2-hydroxybenzophenone Derivatives Research Articles

Visible-Light-Promoted [4π + 2σ] Annulation of Dienes and Alkylamines via Dual Inert C(sp3)-H Bond Activation.

Herein, visible-light-promoted [4π + 2σ] annulation of dienes and alkylamines was achieved via dual C(sp3)-H bond functionalization of alkylamines. The elusive enamine precursors are generated under mild conditions by photoredox catalysis, efficiently annulated by the diene, and simultaneously functionalized with two aliphatic C(sp3)-H bonds, resulting in the productive synthesis of new aromatic rings. The aromatic ring construction provides direct access to 2-hydroxybenzophenone derivatives in high yields (up to 90%). This [4π + 2σ] annulation reaction demonstrates mild reaction conditions, high reaction efficiency, and broad functional group tolerance, and this synthetic protocol has been made available for the late-stage transformation of natural products and commercial drugs.

A new and efficient approach to 2-hydroxybenzophenone derivatives via [5C + 1C] annulation of α-alkenoyl-α-aroyl ketene dithioacetals and nitroalkanes

A new and efficient protocol for the synthesis of 2-hydroxybenzophenone derivatives through [5C+1C] annulation of α-alkenoyl-α-aroyl ketene dithioacetals and nitroalkanes had been developed. In the presence of 1 equivalent of K2CO3 in DMF at 70 °C, a range of α-alkenoyl-α-aroyl ketene dithioacetals smoothly react with nitroalkanes to provide various 2-hydroxy benzophenone derivatives in excellent yields. The protocol featured mild reaction conditions, no the formation of by-products, excellent yield, no involving the problems of both chemoselectivity and regioselectivity and wide substrate scope.

Experimental and Computational Study of the 1,5-O → N Carbamoyl Snieckus-Fries-Type Rearrangement.

The reactions of o-lithiated O-aryl N,N-diethylcarbamates with different C-N multiple bond electrophiles have been thoroughly studied. A 1,5-O → N carbamoyl shift, a new variation of the anionic Fries-type rearrangement, takes place when nitriles, imines, or alkylcarbodiimides are employed. In these cases, the carbamoyl group plays a dual role as a directing group, building up a variety of functional groups through the 1,5-O → N carbamoyl migration. On the other hand, the use of iso(thio)cyanates and arylcarbodiimides led to non-rearranged o-functionalized O-arylcarbamates. This reactivity was further computationally explored, and the governing factor could be traced back to the relative basicity of the alternative products (migrated vs nonmigrated substrates). This exploration also provided interesting insights about the degree of complexation of the lithium cations onto these substrates. A new access to useful 2-hydroxybenzophenone derivatives has also been developed.

Selectivity in the Photo-Fries Rearrangement of Some Aryl Benzoates in Green and Sustainable Media. Preparative and Mechanistic Studies.

Irradiation of a series of p-substituted aryl benzoates under N2 atmosphere in homogeneous and micellar media was investigated by means of steady-state condition and of time-resolved spectroscopy. A notable selectivity in favor of the 2-hydroxybenzophenone derivatives was observed in micellar media. The benzophenone derivatives were the main photoproduct. On the other hand, in homogeneous media (cyclohexane, acetonitrile, and methanol) the observed product distribution was entirely different, viz. substituted 2-hydroxybenzophenones, p-substituted phenols, benzyl and benzoic acid were found. The binding constants in the surfactant were also measured and NOESY experiments showed that the aryl benzoates were located in the hydrophobic core of the micelle. Laser flash photolysis experiments led to the characterization of both p-substituted phenoxy radical and substituted 2-benzoylcyclohexadienone transients in homogeneous and micellar environment.

Series of high spin mononuclear iron(iii) complexes with Schiff base ligands derived from 2-hydroxybenzophenones

Utilization of 2-hydroxybenzophenone derivatives for the preparation of iron(iii) Schiff base complexes resulted in a series of high-spin, mostly antiferromagnetically coupled systems.

