Showing papers on "Benzophenone published in 2008"
TL;DR: The Vibrio fischeri acute toxicity test showed that the solution of malachite green remains toxic after MG has completely disappeared, and this toxicity could be assigned to the formation of 4-(dimethylamine)benzophenone, which is considered "very toxic to aquatic organisms" by current EU legislation.
122 citations
TL;DR: The results indicate that such metabolites of benzophenone (BP)-type UV filters might have more significant adverse effects than the parent compounds over the long term.
111 citations
TL;DR: In this paper, several benzophenone chromophoric groups were incorporated onto cotton fabrics by using 4-hydroxybenzophenone, 4,4′-dihydroxy-dibenzophenone (DBD), 4-chloro-4´-4''-hydroxyphenone, and 4-benzoylbenzoic acid as reagents.
76 citations
TL;DR: In this paper, a simple extraction method and a rapid specific reverse-phase high performance chromatography method with UV detection were developed to quantify benzophenone levels in different packaging materials used for cakes, to evaluate the safety of printed paperboard intended for food contact.
Abstract: Benzophenone is one of the most commonly used photoinitiators, which are mostly used in UV-cured inks for which drying times are much shorter than for conventional solvent or water-based coatings. Benzophenone levels were determined in different packaging materials used for cakes, to evaluate the safety of printed paperboard intended for food contact. For this, a simple extraction method and a rapid specific reverse-phase high performance chromatography method with UV detection were developed. Benzophenone was quantified in different samples by a rapid specific reverse-phase high performance chromatography method after extraction with acetonitrile at 70 °C for 24 h. A novel method for testing benzophenone diffusion towards plastics was also developed and different experiments were conducted in order to measure diffusion coefficients at 70 °C for 2 days and at 40 °C for 10 days. Polypropylene plastics sleeves were found not to be an effective barrier against benzophenone diffusion (3,800 μg/g of benzhophenone was found after 48 h at 70 °C in cakes protected with this film) whereas, the corresponding value in cakes wrapped with a multilayer film of PP/EVOH/PP was reduced to 1,400 μg/g, and the concentration of benzophenone in cakes wrapped with a multilayer film of PET/SiOx/PE was negligible.
56 citations
TL;DR: Amine and phosphine-ligand-containing borane complexes (BoC) are proposed as new, highly efficient coinitiators for acrylate photopolymerization as mentioned in this paper.
Abstract: Amine- and phosphine-ligand-containing borane complexes (BoC) are proposed as new, highly efficient coinitiators for acrylate photopolymerization. In the presence of benzophenone (BP), they are highly reactive and lead, in many cases, to similar or even better polymerization rates than those obtained with a reference amine coinitiator (ethyl dimethylaminobenzoate, EDB). Interestingly, the photopolymerization reaction under aerated conditions is almost unaffected. Laser flash photolysis, ESR, and DFT calculations were also used. The direct detection of the boryl radicals, their transient absorption spectra, and their interaction with acrylates and oxygen as well as the peroxyl radicals/BoC and 3BP/BoC interactions have been studied and allow us to explain the photoinitiation step mechanism under air.
48 citations
TL;DR: Aldehydes and ketones, including acetophenone and benzophenone, are readily protected under mild, neutral conditions in the presence of various alcohols or orthoformates and catalytic amounts of indium(III) trifluoromethanesulfonate as discussed by the authors.
43 citations
TL;DR: Transient grating (TG) spectroscopy has been applied to the photoinduced hydrogen-abstraction reaction of benzophenone (BP) in various kinds of room temperature ionic liquids (RTILs) and the diffusion coefficient of BPK was much smaller than those of the stable molecules and relatively close to that predicted by the SE relation in all solvents.
