Benzonitrile Research Articles

Effect of CN group on isentropic compressibility and volumetric parameters of mixtures of γ-butyrolactam ( n = 5) and nitriles

Ultrasonic speed u and dilatometric measurements of excess volume V E have been carried out for mixtures of pyrrolidin-2-one (PY) with acetonitrile (ACN), propionitrile (PN), butyronitrile (BN), valeronitrile (VN), acrylonitrile (ACRN) and benzonitrile (BEN) at 303.15 K over the entire composition range. All the mixtures exhibit negative excess volumes, the curves being nearly symmetrical. The magnitude of the minimum increases steadily with decreasing molar size of the nitrile. The molar isentropic compressibility K S has been computed by combining ultrasonic velocity and excess volume data. Excess molar isentropic compressibility K S E is also negative in all the mixtures over the whole composition range. The data are interpreted in terms of moderate interactions of all kinds decreasing in importance with increasing nitrile carbon chain length. Partial and apparent molar quantities have been estimated to gain insight into interactions. Prigogine–Flory–Patterson theory has been utilised for the quantitative estimation of different contributions viz. interactional, free volume and P * effect to excess volume.

Photophysical Properties and Photoinduced Electron Transfer between [60]Fullerene‐Containing Cyclic Sulphoxide [ C60‐C6H8SO] and Tetrathiafulvalene (TTF) by Laser Flash Photolysis

AbstractPhotoinduced electron transfer (PET) processes between C60‐C6H8SO and Tetrathiafulvalene (TTF) have been studied by nanosecond laser photolysis. Quantum yields (ϕet) and rate constants of electron transfer (ket) from TTF to excited triplet state of [60] fullerene‐containing cyclic sulphoxide in benzonitrile (BN) have been evaluated by observing the transient absorption bands in the NIR region. With the decay of excited triplet state of [60] fullerene‐containing cyclic sulphoxide, the rise of radical anion of [60] fullerene‐containing cyclic sulphoxide is observed.

A laser trapping-spectroscopy study on the photocyanation of perylene across a single micrometre-sized oil droplets/water interface: droplet-size effects on photoreaction quantum yield

Photoirradiation of perylene in the presence of 1,4-dicyanobenzene and NaCN in a benzonitrile (BN)/water emulsion under vigorous stirring gave 1- and 3-cyanoperylene in a total yield of 15%. For kinetic and mechanistic studies of the photoreaction, we conducted single-droplet measurements by using a laser trapping-microspectroscopy technique. Although determination of the incident light intensity absorbed by a solute in the emulsion is in general very difficult owing to strong light scattering, that in single laser-trapped BN droplets dispersed in water was successful on the basis of the photooxidation reaction of 9,10-disubstituted anthracene. The quantum yield of the photocyanation of perylene (ΦCN) was then determined to be 4.9×10−3. Furthermore, we found that ΦCN was linearly proportional to the inverse of the droplet radius: the reaction efficiency increased with decreasing droplet size through an increase in the surface area/volume (A/V) ratio of a droplet. This is the first demonstration of micrometre droplet size effects on the quantum yield for a photoreaction across the droplet/water interface.

Ligand-Induced and Reductively Induced Alkyne−Isocyanide Coupling Reactions of [Mo(CNBut)3(PhC⋮CPh)(η5-C5Me5)][BF4

