Showing papers on "Benzophenone published in 1977"

Optically detected magnetic resonance spectra of the lowest triplet states of benzophenone, 13C‐benzophenone, and three 4,4′‐dihalobenzophenones

Abstract: We describe measurements of the complete angular dependence of the optically detected magnetic resonance (ODMR) spectra of the lowest triplet states of benzophenone, carbonyl‐13C‐benzophenone, 4,4′‐difluorobenzophenone, 4,4′‐dichlorobenzophenone, and 4,4′‐dibromobenzophenone in 4,4′‐dibromodiphenylether host crystals at liquid helium temperatures. The principal axes and values of D (including the absolute signs) and g are reported and used to evaluate the spin–spin and spin–orbit contributions to the fine‐structure tensor of the parent molecule. It is found that the dipolar contributions to D in 3(n,π*) benzophenone are at least a factor of 2 less than recent ab initio estimates of the spin–spin contributions to D in 3A2 formaldehyde. Carbon‐13 hyperdfine splittings have been observed in the ODMR spectra of 13C‐benzophenone; an analysis of these yields estimates of the orbital spin densities ρ2sC(O)?0.008 and ρ2pxC(O)?0.14 and suggests that the C1–C(O) –C1′ fragment is planar. The fine‐structure parameter...

Products Formed from Analogues of 1,1,1-Trichloro-2,2-Bis(p-Chlorophenyl) Ethane (DDT) Metabolites by Pseudomonas putida

Abstract: Cultures of Pseudomonas putida growing in solutions with diphenylmethane as sole carbon source formed 1,1,1′,1′-tetraphenyldimethyl ether. The product was identified by gas chromatography, mass spectrometry, and infrared and nuclear magnetic resonance spectrometry. The formation of benzophenone, benzhydrol, and phenylglycolic acid was established by gas chromatography and mass spectrometry. Similar techniques also revealed that phenylacetic acid was a major metabolite. Resting cell suspensions converted benzhydrol to phenyl-glycolic acid and products tentatively identified as hydroxybenzhydrols and a hydroxybenzophenone. Cell suspensions of the bacterium also converted the tetraphenyldimethyl ether to benzhydrol and benzophenone. Possible pathways for the degradation of these analogues of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) metabolites are discussed

Benzophenone initiators for the photopolymerization of unsaturated compounds

Abstract: This invention relates to 3,4-bis(halomethyl) benzophenone photoinitiators and these initiators admixed with unsaturated photopolymerizable compounds. When such compositions are irradiated by ultraviolet light, the benzophenone derivatives split off free radicals which initiate the photopolymerization of the unsaturated photopolymerizable compounds.

Ultraviolet light curable coating compositions

Abstract: Ultraviolet light curable coating compositions comprising (1) a monomer and/or prepolymer containing at least one radically crosslinkable ethylenically unsaturated double bond and (2) a photopolymerization initiator containing (a) 4,4'-bis(diethylamino)benzophenone and (b) a lower alkyl ester of p- or o-benzoylbenzoic acid or a derivative thereof in a weight ratio of (a) to (b) of 1 : 1 to 1 : 10.

Benzophenone-containing photopolymerizable binders for printing inks and coating compositions

Abstract: Photopolymerizable binders for UV-curing printing inks and coating compositions, which contain benzophenone-based photoinitiators and photosensitizers including p-dimethylaminobenzaldehyde and esters of p-dimethylaminobenzoic acid.

Photochemistry of Heterocyclic Compounds. VII. Photochemical Reaction of 2,5-Diphenyl-1,3,4-oxadiazole with Benzo[b]thiophenes

Abstract: Irradiation of 2,5-diphenyloxadiazole 1 with benzothiophene 6a gives 3-benzoylbenzothiophene 7, its benzoylhydrazone 8, and/or the oxadiazepine 9; the yields depended on the nature of solvents. With benzophenone as a sensitizer, the photochemical reaction of 1 with 6a forms the [2+2] cycloadduct 12. It is found that 9 is photochemically dissociated to 1 and 6a. In the case of 2-methylbenzothiophene 6b, 3-benzoyl-2-methylbenzothiophene benzoylhydrazone 18 is formed, and with benzophenone as a sensitizer the [2+2] cycloadduct 19 is obtained. In the absence or presence of benzophenone, however, irradiation of 1 with 3-methylbenzothiophene 6c gives the [2+2] cycloadduct 20. The photochemical reaction of 1 with 6a or 6b in the presence of iodine gives the corresponding 3-benzoylbenzothiophene, 7 or 21, and benzoylhydrazone, 8 or 18, respectively. In the case of 6c, however, the [2+2] cycloadduct 23 is formed, together with 2-benzoyl-3-methylbenzothiophene 22. Mechanistic considerations of these reactions are a...