Abstract: Transient grating (TG) spectroscopy has been applied to the photoinduced hydrogen-abstraction reaction of benzophenone (BP) in various kinds of room temperature ionic liquids (RTILs). After the photoexcitation of BP in RTILs, the formation of a benzophenone ketyl radical (BPK) was confirmed by the transient absorption method, and the TG signal was analyzed to determine the diffusion coefficients of BPK and BP. For comparison, diffusion coefficients of carbon monoxide (CO), diphenylacetylene (DPA), and diphenylcyclopropenone (DPCP) in various RTILs were determined by the TG method using the photodissociation reaction of DPCP. While the diffusion coefficients of the stable molecules BP, DPA, and DPCP were always larger than those predicted by the Stokes–Einstein (SE) relation in RTILs, that of BPK was much smaller than those of the stable molecules and relatively close to that predicted by the SE relation in all solvents. For the smallest molecule CO, the deviation from the SE relation was evident. The diffusion coefficients of stable molecules are better represented by a power law of the inverse of the viscosity when the exponent was less than unity. The ratios of the diffusion coefficient of BP to that of BPK were larger in RTILs (2.7–4.0) than those (1.4–2.3) in conventional organic solvents. The slow diffusion of BPK in RTILs was discussed in terms of the fluctuation of the local electric field produced by the surrounding solvent ions.
37 citations
TL;DR: Efficient incorporation of aza‐glycine into aza-peptides using diphenyl hydrazone protection is described and a proof of concept for the use of benzophenone protection has been established by the synthesis of an aze‐peptide analog of a potent activator of caspase 9 in cancer cells.
Abstract: Aza-glycine has been incorporated into peptide mimics as a tool for studying the active conformation and characterizing structure-function relationships for activity. Side reactions, such as intramolecular cyclizations to form hydantoins and oxadiazalones, have, however, inhibited efforts to make activated aza-Gly residues in solution using carbamate protection. Herein, we describe efficient incorporation of aza-glycine into aza-peptides using diphenyl hydrazone protection. Hydrazone acylation with p-nitrobenzyl chloroformate provided the protected aza-Gly activated ester, which was used to acylate a set of amino ester and amino acids to provide aza-Gly-Xaa aza-dipeptide fragments for peptide synthesis. Removal of the hydrazone protection was performed under acidic conditions to provide the hydrochloride salt of the aza-Gly residue for subsequent elongation of the aza-peptide chain using standard coupling conditions. A proof of concept for the use of benzophenone protection has been established by the synthesis of an aza-peptide analog of a potent activator of caspase 9 in cancer cells.
35 citations
TL;DR: The study found that binding-affinity, as indicated by kinase inhibitory potency, did not correlate with photolabeling efficiency, and conformational flexibility was found to be the determining factor for efficient photolabelling by the photoligands.
35 citations
Patent•
27 Mar 2008TL;DR: In this paper, an emulsion copolymer and two hydrophobic aromatic ketones are used for preparation of aqueous coating compositions which yields a relatively hard surface to provide not only short term but also long term dirt pick up resistance effects, after exposure to ultraviolet radiation.
Abstract: The present invention relates to an aqueous copolymer dispersion comprising an emulsion copolymer and two hydrophobic aromatic ketones, wherein the aromatic ketones are, based on the dry weight of the copolymer, from 0.1 to 3 wt % benzophenone and from 0.1 to 4 wt % a benzophenone derivative; wherein the dispersion comprises 0 or less than 0.1 wt % hydrophilic aromatic ketone. The copolymer dispersion is suitable for preparation of aqueous coating compositions which yields a relatively hard surface to provide not only short term but also long term dirt pick up resistance effects, after exposure to ultraviolet radiation.
35 citations
TL;DR: The keto‐enol tautomeric equilibrium at solution‐state was described for these compounds by 1D and 2D NMR spectral methods and one attempt to rationalize the different ratios between the noted tautomers was based on stereochemical features.