The complex [Mo(CO)(PhC≡CPh) 2 (η 5 -C 5 Me 5 )][BF 4 ] reacts with 3 equiv of CNBu t to yield the mixed alkyne-isocyanide complex [Mo(CNBu t ) 3 (PhC≡CPh)(η 5 -C 5 Me 5 )][BF 4 ], 1. Reaction of 1 with a fourth equivalent of CNBu t generates [Mo{=C(NHBu t )C(Ph)=C(Ph)CN}(CNBu t ) 2 -(η 5 -C 5 Me 5 )][BF 4 ], 2, containing an η 3 -vinylcarbene ligand formed from the coupling of two of the coordinated isocyanide ligands with the diphenylacetylene, with concomitant protonation of one of these isocyanide fragments and dealkylation of the other. Complex 2 may be deprotonated to give [Mo{C(=NBu t )C(Ph)=C(Ph)CN}(CNBut) 2 (η 5 -C 5 Me 5 )], 3. Protonation of 1 with HBF 4 .Et 2 O generates [Mo{=C(Ph)C(Ph)C=NHBu t }(CNBu t ) 2 (η 5 -C 5 Me 5 )][BF 4 ] 2 , 4, by inducing the coupling of a protonated isocyanide ligand with diphenylacetylene, and 4 reacts with CNBu t to give 2. A similar reaction of 4 with P(OMe) 3 generates [Mo{=C(NHBu t )C-(Ph)=C(Ph)CN}(CNBu t ){P(OMe) 3 }(η 5 -C 5 Me 5 )][BF 4 ], 5, involving the same coupling and elimination pattern. The diphenylacetylene and CNBu t ligands of 1 may also be reductively coupled. Thus, treatment of 1 with sodium-mercury amalgam and subsequent protonation with HBF 4 .Et 2 O gives the metallacyclopentatriene-like [Mo{=C(NHBut)C(Ph)=C(Ph)C-(NHBu t )}(CNBu t )(η 5 -C 5 Me 5 ][BF 4 ], 6, or [Mo{=C(NHBu t )C(Ph)C(Ph)CH-NHBu t }(CNBu t )(η 5 -C 5 Me 5 )][BF 4 ], 7, depending upon the solvent. Complex 7 contains an N-protonated η 4 -monoazadiene ligand with a pendant carbene functionality that is also coordinated to the metal. The crystal structures of 1, 2, 3, 6, and 7 have been determined.

Synthesis of a carbon-14 analogue of 8-chloro-11-(4-methyl-1-piperazinyl)-11-[ 14C]-dibenz[b,f][1,4]oxazepine

8-Chloro-11-(4-methyl-1-piperazinyl)-dibenz[b,f][1,4]oxazepine labelled with carbon-14 in 11-position was prepared from 2-hydroxy benzonitrile-[cyano- 14C].

The structure of a cyanobiphenyl side chain liquid crystalline poly(silylenemethylene)

The structure of a side chain liquid crystalline poly(silylenemethylene) (–(SiCH 3R–CH 2)–: R=O(CH 2) 11O–Ph–Ph–CN, Ph=phenyl) (CN-11) has been studied by X-ray diffraction and differential scanning calorimetry (DSC). The DSC results showed that CN-11 has transitions at ∼92 °C ( T 2) and ∼147 °C ( T 1) during both cooling and immediate heating. A third transition occurred at ∼50 °C ( T 3) during heating after annealing at room temperature. The X-ray fiber pattern of the CN-11 annealed at room temperature showed several wide and small angle reflections which were indexed by a monoclinic unit cell with parameters a=16.8 Å, b=7.42 Å, c=43.6 Å and β=102.1° ( b: fiber direction), representing a crystal structure with layer thickness of ∼43 Å. Upon heating at T 3, the crystal structure became less ordered (but somewhat more ordered than smectic A ( S A) and smectic C ( S C)). This was followed by S A (or S C) phase at T 2, and ultimately an isotropic state ( I) at T 1. The observed layer thickness (∼43 Å) is about ∼1.5 times the most extended side chain length, indicating a double-layer structure with tilted or interdigitated side chains. The X-ray fiber pattern had a four-point pattern at d=4.52 Å, suggesting that the side chains in the crystal are likely to be tilted by 56° from the polymer fiber axis.

Compressibility studies of some copper (I) and tetraalkylammonium salts in binary mixtures of triethylphosphite with acetronitrile, benzonitrile and pyridine at 298.15 K