Formation of inclusion complexes of benzophenone derivatives; β-cyclodextrin studied by induced circular dichroism

Abstract: Benzophenone derivatives form 1 : 1 inclusion complex with β-cyclodextrin, exhibiting an induced optical activity. The induced c.d. data arising from the n–π* electric transition of the carbonyl group indicate that complex formation is enhanced by hydrophobic substituents and is prevented by hydrophilic ones on the aromatic rings, and that the substituents often exert an influence on the structure of the inclusion complex.

Process for producing imine compounds

Abstract: An imine compound is produced in high yield by reacting a benzophenone with ammonia in the presence of 0.01 to 100% by weight of an oxide of at least one of metals selected from the group consisting of metals of the second to fifth periods of Group III to V of the periodic Table, and iron as a catalyst at a reaction temperature of 150° to 250° C on the basis of benzophenone. Ammonia is fed to the reaction system continuously under a pressure of 2 to 15 atmospheres. A solvent may be used for the reaction. The catalyst metal oxide can be readily recovered and reused without any influence of water formed by the reaction.

Tetracycline studies. Part 5. New syntheses of anthracenes and anthraquinones through benzophenone carbanions

Abstract: The synthesis of anthracenes and anthraquinones by a novel method involving the cyclisation of carbanions derived from substituted benzophenones is described. The procedure gives good yields and is of wide applicability. Regiospecificity has been achieved by preferential displacement of chloride ion. In certain circumstances treatment of 2-cyanomethylbenzophenones with trifluoroacetic anhydride gives derivatives of isoquinolin-3-one.

Electron spin polarization (C.I.D.E.P.) in photosensitized reactions

Abstract: The sensitized and unsensitized photoreductions of biacetyl with triethylamine have been studied using time-resolved e.s.r. spectroscopy. It is confirmed that triethylamine quenches both singlet and triplet biacetyl. However, only the reaction of the triplet leads to efficient radical production, and this is not sufficiently rapid for significant primary electron polarization to be induced by the triplet mechanism in the systems investigated.Polarized e.s.r. spectra of biacetyl radical anions that can be obtained from benzophenone-sensitized reactions are shown to arise via a chemical sensitization mechanism: polarization in the primary radical MeĊHNEt2 results from the rapid reaction of triplet benzophenone with triethylamine and is transferred via reaction with ground state biacetyl to the secondary radical anions. The initial polarizations of both primary radicals (MeĊHNEt2 and Ph2ĊOH) have been estimated and are shown to be equal within experimental error, providing the first quantitative evidence for this requirement of the triplet mechanism for electron polarization.

Study of the degradation of polyurethanes. III. Mechanism of the photodegradation of polyurethane

Abstract: The effect of triplet sensitizers, benzophenone and anthraquinone and metal acetylacetonates [Co(II, III), Cu, Sn, and Ni] on the photodegradation of polyurethane was examined. Ultravioletvisible (UV-V) absorption spectra, gel formation, and luminescence emission of the polymer before and after irradiation were measured. Changes in UV-V absorption of the polymer and the formation of an insoluble fraction in the polymer were accelerated in the presence of the triplet sensitizers, and (Co(II, III)), Cu, and Sn acetylacetonates. Unirradiated polyurethane was excited by irradiation at 290 and 346 nm, and emitted light at 310 and 420 nm. After 1/2 hr irradiation emission of luminescence was observed at 430 nm, excitation at 290 and 346 nm; after 2hr irradiation at 530 nm, excitation at 420 nm was observed. The results suggest that photodegradation of the polyurethane proceeds via excited triplet states forming excimer between the polymers at the initial stage and exciplexes between the polymer and degradation products or intermediates after a certain irradiation.

