Showing papers on "Benzophenone published in 1968"

Crystallization kinetics of polymer-diluent mixtures. Influence of benzophenone on the spherulitic growth rate of isotactic polystyrene

Abstract: As an extension of earlier work on the crystallization kinetics of isotactic polystyrene, the spherulite growth rate in mixtures of isotactic polystyrene and benzophenone has been measured over a concentration range extending from pure polymer to a mixture containing about 30% benzophenone. The glass transition temperature has been measured over the entire range from pure polymer to pure benzophenone. For the mixtures the dependence of the growth rate on temperature is similar to that of the undiluted polymer. The addition of benzophenone causes a shift of the crystallization range to lower temperatures. For mixtures containing up to about 20% benzophenone, the maximum in the growth rate increases with increasing content of benzophenone. On addition of more benzophenone, the maximum rate is depressed. Taking into account the glass transition temperature of the mixtures, the influence of benzophenone on the melting point of isotactic polystyrene, and the volume fraction of polymer, we can describe the influence of benzophenone on the growth rate in a semiquantitative way.

Formation of excited states in the pulse radiolysis of solutions of aromatic compounds in cyclohexane and benzene

Abstract: Measurements have been made on the triplet absorptions produced on irradiation of solutions in cyclohexane and benzene. Triplet yields were determined using the most recent extinction coefficient estimates. The yields were: anthracene; in cyclohexane, G= 0.2 (10–4 M) to G= 1.05 (10–2 M); in benzene, G= 0.15 (10–4 M) to G= 1.5 (5 × 10–3 M). Naphthalene; in cyclohexane, G= 0.25 (10–4 M) to G= 2.4 (9 × 10–1 M); in benzene, G= 0.4 (10–3 M) to G= 2.3 (1 M). Benzophenone; in cyclohexane (ketyl radical); in benzene, G= 0.4(10 –3 M)to G= 2.3 (1 M). Benzophonone; in cyclohexane (ketyl radical); G= 0.4 (10 –4 M) to G= 4.8 (1 M); in these solutions. Dilute nepthalene in cyclohexane and benzene gave monomer fluorescence but at higher concentrations emission due to excimer was also seen. Allowing for excimer formation, the concentration dependence of fluorescence in cyclohexane was similar to that of the triplet states. In benzene the rise in napthalene fluorescence was less than the rise in triplet yield. For cyclohexane solutions, solute triplet states are believed to be formed mainly through neutralization of solute ions, some directly, and some via the intermediate formation of solute singlet states. A similar mechanism may operate in concentrated solutions in benzene, but in dilute solutions, solute triplets may also be formed via singlet and triplet states of the solvent.

Phosphorescence and Triplet←Singlet Absorption Spectra of Benzophenone Crystal at 4.2°K

Abstract: The phosphorescence spectrum of benzophenone crystal at 4.2° has been measured to determine whether or not pure molecular crystals phosphoresce. The comparison of its vibrational structure with the infrared and Raman spectra leads to the conclusion that the phosphorescence really comes from benzophenone, not from some chemical impurities. Furthermore, the triplet←singlet absorption has been observed with the benzophenone crystal at 4.2°K for the purpose of comparison with the emission spectrum. The 0–0 band of the phosphorescence has been found to be lower in energy by 81 cm−1 than that of the triplet←singlet absorption. The origin of the gap between the absorption and the emission is discussed in an effort to understand the mechanism of the phosphorescence in the crystalline state. Finally, the oscillator strength of triplet←singlet absorption is theoretically evaluated to be 1.74 × 10−7, in agreement with the experimentally estimated value of 3.2 × 10−7.

