Showing papers on "Benzophenone published in 1974"
TL;DR: In this article, three different kinds of u.v. oxidative behavior were observed in polyethylene, typical of the efficient triplet activators such as benzophenone and its derivatives, causing an initial rapid oxidation, increasing with ketone concentration, followed by auto-retardation.
103 citations
TL;DR: In this paper, the build-up of triplet-triplet absorption at 5300 A was measured during and subsequent to the excitation of benzophenone by 5 psec pulses of 3545 A radiation (frequency tripled Nd 3+ : glass fundamental).
98 citations
TL;DR: In this article, the authors measured the buildup and decay rates of triplet-triplet absorption of donor solute molecules dissolved in acceptor solvents following picosecond excitation of the first excited singlet state of the solute at room temperature.
Abstract: We have measured the buildup and decay rates of triplet‐triplet absorption of triplet donor solute molecules dissolved in acceptor solvents following picosecond excitation of the first excited singlet state of the solute at room temperature. We have used harmonic pulses from a mode‐locked Nd+3 /glass laser for exciting (3545 A) and probing (5300 A) the samples. We report buildup (k) and decay rates (kQ) for the following solutions: benzophenone in cis ‐piperylene (k−1=7 psec, kQ−1=9 psec) and trans ‐piperylene (k−1=7 psec, kQ−1=11 psec), benzophenone in 1‐methylnaphthalene (k−1<10 psec, kQ−1=20 psec), and 1‐nitronaphthalene in cis‐piperylene (k−1=8 psec, kQ−1=678 psec). We discuss our results in terms of a model of triplet‐triplet energy transfer which depends on good overlap of donor and acceptor energy levels with large Franck‐Condon factors. This model indicates that energy may compete with vibrational relaxation particularly for the benzophenone in piperylene systems, but that thermally assisted energ...
96 citations
TL;DR: In this paper, the build-up of triplet-triplet absorption following singlet excitation was measured for 1- and 2-nitronaphthalene and benzophenone on a picosecond time scale in the condensed phase.
94 citations
Patent•
23 Oct 1974TL;DR: In this paper, the oxygen inhibition of the photopolymerization of acrylic resins is reduced by employing a photocatalyst system containing an aromatic ketone and/or aromatic aldehyde photosensitizer having a triplet energy in the range of from about 54 kilocalories per mole to about 72 kilocalory per mole and which promotes polymerization through bimolecular photochemical reactions of the energy donor type.
Abstract: The oxygen inhibition of the photopolymerization of acrylic resins is reduced by employing a photocatalyst system containing an aromatic ketone and/or aromatic aldehyde photosensitizer having a triplet energy in the range of from about 54 kilocalories per mole to about 72 kilocalories per mole and which promotes polymerization through bimolecular photochemical reactions of the energy donor type and an aromatic ketone photoinitiator which generates a radical pair by way of unimolecular homolysis resulting from photoexcitation An exemplary photocatalyst system is benzophenone and isobutyl benzoin ether
82 citations
TL;DR: In this paper, a simple aromatic compounds undergo two consecutive reversible one-electron transfers to give first the anion radical and then the dianion, both species being stable during the time scale of cyclic voltammetry in several electrophile-free solvents.
Abstract: Anthracene, benzophenone, nitrobenzene, and several other simple aromatic compounds undergo two consecutive reversible one-electron transfers to give first the anion radical and then the dianion, both species being stable during the time scale of cyclic voltammetry in several electrophile-free solvents.
47 citations
TL;DR: In this article, the reaction of diisopropyl formamide with LiCON[CH(CH3)2]2 with lithium diisopsopropylamide produces, by abstraction of the formyl proton, the carbonyl anion, LiCON [CH3]2 ]2.
Abstract: The reaction of diisopropyl formamide with lithium diisopropylamide produces, by abstraction of the formyl proton, the carbonyl anion, LiCON[CH(CH3)2]2. Reactions of this anion with benzaldehyde, benzophenone, ethyl benzoate, acetone, and propionaldehyde occur in yields ranging from 30–92%. Thus, this anion provides a useful method for the synthesis of α-hydroxy and α-keto acids, particularly in cases where cyanohydrin formation is difficult.
45 citations
TL;DR: In this paper, the authors studied the 13C resonance of the carbonyl and carboxyl carbons in the compounds listed in the title and determined the complete shielding tensor σ from a single crystal study.
