Ceria-modified hierarchical Hβ zeolite as a robust solid acid catalyst for alkenylation of p-xylene with phenylacetylene

A ceria‐modified hierarchical Hβzeolite was prepared by a desilication‐dealumination procedure followed by ceria modification.The catalytic performance of the ceria‐modified and unmodified hierarchical Hβzeolite catalysts for alkenylation of p‐xylene with phenylacetylene was investigated.Various characterization techniques,including X‐ray diffraction,X‐ray fluorescence,nitrogen adsorption‐desorption,and NH3temperature‐programmed desorption,were used to examine the structure‐performance relationships.Our results show that the optimized ceria‐modified hierarchical Hβzeolite catalyst demonstrated higher catalytic activity,selectivity,and stability for alkenylation of p‐xylene with phenylacetylene than those of pristine Hβzeolite.This performance was attributed to more acidic sites and improved accessibility to active sites through larger pores,together with a higher mesoporous surface area and volume resulting from the hierarchical pore architecture and ceria modification.Thus,our5wt%CeO2‐Hβ‐B0.2A0.2catalyst shows great potential for producing alkenyl aromatics through solid acid catalyzed alkenylation.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved

EPR and DFT Study of the Polycyclic Aromatic Radical Cations from Friedel-Crafts Alkylation Reactions

Electron paramagnetic resonance and electron-nuclear double resonance methods were used to study the polycyclic aromatic radical cations produced in a Friedel-Crafts alkylating sys- tem, with m-xylene, or p-xylene and alkyl chloride. The results indicate that the observed electron paramagnetic resonance spectra are due to polycyclic aromatic radicals formed from the parent hydrocarbons. It is suggested that benzyl halides produced in the Friedel-Crafts alkylation reactions undergo Scholl self-condensation to give polycyclic aromatic hydrocar- bons, which are converted into corresponding polycyclic aromatic radical cations in the presence of AlCl3. The identification of observed two radicals 2,6-dimethylanthracene and 1,4,5,8-tetramethylanthraeene were supported by density functional theory calculations using the B3LYP/6-31G（d,p）//B3LYP/6-31G（d） approach. The theoretical coupling constants support the experimental assignment of the observed radicals.

Synthesis and Mollucicidal Activity of Some New Bicyclic and Polycyclic Pyrimidine Derivatives

Hydrazinolysis ofethylthiopyrimidine derivative 2 gave 2-hydrazinopyrimidine 3 which used as a convenient precursor for the synthesis of pyrazolylpyrimidines, hydrazones and pyrimidotriazines. Also, treatment of 2 with ethyl chloroacetate yielded N^-carbethoxymethyl-2-ethylthio-pyrimidine 15, which on reaction with ethyl carbazate and hydrazine hydrate afforded pyrimidotriazine and imidazopyrimidine, respectively. Chlorination of 2 using phosphorous oxycbloride yielded 4-chloropyrimidine 18, which reacted with some heterocyclic compounds having vicinal amino cyano groups to give some new polynuclear heterocyclic system. Also, the effect of some active methylene compounds on 18 was also studied. Some of the newly synthesized compounds were tested as mollucicidal agents against Biomphlaria alexandrina snails that caused intestinal bilharzias, the national problem in Egypt.

Biotransformation of nitro-polycyclic aromatic compounds by vegetable and fruit cell extracts

Extracts from various vegetables and fruits were investigated for their abilities to reduce nitro-polycyclic aromatic hydrocarbons （NPAHs）. The extracts from grape and onion exhibited an interesting selectivity, yielding corresponding hydroxylamines or amines as major products under mild conditions of 30 ℃ and pH 7.0. Grape extracts reduced the 4-nitro-l,8-naphthalic anhydride with the highest conversion rate （〉99%） and the highest ratio of hydro- xylamine to amine （95：5）. In contrast, the onion extracts reduced 4-nitro-l,8-naphthalic anhydride with a conversion rate of 94% and a ratio of hydroxylamine to amine of 8：92. The thiol-reducing agent, 13-mercaptoethanol, and metal cations, Ca2＋ and Mg2＋, greatly increased the reductive efficiency. This work provides an alternative strategy for biotransformation of nitro-polycyclic compounds.