Formation Of Benzophenone Research Articles

Mechanism and Thermochemistry of Radical Driven Partial Chain Oxidation of p‐Benzylphenol

AbstractThe thermochemistry of radical driven chain oxidation of gaseous p‐benzylphenol is studied using the DFT (M062X,B3LYP,wB97XD,M08HX,MN15) approaches at 6‐311++G(d,p) level of theory. The values of ΔfHo(Y,MEAN) or ΔfHo(Yi,MEAN)RHp, used for the determination of ΔRxHo of considered reactions, are derived from the intersections of 3SEi intervals of values of ΔfHo(Yi,CORR) or ΔfHo(Yi,CORR)RHp, determined, respectively, using the corrected thermochemistry of atomization (ra) or homodesmotic (RHp) reactions. The linear calibration dependencies are used for the correction of their values of ΔraHo(Yi) and ΔRHpHo(Yi), derived from the calculated values of Ho.According to calculations, the most thermochemically favorable product is benzophenone,4‐ol (ΔfHo298.15(benzophenone,4‐ol)=−126.0±7.6(±2σ) kJ/mol), while, the formation of PhCHPhO (ΔfHo298.15=151.3±7.8 kJ/mol) and PhC(OH)PhO (ΔfHo298.15=39.6±6.5 kJ/mol) is thermochemically unfavorable. The formation of benzophenone,4‐ol is due the tautomerization or dissociation of O−O bond of PhC(O2•)HPhOH (ΔfHo298.15=47.9±4.8 kJ/mol), produced, respectively, OH or PhC(O•)HPhOH (ΔfHo298.15=53.0±7.1 kJ/mol) radicals. However, the formation of PhC(O2•)HPhOH is exoergic only at T<500 K.The formation of PhC(O2H)HPhOH (ΔfHo298.15=−104.2±5.9 kJ/mol) and PhC(OH)HPhOH (ΔfHo298.15=−177.8±5.3 kJ/mol) via transfer of H atom from p‐benzylphenol is also thermochemically favorable, but can only be important, respectively, at low (T<800 K) and at high T. In addition, the tautomerization of PhC(O⋅)HPhOH to PhC⋅ (OH)PhOH (ΔfHo298.15=−61.0±1.3 kJ/mol) is thermochemically favorable and slightly depends upon T.

Laser Interfaced Mass Spectrometry of the Sunscreen Molecule Octocrylene Demonstrates that Protonation Does Not Impact Photostability

AbstractOctocrylene (OCR) is a widely used organic sunscreen molecules, and is a dominant component of many sunscreen formulations. Here, we perform the first measurements on the protonated form of OCR, i. e. [OCR+H]+, to probe whether protonation affects the molecule's photostability. The novel photochemical technique of UV laser‐interfaced mass spectrometry is employed from 400–216 nm, revealing that the electronic absorption spectrum of OCR across the S1 and S2 states red shift by 40 nm upon protonation. Our measurements reveal that [OCR+H]+ predominantly undergoes photofragmentation into the m/z 250 and 232 ionic products, associated with loss of its bulky alkyl side chain, and subsequent loss of water, respectively. We compare the photochemical fragmentation results with higher‐energy collisional dissociation results to investigate the nature of the photodynamics that occur following UV absorption. The excited state decay pathways over the S1 and S2 excited states of [OCR+H]+ are associated with statistical fragmentation in line with dominant ultrafast decay. This behaviour mirrors that of neutral OCR, demonstrating that protonation does not affect the ultrafast decay pathways of this sunscreen molecule. We discuss our results in the context of the known breakdown of OCR into benzophenone, identifying a potential photoactivated pathway to benzophenone formation in solution.

Optimized Photo-Fenton degradation of psychoactive pharmaceuticals alprazolam and diazepam using a chemometric approach—Structure and toxicity of transformation products

The objectives of the present study were: a) to evaluate the photocatalytic degradation of two benzodiazepine pharmaceuticals, alprazolam and diazepam, using Photo-Fenton, b) to optimize the experimental parameters through a central composite experimental design, c) to assess their mineralization and toxicity variations and d) to identify the transformation products during the process and to propose transformation pathways. Response Surface Methodology proved to be a useful tool for the optimization of the degradation process as the statistical coefficients (R2 = 0.967 for alprazolam and R2 = 0.929 for diazepam) showed satisfactory values confirming the adequate correlation between the predicted models and experimental values. Two sets of experimental conditions were proposed taking into consideration criteria related to the reaction rate and the minimum use of iron. Toxicity of the system varied with time after the treatment, indicating the gradual production of transformation products which differ in their toxic potential. Fifteen and twenty-three photocatalytic degradation products were identified for ALP and DZP respectively using LC-(ESI)MS/MS. In the case of ALP, the main degradation reactions included, phenyl-group removal and the opening of the 7-membered ring, while for DZP, degradation occurred through hydroxylation, formation of benzophenone and the opening of the 7-membered cyclic group.

