Aluminatesulfonic acid: Novel and recyclable nanocatalyst for efficient synthesis of aminoalkyl naphthols and amidoalkyl naphthols

In this study, an efficient, mild, and eco-friendly procedure is developed for the preparation of 1-amidoalkyl-2-naphthols and Betti bases from one-pot three-component condensation of aldehydes, 2-naphthol, and nitrogen sources (amides for amidoalkyl naphthols and amine for Betti bases) in the presence of aluminatesulfonic acid nanoparticles (ASA NPs) as recoverable catalyst under solvent-free conditions. ASA NPs were prepared by a simple reaction of net chlorosulfonic acid and sodium aluminate in high purity. ASA NPs were characterized by Fourier transform IR, X-ray powder diffraction, transmission electron microscopy, energy-dispersive X-ray, thermal gravimetric analysis, and UV diffusion/reflectance techniques. On the basis of the thermal gravimetric analysis and some activation parameters evaluated from decomposition thermal steps using Coats–Redfern model, the catalyst showed high thermal stability. High yields, short reaction time, easy workup, inexpensive, and reusability of the catalyst are advantages of this method.     

Determination of naphthols by flow-injection chemiluminescence

1-Naphthol, 2-naphthol, 2-naphthol-6-sulphonic acid, 1-amino-2-naphthol-4-sulphonic acid and 1-amino-2-naphthol hydrochloride are determined by the chemiluminescence produced by acidic permanganate oxidation in a flow system. Rhodamine B is used as sensitizer. The limits of detection are ca. 5×10^?7 M in a 20-μ sample.     

The thermal light emission properties of various polymers

DSC and light emission (LE) curves were obtained in nitrogen, air, and oxygen atmospheres between 300 and 700 K for samples of poly(ethylene), 66 Nylon, polycarbonate, poly(vinyl pyrrolidone), and poly(acrylonitrile). In all atmospheres, initial LE was the “oxyluminescence” type associated with the hydroperoxide radical formation; in nitrogen, after the depletion of absorbed oxygen, a much weaker “chemiluminescence” was observed.     

IPC behaviour of some sulphonated naphthols and nitroso-naphthols

Summary The ion-pair chromatographic behaviour of a naphthol and some sulpho-substituted naphthols and nitroso-naphthols is studied. Formation of the ion-pair compounds is done either by pre-extraction or during elution with long-chained quaternary alkyl- or alkylarylammonium salts. Identification is based in UV/VIS absorption using a diode array detector at 229, 240, 254 or 280 nm. Special emphasis is placed on the column material, the positions of the substituents in the naphthols and the organic ion-pairing agents in the eluent.

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IPC-Verhalten einiger sulfonierter Naphthole und Nitrosonaphthole

     

The oxidative coupling of indole with some phenolic compounds,naphthols and catechols

The oxidative coupling of indole with three naphthols, 2-naphthol, 2,3-dihydroxynaphthalene and 2,7-dihydroxynaphthalene gave 1,1-bis(3′-indolyl)-2(1H)naphthalenone, 1,1-bis(3′-indolyl)-3-hydroxy-2(1H)naphthalenone and 1,1-bis(3′-indolyl)-7-hydroxy-2(1H)naphthalenone, respectively. The coupling of indole with protocatechuic aldehyde gave bis-(3-indolyl)-(3′,4′-di-hydroxyphenyl)methane and that of indole with homocatechol gave 3-(2′-methyl-3′,4′-di-hydroxyphenyl)indole.     

RM values of naphthols and acetophenones in structure-activity studies

The RM values of naphthols obtained in a chromatographic system where the stationary phase consisted of a silica gel G layer impregnated with silicone oil are much more closely related to the log P values in an octanol-water system than the RM values determined on polyamide layers. Similarly, the RM values of a series of acetophenones in the silicone system are closely related to their log P values. The equations describing the structure-activity relationship indicate the importance of lipophilic character and halogen substitution in determining the hemolytic activity and the acute toxicity of compounds.     

Protecting group free synthesis of 6-substituted naphthols and binols

A straightforward route for the preparation of 6-substituted naphthols and 6,6'-disubstituted binols (binol = 2,2'-dihydroxy-1,1'-binaphthyl) is presented. The synthesis has been accomplished by a one-step procedure starting from 6-bromo derivatives via direct lithiation with n-BuLi, followed by the addition of several electrophiles. This C-C functionalization has been successfully achieved with iodomethane, 3-methoxybenzaldehyde, benzophenone, methyl-2-methylbenzoate, methylbenzoate, dimethyl carbonate, ethyl 2-chloro-2-oxoacetate, and 2,2-dimethyloxirane (E). This reactivity offers a useful protecting group free synthetic protocol, toward chiral disubstituted 6,6'-binols with configuration retention of the binol moiety.     

Dimerization of phenols and naphthols using an aqueous sodium hypochlorite

The observation of an unusual dimerization of phenols and naphthols using a sodium hypochlorite (NaOCl) in an aqueous solution is reported. NaOCl is an environmentally friendly and less expensive reagent than previously used reagents for dimerization. The yield of the dimer is moderate to high at ambient temperature.     

A modified reaction for the preparation of amidoalkyl naphthols

An efficient synthesis of amidoalkyl naphthols using FeCl₃·SiO₂ as a heterogeneous catalyst is described. This thermal solvent-free procedure offers advantages such as shorter reaction times, simple work-up, excellent yields, and recovery and reusability of the catalyst.     

Aggregation emission properties and self-assembly of conjugated oligocarbazoles

Conjugated oligocarbazoles with a 9,10-divinylanthracene core have been synthesized, and exhibit the transition from aggregation-induced emission (AIE) to aggregation-induced emission enhancement (AIEE) behaviour with extending conjugation length; self-assembly of the Cz4 molecule affords nanorings with high fluorescent efficiency.     

