Showing papers on "Benzophenone published in 1970"

Ground- and Excited-State Geometries of Benzophenone

Abstract: The equilibrium geometries of benzophenone and benzaldehyde in ground and (n,n*) excited states are calculated using the extended Huckel and CND0/2 methods. The ground state of benzophenone has both phenyl rings twisted out of plane to a CZ geometry by 38'. The excited state has a considerably steeper potential well for a similar geometry in which the angles of twist are 32'. It appears that the carbonyl group remains locally planar in the excited state. Potential surfaces for the interconversion of enantiomeric minima are reported.

The spectroscopy and photochemistry of naturally occurring and synthetic chromenes.

Abstract: — –All naturally occurring and synthetic chromenes studied exhibit photochromism at — 196°C and in some cases at room temperature. Chromenes containing a coumarin moiety have the least photochemistry and also exhibit the strongest emissions. Chromenes containing a hydroxyl group ortho to an acetyl group exhibit solely a phosphorescence. Lapachenole (a 7,8-benzochromene) shows the most rapid and highest percentage conversion to the colored form and no emission. Photocolored form of evodione can be produced by a triplet energy transfer from benzophenone.

Preparation of a polyimide foam

Abstract: The reaction of phenyl isocyanate with phthalic anhydride to form N-phenylphthalimide is strongly solvent dependent and catalyzed by tertiary amines. Water and alcohol promote imide formation, but Lewis acids and organometallic compounds are ineffective. In DMSO solvent, benzophenone tetracarboxylic dianhydride (BTDA) and polymethylene polyphenol isocyanate (PAPI) polymerize with the evolution of carbon dioxide to yield a foamed polyimide. The solvent-freed open-celled foams exhibit exceptional fire resistance and thermal stability.

Benzophenone hydrazones containing perfluoroalkyl,perfluoroalkoxy,and perfluoroalkylthio substituents

Abstract: FLUORINATED BENZOPHENONE HYDRAZONES ARE BIOLOGICALLY ACTIVE AGAINST INSECTS AND SHOW ACTIVITTY IN INFLUENCING THE METABOLISM OF PLANTS.

Flash photolysis of an ortho-alkyl-benzophenone

Abstract: Five transients have been observed in the conventional and laser flash photolysis of 2,4-dimethylbenzophenone: assignments are suggested, together with a sequence of reactions.

Synthesis of an oxetan by photoaddition of benzophenone to a thiophen derivative

Abstract: An oxetan has been synthesised by 1,2-photoaddition of benzophenone to 2,5-dimethylthiophen.

Melting of Three Organic Compounds at High Pressures

Abstract: The melting of napthalene, benzophenone, and p‐dichlorobenzene has been determined up to 25 ∼ 30 kbar. The melting curve for benzophenone determined by Bridgman intersects our curve at 4 kbar and at 8 kbar his melting temperature is 8°C higher than ours. The melting temperature versus volume compression curves are nonlinear and are concave towards the temperature axis. The log(Tm / Tm0) versus log(V0 / V) plots are linear for napthalene and p‐dichlorobenzene. Benzophenone points show a scatter which is attributed to inaccuracies in the compressibilitity data available for this compound.

Acid hardening resins which can be activated by ultraviolet light

Abstract: THE INVENTION RELATES TO ACID-HARDENING RESIN COMPOSITIONS HAVING INCORPORATED THEREIN A BENZOPHENONE COMPOUND EACH OF THE TWO BENZENE NUCLEI OF WHICH BEING SUBSTITUTED BY A HALOGENATED METHYL GROUP. IF SAID COMPOSITIONS ARE IRRADIATED BY UV-LIGHT SAID BENZOPHENONE COMPOUND SPLITS OFF HYDROGEN HALIDE WHICH, IN TURN, CATALYSES THE HARDENING OF THE RESIN COMPOSITION.

Phnolic-solvent-soluble aromatic polyamide-imide and process for producing same

Abstract: A novel aromatic polyamide-imide is synthesized by heating and reacting a mixture of trimellitic acid and 3,3', 4,4'-benzophenone tetracarboxylic acid with a diamine represented by the formula:

Temperature effects on the luminescence of benzophenone in polymers

Abstract: : Using rigid polymer matrices, it was possible to confirm that benzophenone exhibits a delayed thermal fluorescence at 300K and have shown that the spectrum of this emission is an approximate mirror image of the structured singlet-singlet n,pi* absorption spectrum. Lifetimes of benzophenone in various polymers of styrene and its derivatives at 300K are compared with the previously reported lifetime in benzene. It was concluded that, if solvent-solute interactions are responsible for the anomalously short phosphorescence lifetime in benzene, then this interaction has a strong steric requirement. (Author)

Ammonia synthesis catalyst

Abstract: The present invention provides a novel catalyst and improved process for direct synthesis of ammonia from nitrogen and hydrogen which comprises employing a complex of alkali metal or organo-alkali metal with graphite, said organo-alkali metal being an alkali metal benzophenone ketyl or an alkali metal salt of an aromatic hydrocarbon.