Gas and Solution Phase Reactivities of Triplet Aromatic Carbonyls

Abstract: Absolute rate studies pertinent to the gas and solution phase photochemistry of triplet benzaldehyde, acetophenone and benzophenone have been carried out, and it has been confirmed that, in the gas phase, attack on a hydrocarbon by the carbonyl results in the expected hydrogen abstraction. Also absolute rates in both the gas phase and solution (acetonitrile) are quite comparable. For a given carbonyl the differences in the rates of abstraction are largely accounted for by activation energy changes. The activation energies vary from a high of 4.8 kcal mol−1 for abstraction of a primary hydrogen by acetophenone to a low of 1.4 kcal mol−1 for abstraction of tertiary hydrogen by benzaldehyde. At room temperature the relative reactivities of primary, secondary and tertiary C—H bonds for all the carbonyls are 1:23:190. In solution benzophenone is two times more reactive than acetophenone, while benzaldehyde is ten times more reactive. In the gas phase benzaldehyde is about 18 times more reactive than acetophenone. Molecular orbital calculations indicate that the greater reactivity of benzaldehyde as compared to acetophenone stems from steric hindrance in the latter. The quenching of acetophenone triplets by various other substrates including naphthalene, benzene, isopropanol and triethylamine is also discussed.

Reactions of Thiocarboxylic Acids with Oximes and Nitrones. A New Synthesis of Thiones

Abstract: The reactions of ketone derivatives containing carbon-nitrogen double bond such as oximes (3), N-alkyloximes (nitrones, 11), oxime O-alkyl ethers, phenylhydrazones and semicarbazones with thiocarboxylic acids were studied for the purpose of preparing thioketones. Both 3 and 11 reacted with thiocarboxylic acids to give thioketones in good yields. The reaction did not proceed in the cases of other ketone derivatives, the starting materials being recovered. The reaction of benzophenone oxime with thiobenzoic acid gave thiobenzophenone, dibenzoyl disulfide and ammonium benzoate, while that of benzophenone-N-methylnitrone with thioacetic acid gave thiobenzophenone and N-acetyl-N-methylhydroxylamine. The mechanisms of these reactions are presented.

Di:amino-di:phenyl-methane derivs. prepn. - from substd. aniline(s) and formaldehyde; convertible to benzophenone(s) useful as photosensitisers

Abstract: The novel diphenyl methane cpds. have formula (I). (where R' is Et or Pr substd. by CN, Cl, OH, MeO, EtO, acetoxy, beta-cyanethoxy, N,N-dimethyl or N,N-diethylamino; R2 = R' or 1-4C alkyl, and R' and R2 are the same or different, R3 = H, Ml, Et, MeO or Cl). (I) can be converted by oxidn. into novel benzophenone derivs. useful as photosensitisers or components of photo-iniator systems. The benzophenone derivs. are less toxic than Michler's ketone whilst having similar photosensitising activity, are more sol. in many organic solvents and are more compatible with many photopolymerisable mixts.

Photocyclisation and photoisomerisation of 1,3,4- and 1,4,5-triphenylpyrazole

Abstract: Irradiation of 1,4,5-triphenylpyrazole in the presence of iodine gives 1-phenyl-1H-phenanthro[9,10-c]pyrazole, identical with a specimen prepared by an independent route. 1,3,4-Triphenylpyrazole does not react under these conditions; this is thought to be because the intermediate non-aromatic polyene would be dipolar. Irradiation of 1,4,5-triphenylpyrazole in the presence of benzophenone gives 3-anilino-2,3-diphenylacrylonitrile, which is itself inert towards irradiation. 3-Aminoacrylonitriles are postulated as intermediates in some rearrangements of pyrazoles to imidazoles.

Photochemical Reactions of 4-Flavanols in the Presence of Ketone Sensitizers

Abstract: Irradiation of an oxygen-free benzene solution of cis-4-flavanol 1a by a mercury lamp in the presence of benzophenone gave 4-flavanone (32%), benzopinacol (85%), cis- and trans-2-(diphenylhydroxymethyl)-4-flavanols (7.6%), and 2-(diphenylhydroxymethyl)-4-flavanone (7.7%), whereas photolysis of cis-4-acetoxyflavane under similar conditions gave cis-2-(diphenylhydroxymethyl)-4-acetoxyflavane(24%), 2,2′-bi-4-acetoxyflavane (6%), and benzopinacol. Photolysis of 1a in acetone gave 4-flavanone (3.6%), trans-4-(1-hydroxy-1-methylethyl)-4-flavanols (9.9%). The cis isomers of the parent and substituted 4-flavanols showed higher reactivities than the corresponding trans isomers.

Silyl anions. VII. Electron transfer from trimethylsilylpotassium to benzophenone and naphthalene. Generation of anion radicals in nonpolar solvents such as n-hexane.

Abstract: Trimethylsilylpotassium, prepared in a nonpolar solvent by the reaction of hexamethyldisilane with potassium methoxide in the presence of 18-crown-6, is a useful reagent for efficient homogeneous electron transfer. The first esr spectra of anion radicals of benzophenone and naphthalene in n-hexane as well as those in THF and benzene were recorded.