Metal free Lewis acid promoted one-pot synthesis of 14-aryl-14H dibenzo [a,j] xanthenes and their simple biological evolution

A green, competent one-pot synthesis of 14-aryl 14H-dibenzo [a,j] xanthene and its bio-computational studies are reported. Target compounds are prepared by the condensation of 2-naphthol with benzaldehyde and its substituents using metal free benzyltrimethylammonium tribromide (BTMA-Br₃) catalyst under solvent free thermal and microwave conditions. This technique has more advantages such as high yield, a clean procedure, low reaction time, simple workup and mild Lewis organo acid catalyst.     

Convenient Synthesis of 14‐Aryl‐14‐H‐dibenzo[a,j]xanthenes Catalyzed by Acyclic Brønsted Acidic Ionic Liquid [H—NMP]+[HSO4]− under Microwave Irradiation

Efficient method for direct preparation of 14‐aryl‐14‐H‐dibenzo[a,j]xanthenes through condensation of β‐naphthol with various aromatic aldehydes in the presence of the catalytic amount of [H—NMP]⁺[HSO₄]^? under microwave irradiation was described. This method has the advantages such as; very easy reaction workup, absolute separation of catalyst from the reaction mixture and smooth recyclability of catalyst. In this reaction 14‐aryl‐14‐H‐dibenzo[a,j]xanthenes were obtained as desired products in excellent yields and short reaction times via green and one‐pot procedure.     

A facile approach for the synthesis of 14-aryl- or alkyl-14H-dibenzo[a,j]xanthenes under solvent-free condition

A facile, efficient and environment-friendly protocol for the synthesis of 14-aryl- or alkyl-14H-dibenzo[a,j]xanthenes has been developed by one-pot condensation of 2-naphthol with aliphatic and aromatic aldehydes in the presence of P₂O₅ or InCl₃ as catalysts under solvent-free conditions. The present approach offers the advantages of clean reaction, simple methodology, short reaction time, high yield, easy purification, and economic availability of the catalyst.     

Synthesis of 1-14C-17-iodoheptadecanoic acid

1,16-Diiodohexadecane was obtained by reaction of 1,16-hexadecanediol and potassium iodide. The¹⁴C-label was introduced into the 1,16-diiodohexadecan using a substitution reaction which replaced one of the terminal iodine with¹⁴C-cyanide. Hydrolysis and HPLC purification of 1-¹⁴C-17-iodoheptadecanoic acid yielded a product with a radiochemical yield of 17% and a specific activity of approx. 1850 MBq mol^–1.     

Highly efficient heterogeneous acylations of aromatic compounds with acid anhydrides and carboxylic acids by montmorillonite-enwrapped titanium as a solid acid catalyst

Montmorillonite-enwrapped titanium hydroxide species (Ti⁴⁺-mont) acted as a highly efficient heterogeneous acid catalyst for the acylation of aromatic compounds with acid anhydrides or carboxylic acids. The catalytic activity of the Ti⁴⁺-mont was higher than those of other acid catalysts such as zeolites, SO ₄ ^2? /ZrO₂ and p-toluenesulfonic acid. For example, the reaction of anisole with dodecanoic acid in the presence of the Ti⁴⁺-mont catalyst gave 1-(4-methoxyphenyl)-1-dodecanone in 97% yield. Furthermore, the Ti⁴⁺-mont catalyst was easily separated from the reaction mixture and was recyclable.     

BF3·SiO2: an efficient alternative for the synthesis of 14-aryl or alkyl-14H-dibenzo[a,j]xanthenes

Silica-supported boron trifluoride (BF₃·SiO₂) is an efficient, readily available, and reusable catalyst for the synthesis of 14-aryl or alkyl-14H-dibenzo[a,j]xanthenes by condensation of 2-naphthol and aldehydes. This reaction under heating or sonication conditions is very simple, affording good to excellent yields of products.     

