Silica supported sodium hydrogen sulfate(NaHSO_4/SiO_2):A mild and efficient reusable catalyst for the synthesis of aryl-14-H-dibenzo[a,j]xanthenes under solvent-free conditions

A simple and efficient procedure for the preparation of aryl- 14-H-dibenzo [aj]xanthenes by a one-pot condensation reaction of 2-naphthol and aryl aldehydes, in the presence of silica supported sodium hydrogen sulfate （NaHSO4/SiO2） as a catalyst and in the absence of solvent has been developed. The present method offers several advantages such as excellent yields, short reaction time （10-30min）, mild condition, simple work-up, and the use of a cheap and environmentally friendly catalyst with remarkable reusability.

Synthesis of 1,8-dioxooctahydroxanthenes utilizing PMA-SiO_2 as an efficient reusable catalyst

PMA-SiO2 has been utilized as an efficient catalyst system in preparation of 1,8-dioxooctahydroxanthenes.

Silica supported ammonium dihydrogen phosphate(NH_4H_2PO_4/SiO_2):A mild,reusable and highly efficient heterogeneous catalyst for the synthesis of 14-aryl-14-H-dibenzo[a,j]xanthenes

catalyst for the synthesis of 14-aryl- 14-H-dibenzo[aj]xanthenes Silica supported ammonium dihydrogen phosphate （NH4H2PO4/SiO2） is found to be a recyclable heterogeneous catalyst for a rapid and efficient synthesis of various aryl-14-H-dibenzo[a,j]xanthenes with excellent yields under solvent-free conditions. The present methodology offers several advantages such as excellent yields, simple procedure, short reaction times and milder conditions. 2009 Shahnaz Rostamizadeh. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

A rapid and efficient method for the synthesis of 14H-dibenzo[α.j]xanthenes,aryl-5H-dibenzo[b.i]xanthene-5,7,12,14-(13H)-tetraone and 1,8-dioxooctahydroxanthenes by acidic ionic liquid

Various xanthenes have been synthesized by the condensation ofβ-naphthol,2-hydroxynaphthalene-1,4-dione or dimedone with various aldehydes in the presence of trifluoroacetic acid as catalyst in 1,1,3,3-N,N,N′,N′-tetramethylguanidinium trifluoroacetate （TMGT） ionic liquid within 1 h at 75℃.

Fe(HSO_4)_3:An efficient,heterogeneous and reusable catalyst for the synthesis of 14-aryl- or alkyl-14H-dibenzo[a,j]xanthenes

Fe（HSO4）3 has been used as an efficient and recyclable catalyst for the one-pot synthesis of 14-aryl- or alkyl-14Hdibenzo[aj]xanthene derivatives by the reaction of 2-naphtol and aldehydes. Different types of aromatic and aliphatic aldehydes are used in the reaction and in all cases the products were obtained in good to excellent yields.

Oxalic acid as a catalyst for efficient synthesis of bis-(indolyl)methanes,and 14-aryl-14H-dibenzo[a,j]xanthenes in water

A simple, efficient, and environment benign route was developed for the preparation of bis-（indolyl）methanes and 14-aryl-14H- dibenzo[aj]xanthenes from condensation of various aromatic aldehydes or ketones with indole, and 2-naphthol, respectively, using oxalic acid catalyst in aqueous medium. Use of cheap and easily available catalyst, better yields and simple reaction protocol are the advantages of the present method.

A novel soluble polyamide containing xanthene structure and trifluoromethylphenoxy pendent

A novel polyamide containing xanthene structure and trifluoromethylphenoxy pendent was prepared from 9,9-bis[4-(4- aminophenoxy)phenyl]xanthene,a novel diamine with 2-(4-trifluoromethylphenoxy)terephthaloyl chloride,by the low temperature polycondensation.This new polyamide with the inherent viscosity of 0.95 dL/g was amorphous and readily soluble in polar solvents such as DMAc,m-cresol,etc.This polyamide showed the glass transition temperature(T_g) of 236℃,decomposition temperature (Td) at 5%weight loss of...

