Diethyl Ether In Presence Research Articles

Merging Organolithium Chemistry and Stereoselective Biocatalysis: Transformation of Aromatic Nitriles into Chiral Alcohols

AbstractThe combination of RLi‐mediated organic transformations (under air and at room temperature) with a subsequent stereoselective biocatalytic reaction is for the first time presented. Most of the previous asymmetric chemoenzymatic routes have been limited to the concomitant or sequential combination of transition metals/organocatalysts with enzymes. However, the use of polar organometallic reagents (RLi) in the design of these stereoselective hybrid protocols has been totally neglected, as far as we are concerned. Thus, in this work, the combination of organolithium chemistry and asymmetric biocatalysis is described for the first time in a one‐pot fashion. The chemoenzymatic approach converts a series of nitriles into chiral alcohols consisting of two steps, where the key item was the finding of suitable conditions to adapt the reactivities of organolithiums and alcohol dehydrogenases (ADHs) in the same recipient. The organolithium addition occurred with total chemoselectivity (no side reactions were observed) under neat conditions and room temperature leading to the corresponding imines, which were hydrolyzed using a buffer, and adjusting the pH for the subsequent ADH action. Commercial and made in house overexpressed ADHs allowed to produce chiral alcohols with excellent selectivities and good overall yields. The different behavior displayed for the reductive enzymes in the presence of diethyl ether clearly influenced in the decision to let the organolithium solvent evaporate under open‐air conditions before developing the bioreduction step. Our results demonstrate the importance of the fine orchestration of the reaction conditions for the development of efficient hybrid chemoenzymatic cascades without the need of intermediate isolation/purification steps or compartmentalization of the different synthetic systems.

Effect of addition of diethyl ether with custard apple seed oil + hydrogen enrichment on dual-fuel compression ignition engine

Due to the inert chemical properties of custard apple seed oil (CASO), one standard method for overcoming the challenges with its combustion is to use hydrogen as a supplemental fuel in dual-fuel mode. This is a technique that has developed in prominence in recent years. This investigation aims to examine the combustion characteristics of a DI engine that has been fuelled with CASO-blended di-ethyl ether (DEE), as well as hydrogen used as a secondary fuel. The experiment was conducted in atmospheric air with hydrogen enrichment (8 and 10 LPM) using CASO and CASO + 20% DEE as fuel for load condition varying from (25–100%). When compared to diesel at full load, the brake thermal efficiency of CASO was lower by 16%; however, it was improved by 9% with direct hydrogen induction at a knock limit of 10 LPM; and it was improved by 23% with CASO + H2 + 20% DEE when operating at maximum load. NOx emissions for CASO + 10 LPM H2 + 20% DEE at maximum load is 926 ppm, which is around 45.46% less than the emission value for diesel. When more hydrogen was added to the combination, the presence of DEE in the fuel caused a reduction in the emissions of both hydrocarbon and carbon monoxide around 21.70% opacity and 0.711%vol, respectively, which leading to a cleaner environment.

Experimental investigation on reduction of NO<SUB align="right">x emission of compression ignition engine fuelled with bio-diesel and diethyl ether

The present work emphasis on the reduction of diesel engine emission using Jatropha-based bio-diesel and diethyl ether (DEE). The experiments show that with 20% (B20) addition of bio-diesel, the BSFC and BSEC increase by 7% and 10% while efficiency and emissions - CO, CO2, NOx, and HC - decreases by 1%, 64%, 5%, 18% and 48% respectively. However, it also shows that, even optimised blend (B20) is not able to meet stringent emission norms - particularly for NOx - set by EURO IV. For the further reduction of the NOx, DEE is added from 0% to 5% in B20. The results show that addition of 4% DEE, does not significantly influenced the engine performance, however reduction in NOx found to be 40% compared with diesel fuel. A hypothesis is proposed that, "The reduction in engine emission is due to improvement in combustion in presence of DEE". The hypothesis is validated through combustion analysis showing increase in peak pressure (Pmax) by 7% and reduction in delay period by 1.5 degree with addition of 4% DEE in B20.

Experimental investigation on reduction of NO<SUB align="right">x emission of compression ignition engine fuelled with bio-diesel and diethyl ether

present work emphasis on the reduction of diesel engine emission using Jatropha-based bio-diesel and diethyl ether (DEE). experiments show that with 20% (B20) addition of bio-diesel, the BSFC and BSEC increase by 7% and 10% while efficiency and emissions - CO, CO2, NOx, and HC - decreases by 1%, 64%, 5%, 18% and 48% respectively. However, it also shows that, even optimised blend (B20) is not able to meet stringent emission norms - particularly for NOx - set by EURO IV. For the further reduction of the NOx, DEE is added from 0% to 5% in B20. results show that addition of 4% DEE, does not significantly influenced the engine performance, however reduction in NOx found to be 40% compared with diesel fuel. A hypothesis is proposed that, The reduction in engine emission is due to improvement in combustion in presence of DEE. hypothesis is validated through combustion analysis showing increase in peak pressure (Pmax) by 7% and reduction in delay period by 1.5 degree with addition of 4% DEE in B20.