44 citations
TL;DR: These measurements were repeated, keeping the experimental conditions constant and including acetone as an additional sensitizer, to arrive at the conditions most favorable for minimizing chain breaking relative to dimerization.
Abstract: The triplet states of acetophenone, benzophenone and acetone have higher energy than that of thymine (see Table 1). Therefore, the triplet energy of these ketones can be transferred to the triplet of thymine, which in DNA can interact with a neighboring thymine to form a cyclobutane dimer. It has recently been reported that chain breaking occurs during sensitization with either acetophenone (Zierenberg et al., 1971) or benzophenone (Charlier and Helene, 1971), the efficiency being considerably greater with benzophenone. For biological and physical studies on sensitized DNA it is important to know the extent of chain breaking relative to dimerization, and if possible to minimize the chain-breaking process. Since the chain-breaking studies reported above were done under widely varying conditions, it seemed desirable to repeat these measurements, keeping the experimental conditions constant and including acetone as an additional sensitizer. An effort was made to arrive at the conditions most favorable for minimizing chain breaking relative to dimerization.
41 citations
TL;DR: In this article, the initial intensities and lifetimes of the transients over a wide range of acidity were determined as 1.5 ± 0.1 for the triplet B and BH+ species.
Abstract: Transients observed in laser flash photolysis experiments on 2 × 10–4 mol dm–3 benzophenone in aqueous solution are similar to those previously reported in conventional flash experiments and assigned to the triplet B and BH+ species. Measurements of the initial intensities and lifetimes of the transients over a wide range of acidity permit pK(T1) to be determined as 1.5 ± 0.1. Coupled with the widely different values found for the characteristic lifetimes of B and BH+(10–4 s and 6.2 × 10–8 s respectively) this figure for pK(T1) satisfactorily explains the drop in phosphorescence intensity of benzophenone as the acidity increases through pH = 5. It is also in reasonable accord with Forster cycle calculations based on recent revisions of the ground state pK of benzophenone. Similar measurements are reported for the 20 % ethanol + 80 % water system, in which pK(T1) is 0.3 ± 0.2.
26 citations
TL;DR: In this article, the fast formation of cations of benzophenone, biphenyl, naphthalene, anthracene and phenanthrene in liquid cyclohexane was studied by nanosecond pulse radiolysis.
Patent•
02 Apr 1974TL;DR: In this article, a copolymers of diallylamine derivatives of the HO-(-CH2-)m-, in which m is an integer of 1-6 or R 2 and R 3 may form together with the adjacent N atom pyrrolidyl, piperidyl or morpholino, are produced by conducting photopolymerization of a solution or slurry of at least one dially-lamine derivative mentioned above with or without other comonomer such as maleic anhydride, maleic acid, or a vinyl compound, with irradiation
Abstract: Polymers or copolymers of diallylamine derivatives of the formula, CH2=CR1-CH2+R2 ANGLE N ANGLE CH2=CR1-CH2R3 Y wherein R1 is hydrogen or methyl: R2 and R3 are independently hydrogen, allyl, methallyl, straight-chain or branched-chain alkyl having 1-16 carbon atoms, phenylalkyl or hydroxyalkyl of the formula, HO-(-CH2-)m-, in which m ia an integer of 1-6 or R2 and R3 may form together with the adjacent N atom pyrrolidyl, piperidyl or morpholino; and Y is halogen or inorganic acid anion, are produced by conducting photopolymerization of a solution or slurry of at least one diallylamine derivative mentioned above with or without other comonomer such as maleic anhydride, maleic acid, or a vinyl compound, with irradiation of light having wavelengths of 150-500 m mu . The polymerization rate can be accelerated in the presence of a special sensitizer such as benzophenone or acetophenone together with hydroquinone, dioxane, morpholine or derivative thereof, or a charge-transfer complex of sulfur dioxide and a diallylamine derivative.
TL;DR: In this paper, the efficiency of three commercial ultraviolet absorbers, a 2-hydroxy benzophenone, a two-hydroxyl benzotriazole, and a nickel chelate, in preventing the photo-oxidation of polystyrene films has been measured.
Abstract: The efficiency of three commercial ultraviolet absorbers, a 2-hydroxy benzophenone, a 2-hydroxy benzotriazole, and a nickel chelate, in preventing the photo-oxidation of polystyrene films has been measured. When compared with the calculated screening and phosphorescence quenching efficiency, it is found that (i) the nickel chelate protects the substrate by UV screening alone and is a poor photoprotector, and (ii) the 2-hydroxy benzophenone and 2-hydroxy benzotriazole are more efficient photoprotectors and protect by triplet energy transfer from excited polymer carbonyl impurity groups in addition to UV screening.