Abstract: This article reports the structural elucidation by IR, UV and MS spectroscopic data along with 1H and 13C NMR chemical shift assignments of two benzophenones isolated from the fruit pericarp of Garcinia brasiliensis Mart. (Clusiaceae): garciniaphenone, (1R,5S,7S)-3-benzoyl-4-hydroxy-6,6-dimethyl-5,7-di(3-methyl-2-butenyl)bicyclo[3.3.1]non-3-ene-2,9-dione, a novel triprenylated benzophenone; and 7-epi-clusianone, a tetraprenylated benzophenone that has already been extracted from another species of the same family. Furthermore, the keto-enol tautomeric equilibrium at solution-state was described for these compounds by 1D and 2D NMR spectral methods and one attempt to rationalize the different ratios between the noted tautomers was based on stereochemical features.
TL;DR: Drastically different excited-state dynamics of aza-substituted uracil from normal Uracil were clarified, and the mechanism for the enhancement of intersystem crossing by aza -substitution is discussed.
Abstract: Excited-state dynamics of 6-azauracil (6-AU) and sensitized singlet oxygen formation in acetonitrile solution with UV irradiation were investigated for the first time. In the transient absorption measurement, the 248 nm laser photolysis gave a relatively intense absorption band at 320 nm (ϵ = 1100 ± 100 dm3 mol−1 cm−1) and a broadband in the 500 − 700 nm region due to triplet 6-AU. The triplet 6-AU, decaying with the rate constant of (5.3 ± 0.2) × 106 s−1 in Ar saturated acetonitrile, was quenched by molecular oxygen with the rate constant of (2.5 ± 0.1) × 109 dm3 mol−1 s−1. The formation quantum yield of excited triplet 6-AU was estimated to be unity by acetone triplet sensitization and actinometry with benzophenone. The time-resolved thermal lensing signal of 6-AU was also observed by 248 nm laser excitation. In the presence of molecular oxygen, the sensitization from triplet 6-AU gave rise to formation of singlet oxygen O2 (1Δg) with a quantum yield of 0.63 ± 0.03. Drastically different excited-state d...
TL;DR: In this paper, the synthesis of novel methylcoumarin end-functionalized poly(methyl methacrylate) of different molecular weights using atom transfer radical polymerization (ATRP) is reported.
Abstract: The synthesis of novel methylcoumarin end-functionalized poly(methyl methacrylate) of different molecular weights using atom transfer radical polymerization (ATRP) is reported. 7-(2′-Bromoisobutyryloxy)-4-methylcoumarin was used as the ATRP initiator at 70 °C using copper(I) bromide/1,1,4,7,7-pentamethyldiethylenetriamine (PMDETA) as the catalyst system. The theoretical and experimental number-average molecular weights Mn with narrow polydispersities (Mw/Mn = 1.1−1.4) agreed very well. Photochemical drug loading of the methylcoumarin end-functionalized polymer was performed in solution (chloroform/acetone 1:2) with benzophenone as additional photosensitizer using a 50-fold excess of the pro-drug 1-heptanoyl-5-fluorouracil (H5FU). UV/vis and NMR spectroscopy were used for the characterization of the polymer drug conjugate and indicated an almost quantitative conversion of coumarin moieties into photodimers. The change of polymer properties like thermal stability, glass transition, and molecular weight afte...
TL;DR: The stress studies revealed the photostability of the antihistamine fexofenadine hydrochloride as the most adverse stability factor and the importance of appropriate light protection during the drug development process, storage and handling is shown.
TL;DR: The inclination of the two aryl rings (ring twists) in a series of benzophenone molecules has been examined and the dihedral angle relates to both the steric considerations of the single molecule and the packing forces related to the crystal structure.