Support vector machine-based modeling of grafting hyperbranched polyethylene glycol on polyethersulfone ultrafiltration membrane for separation of oil–water emulsion

In present study, a new method based on the support vector machine (SVM) approach was employed to calculate the oil–water permeation flux and grafting yield of maleic anhydride and hyperbranched polyethylene glycol (PEG) on the polyethersulfone (PES) membrane surface. A set of 7 input/output experimental data was applied for training and testing the results of the model. The results of the developed SVM model showed good compliance with the experimental data, as the value of correlation index for the developed model is 0.96, 0.95 and 0.98 for the maleic anhydride and hyperbranched PEG grafting and oil–water permeation flux, respectively. The model was also validated against the kinetic reaction of benzophenone formation on the PES membrane which derives from combination of benzophenone formation reactions and the Lambert–Beer law. Also, to validate the SVM results, the oil–water permeation flux and antifouling characteristics of the modified and neat membranes were investigated, and based on the results, the SVM can be considered as a strong modeling approach in membrane process technologies.

CPh3 as a functional group in P-heterocyclic chemistry: elimination of HCPh3 in the reaction of P-CPh3 substituted Li/Cl phosphinidenoid complexes with Ph2C=O.

P-CPh3 substituted oxaphosphirane complexes 3 were prepared using Li/Cl phosphinidenoid complexes 2 (M = Cr, Mo, W) and benzaldehyde. Employing 2 and benzophenone resulted in the formation of oxaphospholane complexes 4 and 5, the former bearing a benzo[c]-1,2-oxaphospholane and the latter a novel pentacyclic P-ligand. According to DFT studies the latter P-heterocycle arises from formal dimerization of a transient benzofused 2-phosphafurane complex 8, one of the fragments undergoing water-catalyzed [1,3]H shift (4) and the other (11) formed via elimination of HCPh3.

Gamma radiolytic eradication of methoxychlor in aqueous media: the degradation pathways using HPLC and SPME-GC-MS

Abstract The gamma radiation-induced degradation of environmental pollutant methoxychlor in water was investigated. A 60Co gamma radiation source with a dose rate of 372 Gy h−1 was used for gamma irradiation of 1 mg L−1 and 10 mg L−1 methoxychlor in water with a varied absorbed dose of 1–5 kGy. A single step clean up and pre-concentration procedure based on solid phase micro-extraction was optimized. The extent of radiolytic degradation was monitored by reversed phase HPLC-UV and GC-ECD. The trace and ultra trace level degradation products were identified using GC-MS-SPME by comparing their mass spectra with the NIST 98 m mass spectral library. Most of the generated products for 4 kGy dose are substituted chlorophenols. The reaction pathways of these substituted chlorophenols and benzophenone formation are also proposed. However, generated chlorophenols disappeared along with methoxychlor for an absorbed dose of 5 kGy. The attained degradation of methoxychlor is ∼ 95% that reflects the potential use of ionization radiation for wastewater treatment.

Product Selectivity in Semiconductor-Mediated Dehydrazonation of Benzophenone Hydrazone

Product selectivity in the dehydrazonation of benzophenone hydrazone by photocatalytic oxidation with various semiconductor photocatalysts has been investigated using ultraviolet-A light. TiO2-P25 shows greater product selectivity of benzophenone formation with 93.9% conversion. Doping of metals on TiO2 selectively enhances the formation of azine from hydrazone. Solvents such as dichloromethane, chloroform, and dichloroethane also enhance the formation of azine.

Radiation chemical study on benzaldehyde–chlorobenzene system: A novel radiation chemical route for benzophenone formation

The effects of reactants molar ratio, absorbed dose, and absorbed dose rate were studied on benzaldehyde–chlorobenzene system. Irradiation products were identified by GC/MS analysis and their quantities were determined by GC analysis. Study of the reactants molar ratio effect indicates important aspects of the radiation chemistry of this system. It was observed that the yields of the major products increase as absorbed dose increase. On the other hand, these yields decrease as dose rate increases. Which reflects that the major products are formed via inter-spur reactions i.e. in the bulk of the medium. The mechanisms of the formation of the products were suggested. Benzophenone is one of the main products of this system. Therefore, this study gives a spot of light on a novel radiation chemical route for benzophenone formation. The radiation chemical yield (G-value) of benzophenone was determined at different dose rates.

