Reaction Of Benzophenone Research Articles

Noncyclic Diaza Ligands and Their Metal Complexes: Synthesis, Characterization, and Biological Studies

Condensation reactions involving various ketones and amines formed noncyclic ligands denoted as LI, LII, LIII, and LIV. Ethylenediamine, when reacted with acetophenone, benzoylacetone (in the presence of 70% HClO4), and benzophenone, resulted in the following noncyclic ligands: (E,E)-N,N-bis(1-phenylethylidene)ethylenediamine (LI), bis(1-3-hydroxy-3-phenylbut-2-ene-ylidene) (LII) and (E,E)-N,N-bis(1,1-diphenylmethylidene)ethylenediamine (LIII), respectively. The reaction of benzophenone with 1,3-diaminopropane in a 1:1 ratio in a methanolic solution also led to the synthesis of a noncyclic ligand, (E,E)-N,N-bis(1,1-diphenylmethylidene)propylenediamine (LIV). All the synthesized noncyclic ligands, except LII, undergo decomposition during complexation, reverting to the initial ketones and amines. In contrast, LII exhibits remarkable stability and can form square planar complexes with Ni(II), Cu(II), and Co(II) salts. Additionally, the Co(II) complex can convert into a six-coordinated Co(III) complex, [CoLII(H2O)2](NCS), when it reacts with KNCS. All these ligands and derived metal complexes were characterized, and their antimicrobial properties were evaluated against the selected fungi and bacteria.

The Chemistry of [1,1′‐bis(o‐Carboranyl)]Borane η2‐σ‐Silane Adduct

AbstractWe report here a new route for the preparation of [1,1′‐bis(o‐carboranyl)]borane, a 3D analogue of 9‐borafluorene, η2‐σ‐silane adduct (1‐H‐SiEt3) in high yields (>80 %). The nature of B−H−Si bonding was studied by density functional theory (DFT) computations. Preliminary reactivity study of 1‐H‐SiEt3 with small molecules was carried out. Interestingly, 1‐H‐SiEt3 reacts with benzophenone in hexane producing the deoxygenation product Ph2CH2. While in benzene, 1‐H‐SiEt3 reacts with benzophenone leading to mixture of Ph2CH2 and Ph3CH (3 : 1). Ph3CH is formed via addition of benzene to the carbonyl followed by deoxygenation. In contrast, the reaction of benzophenone with Et3SiH in presence of a catalytic amount of 1‐H‐SiEt3 leads to hydrosilylation product Ph2(H)C−OSiEt3.