TL;DR: Germylmetallic compounds, such as Et 3 GeM, have been prepared in high yield in n-hexane or benzene by the reaction of bis(triethylgermyl)mercury with the appropriate alkali metal as mentioned in this paper.
TL;DR: In contrast to the direct irradiation of paraquat in aqueous alcohols, the yield of radical which may be obtained is not limited by reversible electron transfer, and the reactions are further complicated by a highly efficient process in which all the cation-radical produced is subsequently destroyed (photobleaching phenomenon) by an apparent chain reaction initiated by hydrogen transfer from intermediate semipinacol radicals.
Abstract: Photoreduction of paraquat salts by aqueous propan-2-ol is very efficient with light of wavelength 366 nm in the presence of typical triplet sensitisers such as benzophenone, decafluorobenzophenone, and xanthone. Quantum yields for production of paraquat cation-radical are very similar to those for photoreduction of the ketone sensitiser under identical conditions. In contrast to the direct irradiation of paraquat in aqueous alcohols, the yield of radical which may be obtained is not limited by a reversible electron transfer, and the reactions are further complicated by a highly efficient process in which all the cation-radical produced is subsequently destroyed (photobleaching phenomenon) by an apparent chain reaction initiated by hydrogen transfer from intermediate semipinacol radicals. The reactions illustrate further the electron transfer capabilities of semipinacol radicals and paraquat. Photoreduction of xanthone (but not benzophenone) by aqueous propan-2-ol is efficiently quenched by iodide ion.
TL;DR: In this article, the losses of CO, hydrogen and CO, OH and HNOH radicals from the benzophenone oxime molecular ion have been studied by means of deuterium labelled compounds.
Abstract: The losses of CO, hydrogen and CO, OH and HNOH radicals from the benzophenone oxime molecular ion have been studied by means of deuterium labelled compounds. Hydrogen scrambling and/or exchange and rearrangement reactions of interest, taking place prior to fragmentation, were observed.
TL;DR: In this article, a weak fluorescence was observed from benzophenone at 25650 cm −1 with a quantum yield of ≈10 −5 at 5°K at the 3 π,π* level.
TL;DR: The photostabilizing effect of six Ni(II) chelates in films of polystyrene is compared with their efficiency in quenching triplet benzophenone and a correlation between the two established as mentioned in this paper.
Abstract: The photostabilizing effect of six Ni(II) chelates in films of polystyrene is compared with their efficiency in quenching triplet benzophenone and a correlation between the two established. In both polymer stabilizing and triplet quenching experiments, the diamagnetic chelates are more effective than the paramagnetic chelates, indicating that the structural arrangement of the ligand around the Ni atom is an important factor in both cases.
TL;DR: The conformational isomers of the ketyl radicals (I)−(III) generated from di-2-thienyl ketone, bis-2 -thieno[3,2-b] thienyl thieny ketone and bis -2-THENO[2,3-b]-thieny thienys, have been detected by e.s.r. spectroscopy as discussed by the authors.
Abstract: The conformational isomers of the ketyl radicals (I)–(III) generated from di-2-thienyl ketone, bis-2-thieno[3,2-b] thienyl ketone, and bis-2-thieno[2,3-b]thienyl ketone, have been detected by e.s.r. spectroscopy. The two preferred conformations are cis–trans and trans–trans. Study of the line shape variations with temperature of the e.s.r. spectra allowed the determination of the activation parameters for the rotation of the aromatic rings. The activation energies follow the same order as the electron-delocalizing power of the nuclei, the values being 31·30, 37·95, 35·73, and 26·57 kJ mol–1 for (I), (II), (III) and for benzophenone ketyl, respectively.
TL;DR: In this article, the photoreduction of fluorenone by dimethylaniline in benzene leads to the 9-hydroxy-9-fluorenyl radical I and the N-methylan-inomethyl radical II, and combination and cross combination of radicals I and III.