Electron spin resonance study of radicals photolytically generated from aromatic carbonyl compounds. The diphenylhydroxymethyl and α-hydroxybenzyl radicals

Abstract: Electron spin resonance observations on the diphenylhydroxymethyl radical, Ph2ĊOH, and the α-hydroxybenzyl radical, PhCHOH, generated by the photolysis of benzophenone and benzaldehyde respectively in various protic and aprotic solvents and at various temperatures are reported With the exception of aOH, the hyperfine proton coupling constants are relatively independent of solvent This contrasts with observations reported elsewhere on the corresponding isoelectronic carbonyl radical-anions and suggests that direct solvent influence at sites other than the oxygen atom of the radical-anions has small effect on the unpaired electron spin density distribution This supports the technique of varying the Coulomb integral of the oxygen atom so as to account theoretically for the dependence of unpaired spin distribution on solvent Pertinent molecular orbital calculations are reportedIn the case of the PhĊHOH radical, a high barrier to the relative rotation of the CHOH and Ph groups is indicated Also, there is evidence of torsional motion of the OH group In the case of the Ph2ĊOH radical, the marked dependence of aOH on solvent and temperature indicate that intramolecular motions are complex

Electron spin resonance study of radicals photolytically generated from aromatic carbonyl compounds. Part II. Hydroxy-radicals from acetophenone, xanthone, thioxanthone, p-hydroxybenzophenone, perinaphthenone and p-benzoquinone

Abstract: Previously reported work on photolytically generated hydroxy-radicals from benzophenone and benzaldehyde has been extended to radicals from acetophenone, xanthone, thioxanthone, and p-hydroxybenzophenone. In each case, hyperfine structure in the e.s.r. spectrum indicates the corresponding hydroxy-radical which is produced via the (nπ*) triplet. A radical from p-hydroxybenzophenone was observed in aprotic solvents and not in protic solvents in which the ‘charge transfer’ excited states are more accessible; these tend not to favour hydrogen atom abstraction from the solvent.All proton coupling constants except that for the hydroxy-group proton, aOH, are relatively independent of temperature and of solvent. This is also the case for the previously reported hydroxyperinaphthenyl and monoprotonated p-benzosemiquinone radicals. The temperature dependence of aOH suggests torsional rotation of the hydroxy-group about the C–OH bond.

Aqueous process for the preparation of polyimide resins

Abstract: DISCLOSED HEREIN IS AN AQUEOUS PROCESS FOR THE PREPARATION OF POLYIMIDE RESINS WHICH PROCESS COMPRISES REACTING IN AN AQUEOUS MEDIUM: TSP@ (1) BENZOPHENONE TETRACARBOXYLIC DIANHYDRIDE OR BENZOPHEONE TETRACARBOXYLIC ACID AND (2) A WATER SOLUBLE POLYAMINE HAVING AT LEAST TWO PRIMARY AMINO GROUPS PER MOLECULE AT TEMPERATURES OF AT LEAST 60*C. FOR A TIME SUFFICIENT TO FORM RECURRING IMIDE UNITS IN THE POLYMER.

Flow birefringence of short‐chain molecules: Cellulose tricarbanilates in benzophenone

Abstract: Measurements of flow birefringence of cellulose tricarbanilates were carried out on nine fractions (0.27 × 105 < M ≤ 12 × 105) in a temperature range of 55–110°C, with benzophenone as a matching solvent (dn/dc = 0). The ratio of Maxwell constant to intrinsic viscosity, which has been found to be independent of molecular weight for the limiting case of Gaussian molecules, is successfully interpreted as a function of molecular weight in terms of the recent theory of Gotlib and Svetlov (based on the wormlike chain model of Kratky and Porod). From the measurements at 55°C a number of 36.6 monomer units per random link is deduced. This is in accord with results of small-angle x-ray scattering. For the extinction angle curves a clear transition is observed from rodlike to statistical molecules when the molecular weight is increased. At high molecular weights the master curves obtained for anionic polystyrenes and cellulose tricarbanilates coincide. Implications of this observation on the kinetic stiffness of the cellulose tricarbanilate chain are discussed. The intrinsic viscosity-molecular weight relationship is considered. From a comparison with the results of the theory of Eizner and Ptitsyn it is concluded that the cellulose tricarbanilate chain must be highly solvated in benzophenone.