Preface for the special issue of ISRIUM‐2015 in Honolulu, Hawaii, USA

The International Symposium on Reactive Intermediates and Unusual Molecules (ISRIUM-2015) was held in Honolulu as part of the International Chemical Congress of Pacific Basin Societies (Pacifichem) in 2015. The ISRIUM-2015 was the 33rd of a series of roughly annual meetings that were started in 1978 in Geneva (organized by Professors Charles Jefford and Curt Wentrup). The Journal of Physical Organic Chemistry has devoted so far 4 special issues to the ISRIUM conferences in 2010, 2012, 2013, and 2014. Now, the Journal offers a new ISRIUM special issue containing papers delivered at the December 2015 Honolulu conference. There were 36 oral presentations by scientists from 6 different countries, as well as 34 posters in a separate poster session. This special issue of the Journal of Physical Organic Chemistry includes 10 papers, including 1 mini review article and 9 original research articles. Professor Robert Moss and his coworkers describe in detail the chemistry of extremely reactive carbenes,1 in which the phenomena of negative activation energies are discussed for addition reactions of reactive carbenes with alkenes. Oxidations of allenes bearing 1,8-diphenoxy or diaryloxyacridene moieties are performed by the research group of Professor Yohsuke Yamamoto to generate persistent triplet carbenes. They isolate a cyclized compound that is characterized by X-ray analysis.2 The research group of Professor Wolfram Sander reports the generation of a new sextet ground-state molecule, the 2,4,6-trichloro-1,3-dinitrenophenoxyl radical, in the UV photolysis of the corresponding diazido precursor in argon at 5 K.3 They found that the sextet molecule is formed in a stepwise fashion, with the triplet nitrene, the quartet nitreno radical, and the quintet dinitrene as intermediates that are detected by electron paramagnetic resonance spectroscopy. Chemists in Hiroshima, Japan, describe a first report on the regioselective formation of a bicyclic oxetane derivative in the photochemical [2 + 2] cycloaddition, or so-called Paternó-Büchi reaction of benzophenone with 2-siloxypyrole.4 They propose that the relative stability of intermediary triplet diradicals plays an important role for the regioselectivity. Professor Anna Gudmundsdottir and coworkers find the photochemical transformation of 3,5-diphenylisoxazole to an azirine in argon.5 Further irradiation was found to produce the corresponding ylide in the low-temperature matrix conditions. The formation of the azirine from the isoxazole is proposed to occur via a triplet nitrene intermediate, which is confirmed by theoretical calculations. Professor Hiroshi Ikeda and coworkers report luminescence from an excited-state biradical generated by irradiation of benzopheone-substituted cyclopropanes. The excited state is proposed to be generated from an adiabatic process of higher electronically excited states.6 Professor Weston Borden and coworkers computationally predict the low-lying electronic states of dioxatrimethylenemethane (DOTMM), H2CCO2, and the photoelectron spectrum of its anion.7 They find that DOTMM has a triplet ground state. An open-shell singlet state is found to lie very close in energy to the triplet state. However, the open-shell singlet is predicted to be a transition-state structure leading to barrierless formation of α-lactone. Professor Masayoshi Nakano and coworkers report a theoretical investigation of curved π-conjugated fullerene flakes,8 in which they discuss open-shell character, aromaticity, and third-order nonlinear optical properties of fragments of C60 fullerene. Professor Torsten Linker et al9 discuss the decomposition of anthracene endoperoxides. Interestingly, they observed not only homolytic O–O but also C–O bond cleavages in the thermolyses. In general, barbaralanes and semibullvalenes are fluxional molecules renowned for their exceedingly low–Cope rearrangement activation barriers and their close approach to homoaromaticity. However, Professor Richard Williams and coworkers find that 4,6-barbaralanedicarboxyl-2,8-dicarboxylic anhydride and 1,5-dimethyl-4,6-semibullvalenedicarboxy-2,8-dicarboxylic anhydride are unusual barbaralanes and semibullvalenes that are locked as the closed tautomers and do not undergo Cope rearrangement.10 This total lack of the Cope rearrangement was demonstrated through variable-temperature 13C nuclear magnetic resonance spectroscopy and computational studies. The reactive intermediates community looks forward to the next ISRIUM conference, organized by Professor Dasan M. Thamattoor, which will be in Sorrento Italy in 2017. We hope that readers of this special issue of the Journal of Physical Organic Chemistry will attend that meeting. Finally, the guest editors especially wish to acknowledge the invaluable assistance of Dr Sarah Ryan, Managing Editor, and Dr Peter Creaton, Journals Publishing Manager from Wiley, in the preparation of this issue.

Yttrium complexes containing heteroscorpionate ligands [(3,5-But 2C3HN2)2CHC(Ph)2O]– and [o-Me2NC6H4CH2C(NCy)2

