirmed by a monomer addition experiment, followed by ¹H NMR and matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry (MALDI‐TOF‐MS) analyses. In contrast, the polymerization of αNpOVE was not fully controlled; under similar conditions, it produced polymers with broad molecular weight distributions. The ¹H NMR and MALDI‐TOF‐MS spectra of the resultant poly(αNpOVE) revealed that the products had undesirable structures derived from Friedel–Crafts alkylation. The higher reactivity of αNpOVE in electrophilic substitution reactions, such as the Friedel–Crafts reaction, was attributable to the greater electron density of the naphthyl ring, which was calculated based on frontier orbital theory. The naphthyl groups significantly affected the properties of the resultant polymer. For example, the glass transition temperatures (T_g) of poly(NpOVE)s are higher by approximately 40 °C than that of poly(2‐phenoxyethyl vinyl ether). © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Rhodium-Catalyzed Dimerization of Diaryl Acetylenes in the Presence of Grignard Reagents: Synthesis of 1,2,3-Triphenyl Naphthalene Derivatives

An efficient Rh-catalyzed dimerization of diaryl acetylenes was achieved in the presence of Wilkinson catalyst, AgF₂, and 1.5 equivalent of PhMgBr in toluene, providing the 1,2,3-triaryl naphthalene derivatives in moderate to good yields.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications to view the free supplemental file.     

A scalable synthesis of 1-amino-5-cyanonaphthalene,a precursor for a nitric oxide probe(NO550) designed via the "dye assembly" principle

A convenient and scalable synthesis of l-amino-5-cyanonaphthalene was described.     

Trifluoroethylxanthate as an Analytical Reagent: AAS of Zinc,Antimony and Lead After Coprecipitation of Their Trifluoroethylxanthates onto Microcyrstalline Naphthalene

Abstract

A sensitive method has been developed for the direct atomic absorption spectrometric determination of zinc, antimony and lead after coprecipitation of their trifluoroethylxanthates onto microcrystalline naphthalene. The metal xanthates are quantitatively coprecipitated over the pH ranges: Zn, 5.9–8.4; Sb, 4.0–6.0 and Pb, 4.0–11.0. The solid mass consisting of the metal complex and naphthalene is dissolved in DMF. This solution is aspirated into an air-acetylene flame at 213.9, 217.6 and 217.0nm for Zn, Sb and Pb, respectively. Beer's law is obeyed in the concentration range 2–50, 3–90 and 5–60 μg of Zn, Sb and Pb, respectively in 10ml of the final DMF solution. RSDs are at the ± (0.5–0.6)% level (n=10). The concentration for 1% absorption is 0.019, 0.035 and 0.060μg/ml for Zn, Sb and Pb, respectively. The method is suitable for the preconcentration of the metals from a larger volume of the aqueous phase, and has been employed for their determination in standard reference materials. It may be employed for the simultaneous determination of Zn, Pb and Sb in a solution by pH control.     

Solution‐processable transmissive‐to‐green switching electrochromic polyamides bearing 2,7‐bis(diphenylamino)naphthalene units

A new 2,7‐bis(diphenylamino)naphthalene‐based diamine monomer, N,N′‐bis(4‐aminophenyl)‐N,N′‐bis(4‐methoxyphenyl)‐2,7‐naphthalenediamine, was synthesized and polymerized with various aromatic dicarboxylic acids via the phosphorylation polyamidation reaction leading to a new series of redox‐active and electrochromic aromatic polyamides. The polyamides exhibited high solubility in many polar aprotic solvents, good film‐forming ability, and high thermal stability. They also showed stable electrochemical stability and anodically green coloring when oxidized. The two arylamino centers showed a weak electronic interaction via the 2,7‐naphthalenediyl bridge, and thus they started to oxidize almost at the same time. No intervalence charge transfer (IVCT) absorption was observed during the oxidation processes of these polyamides. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1409–1421