Reaction of 2-methylene-3-oxoquinuclidine with phenol and naphthols

C-Alkylation in the ortho position of phenol and naphthols occurs in the reaction of 2-methylene-3-oxoquinuclidine with sodium phenoxide and sodium derivatives of naphthols. The structures of the products were confirmed by IR, PMR, and mass spectroscopic data.     

Organocatalytic asymmetric Friedel-Crafts alkylation/cascade reactions of naphthols and nitroolefins

The asymmetric Michael-type Friedel-Crafts reaction of naphthols and nitroolefins promoted by bifunctional thiourea-tertiary amine organocatalysts (up to 95% ee) was investigated; on simply extending the reaction time further cascade reactions could occur to generate enantiopure dimeric tricyclic 1,2-dihydronaphtho[2,1-b]furanyl-2-hydroxylamine derivatives.     

Fluorescence quenching of naphthols by Cu2+ in micelles

Effect of the micelles of anionic, cationic and non-ionic surfactants on the fluorescence quenching of 1- and 2-naphthols has been studied in the presence of copper ion. The excited state lifetime, dynamic and static quenching constants for these systems have been determined. Fluorescence quenching in water and SDS micelle is due to the collision of the fluorophore with the quencher with a small static component. The negatively charged naphtholate ions in the excited state are quenched with significantly higher rates than the neutral naphthol molecules, which are located further inside the mesophase. CTAB micelle is less effective than the SDS micelle for fluorescence quenching. The effect of CTAB on water-assisted excited-state deprotonation has been investigated in the presence of ZnSO₄. For TX-100 micelle there is negligible quenching even at higher concentration of the quencher.     

Magnetic molecularly imprinted polymers for selective extraction and determination of naphthols

Microchimica Acta - The authors describe a magnetic molecular imprinted polymer (MMIP) for the extraction and detection of naphthols synthesized by surface imprinting technology using 1-naphthol as...     

Fluorinated diphenylpolyenes: crystal structures and emission properties

(E,E,E)-1,6-Diaryl(Ar)-1,3,5-hexatrienes (2, Ar = 4-fluorophenyl; 3, Ar = 2,4-difluorophenyl; 4, Ar = 2,4,6-trifluorophenyl; 5, Ar = perfluorophenyl) and (E,E,E)-1-perfluorophenyl-6-phenyl-1,3,5-hexatriene (6) were prepared. The absorption and fluorescence spectra in methylcyclohexane solution showed only a small dependence on the fluorine ring substituent, and were similar to those of the unsubstituted parent compound (1, Ar = phenyl). The solid-state absorption and fluorescence spectra shifted to red relative to those in solution and strongly depended on the substituent. The emission from crystals 1-5 originated mainly from monomeric species with the maximum wavelength (lambda f(max)) of 440-465 nm, which overlapped the emission from molecular aggregates (1-4) or excimeric species (5) in the red region. Crystal 6 exhibited red-shifted (lambda f(max) = 530 nm) and structureless emission due to excimers. The cocrystal of 1 and 5 (1/5) showed red-shifted (lambda f(max) = 558 nm) and distinctly structured emission, not from exciplexes but from the excited states of molecular aggregates in which molecules 1 and 5 strongly interact already in the ground state. These assignments were confirmed by the results of fluorescence lifetime and quantum yield measurements in the solid state. Single-crystal X-ray structure analyses showed that the molecules were basically planar in each crystal, whereas the crystal packing was strongly substituent-dependent. Weak pi-pi interactions in the herringbone (1 and 2) and in the pi-stacked but largely offset structures (3 and 4) account for their predominantly monomeric origin of emission. The observation of excimer fluorescence from 5 was rather unexpected, since the molecules in this crystal were arranged in an offset stacking fashion due to perfluorophenyl-perfluorophenyl (C6F5...C6F5) interaction. The structures of 6 and 1/5 considerably resembled each other, in which molecules were pi-stacked with more face-to-face geometries than those in 5, as a result of strongly attractive perfluorophenyl-phenyl (C6F5...C6H5) interaction. Nevertheless, the fluorescence origin was clearly different for 6 and 1/5. This can be ascribed to the difference in the strength of orbital-orbital interaction between molecular pi-planes in the ground and excited states in crystals.     

Absorption and emission properties of the six isomeric di-pyridyl-ketones

The absorption and emission spectra of the six isomeric di-pyridyl-ketones have been investigated in solvents of different polarity. The experimental data have shown that the lowest singlet and triplet states of these molecules are due to nπ* excitation, localized on the carbonyl. CNDO/S calculations of singlet excitation energies on geometries optimized by means of MNDO were performed and found to be in satisfactory agreement with the experimental data.     

Field emission and electrical bistable properties of CuTCPQ nanostructures

The organic charge-transfer (CT) complex nanostructures of CuTCPQ (copper tetracyanopentacenequinodimethane) were first successfully fabricated by organic solid phase reaction. The morphologies of CuTCPQ nanosrods can be prepared by controlling the reaction temperature. The electron field-emission properties on these nanostructures were investigated. The current density and turn-on field are 3.5 mA cm(-2) and 2.70 V μm(-1) for the nanorods of CuTCPQ. The results demonstrate that the nanorods of CuTCPQ are potential candidates for field emission cathodes. Stable and reproducible current-controlled electrical switch has been observed in amorphous organic nanorods of CuTCPQ films. The current-voltage characteristics reveal an abrupt decrease in impedance form 1.2 MΩ to less than 1.1kΩ. The maximum ON/OFF ratio of CuTCPQ nanorod arrays is up to 1100.