Showing papers on "Benzophenone published in 1979"

Polyesters derived from 3,4'-dihydroxy-benzophenones or 3-hydroxy-4'-(4-hydroxyphenyl-)benzophenone and certain aromatic dicarboxylic acids and filaments thereof

Abstract: High modulus filaments are melt-spun from polyesters which are derived from 3,4'-dihydroxybenzophenones or 3-hydroxy-4'-(4-hydroxyphenyl-)benzophenone and terephthalic, 2,6-naphthalene dicarboxylic, or bibenzoic acid. The polyesters are optically anisotropic in the melt. As-spun filaments from these polyesters can be heat treated while free from tension to increase their tenacity.

Theoretical investigations of the metastable triplet state of benzophenone

Abstract: A one‐parameter conformational analysis using open‐shell SCF wavefunction gives a C=O bond length (rCO) equal to 1.33 in the lowest 3nπ* state of benzophenone. A study of the correlation between some properties of this state, such as the electric dipole moment or the molecular orbital localizations, and rCO is made. The zero‐field splitting (ZFS) parameters D and E of this state are computed. A study of the variation of the spin–spin contribution to D and E with rCO is carried out. On the other hand, the spin–orbit coupling contribution is observed to have a large effect on the D parameter. The final value of D corresponding to the equilibrium rCO distance in the metastable triplet state is found to be equal to −0.141 cm−1, in good agreement with the experimental value (−0.151 cm−1).

THE USE OF BENZOPHENONE AS A PHOTOAFFINITY LABEL, LABELING IN p‐BENZOYLPHENYLACETYL CHYMOTRYPSIN AT UNIT EFFICIENCY

Abstract: —p-Benzoylphenylacetyl chymotrypsin, an acyl enzyme derivative containing the benzophenone group in the hydrophobic binding pocket, was prepared and is indefinitely stable at low pH. Photolysis of this covalent derivative leads to loss of enzymic activity and incorporation of the labeling group via formation of a second covalent bond. The efficiency of the photochemical processes is exceptionally high, producing 100% incorporation and at least 92% inactivation. Analysis of active site titration data for the photolyzed enzyme show that at least two different photochemical processes must be involved. Elimination of phosphorescence emission and reduction of UV absorption upon photolysis are consistent with initial hydrogen abstraction by benzophenone triplet state, followed by radical coupling, much as has been observed for the photoreaction of benzophenone with model systems. Photoaffinity labeling of chymotrypsin is also efficiently accomplished using two benzophenone derivatives which bind noncovalently to the enzyme's active site, although the rates of labeling are somewhat less than in the covalent complex.

SYNTHESIS AND CONFORMATION OF R-(+)-2-(α-PHENYLETHYL)BENZOPHENONE

Abstract: As a model of chiral benzophenone, R-(+)-2-(α-phenylethyl)benzophenone was prepared. The NMR and optical data indicate that rotations of the benzoyl and α-phenylethyl moieties are unrestricted in the range of −100 to 150°C, and therefore benzophenone skeleton is not chiral. A preferable conformation is discussed.

Polymer effect on the photochemical reaction of benzophenone with tetrahydrofuran and with diphenylamine in benzene.

Abstract: The rate constant of hydrogen abstraction by the n, π* triplet state of poly(4-vinylbenzophenone) (PVBP) from tetrahydrofuran was compared with that of benzophenone (BP) in benzene solution at 25°C, the former being about twice as large as the latter. The electronic behavior of the triplet BP group in the polymer was investigated by T—T absorption and phosphorescence, being the same as that of BP. A well-resolved ESR spectrum of the diphenylamino radical was detected upon UV irradiation of a benzene solution of PVBP and diphenylamine (DPA) and its concentration was compared with that of the poly(vinylbenzophenone-co-methyl methacrylate)—DPA or BP—DPA system. The concentration decreased in the order: PVBP>copolymer>BP. The polymer effect on the rate constant and the radical formation was explained in terms of the increase in the reaction efficiency on account of energy migration along the side chain of the polymer.

The effects of strong excitation‐phonon coupling on mixed crystal spectra: Diphenylmethylene in benzophenone

Abstract: We present low temperature absorption and emission spectra of diphenylmethylene in benzophenone. Although the spectra are broad at temperatures greater than ∼20 K, considerable structure appears at lower temperatures. The spectra and their temperature dependence are readily explained by a large excitation‐phonon coupling which is expected for this type of mixed‐crystal system.

