Brønsted acidic ionic liquid as an efficient and reusable catalyst for one-pot synthesis of 1-amidoalkyl 2-naphthols under solvent-free conditions

A mild and efficient method has been developed for the preparation of amidoalkyl naphthols from condensation of aldehydes with amides or urea and 2-naphthol in the presence of a catalytic amount of Brønsted acidic ionic liquid ([TEBSA][HSO₄]) under thermal solvent-free conditions. High yields, short reaction time, easy work-up and reusability of the catalyst are advantages of this procedure.     

Zr(HSO4)4 catalyzed one-pot strecker synthesis of α-amino nitriles from aldehydes and ketones under solvent-free conditions

A mild and efficient method has been developed for the preparation of α-amino nitriles from the condensation of aldehydes and ketones with aniline and TMSCN in the presence of a catalytic amount of Zr(HSO₄)₄ under solvent-free conditions at room temperature.     

Effects of geometrical parameters on optical characteristics of erbium doped photonic crystal fiber based on FVEIM

In this paper, using the fully vectorial effective index method (FVEIM), dependence of the refractive index of fundamental mode, mode field diameter and normalized frequency of the photonic crystal fiber on geometrical parameters of fiber are investigated. Simulations show that the normalized frequency of the photonic crystal fiber increases gently with increase of the air filling factor. Range of parameters in which erbium doped photonic crystal fiber is single mode at both the pump wavelength and the signal is determined. Wavelength dependence of the normalized frequency implies that single mode region of the signal in the case of using dopants such as ytterbium or erbium is significantly (about 1.6 times) more than the pump. In addition, it is shown that by changing dopant material to obtain a higher gain for an optimum set of geometrical parameters, no considerable change in the area of single mode occurs.     

Chemoselective synthesis of 1,1-diacetates from aldehydes in the presence of Al(HSO<Subscript>4</Subscript>)<Subscript>3</Subscript> under mild solvent-free conditions

A novel efficient procedure has been developed for the preparation of acylals in high yields by reaction of the corresponding aldehydes with acetic anhydride in the presence of Al(HSO₄)₃ as catalyst under mild (room temperature) solvent-free conditions. Published in Russian in Zhurnal Organicheskoi Khimii, 2007, Vol. 43, No. 6. pp. 855–857. The text was submitted by the authors in English.     

Brønsted Acidic Ionic Liquid as an Efficient and Reusable Catalyst for One-Pot,Three-Component Synthesis of Pyrimidinone Derivatives via Biginelli-Type Reaction Under Solvent-Free Conditions

A mild and efficient method has been developed for the preparation of pyrimidinone derivatives from the reaction of aromatic aldehydes with cyclopentanone and urea or thiourea in the presence of N-(4-sulfonic acid) butyl triethyl ammonium hydrogen sulfate ([TEBSA][HSO₄]) as the Brønsted acidic ionic liquid and effective catalyst under thermal and solvent-free conditions. Good yields, short reaction times, straightforward workup, reusability of the catalyst, and green conditions are the most obvious advantages of this procedure.

Solvent‐Free Preparation of 1,1‐Diacetates from Aldehydes Mediated by Zirconium Hydrogen Sulfate at Room Temperature

A mild and efficient method has been developed for the preparation of acylals in good yields through a reaction of aldehydes with acetic anhydride using Zr(HSO₄)₄ as catalyst at room temperature and under solvent‐free conditions.