Systematic Study of the Luminescent Europium-Based Nonanuclear Clusters with Modified 2-Hydroxybenzophenone Ligands

The reaction of 2-hydroxybenzophenone derivatives with europium ions has afforded a new family of luminescent nonanuclear Eu(III) clusters. Crystal structure analysis of the clusters reveals that the metal core comprises two vertex-sharing square pyramidal units. Most of these complexes show emissions typical of Eu(3+) ion under visible light excitation (400-420 nm) at room temperature. Photophysical characterization and DFT study reveal a correlation between luminescent efficiencies of Eu(III) complexes and the electronic features of the ligands, which can be tuned by the nature of substituents in the 4-position of the ligands. The ligands with a fluorine substituent possess more suitable triplet energy levels, resulting in more intensive luminescence.

Solid-phase extraction followed by liquid chromatography–tandem mass spectrometry for the determination of hydroxylated benzophenone UV absorbers in environmental water samples

A procedure for the determination of six derivatives of 2-hydroxybenzophenone, used as UV absorbers, in water samples is presented. Compounds were first concentrated using a solid-phase extraction (SPE) cartridge and then selectively determined by liquid chromatography–tandem mass spectrometry (LC–MS/MS) using electrospray ionization (ESI). The effect of different parameters on the performance of concentration and determination steps is discussed. The highly polar and acidic 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (BP-4) required the use of ammonium acetate as modifier during desorption of SPE cartridges and also to improve the performance of its separation in the LC column. Under optimized conditions, the proposed method provided limits of quantification from less than 1 to 32 ng L −1, depending on the compound and the type of water sample. Recoveries from the SPE step (83–105%) remained unaffected by the nature of the matrix; however, the efficiency of electrospray ionization was compound and sample dependant. Real sample analysis reflected the presence of three of the six investigated species (BP-4, 2-hydroxy-4-methoxybenzophenone, BP-3, and 2,4-dihydroxybenzophenone, BP-1) in the aquatic environment, particularly in raw wastewater samples. In this latter matrix, BP-4 was the compound presenting the highest concentrations; moreover, it was poorly removed in sewage treatment plants and consequently it also appeared in river water.

A convenient modification of 2-hydroxybenzophenoneUV-absorbers

2-Hydroxybenzophenone derivatives ( 3a–f ) were synthesized from 2,4-dihydroxybenzophenone ( 1a ) using 4- O-alkylation of the 4-hydroxyl group with 1-(2-chloroethyl)-2,2,6,6-tetramethylpiperidine ( 2a) and from the carboxyl derivatives of 2-hydroxybenzophenone ( 1b–e) using the esterification as well as transesterification reactions with the hydroxyl derivatives of 2,2,6,6-tetramethylpiperidine ( 2b–d) .

Comparison of the thermal and light stabilising action of novel aromatic phosphites substituted with 2-hydroxybenzophenone and hindered piperidine moieties in polyolefins

Three novel phosphite stabilisers have been synthesised and characterised and their thermal and photochemical effectiveness examined in polyethylene and polypropylene films. Two structures are based on a bis-hindered phenolic moiety coupled to a 2-hydroxybenzophenone (2) and a 4-amino-tetramethylpiperidine (3) chromophore. The third is a tris-2-hydroxybenzophenone based phosphite (4). Thermal oven aging and thermal analysis on the polymer films showed that the hindered piperidine phosphite is an effective primary and secondary antioxidant compared with the 2-hydroxybenzophenone derivatives. These results are consistent with its ability to inhibit the formation of hydroperoxides during thermal aging. The 4-aminopiperidine phosphite compound is also an effective light stabiliser for polypropylene. The 2-hydroxybenzophenone derivative (2) was ineffective as a light stabiliser in all cases and antagonised the effectiveness of a commercial polymeric hindered piperidine stabiliser (Chimassorb 944). The tris-2-hydroxybenzophenone phosphite compound (4), however, was more effective as a light stabiliser in polypropylene than in polyethylene. Both mass spectrometry and thermal analysis indicated initial fragmentation resulting in the loss of the 2-hydroxybenzophenone and 4-aminopiperidine stabiliser moieties from the phosphorus atom. the importance of combining different stabiliser moieties within the same structure in terms of performance is discussed.