Studies on14CO2 exchange reaction with p-fluorophenyl acetic acid and microsynthesis of carboxyl-14C labelled p-fluorophenyl acetic acid

The exchange reaction between¹⁴CO₂ and sodium salt of p-fluorophenyl acetic acid was found to proceed with greater than 50% isotope incorporation when salt to CO₂ ratio was 61. The carboxyl-C-14 labelled p-fluorophenyl acetic acid was isolated in a pure form using small chemical concentrations of radioactive¹⁴CO₂ of high specific activity /30 mCi/mmol/.     

Aluminum phosphate-based solid acid catalysts: Facile synthesis,characterization and their application in the esterification of propanoic acid with n-butanol

Novel solid acid catalysts synthesized from aluminum phosphate were prepared via a precipitation method and a subsequent sulfating treatment. Their catalytic performances for the esterification of propanoic acid with n-butanol were investigated. The as-prepared catalysts were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption–desorption, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), temperature programmed desorption of ammonia (NH₃-TPD), infrared spectroscopy of adsorbed pyridine, and other techniques. Experimental results of esterification reactions indicated that the calcination temperature can significantly affect the catalytic performances and the catalyst calcined at 500 °C (SO₄²⁻/AlPO₄-500) exhibited the highest activity. The effects of different reaction conditions including reaction time, reaction temperature, catalyst amount and alcohol/acid molar ratio were studied in detail. The maximum propanoic acid conversion of 91% was achieved under optimum reaction conditions. Furthermore, the as-prepared SO₄²⁻/AlPO₄-500 catalysts were tested for their reusability in repeated reaction cycles and could be effectively regenerated by a simple reactivation method.     

Preparation,characterization and use of sulfonylbis(1,4-phenylene)<Emphasis Type="Italic">bis</Emphasis>(sulfamic acid) as an eco-benign,efficient, reusable and heterogeneous catalyst for the synthesis of mono- and <Emphasis Type="Italic">bis</Emphasis>-chromenes

Sulfonylbis(1,4-phenylene)bis(sulfamic acid) (SPSA) is easily prepared and recognized as a new heterogeneous catalyst by the reaction of 4,4′-sulfonyldianiline with chlorosulfonic acid. This reagent was used for the synthesis of the mono- and bis-chromene derivatives. All reactions were performed under mild reaction conditions in high to excellent yields. The advantages of using the SPSA as a heterogeneous catalyst in these reactions are: being environmentally friendly, low cost, commercially availability and easy to separate from the mixture of the reaction and high reusable catalyst. Using this catalyst, results in acceptable reaction time and high yields with high purity of the obtained products without utilizing any organic solvents. The catalyst was characterized by FT-IR, ¹H NMR, ¹³C NMR, mass and TGA studies. All the products were characterized by FT-IR, ¹H, ¹³C NMR, HRMS, melting point and elemental analyses.     

Green catalytic synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes using recyclable mesoporous zirconia modified with tungstophosphoric acid

Abstract

A simple and efficient procedure has been developed for the preparation of aryl-14H-dibenzo[a,j]xanthenes by a one-pot condensation of 2-naphthol and aryl aldehydes, in the presence of mesoporous zirconia modified with tungstophosphoric acid (ZrTPA60B_T100), to be used as a heterogeneous catalyst in a solvent-free medium using conventional heating. The present approach offers the advantages of clean reaction, simple methodology, short reaction time, and high yield. The reaction work-up is very simple and the catalyst can be easily separated from the reaction mixture and reused several times in subsequent reactions without appreciable loss of the catalytic activity.     

Degradation studies of14C labelled p-fluorophenylacetic acid prepared by exchange reaction

Carbon-14 labelled p-fluorophenylacetic acid was prepared by heating its sodium salt with¹⁴CO₂ at 325 °C. The labelled acid after isolation from the reaction mixture was degraded by reaction with sodium azide. From the radioactivity measurements it was observed that no scrambling of¹⁴C had taken place and the acid could be designated as carboxyl-¹⁴C.Paper presented at the DAE Symposium on Nuclear Chemistry and Radiation Chemistry in February 1988 at Bombay, India.     