A new fluorinated poly(ether amide) bearing xanthene group

A new fluorinated poly(ether amide) bearing xanthene group was prepared from 9,9-bis[4-(2-trifluoromethyl-4-aminophenox- y)phenyl]xanthene (BTFAPX) with 9,9-bis[4-(4-carboxyphenoxy)phenyl]xanthene (BCAPX) in the presence of triphenyl phos- phate and pyridine (Py). The polymer had the weight-average molecular weight (Mw) of 69,000 and number-average molecular weight (Mn) of 39,000, showed the glass transition temperature (Tg) of 267 ℃, 5% weight loss temperature (Tds) over 460 ℃ both in N2 and air, and char yield of 62% at 800 ℃ in N2. This polymer was amorphous and readily soluble in amide-type solvents such as N,N-dimethylacetamide (DMAc), and even in m-cressol, Py and tetrahydrofuran (THF) at room temperature, and exhibited tensile strength of 74 MPa, elongation at break of 6%, tensile moduli of 2.2 GPa. The polymer had low dielectric constant of 3.69 (100 Hz), low moisture absorption of 0.56%, and high transparency with an ultraviolet-visible absorption cut-off wavelength at 334 nm.

Highly Sensitive Spectrophotometric Determination of Trace Amounts of Uranium ( Ⅵ ) with Thiocyanate-Basic Xanthene Dye-Gum Arabic Systems

Spectrophotometric determination of molybdenum, zinc, cobalt(Ⅱ), indium, selenium (Ⅳ), iron (Ⅲ), vanadium (Ⅴ), which is based on the ion-associate complexes formed by the reaction of metal ion-thiocyanate anionic complexes with some basic dyes in aqueous solution in the presence of a surfactant has been reported.

Co-colouration Effects in the Systems of Metal(Ⅱ)-Rare Earth(Ⅲ)-Xanthene Dye and Their Influences on Photometric Determination of Metal Ions

After comparing the influences of each rare earth(Ⅲ),11 species of metal(Ⅱ)and 8 species of acidic triphenylmethane dye on the formation of coloured coordination compound in the system of Metal(Ⅱ)-RE (Ⅲ)-Dye,it was proven that the co-colouration effect can be caused only by the xanthene dyes(XD)con- taining substituting hydroxy.group on the ortho-position of etheric oxygen group.Besides,the radius of met- al(Ⅱ)must not be smaller than a definite limit;otherwise,no co-colouration appears.Furthermore,the acid- ity of medium is another important factor to affect co-colouration,Bromopyrogallol red causes co-colouration of Pb(Ⅱ)-RE(Ⅲ)only,owing to its higher chromophoric acidity;while alizarin violet causes co-colouration of M(Ⅱ)-RE(Ⅲ)(M=Pb,Ca,Sr and Ba),due to its lower chromophoric acidity.The condi- tions causing co-colouration,the regularities of co-colouration and the influences of co-colouration in photometric determination of metals were discussed.

Synthesis and Crystal Structure of 9-（4-Methoxylphenyl）-1,8-di-oxo-3,4,5,6,7,9-hexahydroxanthene under Microwave Irradiation

The crystal structure of the title compound (C20H20O4, Mr = 324.36) has been determined by single-crystal X-ray diffraction. The crystal is of orthorhombic, space group Pbcn with a = 15.823(2), b = 18.002(3), c = 11.674(2) ?, V = 3325.34(67) ?3, Dc = 1.296 g/cm3, μ = 0.090 mm-1, Z = 8, F(000) = 1376, the final R = 0.0421 and wR = 0.0996. In the molecular structure, the pyran ring is of boat conformation, and the two six-membered rings fused with it adopt twisting-boat conformations.

L-Pyrrolidine-2-Carboxylic Acid Sulfate (LPCAS): A New Ionic Liquid for the Synthesis of 14-Aryl-14H-Dibenzo[a,j] Xanthenes under Solvent Free Condition

A new Bronsted acidic ionic liquid, L-Pyrrolidine-2-carboxylic acid sulfate (LPCAS) was employed to promote one-pot synthesis of 14-aryl-14H-dibenzo [a,j] xanthenes via condensation reaction of aldehydes and 2-naphthol under solvent free condition. Distinguishing features of the methodology are excellent yield of products in shorter reaction time, cleaner reaction profile, eco-friendly nature and the use of inexpensive catalyst.

Synthesis of 14-aryl or alkyl-14H-dibenzo[a,j]xanthenes promoted by Mg(HSO_4)_2

14-Aryl or alkyl-14H-dibenzo[a,j]xanthenes were prepared by condensation of 2-naphthol and aldehydes in the presence of Mg（HSO4）2 as an efficient, cheap, readily available and eco-friendly catalyst. This procedure has the advantages of high yields, easy work-up, short reaction times, and green conditions.