A reaction of benzophenone with bis(3,5-di-tert-butylpyrazolyl)methyllithium (3,5-But2C3HN2)2CHLi (obtained in situ by metallation of (3,5-But2C3HN2)2CH2 with n-butyllithium in THF at–70 °C) led to the synthesis of alkoxide lithium complex [(3,5-But2-C3HN2)2CHCPh2O]Li(THF) (1) containing a new monoanionic heteroscorpionate ligand [(3,5-But2C3HN2)2CHCPh2O]–. Hydrolysis of complex 1 gave 2,2-bis(3,5-di-tert-butylpyrazolyl)-1,1-diphenylethanol (2) in 90% yield. The structure of alcohol 2 was established by X-ray crystallography. A reaction of anhydrous YCl3 with two molar equivalents of lithium alkoxide 1 in THF furnished yttrium monochloride complex [(3,5-But2C3HN2)2CHCPh2(μ-O)]2-YCl(THF)[(μ-Cl)Li]2 (3). According to X-ray diffraction data, chloride 3 is a monomeric ate-complex with one terminal and two bridging chloride ligands. The nitrogen atoms of the pyrazole rings are not involved in the coordination of the ligand with the yttrium ion. The bisalkyl complex [(3,5-But2C3HN2)2CHCPh2O]Y(CH2SiMe3)2(THF)2 (4) obtained by the reaction of alcohol 2 with an equimolar amount of Y(CH2SiMe3)3(THF)2 turned out to be unstable and completely decomposed in solution in C6D6 at 25 °C within two hours. An exchange reaction of equimolar amounts of YCl3 and {[o-Me2NC6H4CH2C(NCy)2]Li(THF)2}2 (5) (Cy is the cyclohexyl) in THF led to the formation of a neutral monochloride complex [o-Me2NC6H4CH2C(NCy)2]2YCl(THF)2 (6). A reaction of complex 6 with an equimolar amount of o-Me2NC6H4CH2Li in toluene led to the synthesis of a new yttrium aminobenzyl complex [o-Me2NC6H4CH2C(NCy)2]2Y[CH2C6H4-o-NMe2] (7). X-ray diffraction studies showed that in complexes 6 and 7 the donor NMe2 groups of amidinate ligands are not involved in the metal—ligand interaction. Yttrium complexes 4 and 7 exhibited catalytic activity in polymerization of isoprene.

Normal-to-Abnormal NHC Rearrangement of Al(III) , Ga(III) , and In(III) Trialkyl Complexes: Scope, Mechanism, Reactivity Studies, and H2 Activation.

The present contribution reports experimental and theoretical mechanistic investigations on a normal-to-abnormal (C2-to-C4-bonded) NHC rearrangement processes occurring with bulky group 13 metal NHC adducts, including the scope of such a reactivity for Al compounds. The sterically congested adducts (nItBu)MMe3 (nItBu=1,3-di-tert-butylimidazol-2-ylidene; M=Al, Ga, In; 1 a-c) readily rearrange to quantitatively afford the corresponding C4-bonded complexes (aItBu)MMe3 (4 a-c), a reaction that may be promoted by THF. Thorough experimental data and DFT calculations were performed on the nNHC-to-aNHC process converting the Al-nNHC (1 a) to its aNHC analogue 4 a. A nItBu/aItBu isomerization is proposed to account for the formation of the thermodynamic product 4 a through reaction of transient aItBu with THF-AlMe3 . The reaction of benzophenone with (nItBu)AlMe3 afforded the zwitterionic species (aItBu)(CPh2 -O-AlMe3 ) (6), reflecting the unusual reactivity that such bulky adducts may display. Interestingly, the nItBu/Al(iBu)3 Lewis pair behaves like a frustrated Lewis pair (FLP) since it readily reacts with H2 under mild conditions. This may open the way to future reactivity developments involving commonly used trialkylaluminum precursors.

Time-Resolved Detection of Magnetic Field Effects on Radical Pairs in Micelles: Two-Step Two-Laser Fluorescence Spectroscopy of Transient Radicals

A two-step two-laser fluorescence spectroscopy method was employed to enable time-resolved detection of magnetic field effects (MFEs) on radical pairs (RPs). In the photoinduced hydrogen abstraction reaction of benzophenone (BP) in sodium dodecyl sulfate (SDS) micellar solution, fluorescence from the BP ketyl radical (BPH•) was observed under various magnetic fields; BPH• forms RPs with hydrogen-abstracted SDS radicals (•SDS) in the micelles. Kinetic parameters of the RP dynamics such as the spin relaxation rate, the generation rate, and the escape rate were determined from the simple analysis. The MFEs on BPH• observed from the fluorescence measurements were explained by the spin relaxation mechanism proposed by Hayashi and Nagakura. In this study, we demonstrate that two-step two-laser fluorescence spectroscopy in combination with a magnetic field provides valuable information about photochemical reactions in which RPs play important roles.