Ultrasonic velocity (u) and density (ϱ) of tetrabenzonitrile copper (I) perchlorate (CuClO 44C 6H 5CN), tetrabutylammonium tetraphenylborate (Bu 4NBPh 4) and tetrabutylammonium perchlorate (Bu 4NClO 4) have been measured at different salt concentrations in the concentration range 0.002–0.28 mol kg −1 in binary mixtures of triethylphosphite (TEP) with acetonitrile (AN), benzonitrile (BN) and pyridine (PY) containing 0, 20, 40, 60 and 80 mol % TEP. The isentropic compressibility (K s) and apparent molal isentropic compressibility (K s,ø) in various solvent systems have been calculated. Limiting apparent molal isentropic compressibilities (K 0 s,φ for various salts have been evaluated and split into contributions of individual ions i.e. into (K 0 s,φ) ± values. The variation of (K 0 s,φ) ± values with solvent composition shows that Cu + indicates strong solvation in AN + TEP, BN + TEP and PY + TEP mixtures over the entire solvent composition range and the solvation with TEP is relatively stronger than that with AN, BN and PY. ClO 4 − is better solvated in AN + TEP mixture by having some interaction with AN but is poorly solvated in BN + TEP and PY + TEP mixtures. Both Bu 4N + and Ph 4B − show some interaction with TEP in the TEP-rich region of all the solvent systems.

Electron-Transfer (ET) Fluorescence Quenching in Benzonitrile. Evidence of an Intermolecular ET with ΔG < −0.5 eV being a Diffusion-Controlled Process

The fluorescence quenching electron-transfer (ET) and the back ET within geminate radical ion pairs (GRIP) were studied in benzonitrile (BN) using anthracenecarbonitriles as electron-accepting fluorescers and amino-, methyl- and methoxybenzenes as electron-donating quenchers. A direct evidence that the long-distance ET fluorescence quenching takes place at the diffusion-controlled limit was found for the first time. Furthermore, the present results were compared with the previous ones obtained for the same fluorescer and quencher pairs in acetonitrile (AN) in order to examine whether the photoinduced ET reactions can be affected by the kind of solvent, i.e., aliphatic and aromatic, and particularly to make clear whether there happens to be a π-electron-mediate superexchange ET in BN. The free energy dependence of fluorescence quenching rate constant (k q ), effective quenching distance (rq), free radical yield (Φ R ), and rate constant (k b e t ) of back ET within GRIP in BN was the same as that in AN as long as the differences in dielectric constant, diffraction index, and viscosity between BN and AN were taken into account. The fact that there is no particular difference between photoinduced ET reactions in AN and BN evidences the absence of π-electron-mediate superexchange ET in BN.

Temperature Dependence of the Viscosity of Isotropic Liquids

Temperature dependence of the shear viscosity measured for isotropic liquids belonging to the three homologous series: 4-(trans-4'-n-alkylcyclohexyl) isothiocyanatobenzenes (C n H 2 n + 1 CyHx Ph NCS; nCHBT, n = 0 + 12), n-alkylcyanobiphenyls (C n H 2 n + 1 Ph Ph CN; nCB, n = 2 + 12) and 1, n-alkanediols (HO(CH 2 ) n OH; 1,nAD, n = 2+10) were analysed with the use of Arrhenius equation and its two modifications: Vogel-Fulcher and proposed in this paper. The extrapolation of the isothermal viscosity of 1, n-alkanediols (n = 2 + 10) to n = 1 leads to an interesting conclusion concerning the expected viscosity of methanediol, HOCH 2 OH, the compound strongly unstable in a pure state.

N-Arylbenzonitrilium ions. Photochemical generation and effect of substituents in the phenyl rings on lifetimes in water and reactivity with azide ion

Nitrilium ions Ar–CN+–Ar′ have been studied by laser flash photolysis in aqueous solutions containing 20% acetonitrile. The cations were generated by photoheterolysis of benzimidate esters Ar–CZN–Ar′ (Z = –OC6H4-4-CN) with 4-cyanophenoxide as the photochemical leaving group. Rate constants for the reaction with water (kw), azide ion (kaz) and hydroxide (kOH) were measured. The cation Ph–CN+–Ph is only 50-fold shorter lived in water compared to Ph–CN+–iPr (2); thus the effect of replacing an N-alkyl group with N-phenyl is modest. These two cations are also shown to have similar lifetimes to iminium analogs, e.g. Ph–CHN+(Me)–Ph. Thus, addition of water to analogous sp and sp2 hybridized systems occurs at a similar rate, and the increased steric access to the nitrilium plays at most a modest role. For the series where substituents in Ar′ were varied with Ar equal to phenyl, the Hammett plot for log kw correlated with σ, with ρ = −1.4. For the series where Ar was varied, the data correlated much better with σ+, although ρ+ was only −0.6. This remarkably small effect of substituents in Ar contrasts with the effects seen in benzylic carbocations, but is consistent with the nitrilium structure, with most of the positive charge located on the nitrogen. Rate constant ratios kaz ∶ kw, including the N-alkylnitrilium ion 2, are constant at ∼104, with values of kaz well below the diffusion limit, even for the most reactive nitrilium ions. This is very different behaviour from that of carbocations and arylnitrenium ions of similar lifetimes in water. For these cations the rate constants kaz would be at or at least approaching the diffusion limit.