Abstract: The inclination of the two aryl rings (ring twists) in a series of benzophenone molecules has been examined. For each structure the dihedral angle (between the planes of the two sets of six aromatic C atoms) relates to both the steric considerations of the single molecule and the packing forces related to the crystal structure. Six new benzophenone structures are incorporated into the study including 2,2'-dihydroxy-4,4'-dimethoxybenzophenone (I), C(15)H(14)O(5), that appears to have the smallest reported twist angle, 37.85 (5) degrees , of any substituted benzophenone reported to date. Three further benzophenones, 4,4'-bis(diethylamino)benzophenone (II), C(21)H(28)N(2)O, 3,4-dihydroxybenzophenone (III), C(13)H(10)O(3), and 3-hydroxybenzophenone (IV), C(13)H(10)O(2), have similar ring twists [49.83 (5), 49.84 (5) and 51.61 (5) degrees , respectively] that are comparable with the value of 54 degrees found for the orthorhombic form of unsubstituted benzophenone. 4-Chloro-4'-hydroxybenzophenone (V), C(13)H(9)ClO(2), has a ring twist of 64.66 (8) degrees that is close to the value of 65 degrees found in the metastable monoclinic form of unsubstituted benzophenone and 2-amino-2',5-dichlorobenzophenone (VI), C(13)H(9)Cl(2)NO(2), has a large ring twist of 83.72 (6) degrees . Comparisons with a further 98 substituted benzophenone molecules from the Cambridge Structural Database (CSD) have been made.
TL;DR: A new version of a benzophenone antenna-sensitised photolabile derivative of l-glutamate, which has a dicarboxylic acid substituent on the Benzophenone to promote water solubility, has been synthesised and pharmacological evaluations have shown that the compound itself has no evidence of agonist or antagonist activity in its unphotolysed form.
Abstract: A new version of a benzophenone antenna-sensitised photolabile derivative of L-glutamate, which has a dicarboxylic acid substituent on the benzophenone to promote water solubility, has been synthesised. It does not show problems of precipitation in the presence of calcium ions that were encountered with related compounds in which one or two phosphate groups were present as water-solubilising substituents but retains the enhanced photolytic efficiency that results from the benzophenone antenna. Photolysis of the compound proceeds with stoichiometric release of L-glutamate and pharmacological evaluations have shown that the compound itself has no evidence of agonist or antagonist activity in its unphotolysed form.
TL;DR: The magnetic field effects on photoinduced hydrogen abstraction reactions between benzophenone and thiophenol in an ionic liquid were studied by a nanosecond laser flash photolysis technique under ultrahigh fields of up to 28 T.
Abstract: The magnetic field effects (MFEs) on photoinduced hydrogen abstraction reactions between benzophenone and thiophenol in an ionic liquid, N,N,N-trimethyl-N-propylammonium bis(trifluoromethanesulfonyl) imide (TMPA TFSI), were studied by a nanosecond laser flash photolysis technique under ultrahigh fields of up to 28 T. Extremely large and anomalous stepwise MFEs were observed for the first time. The escape yield of benzophenone ketyl radical decreased with increasing magnetic field strength (B) at 0 T < B ≤ 2 T. The decrease was almost saturated at 2 T < B ≤ 10 T. At much higher fields (10 T < B ≤ 28 T), the yield decreased again with increasing B, producing a 25% decrease at 28 T.
01 Sep 2008
TL;DR: The photoirradiation of benzophenone in the Ru(III) ionic solutions is an efficient and convenient method to produce metallic Ru particles in polymer solutions rather than the refluxing and the hydrothermal method of ionic solution of Ru.
Abstract: Colloidal dispersions of poly(N-vinyl-2-pyrrolidone)-protected ruthenium (Ru) particles have been synthesized by the photoreduction of Ru(III) ionic solutions in the presence of photo-activator such as benzophenone and benzoin. The size and the structure of the synthesized particles have been extensively investigated by UV-vis, transmission electron micrograph (TEM) and extended X-ray absorption fine structure (EXAFS). Metallic Ru particles with an average diameter of 1.3 nm were successfully synthesized in the presence of benzophenone, although mixtures of partly oxidized Ru particles and metallic Ru particles were synthesized in the presence of benzoin. Photoreduction of Ru(III) ionic precursors to Ru atoms was promoted by ketyl radicals, which is more efficiently generated by the photoirradiation of benzophenone than by that of benzoin. The photoirradiation of benzophenone in the Ru(III) ionic solutions is an efficient and convenient method to produce metallic Ru particles in polymer solutions rather than the refluxing and the hydrothermal method of ionic solutions of Ru.