Effects of binder, coking and regeneration on acid properties of H-mordenite during TDP reaction

The effects of binder, coking and regeneration on the acid properties of H-mordenite zeolite during toluene disproportionation reaction (TDP) have been investigated by solid-state ³¹P-MAS-NMR of various adsorbed phosphorous probe molecules in conjunction with elemental analysis by ICP-MS technique. A series of fresh, spent and regenerated mordenite-based commercial catalysts were examined and the results were also compared with binder-free H-mordenite zeolite and unformulated γ-alumina binder. It is found that parent H-mordenite zeolite possessed only Brønsted acidity, which is responsible for the observed catalytic activity. In contrast, the γ-Al₂O₃ binder exhibited only Lewis acidity and plays a minor role during the catalytic reaction. While the amount of strong Brønsted acid sites decreased rapidly during initial coking, it reached a plateau at a total coke content of ca. 7 wt%, corresponding to ca. 80% decrease in total acidity. That the catalyst remained active even under deep coke deposition (>7 wt%) condition indicated catalytic activity may be invoked by subsequent coking taking place on the external surface rather than intracrystalline channels of the zeolite catalyst. Furthermore, upon catalyst regeneration treatment, ca. 75% of the total acidity could be effectively recovered.     

The catalysis, synthesis and characterization of ferrocenylchalcone

Eight kinds of ferrocenylchalcone derivatives were synthesized by the reaction of acetylferrocene and aromatic aldehyde using solid as catalyst in the experiment. The influrence of the catalysts, the raw material molar ratios and reaction times on the yield of ferrocenylchalcone derivatives are discussed. The optimal conditions of synthesis reaction have been selected: the catalyst was KF/Al₂O₃, n(acetyl ferrocene)/n(formal dehyde) = 1:1.2. The structures of the products were characterized by melting point test, IR, ¹HNMR, ¹³CNMR and elemental analysis.     

Rapid,efficient and solvent-free synthesis of (un)symmetrical xanthenes catalyzed by recyclable sulfated polyborate

The present study describes a rapid, simple and straightforward approach to the synthesis of 1,8-dioxo-octahydroxanthenes, 14-phenyl-14H-dibenzo[a,j]xanthene and tetrahydrobenzoxanthene-11-ones under solvent-free conditions using sulfated polyborate as a highly efficient catalyst. The procedure offers several advantages including cleaner reaction profile, mild reaction condition, economic, recyclable and environmentally benign catalyst, high yields, simple experimental and workup procedures. While non-extractive work up/purification, along with reusability of catalyst make this method economically affordable for large scale.     

Synthesis of14C-propoxur (o-isopropoxyphenyl N-methylcarbamate-14C) insecticide

Propoxur (Baygon^®) is an insecticide with a broad spectrum of activity and a very low order of mammalian toxicity. Radiosynthesis of propoxur was performed by the reaction of acetyl-1¹⁴C chloride and sodium azide to produce methyl isocyanate which then reacted with o-isopropoxyphenol at 100°C. A two compartment reaction tube with a break seal was utilized. Chromatographic procedures for isolating the N-methylcarbamates from their reaction mixtures are reported. Acetyl-1–¹⁴C chloride was prepared from thionyl chloride and sodium acetate-1–¹⁴C. Grignard reaction between methyl iodide and carbon –14 dioxide yielded acetic acid –¹⁴C which was neutralized by sodium hydroxide solution to give sodium acetate 1-¹⁴C.     

Nano-TiO<Subscript>2</Subscript>: An eco-friendly and re-usable catalyst for the synthesis of 14-Aryl or alkyl-14<Emphasis Type="Italic">H</Emphasis>-dibenzo[<Emphasis Type="Italic">a,j</Emphasis>]xanthenes

Synthesis of 14-aryl or alkyl-14H-dibenzo[a,j]xanthenes using nano-TiO₂ as eco-friendly and efficient catalyst is reported. Short reaction times, high yields, a clean process, simple methodology, easy work-up and green conditions are advantages of this protocol.     