Reduction of p-benzoquinone in the presence of phospholipid molecules in a lipophilic environment at the thin benzonitrile layer modified electrode

Electrochemical reduction of p-benzoquinone (BQ) across the benzonitrile (BN) layer was investigated in 0.1 M phosphate buffer. Using the method reported by Shi and Anson (Anal. Chem. 70 (1998) 3114), we produced a modified electrode with a thin BN layer of 200 m thickness containing 0.1 M tetrabutylammonium perchlorate. We could observe a two-step reduction process of BQ in the absence of lipid molecules in the BN layer, like that recorded in aprotic solvents. However, introducing 1.0 mM dilauroyl phosphatidylcholine (PC) in the BN layer, the redox response of BQ accompanying the formation of the hydrated form of BQ could be observed as it was formed in aqueous solution simultaneously with the two-step reduction of BQ. Judging from the pH dependence of the redox potential, we believe that HBQ was generated in the reduction of BQ with dilauroyl–PC. This indicates that the hydrated form of the phosphate group (–P(O)OH) provides H + on the reduction of BQ even in BN. Thus, the function of dilauroyl–PC to carry H + in the lipophilic atmosphere has been clarified. The same function was found in the case of dipalmitoyl–PC, while the redox response involving the hydrated form of BQ was not observed with diarachidoyl–PC, which has longer alkyl chains.

On the additivity of bond dipole moments. Stark effect studies of the rotationally resolved electronic spectra of aniline, benzonitrile, and aminobenzonitrile

We study the influence of an applied electric field on the fully resolved electronic spectra of aniline (AN), benzonitrile (BN), and 4-aminobenzonitrile (ABN) in the gas phase. Using these data, we test the commonly held but rarely proven assumption that the total dipole moment of a polyatomic molecule is the vector sum of bond dipole moments, localized in different parts of the molecule. We find that μ a (ABN)≈ μ a (AN)+ μ a (BN) in the excited S 1 state, but not in the ground S 0 state. Possible reasons for this non-additivity are discussed.

Scanning Electrochemical Microscopy. 43. Investigation of Oxalate Oxidation and Electrogenerated Chemiluminescence across the Liquid−Liquid Interface

To treat the problem of oxalate oxidation in an aqueous phase by a Ru(III) species (mediator) generated in an immiscible nonaqueous phase (benzonitrile) at a scanning electrochemical microscope (SECM tip), the theory of the feedback mode of the SECM is extended to include both finite heterogeneous electron transfer (ET) kinetics at the substrate and homogeneous decomposition of the mediator. As for the classical electrochemical (EC) scheme, a zone diagram is constructed showing pure ET heterogeneous kinetic control, pure homogeneous kinetic (C) control (insulating behavior), and mixed EC kinetic control. The model allows interpretation of the anomalous approach curves obtained for oxalate oxidation by a ruthenium(III) coordination complex at the benzonitrile (BN)−water interface and allows calculation of the rate constant for the ET at the liquid−liquid interface. Attempts are made to relate these rates to the homogeneous rate constant in terms of Marcus theory. The second ET (oxidation of CO2•-) at the l...