Cage lifetimes of ionic liquids as studied by the magnetic field effect probe

Magnetic field effects (MFEs) on the photoinduced hydrogen abstraction reaction of benzophenone with phenol were investigated in ionic liquids (ILs) with a short alkyl chain (N,N,N-trimethyl-N-propylammonium bis(trifluoromethanesulfonyl)amide (TMPA TFSA)) and long alkyl chains ((N,N,N-trimethyl-N-octylammonium bis(trifluoromethanesulfonyl)amide (TMOA TFSA) and N-decyl-N,N,N-trimethylammonium bis(trifluoromethanesulfonyl)amide (DTMA TFSA)) by a nanosecond laser flash photolysis technique. In each ionic liquid, escaped radical yield of a benzophenone ketyl radical rapidly increased with increasing magnetic field strength (B) of 0 T < B≤ 0.01 T. At 0.01 T < B≤ 0.4 T, the escaped radical yield almost saturated in TMPA TFSA or gradually increased in TMOA TFSA and DTMA TFSA. At much higher fields of 0.4 T < B≤ 30 T, the yield gradually decreased, resulting in 10-15% decrease at 30 T. The observed MFEs can be explained by the hyperfine coupling and Δg mechanisms together with the relaxation mechanism. On the time profiles of the transient absorption observed for the benzophenone ketyl radical, MFEs were generated in the time range of 0 < t < 0.6 μs. The cage lifetimes of TMOA TFSA and DTMA TFSA were estimated to be at least 120 ns.

Cu(OAc)2-Mediated Cross-Coupling Reaction of Benzophenone N,N,N-Trimethylhydrazonium Salts and Aryl Boronic Acids

Cu(OAc)2-mediated coupling of benzophenone N,N,N-trimethylhydrazonium salts and aryl boronic acids proceeded to afford N-aryl imines.

Magnetic Field Effects on Photochemical Reactions in Ionic Liquids with Short Alkyl Chains

Magnetic field effects (MFEs) on the photoinduced hydrogen abstraction reactions of benzophenone and thiobenzophenone from thiophenol were investigated in several ionic liquids with short alkyl chains by a nanosecond laser flash photolysis technique. In each ionic liquid, escaped radical yields of benzophenone and thiobenzophenone ketyl radicals gradually decreased with increasing magnetic field strength. The observed results were analyzed by using the stochastic Liouville equation (SLE), employing a solvent separated radical pair (SSRP) model where the SSRP with a specific radical–radical distance is stable and has a long lifetime. The SLE analysis revealed that the lifetime of the SSRP and the radical rotation in the SSRP states are strongly correlated with the macroviscosity of the ionic liquids.

ChemInform Abstract: Reaction of Benzophenone with Alkyl, Acyl, and Silyl Halides Promoted by Ytterbium Metal.

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ChemInform Abstract: Use of Competition Kinetics with Fast Reactions of Grignard Reagents.

Competition kinetics are useful for estimation of the reactivities of Grignard reagents if the reaction rates do not differ widely and if exact rates are not needed. If the rate of mixing is slower than the rate of reaction, the ratios between the rates of fast and slow reagents are found to be too small. This is concluded from experiments in which results obtained by competition kinetics are compared with results obtained directly by flow stream procedures. A clearer picture of the reactivity ratios is obtained when the highly reactive reagent is highly diluted with its competitor. A fast reagent may account for almost all the product even when present as only 1 part in 100 parts of the competing agent. In this way allylmagnesium bromide is estimated to react with acetone, benzophenone, benzaldehyde, and diethylacetaldehyde ca. 1.5 x 10(5) times faster than does butylmagnesium bromide. The rates found for the four substrates do not differ significantly, and it seems possible that there is a ceiling over the rate of reaction of this reagent, for example, caused by diffusion control. This may explain that competition kinetics using allylmagnesium bromide have failed to show kinetic isotope effects or effects of polar substituents with isotopically or otherwise substituted benzophenones. A recently reported alpha-deuterium secondary kinetic isotope effect for the reaction of benzaldehyde with allylmagnesium bromide was observed at -78 degrees C, but was absent at room temperature. It is suggested that the reaction of benzophenone and benzaldehyde with allylmagnesium bromide has a radical-concerted mechanism since no radical-type products are produced and since no color from an intermediate ketyl is observed even at -78 degrees C.