Selective Palladium‐Catalysed ipso Arylation of α,α‐Disubstituted Benzo[b]thien‐2‐ylmethanols with Aryl Bromides using PCy3 as Ligand

Abstractα,α‐Diphenylbenzo[b]thien‐2‐ylmethanol was treated with a series of aryl bromides in the presence of palladium(II) acetate and tricyclohexylphosphane to give the appropriate 2‐aryl‐benzo[b]thiophenes in good to excellent yield with concomitant formation of benzophenone. The reaction wassuccessfully extended to α,α‐diphenylbenzo[b]thien‐3‐ylmethanol, although in certain cases the transformation was biased by concurrent ortho arylation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Corrigendum to: Oxidation of Aromatic Alkynes with Nitrate Radicals (NO3•): An Experimental and Computational Study on a Synthetically Highly Versatile Radical

Addition of electro- and photochemically generated nitrate radicals, NO3•, to the C≡C triple bond of aromatic alkynes 9a–9h leads to formation of 1,2-diketones 10a–10h. Surprisingly, benzophenones 11a–11h are obtained as by-products, which formally result from loss of a carbon atom. Density functional studies performed with the BHandHLYP method in combination with various basis sets revealed that 1,2-diketones result from 5-endo cyclization of the initially formed vinyl radical and loss of NO•. The key step to benzophenone formation is a γ-cleavage at the stage of the vinyl radical with release of NO2•, followed by Wolff rearrangement of the resulting α-oxo carbene.

Oxidation of Aromatic Alkynes with Nitrate Radicals (NO3•): An Experimental and Computational Study on a Synthetically Highly Versatile Radical

Addition of electro- and photochemically generated nitrate radicals, NO3•, to the C≡C triple bond of aromatic alkynes 9a–9h leads to formation of 1,2-diketones 10a–10h. Surprisingly, benzophenones 11a–11h are obtained as by-products, which formally result from loss of a carbon atom. Density functional studies performed with the BHandHLYP method in combination with various basis sets revealed that 1,2-diketones result from 5-endo cyclization of the initially formed vinyl radical and loss of NO•. The key step to benzophenone formation is a γ-cleavage at the stage of the vinyl radical with release of NO2•, followed by Wolff rearrangement of the resulting α-oxo carbene.

Photochemically masked benzophenone: Photoinitiated free radical polymerization by using benzodioxinone

A new photoinitiating system for free radical polymerization of methyl methacrylate (MMA) is reported. This system consists of benzodioxinone and hydrogen donors such as triethylamine (TEA), N, N-dimethyl ethanol amine (DMEA) and tetrahydrofuran (THF). A feasible mechanism involves photoinduced formation of benzophenone from benzodioxinone and subsequent hydrogen abstraction of photoexcited benzophenone from hydrogen donors to yield radicals capable of initiating polymerization of MMA.

Highly Selective Oxidation of Diphenylmethane to Benzophenone over Co/MCM-41

Abstract Highly selective formation of benzophenone (99.1%) from diphenylmethane is reported for the first time using H2O2 (30%) as an oxidant and Co/MCM-41 as the catalyst.

Enantioselective Reactions of tert‐Butyl Glycinate—Benzophenone Schiff Base Catalyzed by Chiral Phase‐Transfer Catalyst in Aqueous Media Without Any Organic Solvent.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Enantioselective reactions of tert-butyl glycinate–benzophenone Schiff base catalyzed by chiral phase-transfer catalyst in aqueous media without any organic solvent

Chiral phase-transfer catalyzed enantioselective alkylations of tert-butyl glycinate–benzophenone Schiff base were investigated in aqueous media without any organic solvent. Reactions in aqueous media smoothly proceeded to give the desired product in higher yield than under standard liquid–liquid biphasic conditions. In aqueous media the formation of benzophenone, which was caused by in situ hydrolysis of Schiff base, was depressed.