Catalysis of the electroreduction of O 2 by cobalt 5,10,15,20-tetraphenylporphyrin dissolved in thin layers of benzonitrile on graphite electrodes

The electroreduction of O 2 was examined at graphite electrodes that were covered with thin layers (∼30 μm) of benzonitrile (BN) and equilibrated with aqueous solutions of HClO 4 saturated with air. The presence of the BN layers enhanced the rate of the electroreduction and affected its stoichiometry compared with results obtained at uncoated electrodes. Dissolving cobalt 5,10,15,20-tetraphenylporphyrin (CoTPP) in the thin layers of BN produced further increases in reaction rates and greater fractions of the O 2 were reduced to H 2O. The primary factors affecting the rate of the catalyzed reduction were the quantities of acid that partitioned into the BN layers and the concentration of CoTTP in the layers. The catalytic efficiency of CoTTP is greater when it is dissolved in thin layers of acidified BN than when it is adsorbed on the surface of the graphite electrodes. A possible catalytic mechanism is offered that is compatible with the experimental observations.

Molybdenum-based alkyne–isocyanide coupling reactions: synthesis of a reactive diiminometallacyclopentene complex

The complex [Mo(CO)(PhCCPh)2(η-C5Me5)][BF4] reacted with three equivalents of 2,6-dimethylphenyl isocyanide, CNxyl, to give the tris(isocyanide) complex [Mo(PhCCPh)(CNxyl)3(η-C5Me5)][BF4] 1. With four equivalents of CNxyl, alkyne–isocyanide coupling leads to the formation of the diiminometallacyclopentene [Mo{C(Nxyl)C(Ph)C(Ph)CNxyl}(CNxyl)2(η-C5Me5)][BF4] 2 which decomposes in thf at room temperature to give the tetrakis(isocyanide) complex [Mo(CNxyl)4(η-C5Me5)][BF4] 3. In dichloromethane, 2 gives the diiminocyclobutene xylNCC(Ph)C(Ph)CNxyl 4, the η2-iminoacyl complex [MoCl(CNxyl)2(η2-xylNCCH2Cl)(η-C5Me5)][BF4] 5, formed by an addition reaction with dichloromethane, and the metallacyclobutene complex [Mo{C(Ph)C(Ph)CN(H)xyl}(CNxyl)3(η-C5Me5)][BF4]26. Complex 5 is more efficiently synthesized by photolysis of 3 in dichloromethane, but the same reaction in chloroform produces the dichloromethyl complex [MoCl(CHCl2)(CNxyl)3(η-C5Me5)][BF4] 7 which thermally decomposes to [MoCl2(CNxyl)3(η-C5Me5)][BF4] 8. Reaction of 2 with HCl in diethyl ether results in protonation of the metallacyclic ring and formation of the iminium metallacyclopentene [MoCl{C(Nxyl)C(Ph)C(Ph)CN(H)xyl}(CNxyl)2(η-C5Me5)][BF4] 9. Compound 3 is oxidised by AgBF4 to give the molybdenum(IV) complex [MoF(CNxyl)4(η-C5Me5)][BF4]210. The molecular structures of 3–6, 7/8 and 10 have been determined by X-ray crystallography.

Vibrational studies of ground state 4-dimethylaminobenzonitrile (DMABN) and its ring deuterated isotopomer DMABN-d4

IR and Raman spectra of DMABN (4-dimethylaminobenzonitrile) and its ring deuterated isotopomer DMABN-d4 have been measured. Hartree–Fock (HF/6-31G*) and density function theory (DFT, B3LYP/6-31G*) ab initio calculations have been performed to interpret the observed vibrational spectra and isotopic shifts. Assignments of several controversial bands have been made. A large change of vibrational composition and mode pattern upon ring deuteration has been found for bands that have dominant contributions from the Wilson 19a, 19b, ν(Ph–N) and ν(Ph–CN) vibrations in DMABN.

Photoinduced electron transfer between chlorophylls (a/b) and fullerenes (C60/C70) studied by laser flash photolysis.

Photoinduced electron-transfer processes in the systems of chlorophylls (Chl) (chlorophyll-a [Chl-a] and chlorophyll-b) and fullerenes (C60/C70) in both polar and non-polar solvents have been investigated with nanosecond laser photolysis technique, observing the transient spectra in the visible/near-IR regions. By the excitation of Chl in benzonitrile (BN) it has been proved that electron transfer takes place from the triplet excited states of Chl to the ground states of C60/C70. By the excitation of C70 in BN electron transfer takes place from the ground states of Chl to the triplet excited state of C70. In both Chl the rate constants and quantum yields for the electron-transfer processes are as high as those of zinc porphyrins and zinc phthalocyanines, indicating that the long alkyl chains of Chl play no role in retarding the electron transfer. The rate constant for the electron-mediating process from the radical anion of C70 to octylviologen dication yielding the octylviologen radical cation was evaluated. The back electron-transfer process from the viologen radical cation to the radical cation of Chl-a takes place in a longer time-scale, indicating that a photosensitized electron-transfer/electron-mediating cycle is achieved.