TL;DR: In this article, photoactive structures such as benzophe-none chromophoric groups were incorporated onto poly- mers by using a Friedel-Crafts acylation reaction.
Abstract: Photoactive structures such as benzophe- none chromophoric groups were incorporated onto poly- mers by using a Friedel-Crafts acylation reaction. The structures and properties of the resultant polymers, poly (styrene-co-vinylbenzophenone) were evaluated as the ratio of benzoyl chloride to phenyl groups in polystyrene in the acylation bath increased. The results proved that the poly (styrene-co-vinylbenzophenone) in different contents of benzophenone groups was successfully prepared, and the contents of the benzophenone chromophoric group branched in the resultant polymer increased as the amount of benzoyl chloride in acylation bath increased. Also, the poly (styrene-co-vinylbenzophenone) copolymers revealed superior special activities such as antibacterial abil- ity. � 2008 Wiley Periodicals, Inc. J Appl Polym Sci 109: 3173- 3179, 2008
TL;DR: Optimization showed that catechol as an external ligand and a hydroxy group on benzophenone facilitated the generation of a quinonemethide (intermediate II) that is involved in the pinacol-type rearrangement of intermediate I to give the rearranged product.
Abstract: 2,2-Bis-(4-hydroxyphenyl)-cyclopentanone (3a) was unexpectedly obtained in 76% yield from a reductive coupling reaction of 4,4'-dihydroxybenzophenone (1a) and cyclobutanone with TiCl4 and Zn. Further optimization showed that catechol as an external ligand and a hydroxy group on benzophenone facilitated the generation of a quinonemethide (intermediate II) that is involved in the pinacol-type rearrangement of intermediate I to give the rearranged product.
Patent•
01 Feb 2008
TL;DR: In this paper, an acrylate dispersion adhesives containing at least one UV absorber selected from the group consisting of benzoate esters and benzoic ester derivatives, cinnamic esters, benzamide and benzophenone derivatives, octocrylene, avobenzene and camphor derivatives, and also the laminates produced using these adhesive.
Abstract: The invention relates to acrylate dispersion adhesives containing at least one UV absorber selected from the group consisting of benzoate esters and benzoic ester derivatives, cinnamic esters and cinnamic ester derivatives, benzophenone and benzophenone derivatives, octocrylene, avobenzene and camphor derivatives, and also to the laminates produced using these adhesives. It additionally relates to a process for producing these laminates and to their use for producing no-label-look labels.
TL;DR: In this paper, two oligothiophene based organic semiconductors with photo-cross-linkable benzophenone (BP) groups were synthesized and characterized, and the stability and crosslinking of the semiconducting films were monitored by Fourier Transform Infrared Spectroscopy (FTIR).
TL;DR: The reactivities of adrenaline toward hydrogen abstraction by the tert-butoxyl radical and the excited triplet state of benzophenone have been examined in solution using laser flash photolysis techniques.
Abstract: The reactivities of adrenaline toward hydrogen abstraction by the tert-butoxyl radical and the excited triplet state of benzophenone have been examined in solution using laser flash photolysis techniques. The rate constants obtained in acetonitrile-rich solvents are 13 and 1.5 × 108 M−1 s−1 for benzophenone triplet and the tert-butoxyl radical, respectively. Adrenaline is a better hydrogen donor than phenol, but not as efficient as α-tocopherol.
TL;DR: A polymeric one-component type II photoinitiator (PDABPP) based on 4,4′-dihydroxybenzophenone (DHBP), acryloyl chloride, and piperazine was synthesized, and its structure was confirmed by GPC and 1H NMR.