The microwave spectrum of isoselenocyanic acid,HNCSe

A new molecular species has been detected by passing HBr gas through dry AgNCSe, which is shown by consideration of the rotational constants of the four isotopic species H¹⁴N¹²C⁸⁰Se, H¹⁴N¹²C⁷⁸Se, H¹⁴N¹³C⁸⁰Se and D¹⁴N¹²C⁸⁰Se to be HNCSe. The spectrum is consistent with that of a quasilinear molecule. A preliminary structure has been determined having r(HN) = 0.99 A, r(NC) = 1.95 A, r(CSe) = 1.717 A and a mean HNC angle of 143°. The quadrupole interaction parameter eQq = 1.17 MHz and the dipole moment component μ_a = 1.98 D have also been determined.     

Synthesis of allylamides from allyl halides, carbon monoxide, and titanium-nitrogen complexes prepared from molecular nitrogen

4-Phenylbut-3-enamide could be synthesized from corresponding 3-chloroprop-2-enylbenzene, carbon monoxide (1 atm), and titanium-nitrogen complexes, prepared from Ti(OⁱPr)₄, Li, TMSCl, and molecular nitrogen (1 atm), using a palladium catalyst. The reaction proceeds via transmetalation of the titanium-nitrogen complex to an acylpalladium complex. P^tBu₃ as a ligand of the palladium catalyst, afforded a good result, and the amounts of Li and TMSCl affected the yield of amide. When the reaction was carried out using a bidentate ligand on the palladium complex under an atmosphere of argon instead of carbon monoxide, an allylamine derivative was obtained.     

Characteristics of a simultaneous sampling system for the speciation of atmospheric T and 14C, and its application to surface and soil air

A simultaneous sampling system for the speciation of atmospheric T and ¹⁴C has been developed. Firstly tritiated moisture together with all water vapor in air is adsorbed on Drierite after coagulation using an electric cooler. Then ¹⁴CO₂ plus stable CO₂ in the dried air is adsorbed on molecular sieve 4A. Elemental tritium gas (HT) plus hydrogen gas (H₂) in the atmosphere along with H₂ gas generated from electrolysis of groundwater which does not contain any T, are oxidized on Pd catalyst to water and adsorbed on molecular sieve 3A. Tritiated methane (CH₃T) and ¹⁴CH₄ plus stable methane in the atmosphere are oxidized on Pt catalyst to water and CO₂ under 400 °C. Then, Drierite and molecular sieve 4A adsorb the oxidized T (HTO) and C-14 (¹⁴CO₂), respectively. Tritium and C-14 in surface and soil air have been measured using this system     

One-step synthesis of solid sulfonic acid catalyst and its application in the acetalization of glycerol: crystal structure of cis-5-hydroxy-2-phenyl-1,3-dioxane trimer

A one-pot method was employed to immobilize sulfonic acid onto silica obtained from rice husk ash using 3-(mercaptopropyl)trimethoxysilane to form a solid catalyst denoted as RHASO₃H. BET measurements of the catalyst showed the surface area to be 340 m² g^?1 with the average pore volume of 0.24 mL g^?1 and the pore diameter of 2.9 nm. Acidity test of cation exchange capacity and pyridine adsorption studies revealed the presence of Br?nsted acid sites on the catalyst surface. The catalyst was used in the acetalization reaction of glycerol with benzaldehyde. Under optimized conditions, the reaction showed the maximum conversion of 78 % after 8 h with 67 % selectivity towards the five membered ring isomer. Variation in the glycerol concentration had a significant effect on the reactants conversion. A single crystal X-ray study of one of the products proved the existence of a unique trimer formed by hydrogen bonding by the six-membered cis-isomer. The catalyst was several times recycled without any loss of its catalytic activity.