First observation of metal-mediated nitrile–imine coupling giving ligated 1,3-diaza-1,3-dienes

Coupling between benzophenone imine and coordinated organonitriles in the platinum(IV) complexes [PtCl4(RCN)2] (R = Me or Et) proceeded rapidly under mild conditions to afford the 1,3-diaza-1,3-diene compounds [PtCl4{NHC(R)NCPh2}2] in good yield and this reaction is the first observation of metal-assisted nucleophilic addition of an imine to a ligated nitrile. [PtCl4{NHC(R)NCPh2}2] were reduced to the corresponding platinum(II) complexes [PtCl2{NHC(R)NCPh2}2] by the carbonyl-stabilized phosphorus ylide Ph3PCHCO2Me. The [PtCl2{NHC(Me)NCPh2}2] complex was also detected in a mixture formed in the reaction between the platinum(II) nitrile complex [PtCl2(MeCN)2] and Ph2CNH, but the selectivity of the platinum(II)-mediated nitrile–imine coupling was enhanced by employing for the reaction with benzophenone imine the phenyl cyanide complex [PtCl2(PhCN)2] to give [PtCl2(NHCPh2){NHC(Ph)NCPh2}]. Liberation of 1,3-diaza-1,3-dienes was exemplified by the reaction of [PtCl2{NHC(Et)NCPh2}2] with two equivalents of 1,2-bis(diphenylphosphino)ethane in CHCl3 to give, along with free NHC(Et)NCPh2 retained in solution, the solid complex [Pt(dppe)2]Cl2. All isolated metal complexes were characterized by elemental analyses, FAB mass spectrometry, IR, 1H, 13C-{1H} and 195Pt NMR spectroscopies and cis-[PtCl4{Z-NHC(Et)NCPh2}2] also by X-ray single-crystal diffraction.

Electrochemical monitoring of proton transfer across liquid/liquid interfaces on the surface of graphite electrodes.

Equilibrium partitioning of HClO4 between aqueous solutions and benzonitrile (BN) or nitrobenzene (NB) was measured and used to evaluate the pKa of the acid in the two organic solvents. The potential drop across the BN/ H2O interface was evaluated from the known potential drop across the NB/H2O interface and the voltammetrically measured formal potential of a ferrocenium/ferrocene redox couple confined within thin layers of the two organic solvents. The voltammetric reduction of tetrachloro-1, 4-benzoquinone in thin layers of BN was used to monitor changes in the concentration of protons in the layer during proton-consuming faradaic reactions. The rate of proton transfer from the aqueous to the nonaqueous phase across the BN/H2O interface was shown to be adequate to sustain proton-consuming reactions at the electrode/BN interface.

Cobalt(II)–dibenzotetraaza[14]annulene complex electropolymerization for electrode modification

Abstract Cobalt complexes of dibenzotetraaza[14]annulene (CoTAA), 5,7,12,14-tetramethyldibenzotetraaza[14]annulene (CoTMTAA), and dichlorodibenzotetraaza[14]annulene (CoTAACl 2 ) have been studied by voltammetry in benzonitrile (BN). Their electropolymerization from solutions in BN was performed by oxidation at carbon and platinum electrodes. The Co(II)/Co(I) and Co(III)/Co(II) redox systems are clearly apparent on the voltammograms, as well as the electroactivity of the conducting polymer, when the electrode is in contact with the non-aqueous solvent. More surprising is the fact that the modification of electrode surfaces is also possible from the oxidation of aqueous acidic solutions of CoTAA and CoTAACl 2 (2.25 M H 2 SO 4 ). In contact with an acidic aqueous medium (0.5 M H 2 SO 4 ), the Co(III)/Co(II) system of poly(CoTAA) is fully reversible. The polymer thus obtained can grow as a remarkably thick, dense and conducting phase.