Conductivity and Optical Properties of a Polyiodine Canal Complex (Benzophenone)9(KI)2I7, CHCl3

Abstract: (Benzophenone)9(KI)2I7, CHCl3 single crystals have a golden metallic reflection on the surfaces parallel to the polyiodine chain axis. The compound is a member of a large class of channel-like inclusion compounds in which isolated iodine atom chains are the only possible conducting strands in an otherwise insulating matrix. The (contactless) microwave conductivity is ∼ 10 Ω−1 cm−1 at room temperature with an activation energy of ∼0.03 eV down to 70°K, while the dc conductivity is ∼10−-6. Conductivity is strongly frequency dependent and contact problems are severe.

Photoimaging systems with cyclic hydrazides

Abstract: A photosensitive system comprising in intimate admixture (1) a dye in its leuco form, (2) a photooxidant taken from the group of hexaarylbiimidazole compounds, benzophenone, para-aminophenyl ketones, polynuclear quinones and thioxanthenones, and mixtures thereof and in the presence of the admixture is a 5-member-heterocyclic phenylhydrazide compound. The cyclic phenylhydrazide can be present in the admixture, or a dry coating of the admixture, after imagewise exposure, is treated with a solution of the heterocyclic compound. The system is useful in formation of colored images.

Syntheses with ethynylphosphonium salts; nucleophilic additions to phenylethynyltriphenylphosphoniun bromide

Abstract: Acyclic and heterocyclic adducts have been prepared by additions to phenylethynyltriphenylphosphoniun bromide of behnoylhydrazine, hydroxylamine, o-aminobenzophenone, o-aminophenol, o-aminobenzenethiol, o-aminoaniline, ethylenediamine, 2, 3-diamionopyridine, 1, 2-diaminonaphthalene, 1, 8-diaminonaphthalene, and benzophenone hydrazone. A useful feature of the title compounds is that the triphenylphosphonium group activtes the triple bond and then can be removed either as phosphine oxide or as a quaternary salt; thus, they are potential ethynyl equivalents.

The compound 3,6-bis(hydroxyethoxy)xanth-9-one, linear polyesters, and shaped articles obtained from the linear polyesters

Abstract: UV stable linear polyesters, e. g. PET, contain in their chain copolymerised bis(hydroxyalkoxy)xanth-9-ones, preferably 3,8-bis-(2-hydroxyethoxy)xanth-9-ones. The polymers are obtained by polymerisation in the presence of a tetrahydroxy benzophenone, preferably the 2,2',4,4'-isomer. The method of polymerising in the presence of dihydric phenols to obtain ethoxyaryloxy polyesters is also described.

Intermediates in the decomposition of aliphatic diazo-compounds. Part 15. Radical cations in the decomposition of diazodiphenylmethane by copper(II) perchlorate and by tris(p-bromophenyl)ammoniumyl perchlorate

Abstract: The kinetics and products of the decomposition of diazodiphenylmethane by copper(II) perchlorate and by tris-(p-bromophenyl)ammoniumyl perchlorate in acetonitrile solvent have been investigated. The similarity of the two reactions suggests that both the copper and the ammoniumyl salt act as initiators of a chain decomposition in which the chain carriers are radical cations. E.s.r. studies of reaction mixtures in other solvents, notably n-heptyl cyanide, indicate that two different radical cations are formed during the reaction; one, detectable at low temperatures, is believed to be the radical cation formed by simple removal of one electron from the diazoalkane by the initiator, and the other is shown to be the radical cation of benzophenone azine, one of the products of the reaction. In acetonitrile as solvent the major reaction product is tetraphenylethylene, but the ratio of this olefin to benzophenone azine changes from solvent to solvent and in some cases depends upon whether or not oxygen is present. The addition of water to acetonitrile leads to changes in the rate of decomposition of the diazo-compound with both initiators which indicate progressive, and at water concentrations greater than about 0.3M almost total, incursion of a perchloric acid-catalysed decomposition pathway involving rate-limiting formation of diphenylmethyl cations. This has been confirmed by measurement of the kinetic deuterium isotope effect of replacing the added water by deuterium oxide.

Process for preparing 3,4,3,4-benzophenone-tetracarboxylic dianhydride

Abstract: A process for preparing 3,4,3',4'-benzophenonetetracarboxylic dianhydride which comprises condensing an impure ortho-xylene mixture with acetaldehyde in contact with an acid catalyst to obtain an impure 1,1-bis(3,4-dimethylphenyl) ethane mixture, oxidizing the 1,1- bis(3,4-dimethylphenyl) ethane mixture with nitric acid to obtain a mixture of carboxylic acids, from which by crystallization and dehydration substantially pure 3, 4, 3', 4'-benzophenonetetracarboxylic dianhydride is recovered.