Uncertainties and error propagation in kinetic hard-modelling of spectroscopic data

A novel method is presented for the rigorous propagation of uncertainties in initial concentrations and in dosing rates into the errors in the rate constants fitted by multivariate kinetic hard-modelling of spectroscopic data using the Newton–Gauss–Levenberg/Marquardt optimisation algorithm. The method was successfully validated by Monte-Carlo sampling. The impact of the uncertainties in initial concentrations and in the dosing rate was quantified for simulated spectroscopic data based on a second and a formal third order rate law under batch and semi-batch conditions respectively. An important consequence of this study regarding optimum experimental design is the fact that the propagated error in a second order rate constant is minimal under exact stoichiometric conditions or when the reactant with the lowest associated uncertainty in its initial concentration is in a reasonable excess (pseudo first order conditions). As an experimental example, the reaction of benzophenone with phenylhydrazine in THF was investigated repeatedly (17 individual experiments) by UV–vis and mid-IR spectroscopy under the same semi-batch conditions, dosing the catalyst acetic acid. For all experiments and spectroscopic signals, reproducible formal third order rate constants were determined. Applying the proposed method of error propagation to any single experiment, it was possible to predict 80% (UV–vis) and 40% (mid-IR) of the observed standard deviation in the rate constants obtained from all experiments. The largest contribution to this predicted error in the rate constant could be assigned to the dosing rate. The proposed method of error propagation is flexible and can straightforwardly be extended to propagate other possible sources of error.

Synthesis of 3‐(2‐Oxo‐2,3‐dihydrobenzo[b]furan‐3‐ylidenehydrazono)‐2,3‐dihydrobenzo [b]furan‐2‐one

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The Magnetic Field Effects on Photochemical Reactions in Ionic Liquids

The magnetic field effects (MFEs) on photoinduced hydrogen abstraction reactions of benzophenone (BP) with thiophenol (PhSH) in the ionic liquids (ILs) N,N,N-trimethyl-N-propylammonium bis(trifluoromethanesulfonyl) imide (TMPA TFSI), N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl) imide (P13 TFSI), and N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl) imide (PP13 TFSI) were investigated at 296 K by using a nanosecond laser flash photolysis technique under magnetic fields of 0-1.7 T. Large MFEs were observed for the first time in the ILs. In TMPA TFSI, the yield of the benzophenone ketyl radical gradually decreased with increasing magnetic field strength from 0 to 1.7 T, producing a 20% decrease at 1.7 T.

Synthesis of 3-(2-Oxo-2,3-dihydrobenzo[b]furan-3-ylidenehydrazono)-2,3-dihydrobenzo[b]furan-2-one

Reactions of benzophenone and fluoren-9-one hydrazones with (2-hydroxyphenyl)oxoacetic acid gave [carboxy(2-hydroxyphenyl)methylidenehydrazono](2-hydroxyphenyl)acetic acid which underwent intramolecular cyclization with formation of 3-(2-oxo-2,3-dihydrobenzo[bfuran-3-ylidenehydrazono)-2,3-dihydrobenzo[b]furan-2-one. The symmetric azine was also obtained by reactions of (2-hydroxyphenyl)oxoacetic acid with triphenylphosphoranylidenehydrazones derived from benzophenones, fluoren-9-one, and 1-methyl-2,3-dihydro-1H-indole-2,3-dione.