Method of producing Compounds of the Benzophenone Series

Abstract: 1,186,818. Benzophenone derivatives. DEUTSCHE ADVANCE PRODUKTION G.m.b.H. 4 Nov., 1968 [21 Dec., 1967], No. 52214/68. Heading C2C. [Also in Division C3] The invention comprises compounds of the formula wherein R is H, alkyl or aryl. They may be obtained by reacting a compound of formula in the presence of basic catalysts and organic solvents with ethylene carbonate or ethylene oxide. Also, compounds of the formula wherein R 1 is a mono- or di-valent carboxylic acid radical which may contain a thioether group, or an alcohol or phosphonate radical are obtained by esterifying or etherifying the compounds of Formula II. Examples are given for the preparation of these compounds.

Photochemical cycloadditions of organic compounds

Abstract: — Oxetanes were synthesized by 1,2-photoaddition of benzophenone to several methyl-substituted furans. The photochemical conversion of oxobicyclic analogues of norbornadiene to the corresponding oxoquadricyclenes was studied, and finally the sensitized 1,2-photoaddition of citraconic anhydride to furan was accomplished. RESUMEN Se han sintetizado oxetanos por fotoadicion 1,2 de benzofenona a distintos metil furanos. Se ha estudiado la conversion fotoquimica de analogos oxobiciclicos del norbonadieno, y finalmente se ha logrado la fotoadicion 1,2 sensitivizada de anhidrido citraconico a furano.

On the lead tetraacetate and related oxidations of aromatic ketoximes

Abstract: Fluorenone and benzophenone oxime react in glacial acetic acid with lead tetraacetate to give parent ketones, geminal dinitromethanes, iminyl ketal derivatives (9,9-difluorenylideniminoxylfluorene ...

Anomalous reaction products from the alkylation of the disodium adduct of benzophenone anil

Abstract: Treatment of the disodium adduct of benzophenone anil with isopropyl bromide produced substantial amounts of a by-product as well as the previously reported product, 2-methyl-N,1,1-triphenylpropylamine. This by-product is shown to be N(o-isopropylbenzhydryl)aniline, formed by alkylation of the adduct on the aromatic ring.The structural proof relies both upon the synthesis of the unknown amine and upon the oxidation of the unknown amine to o-isopropylbenzophenone.

Photosensitised reactions of α-pinene

Abstract: The photosensitised decomposition of α-pinene in the liquid phase, using acetophenone or propiophenone as the sensitiser, yields cis- and trans-β-ocimenes as the only products. This is in contrast to pyrolysis, radiolysis, and direct photolysis, where mixtures of products are obtained. Benzophenone does not act as a photosensitiser. It is possible that the reaction involves a vibrationally excited ground-state intermediate. The initial polychromatic quantum yield, (λ= 280–366 mµ), with acetophenone as sensitiser is 0·8.

Irradiation cross linked copolymers of n-substituted amides of unsaturated carboxylic acids containing aceto or benzophenone groups

Abstract: COPOLYMERS OF OLEFINICALLY UNSATURATED COMPOUNDS AND LIGHT-SENSITIVE, N-SUBSTITUTED AMIDES OF UNSATURATED CARBOXYLIC ACIDS CONTAINING ACETO- OR BENZOPHENONE GROUPS ARE PREPARED AND SUBSEQUENTLY CROSS-LINKED BY THE ACTION OF LIGHT.

Some phenyl migrations in organophosphorus compounds

Abstract: Alkaline hydrolyses of buta-1,3-dien-1-yltriphenylphosphonium bromide, triphenyl-2-phenylvinylphosphonium bromide, methyldiphenyl-2-phenylvinylphosphonium bromide, and halomethyltriphenylphosphonium halides are accompanied by phenyl migration from phosphorus to adjacent carbon. It is suggested that this migration is explained by the presence on the α-carbon atom of an electron-delocalizing substituent or a good leaving group.Under carefully controlled conditions phenylphosphonous dichloride reacts with benzophenone to give phenyltriphenylmethylphosphinic chloride. The reaction of triphenylmethanol with phenylphosphonous dichloride gives low yields of benzophenone together with the same acid chloride.