Zinc oxide nanoparticles:A highly efficient and readily recyclable catalyst for the synthesis of xanthenes

A novel and efficient route for the synthesis of 1,8-dioxooctahydroxanthenes and 14-aryl-14H-dibenzo[a,j]xanthenes is described through one-pot multi-component reaction of dimedone and 2-naphthol with various aryl aldehydes using ZnO nanoparticles under solvent-free conditions. This method provides a novel and improved pathway for the synthesis of xanthenes in the terms of excellent yields, short reaction times, reusability and low catalyst loading.

One-pot synthesis of various xanthene derivatives using ionic liquid1,3-disulfonic acid imidazolium hydrogen sulfate as an efficient and reusable catalyst under solvent-free conditions

In this study, 1,3-disulfonic acid imidazolium hydrogen sulfate （DSIMHS） is used as an efficient and reusable ionic liquid for the green, mild, and efficient synthesis of xanthenes under solvent-free conditions. Simple and easy work-up, low cost, green process, short reaction times and excellent yields of the products are the advantages of this procedure. Further, the catalyst can be recycled and reused at least for four times without a noticeably decrease in its catalytic activity.

Silica Gel-Supported Polyphosphoric Acid （PPA/SiO2）： An Efficient and Reusable Heterogeneous Catalyst for Facile Synthesis of 14-Aryl-14H-dibenzo[aj]xanthenes under Solvent-free Conditions

A simple, efficient and green method for the synthesis of 14-aryl-14H-dibenzo[aj]xanthenes by a one-pot condensation reaction of β-naphthol and aryl aldehydes using silica gel-supported polyphosphoric acid （PPA/SiO2）, an effective and reusable catalyst, under solvent-free conditions is described. The present methodology offers several advantages, such as a simple procedure with an easy work-up, short reaction times, high yields, and the absence of any volatile and hazardous organic solvents.

Highly efficient and green synthesis of 14-aryl(alkyl)-14H-dibenzo[a,j]xanthene and 1,8-dioxooctahydroxanthene derivatives catalyzed by reusable zirconyl triflate[ZrO(OTf)_2]under solvent-free conditions

An efficient, convenient and green method has been introduced for the preparation of 14-aryl（alkyl）-14H-dibenzo[a,j]xanthene and 1,8-dioxooctahydroxanthene derivatives by the reaction of aldehydes with 2-naphthol and 5,5-dimethyl-1,3-cyclohexanedione, respectively, in the presence of ZrO（OTf）2 as a reusable catalyst under solvent-free conditions. In addition, very short reaction times, excellent yields, straightforward procedure, and relatively non-toxicity of the catalyst are other noteworthy advantages of the present method.

An efficient and eco-friendly synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes using H_4[SiW_(12)O_(40)]as a heterogeneous and reusable catalyst under solvent-free conditions

A simple and efficient catalytic protocol for the synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes via the one-pot condensation ofβ-naphthol and aryl aldehydes using silicotungstic acid（H_4[SiW_（12）O_（40）]） is reported.The present method offers several advantages such as high to excellent yields,short reaction times,recovery and reusability of catalyst,mild reaction conditions and easy workup procedures.

“Xanthene” is a premium bridging group for xanthenoid dyes

Novel xanthenoid dyes by replacing the central oxygen atom of the xanthene dyes with less electronrich bridging groups have been intensively sought after primarily for their long spectral wavelengths.However, the new scaffolds are likely prone to nucleophilic attack at their central methane carbon, as the result of the reduced electron density of the fluorochromic scaffolds. We envisage that the bridging group may be harnessed to sterically shield the central methane carbon from incoming nucleophiles and render high stability and synthesized xantheno-xanthene dyes. Additionally, the xantheno-bridging group can be modified via electrophilic aromatic substitution to introduce functionalities, e.g., sulfonate groups.

Synthesis of 14-Fluorophenyl-14H-Dibenzo[a,j]xanthenes and Their Derivatives under Microwave Irradiation and Solvent-free Conditions

A facile and efficient synthesis of 14-fluorophenyl-14H-dibenzo[a,j]xanthenes has been developed by one-pot condensation of fluorinated benzaldehydes with β-naphthol in the presence of p-TSA·H2O under microwave irradiation and solvent-free conditions. These products are conveniently oxidized to 14-fluorophenyl-14-hydroxydibenzo[a,j]xanthenes by PbO2 in acetic acid in good yields.