The photosensitised oxidation of amines

Abstract: Benzophenone, Methylene Blue, and Rose Bengal have been shown to photosensitise the oxidation of a number of amines, and from product studies it is concluded that the reactions occur by abstraction of hydrogen from the amines by the excited sensitiser, followed by reaction of the amine radicals with oxygen.

The mass spectral behavior of β‐bromoethyl benzoate and some of its ring substituted derivatives: Evidence for oxygen participation in the formation of [M Br]+

Abstract: The expulsion of a bromine atom from the molecular ion of β-bromoethyl benzoate displays a kinetic behavior which resembles that of a rearrangement reaction. The two oxygen atoms in the resulting [M Br]+ ion become equivalent before or during the secondary decomposition of this ion, as shown by oxygen labeling. In addition, the primary ions generated from benzophenone ethylene ketal and acetophenone ethylene ketal by phenyl and methyl expulsion, respectively, undergo subsequent fragmentation in the same way as the [M Br]+ from β-bromoethyl benzoate. These results strongly indicate that the carbonyl-oxygen atom participates in the expulsion of bromine. The effect of ring substituents on the competing loss of bromine and McLafferty rearrangement is also discussed.

Electron spin resonance study of radicals photolytically generated from aromatic carbonyl compounds. Part III. Reduction of fluorenone and benzophenone in amines

Abstract: E.s.r. spectra of the 9-hydroxyfluorenyl radical, which is produced by the u.v. photolysis of fluorenone in tertiary amines, are presented and discussed. Tertiary amines appear to have a vital and unique role in the reduction process as the 9-hydroxyfluorenyl radical was not observed in photolysed solutions of fluorenone in other amines or in many non-amine solvents. Reduction probably occurs by electron transfer from the nitrogen atom to the excited carbonyl group to form the fluorenone radical anion which then rapidly abstracts a proton from the amine radical cation.Amines can effect markedly the e.s.r. spectra of hydroxy-substituted radicals. Results on the Ph2ĊOH radical in various amine solvents are presented and compared with results for the same radical in solvents in which the effects of solvation are likely to be minimal. Such solvents are cyclohexane and toluene. In the latter, the spectrum of the benzyl radical, PhĊH2, is clearly resolved in addition to that for the Ph2ĊOH radical. The observations can be explained in terms of solvation via hydrogen bonding between the hydroxy-group protons and the nitrogen atom of some amines. Triethylamine appears to be a particularly potent solvator and affects the coupling constants to the hydroxy-protons and, in the case of the 9-hydroxyfluorenyl radical, the ring proton coupling constants quite drastically.

Organic Photochemical Reactions. VII. Photolysis of 1-Benzyl-2-ethylbenzimidazole 3-Oxide

Abstract: It is suggested that photolysis of 1-benzyl-2-ethylbenzimidazole 3-oxide (I) involves two different pathways ; one goes via an oxaziridine intermediate (VI) formed from the excited singlet state ; and the other is deoxygenated via the excited triplet state, enhanced by the presence of benzophenone or anthraquinone. Deoxygenation of several aromatic N-oxides is shown to be effected by anthraquinone.

The interaction of pyridine, n-butyl-lithium, and carbonyl compounds

Abstract: 1-Lithio-2-n-butyl-1,2-dihydropyridine (V) prepared from pyridine and n-butyl-lithium in the presence or absence of TMEDA, reacts with benzophenone to give a number of products: (I), (II), (III), and of particular interest, the reduction product, (IV).

Initiators for the photopolymerisation of unsaturated compounds

Abstract: THE INVENTION RELATES TO UNSATURATED POLYMERISABLE COMPOUNDS AND MIXTURES OF SUCH COMPOUNDS ADMIXED WITH BENZOPHENONES EACH OF THE TWO NUCLEI OF WHICH BEING SUBSTITUTED BY A HALOGENATED METHYL GROUP. IF SAID COMPOSITIONS ARE IRRADIATED BY ULTRAVIOLET LIGHT, THE BENZOPHENONE DERIVATIVES SPLIT OFF FREE RADICALS WHICH INITATE THE POLYMERISATION OF THE UNSATURATED COMPOUNDS.

Extractives from Guttiferae. Part XVI. Biogenetic-type synthesis of xanthones from their benzophenone precursors

Abstract: A general synthesis of polyhydroxybenzophenones is described. 2,3′,4′,6-Tetrahydroxy- 2,2′,3′,6-tetrahydroxy-, and 2,3,3′,4′,6-pentahydroxybenzophenones were prepared and oxidised to 1,6,7-trihydroxy-, 1,2,8-trihydroxy-, and 1,2,6,7-(or 1,4,6,7-) tetrahydroxyxanthones, respectively, by oxidative coupling.