Benzophenone Imine

Benzophenone imine or (diphenylmethylene)amine ­(DPMA-H, 1) is a valuable reagent in organic synthesis. [1] It is a commercially available liquid which is easily prepared by addition of phenylmagnesium bromide to benzo­nitrile followed by hydrolysis with methanol [2] or by reaction of benzophenone with ammonia. [3]

Photochemistry of benzophenone adsorbed on MCM-41 surface

The photochemistry of benzophenone adsorbed on a channel-type solid support MCM-41 was studied by the use of diffuse reflectance and chromatographic techniques. For comparison purposes parallel studies were also conducted on silicalite and H-ZSM-5. The observed ground state absorption, luminescence and transient absorption spectra and photoproduct distribution strongly depend on the substrate under study. Triplet state luminescence was observed in all solids, hydrogen-bonded excited benzophenone emission was detected on MCM-41 while protonated excited benzophenone luminescence was observed only on H-ZSM-5. Transient absorption showed the triplet state in all solids and formation of the OH benzophenone adduct on MCM-41 and H-ZSM-5. Ketyl radical formation occurs after 355 nm irradiation but is a minor degradation pathway. The formation of transients resulting from the reaction of benzophenone with molecular oxygen was also detected on MCM-41, in air-equilibrated conditions and benzoic acid is the main degradation product. 2-Hydroxybenzophenone is one of the major photodegradation products on MCM-41 and H-ZSM-5. Products resulting from the α-cleavage were also detected under 266 nm irradiation. Benzophenone was found to be very stable in silicalite under all used conditions.

Pyrolysis of Aromatic Carboxylic Acid Salts: Does Decarboxylation Play a Role in Cross-Linking Reactions?

The pyrolysis of sodium benzoate, potassium benzoate, and calcium benzoate has been investigated between 435 and 500 °C as models for carboxylic acid salts in low-rank coals to determine if the decarboxylation of benzoate salts can contribute to cross-linking reactions during the thermal processing of low-rank coals. Decarboxylation was the dominant reaction pathway for all three salts. However, char formation (leading to poor mass balance) was also observed in all cases. The reaction proceeds via an anionic pathway, where the initial decarboxylation of benzoate salt leads to the formation of a phenyl anion as the key intermediate. Proton abstraction by the phenyl anion from another molecule of benzoate leads to the formation of benzene and benzoate dianion, which can react with CO2 to form a di-salt of phthalic acid (i.e., the Henkel reaction). Both benzene and phthalate account for >95% of the total products in the pyrolysis of sodium and potassium benzoates. The minor products diphenylmethane, benzophenone, triphenylmethane, and 9-phenylfluorene can form by a mechanism involving the reaction of phenyl anion with alkali benzoate to generate benzophenone, which reacts further to form the other products. Contrary to previous reports, calcium benzoate pyrolysis proceeds via an anionic mechanism to form benzene and benzophenone as the major products. No evidence of any calcium phthalate formation is observed in the pyrolysis of calcium benzoate. Furthermore, the reaction of benzophenone with the phenyl anion to form diphenylmethane, triphenylmethane, and 9-phenylfluorene seems to be slowed considerably (compared to sodium and potassium benzoates), based on the observed yield of these minor products. The rate constant for the pyrolysis of these benzoate salts, which decarboxylate slower than corresponding acids, decreases in the following order: potassium benzoate > sodium benzoate ≫ calcium benzoate. The pyrolysis rate is increased by at least a factor of 3 in the presence of water. Water traps the intermediate phenyl anion very efficiently to form benzene almost exclusively. Based on these findings, it can be concluded that the presence of water can drastically reduce cross-linking reactions and significantly improve liquefaction.

Pulse-shift measurement: a direct observation of radical pair dynamics in a micelle

The hydrogen abstraction reactions of benzophenone in a micellar solution in the absence and presence of 1,4-cyclohexadiene are compared with time-resolved electron spin resonance (ESR) and optically detected (OD) ESR. “Pulse shift” measurement by OD-ESR, which observes the effect of a resonant microwave pulse at different delay times after laser excitation, reveals that the lifetime of the radical pair becomes much shorter in the presence of 1,4-cyclohexadiene. This explains the change of chemically induced dynamic electron polarization from spin-correlated radical pair polarization in the absence of 1,4-cyclohexadiene to conventional, E*/A polarization in its presence. The rate constants determined by this technique indicate that the escaping rate of cyclohexadienyl radical is ten times larger than those of alkyl and benzophenone ketyl radicals.

The Reactions of DMSO with Arylaldehydes in the Presence of Sodium Hydride.

AbstractFor Abstract see ChemInform Abstract in Full Text.