Abstract: A polymeric one-component type II photoinitiator (PDABPP) based on 4,4′-dihydroxybenzophenone (DHBP), acryloyl chloride, and piperazine was synthesized, and its structure was confirmed by GPC and 1H NMR. The photopolymerization kinetics of the photoinitiator was studied by real-time infrared spectroscopy. It indicated that PDABPP was a more effective photoinitiator than that of benzophenone (BP)/triethylamine (TEA). The rate of polymerization and final conversion increased, and the induction period shortened with increase of PDABPP concentration, light intensity, and amine concentration. The kinetics of photopolymerization for tripropylene glycol diacrylate (TPGDA) incorporating PDABPP in the presence of different tertiary amines as the initiating system indicated that the PDABPP/TEA combination exhibited the highest polymerization rates among the PDABPP/amines combinations. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Patent•
20 Oct 2008
TL;DR: In this article, a fungicidal composition comprising synergistically effective amounts of a carboxylic acid amide derivative of the formula (I) or its salt is provided, wherein B is a heterocyclic group which may be substituted; each of R1 and R2 which are independent of each other, is alkyl; X is halogen, alkyls or alkoxy; and n is an integer of from 0 to 5, and at least one fungicidal compound selected from the group consisting of an azole compound, an anilinopyrimidine compound
Abstract: A fungicidal composition is provided. A fungicidal composition comprising synergistically effective amounts of (a) a carboxylic acid amide derivative of the formula (I) or its salt: wherein B is a heterocyclic group which may be substituted; each of R1 and R2 which are independent of each other, is alkyl; X is halogen, alkyl or alkoxy; and n is an integer of from 0 to 5, and (b) at least one fungicidal compound selected from the group consisting of an azole compound, an anilinopyrimidine compound, a triazolopyrimidine compound, a strobilurin compound, an N-halogenothioalkyl compound, a pyridinamine compound, a bicarbonate, an inorganic sulfur compound, a dithiocarbamate compound, an organic chlorine compound, a dicarboxyimide compound, an amine compound, a phenylpyrrole compound, a benzophenone compound, a dinitrobenzene compound, a piperidine compound, a morpholine compound, etc.
TL;DR: In this paper, the curing kinetics of diglycidyl ether of bisphenol-A (DGEBA) in the presence of varying molar ratios of aromatic imide-amines and 4,4′-diaminodiphenylsulfone (DDS) were investigated by the dynamic differential scanning calorimetry.
Abstract: Curing kinetics of diglycidyl ether of bisphenol-A (DGEBA) in the presence of varying molar ratios of aromatic imide-amines and 4,4′-diaminodiphenylsulfone (DDS) were investigated by the dynamic differential scanning calorimetry. The imide-amines were prepared by reacting 1 mole of benzophenone 3,3′,4,4′-tetracarboxylic acid dianhydride (B) with 2.5 moles of 4,4′-diaminodiphenyl ether (E)/ or 4,4′-diaminodiphenyl methane (M)/ or 4,4′-diaminodiphenylsulfone (S) and designated as BE/ or BM/ or BS. The mixture of imide-amines and DDS at ratio of 0:1, 0.25:0.75, 0.5:0.5, 0.75:0.25 and 1:0 were used to investigate the curing behaviour of DGEBA.
TL;DR: A nanosecond time-resolved resonance Raman (ns-TR3) spectroscopic investigation of the intermolecular hydrogen-abstraction reaction of the triplet state of 4-benzoylpyridine (4-BPy) in 2-propanol solvent is reported in this article.