New class of cationic ring‐opening polymerizations of 2,2‐diphenyl‐1,3‐oxathiolanes accompanying quantitative elimination of benzophenone

AbstractCationic polymerizations of three 2‐substituted 1,3‐oxathiolanes, 2,2‐diphenyl‐1,3‐oxathiolane (1a), 5‐methyl‐2,2‐diphenyl‐1,3‐oxathiolane (1b), and 4‐methyl‐2,2‐diphenyl‐1,3‐oxathiolane (1c), were carried out with boron trifluoride etherate (BF3 · OEt2) in dichloromethane at 30 °C to obtain poly(alkylene sulfide)s accompanying the elimination of benzophenone. In the cationic polymerization of 1b and 1c, the consumption of the monomers and formation of benzophenone proceeded simultaneously. The obtained poly(propylene sulfide)s from 1b and 1c contain 41% head–head units, which is in good agreement with that of the polymer from methylthiirane with BF3 · OEt2. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2943–2949, 2004

Reactivity of Benzophenone O‐Vinyloxime.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Protonation of two adjacent tyrosine residues influences the reduction of cytochrome c by diphenylacetaldehyde: a possible mechanism to select the reducer agent of heme iron

We have shown that diphenlacetaldehyde (DPAA) is able to promote mitochondrial ΔΨ disruption accompanied by damage in mitochondrial DNA, lipids, and proteins [Almeida, A. M.; Bechara, E. J. H.; Vercesi, A. E.; Nantes, I. L. Free Radic. Biol. Med. 27:744–747; 1999]. In this work, DPAA was used as a model of carbonyl reagent for cytochrome c. The results suggest that DPAA is a redox cytochrome c modifier. Conversion of Fe(III) to Fe(II) cytochrome c promoted by DPAA is pH dependent. The second-order rate determined for heme iron reduction ( k 2) is 698 M −1 s −1 and this process occurs with an activation energy of 8.5 ± 0.8 kcal/mol. Analysis of the pH profile suggests the presence of two ionizable cytochrome c groups (p K a1 = 8.9 and p K a2 = 11.4) related to the electron transfer from DPAA to heme iron. The heats of ionization of the two prototropic groups, p K a1 (Δ H ion = 6.5 kcal/mol, Δ S ion = −29.0 cal/mol·K), and p K a2 (Δ H ion = 5.0 kcal/mol, Δ S ion = −24.0 cal/mol·K), suggest involvement of two tyrosine residues, probably Y67 and Y74, related to DPAA-promoted heme iron reduction. The cytochrome c chemical modification by iodination of tyrosine groups significantly decreased the reduction rate promoted by DPAA, and shifted the pH opt value from 10.0 to 9.25. The cytochrome c-promoted DPAA electron abstraction quickly produces the expected enol-derived radical, as indicated by 3,5-dibromo-4-nitrosobenzenesulfonate (DBNBS) spin trapping EPR measurements. This radical reacts with molecular oxygen, producing a peroxyl intermediate radical that, via a putative dioxetane intermediate, promotes formation of benzophenone as the main final product of this reaction, detected by high-performance liquid chromatography coupled with tandem mass spectrometry.

Reactivity of Benzophenone O-Vinyloxime

Benzophenone O-vinyloxime readily takes up bromine and hydrogen chloride to give benzophenone O-(1,2-dibromoethyl)oxime and benzophenone O-(1-chloroethyl)oxime, respectively. Its reactions with methanol, trifluoroacetic acid, and acetic acid lead to formation of the corresponding O-(1-methoxyethyl), O-(1-trifluoroacetoxyethyl), and O-(1-acetoxyethyl) derivatives. Slow heating of the title compound induces its decomposition with formation of benzophenone as the major product; fast heating leads to a complex mixture of products containing benzophenone, benzophenone imine, and acetaldehyde.

Photochemical reactions of trans-stilbene and 1,1-diphenylethylene on silica gel: mechanisms of oxidation and dimerization

The photochemical reactions of trans-stilbene and 1,1-diphenylethylene have been studied at a silica gel–air interface. Irradiation of trans-stilbene leads to the formation of a substantial amount of two dimers, along with the formation of cis-stilbene, phenanthrene and a small amount of benzaldehyde. Photochemical dimer formation from trans-stilbene on silica is promoted by inhomogeneous surface loading and slow surface diffusion. Benzaldehyde arises from a Type II oxidation mechanism. Irradiation of 1,1-diphenylethylene at a silica gel–air interface leads primarily to the formation of benzophenone. The oxidation of 1,1-diphenylethylene occurs by a Type I mechanism, as previously proposed [J. Org. Chem. 50 (1985) 149]. The differences in observed photochemistry for these two substituted phenylethylenes on silica is attributed to two factors. Isomerization of trans-stilbene competes efficiently with oxidation, whereas this pathway appears not to be important for 1,1-diphenylethylene. Singlet molecular oxygen is shown to be quenched in solution and at the silica gel–air interface at a faster rate by cis-stilbene than by trans-stilbene or 1,1-diphenylethylene, thus providing an enhanced Type II oxidation pathway for stilbene.