Polymeric light stabilizers based on siloxanes

Polymeric light stabilizers were synthesized by hydrosilylation of unsaturated 2-hydroxybenzophenone derivatives or pentamethylpiperidine derivatives with different hydridosiloxanes. Investigations of the hydrosilylation reaction by NMR and HPLC show that the stabilizer groups are mainly bound to the siloxane chain by non-hydrolysable SiC bonds. When allyl ethers are used as starting material, side reactions such as ether cleavage, hydrogenation and isomerization take place. To avoid these side reactions, unsaturated ethers or esters with long methylene chains between the double bond and the oxygen were used. The polymeric light stabilizers were tested as stabilizers of polypropylene and compared with TINUVIN 770. The activity of polymeric light stabilizers decrease, with increasing molecular weight. Extraction experiments demonstrate that the polymeric stabilizers are resistant against extraction by organic solvents while TINUVIN 770 is extracted under the same conditions. Thus, our polymeric HALS show a higher effectiveness than TINUVIN 770. The polymeric HALS derivatives with the best activity have molecular weights ( M n) between 2000 and 4000.

Five-coordinated rhodium(I) carbonyl compounds

The title compounds were synthesised by the replacement of chlorine in Rh(CO)(PPh 3) 2Cl with monobasic bidentate chelating ligands such as salicylaldehyde, acetylacetone, benzoylacetone, dibenzoylmethane, 8-hydroxyquinoline, benzoylphenyl hydroxylamine, 2-hydroxyacetophenone and 2-hydroxybenzophenone. IR spectral evidence points out that these compounds have a trigonal bipyramidal geometry around rhodium in the solid state. However, in benzene solutions, except for the 8-hydroxyquinoline and 2-hydroxybenzophenone derivatives they all take a square planar structure, as seen from their electronic spectra.

Determination of the molecular weight of derivatives of 2-hydroxybenzophenone and 2-hydroxyphenylbenzotriazole by the spectrophotometric method

Determination of the molecular weight of derivatives of 2-hydroxybenzophenone and 2-hydroxyphenylbenzotriazole by the spectrophotometric method

Basicity and intramolecular proton transfer in 2-hydroxybenzophenone derivatives

Basicity and intramolecular proton transfer in 2-hydroxybenzophenone derivatives

Spectroscopic detection of an intramolecular hydrogen bond in 2-hydroxybenzophenone derivatives

The present paper is devoted to an analysis of the infrared spectra of 2-hydroxybenzophenone derivatives in order to determine the influence of intramolecular interactions on the positions and shapes of the vibrational bands of the various atomic groups in the solid, liquid (solution) and vapor states. There is scattered information in the literature only on the positions of individual absorption bands [2-4]. We have made a systematic investigation of the IR spectra of 11 derivativesof 2-hydroxybenzophenone over a wide spectral range. The possible assignment of the vibrational frequencies has been given. The selection of substances for investigation was governed by the fact that we subsequently used the 2-hydroxybenzophenone derivatives to investigate the nature of the intermolecular interactions in solutions. To prepare solid samples, the substances were molded with KBr in vacuum under a pressure of seven tonnes/cm 2. The IR spectra were recorded on a UR-20 double-beam spectrophotomete r in the range from 3700 to 400 cm -1 (program 4). The spectra of solutions were obtained by means of dismountabte cells with KBr windows. The spectral slit width in the region of absorption of carbonyl groups was ~8 cm -I and in that of hydroxy groups ~4 cm -t. The spectra of the vapors were recorded* on a Perkin--Elmer 325 double-beam speetrophotomete r using heated ceils 7.8 cm long with NaC1 windows. The spectral slit width in the 1600 cm -1 region was 0.5-1 cm -1. The following structural formula and numbering were adopted for benzophenone:

Absorption spectra of 2-hydroxybenzophenone derivatives in alkaline alcoholic solutions

Absorption spectra of 2-hydroxybenzophenone derivatives in alkaline alcoholic solutions

Substituent effects on chemical shift of hydroxyl group in 2-hydroxybenzophenone derivatives

Substituent effects on chemical shift of hydroxyl group in 2-hydroxybenzophenone derivatives

Substituent effect on the lowest singlet and triplet states in the derivatives of 2-hydroxybenzophenone

Substituent effect on the lowest singlet and triplet states in the derivatives of 2-hydroxybenzophenone

Dissociation constants of 2-hydroxybenzophenone derivatives in ground and excited states

Dissociation constants of 2-hydroxybenzophenone derivatives in ground and excited states