Abstract: A nanosecond time-resolved resonance Raman (ns-TR3) spectroscopic investigation of the intermolecular hydrogen-abstraction reaction of the triplet state of 4-benzoylpyridine (4-BPy) in 2-propanol solvent is reported. The TR3 results reveal a rapid hydrogen abstraction (<10 ns) by the 4-BPy triplet state (nπ*) with the 2-propanol solvent, leading to formation of a 4-BPy ketyl radical and an associated dimethyl ketyl radical partner from the solvent. The recombination of these two radical species occurs with a time constant about 200 ns to produce a para-N-LAT (light absorbing transient). The structure, major spectral features, and identification of the ketyl radical and the para-N-LAT coupling complex have been determined and confirmed by comparison of the TR3 results with results from density functional theory (DFT) calculations. A reaction pathway for the photolysis of 4-BPy in 2-propanol deduced from the TR3 results is also presented. The electron-withdrawing effect of the heterocyclic nitrogen for 4-BPy on the triplet state makes it have a significantly higher chemical reactivity for the hydrogen abstraction with 2-propanol compared to the previously reported corresponding benzophenone triplet reaction under similar reaction conditions. In addition, the 4-BPy ketyl radical reacts with the dimethyl ketyl radical to attach at the para-N atom position of the pyridine ring to form a cross-coupling product such as 2-[4-(hydroxy-phenyl-methylene)-4h-pyridin-1-yl]-propan-2-ol instead of attacking at the para-C atom position as was observed for the corresponding benzophenone reaction reported in an earlier study. Copyright © 2008 John Wiley & Sons, Ltd.
TL;DR: A photosensitizer core has been covalently incorporated into a hyperbranched polyether polyol structure, using a one-step protocol as discussed by the authors, which was used as initiator in the anionic polymerization of glycidol.
Abstract: A photosensitizer core has been covalently incorporated into a hyperbranched polyether polyol structure, using a one-step protocol. Partially deprotonated 2,2‘,4,4‘-tetrahydroxybenzophenone was used as initiator in the anionic polymerization of glycidol, yielding hyperbranched polyglycerols with benzophenone core in every macromolecule formed. Molecular weights in the range of 1500 to 5800 g/mol and moderate polydispersity (1.3 < Mw/Mn < 2) were obtained. Incorporation of the functional core was unequivocally evidenced by MALDI−TOF mass spectroscopy. Further modification via acetylation of the polyglycerol hydroxyl groups afforded polymers of lowered polarity. The photochemical and photophysical behavior of the obtained benzophenone core-containing hyperbranched polyglycerols has been investigated in a variety of solvents and compared with that of the model compound 2,2‘,4,4‘-tetramethoxybenzophenone. The hyperbranched polymer periphery induced molecular weight-dependent properties in the photoactive core...
TL;DR: In this paper, p-nitrobenzyl alcohol is oxidized to p-n-nitronzaldehyde with good selectivity using 30% H2O2 and 10% Ni/SiO2 as catalyst in acetonitirle, as refluxing solvent.
TL;DR: In this article, the formation, stability, and reactivity with oxygen of the so-called light absorbing transient (LAT) photoproducts formed on photoreduction of benzophenone and several benophenone derivatives in poly(ethylene-vinyl alcohol) (EVOH) films were investigated.
Abstract: The formation, stability, and reactivity with oxygen of the so-called light-absorbing transient (LAT) photoproducts formed on photoreduction of benzophenone and several benzophenone derivatives in poly(ethylene-vinyl alcohol) (EVOH) films were investigated. The maximum total yield of LAT photoproducts on photoreduction of benzophenone was estimated to be approximately 50%, which was found to comprise around 75% of the para -LAT isomer with the remainder being attributed to the ortho -LAT isomer. The concentrations of these LAT isomers were found to decay over a period of weeks at room temperature in the absence of oxygen, with the decay of the para -LAT isomer being substantially slower than the ortho -LAT isomer. Furthermore, the decay rate of the para -LAT isomer was found to increase markedly in the presence of oxygen. Mechanisms for the decay of the LAT isomers that are consistent with available data are postulated. The presence of alkyl, alkoxy, or aryloxy moieties on the phenyl rings of benzophenone appears to have little effect on the efficiency of formation, stability, and reactivity with oxygen of the LAT photoproducts in EVOH films, for the benzophenone derivatives studied in this work.