Photosynthesis of mercaptans

Abstract: Synthesis of mercaptans by the photochemical reaction of an olefin with hydrogen sulphide in the presence of an initiator constituted by benzophenone, thiobenzophenone or a mixture of the two, preferably accompanied by an organic compound of an element of Group VA of the Periodic Classification. These initiators can carry substituents on either or both of the two benzene rings. The light utilized can have a wavelength of 300 to 600 nm. The process allows various mercaptans to be obtained with good yields.

Organic sulfur mechanisms. 21. The reaction of arylsulfenes with sulfur dioxide

Abstract: Phenylsulfene and diphenylsulfene (2), obtained by reaction of 2,6-lutidine with appropriate precursors, react with sulfur dioxide to give, respectively, benzaldehyde and benzophenone, in confirmat...

Photo-oxygenation of diphenyldiazomethane in the presence of phenyl trimethylsilyl ketone. Oxygen transfer from carbonyl oxide to the silyl ketone

Abstract: Dye-sensitized photo-oxygenation of diphenyldiazomethane in the presence of phenyl trimethylsilyl ketone produced trimethylsilyl benzoate by reaction of a carbonyl oxide with the silyl ketone accompanied by 1,2-rearrangement of the trimethylsilyl group, together with benzophenone.

Chemical modification of polymers. XI. Photoreactive polymers from poly(vinylbenzyl chloride)

Abstract: Photocrosslinking has been observed in a number of polymers derived by chemical modification of poly(vinylbenzyl chloride). Included are polymers bearing pendant benzophenone, stilbazolium, fluorenone, carbazole, and sulfonylazido moieties. The synthesis and properties of these polymers are described.

Process for preparing benzophenone derivatives

Abstract: A process is described for preparing benzophenone derivatives of a high purity in an extremely high yield from 3-phenylphthalide derivatives with the use of at least one oxidizing agent.

Adducts of Group IVB radicals with sulphur-containing Diaryl ketones

Abstract: The hyperfine splitting constants for the paramagnetic adducts of ·MR3 radicals (M = Si, Ge, or Sn) with some dithienyl and bisthienothienyl ketones, benzophenone, and fluorenone are reported and compared with those for the corresponding diarylhydroxymethyl radicals. From the results, and with the aid of INDO calculations, it has been found that in the former derivatives the O–M bond eclipses the 2Pz orbital of the carbonyl atom, at variance with the hydrogen adducts, which exhibit practically planar conformations. Barriers to rotation of the OH group in benzophenone and fluorenone derivatives have been determined from the temperature dependence of the aHOH splitting and are 5.1 and 6.5 kcal mol–1, respectively.

Novel acetylene end-capped polyesters

Abstract: A group of heat curable resins are provided which have good physical properties, which properties are retained to a surprising degree after prolonged exposure to temperatures as high as 300° C. The products are acetylene end-capped polyesters prepared by reacting a hydroxyphenylacetylene with a diacid chloride of an aromatic dibasic acid such as 4,4'-benzophenone dicarboxylic acid dichloride.

Photochemistry of 2-halogeno-1,1-diphenylethylenes. The photo-Fritsch–Buttenberg–Wiechell rearrangement

Abstract: Competing ionic and radical photobehaviour has been observed for 2-halogeno-1,1-diphenylethylenes. Irradiation of 2-fluoro-1,1-diphenylethylene in cyclohexane or ether afforded cis- and trans-fluorostilbene. Irradiation of the chloro, bromo, or iodo analogues gave a complex mixture of up to eight products, the three major products being diphenylacetylene, 1,1-diphenylethylene, and 1,1,4,4-tetraphenylbutadiene. The product distribution proved to depend on the halogen and on the solvent. Benzophenone or xanthone sensitised irradiation of 2-fluoro-1,1-diphenylethylene in cyclohexane gave 1-cyclohexyl-1-fluoro-2,2-diphenylethane, while irradiation of 2-chloro 1,1-diphenylethylene gave 2-cyclohexyl-1,1-diphenylethylene.

Reactions of spiro[2.6]nona-4,6,8-triene derivatives with acids and bases. Rearrangement to a heptafulvene derivative and formation of ether linkage compounds.

Abstract: Reaction of dimethyl trans-spiro[2.6]nona-4,6,8-trien-1,2-dicarboxylate with phenyllithium afforded trans-1,2-bis(hydroxydiphenylmethyl)spiro[2.6]nona-4,6,8-triene (2) in a good yield. Spirotriene 2 is very sensitive to acids and gave 8-(2,2-diphenylvinyl) heptafulvene accompanied with a quantitative amount of benzophenone by acid treatments. Although 2 is stable to basic reagents, upon treating with sodium hydride, 2 afforded 11-hydroxydiphenylmethyl-8-oxa-9-diphenyltricyclo[5.4.0.01,10]undeca-2,4-diene, and its double bond isomers. Mechanisms of the above reactions are discussed.