Abstract: Photoreduction of fluorenone by dimethylaniline in benzene leads to the 9-hydroxy-9-fluorenyl radical I and the N-methylanilinomethyl radical II, addition of II to the oxygen of ground state fluorenone forming radical III, and combination and cross combination of radicals I and III. Hydrolysis of these products leads to fluorenone pinacol, 97 percent yield, and to high yields of N-methylaniline and formaldehyde. Quantum yields for the photoreduction are at a maximum, approximately 0.8, with the unsubstituted dimethylaniline and with weak electron donating or withdrawing substituents. Quantum yields decrease with strong electron donating or withdrawing substituents. Very strong electron donation may lead to no photoreduction but to efficient quenching, presumably due to excessive stability of the initially formed charge-transfer complex. Values of k/sub ir/, rate constant for charge-transfer interaction of excited fluorenone triplet with the substituted dimethylanilines, have been measured in quenching studies. They vary from 3.2 x 10/sup 6/ M/sup -1/ sec/sup -1/ for the p-CN compound to approximately 10/sup 10/ M/sup -1/ sec/sup -1/ for the p-OEt and p-N(CH/sub 3/)/sub 2/ compounds and lead to a linear plot of log k/sub ir/ vs. sigma values, sigma/sup +/ for the strong electron donating substituents, sigma/sup -/ for p-CN, with rho = -1.96. more » Photoreductions of Methylene Blue by substituted phenylglycines, of benzophenone by substituted dimethylanilines and benzylamines, and of p-aminobenzophenone by dimethylanilines are discussed. « less
TL;DR: In this paper, the 1,1-dihalo-2-phenylvinyl methyl ethers were derived by reaction between the chromium-carbene complex and the phenylmercuric halides derived by decomposition of the starting mercurials.
Patent•
04 Sep 1974
TL;DR: In this paper, a photo-sensitive coating composition comprising a prepolymer containing radically cross-linkable ethylenically unsaturated double bonds and a sensitizer which comprises predominantly a mixture of (a) benzophenone, halogenated benzphenone or a combination thereof and (b) 4,4'-bis(diethylamino)benzophenone in a weight ratio of about 1:2 to 10:1.
Abstract: A photosensitive coating composition comprising (1) a prepolymer containing radically cross-linkable ethylenically unsaturated double bonds and (2) a sensitizer which comprises predominantly a mixture of (a) benzophenone, halogenated benzophenone or a combination thereof and (b) 4,4'-bis(diethylamino)benzophenone in a weight ratio of about 1:2 to 10:1.
TL;DR: The results of photoselection and magnetophotoselection studies are compared with studies of intramolecular energy transfer between chromophores of known molecular orientation in this article, showing that if an orientation effect exists for triplet-triplet energy transfer it is a slower moving function than the square of the sine of the angle between the CO axis of benzophenone and the normal to the molecular plane of phenanthrene.
Abstract: The method of photoselection has been used to measure the degrees of polarisation for benzophenone and phenanthrene phosphorescence in poly(methyl methacrylate)(PMMA) at room temperature and 77 K These measurements are compared with the degrees of polarisation of benzophenone phosphorescence and sensitised phenanthrene phosphorescence obtained upon selective excitation of benzophenone in a mixture of benzophenone and phenanthrene in PMMA The studies indicate that if an orientation effect exists for triplet–triplet energy transfer it is a slowermoving function than the square of the sine of the angle between the CO axis of benzophenone and the normal to the molecular plane of phenanthrene The results of photoselection and magnetophotoselection studies are compared with studies of intramolecular energy transfer between chromophores of known molecular orientation
TL;DR: In this article, the photorearrangement of thiol ester 1 into thiaxanthone derivative 4 is discussed and the normal photo-Fries reaction is demonstrated.
TL;DR: Anions of benzophenone, acetophenone and 4-hydroxy-benzophenone were produced in ethanol at 4.2°K by steady γ irradiation as mentioned in this paper.
Patent•
03 Jun 1974TL;DR: In this article, the authors describe a mixture of novel poly(arylacetylenes) and, as fluidizers, certain aromatic organic compounds containing at least two aromatic rings, such as benzophenone and Diethynylbenzene.
Abstract: The invention relates to thermosetting compositions which are blends of novel poly(arylacetylenes) and, as fluidizers, certain aromatic organic compounds containing at least two aromatic rings. The poly(arylacetylenes) are prepolymers of polyacetylenically substituted aromatic compounds, which prepolymers have a number average molecular weight of from about 900 to about 12,000 and contain from about 5 to about 20 percent by weight of acetylenic groups. Diethynylbenzene is one of the preferred monomers used in preparation of the prepolymers. Representative of the compounds containing at least two aromatic ring is benzophenone. The compositions are curable by heat to produce thermoset resins which have very desirable physical properties at both normal and high temperatures.