Hydrodynamic cavitation of binary liquid mixtures in laminar and turbulent flow regimes

Hydrodynamic cavitation of several binary liquid mixtures (diethyl ether – 2-butanol, diethyl ether – ethanol, water – isopropanol) has been performed at different relative mass fractions. Different cavitating flows have been studied downstream two sorts of constrictions: micro-diaphragm profiles, that correspond to shear rate induced cavitation, and micro – venturi profiles, that correspond to sheet cavitation. Using microsystems as ‘labs on chip’ has made possible these investigations, with a low amount of the mixtures. Moreover, these microsystems have also made possible the inception of cavitation from a laminar single phase flow, because of the small hydraulic diameter of the orifices. Characterization of the binary liquid mixtures is presented with the help of σ(Re) diagrams, where σ is the cavitation number and Re is the Reynolds number in the constriction. It has been observed that when the inception of cavitation arises from a laminar single liquid phase regime at a fixed pressure drop, the flow rate is then slightly increased. Moreover, an anomalous behaviour of the pure ethanol liquid has been consistently recorded, with both types of devices. The presence of diethyl ether in the mixture may aid the inception of cavitation because it increases the vapour pressure of the blend and lowers its viscosity. The presence of isopropanol in water increases the viscosity of the blend and shifts the inception of cavitation towards lower Reynolds numbers. The shape of the constriction has also revealed to be a major parameter associated to the two phase flow transition of the mixtures.

Enhanced adsorptive desulfurization with flexible metal-organic frameworks in the presence of diethyl ether and water.

Several metal-organic frameworks (MOFs) were employed in adsorptive desulfurization in the presence of oxygen-containing compounds (OCCs). Unlike conventional MOFs and activated carbon, flexible MOFs with a MIL-53 topology showed remarkable performances for the desulfurization in the presence of OCCs.

Adsorptive removal of benzothiophene from model fuel, using modified activated carbons, in presence of diethylether

The adsorptive removal of benzothiophene (BT) over three activated carbons (ACs) was carried out using a model fuel containing various concentrations of diethylether (DEE) as a typical example of an oxygenate additive for fuel. ACs treated with either an acid or a base improved the adsorptive removal of BT from solutions without any DEE, showing the beneficial effect of functional groups on the ACs on the adsorption of BT. DEE generally decreased the adsorption of BT in adsorptive removal with ACs. However, an acid-treated AC gave relatively better performances in the BT adsorption (when DEE was present) than virgin AC and a base-treated AC. Therefore, treatment of ACs with an acid is suggested as a way of improving BT adsorption, even in the presence of oxygenates such as DEE. Moreover, the small decrease in the performance of the acid-treated AC in BT adsorption in the presence of DEE may be explained by hydrogen bonding between the O and HO- group of DEE and the AC, respectively.

The curing reaction of epoxidized methyl esters of corn oil with Diels–Alder adducts of resin acids. The kinetic study and thermal characterization of crosslinked products

The methyl esters of corn oil (COE) obtained by the optimized transesterification reaction using Ba(OH)2 as catalyst, in presence of diethyl ether as solvent were converted in monomer by in situ epoxidation using peracid method (H2O2/acetic acid solutions). The epoxidation was carried out in presence of Amberlite IR 120H as catalyst and cyclohexane as solvent, at molar ratio 0.5/1.5/1 (acetic acid/hydrogen peroxide/ethylenic double bonds) resulting epoxy methyl esters with an epoxide number (E.N.)=0.39mol100g−1).The kinetic analysis of the curing reaction of epoxidized methyl esters of corn oil (ECOE) with Diels–Alder adducts of resin acids (D–A) and thermal characterization of crosslinked products were achieved using nonisothermal differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The obtained data were processed using the Thermokinetics software (Netzsch). Depending on the chemical structure of curing agent, the crosslinking and thermal degradation reactions have took place in three steps. Taking into account of the chemical structure of the evolved gases obtained at the thermal decomposition and identified with the FT-IR and MS techniques, a schematic mechanism for the thermal degradation process was proposed.

The Optimization of the Production of Methyl Esters from Corn Oil Using Barium Hydroxide as a Heterogeneous Catalyst

AbstractIn recent years, vegetable oils, as renewable raw materials, became a promising feedstock for chemicals and biodiesel production. The main products derived from oils are esters of fatty acids, especially methyl esters, obtained by their transesterification with methanol, in presence of acid or alkaline catalysts. The use of such catalysts implies the need for washing operations, which leads to environmental pollution. In the present paper, the response surface methodology based on a central composite design, has been developed to optimize the process of transesterification of corn oil. Ba(OH)2 in presence of diethyl ether was used as catalyst. A quadratic polynomial equation was obtained. It correlates the reaction parameters [methanol/oil molar ratio (xr), reaction time (xt) and catalyst concentration (xc)] with methyl esters yield. Analysis of variance analysis showed that only methanol/oil molar ratio and catalyst concentration have had the most significant influences on the conversion. The maximum methyl esters yield was obtained using the following optimum parameters: methanol/corn oil ratio of 11.32, reaction time of 118 min and catalyst concentration of 3.6 wt%.

Synthesis, Characterization and Antimicrobial Activity of 4-Benzoyl-1-(pyrazin-2-ylcarbonyl)-thiosemicarbazide

Benzoyl-1-(pyrazin-2-ylcarbonyl)-thiosemicarbazide was synthesised by reacting pyrazine-2-carboxylic acid hydrazide with benzoylisothiocyanate in the presence of diethyl ether. Antibacterial activity was tested against Gram-positive and Gram-negative strains and antifungal action was examined towards Candida spp. The results showed that antibacterial activity against Gram-positive and Gram-negative bacteria expressed as minimal inhibitory concentration (MIC) ranged from 25 to 100 μg/mL and from 100 to 200 μg/mL, respectively. The compound exhibited also antifungal potency with MIC ranged between 50 and 200 μg/mL.

Byproducts formation in the ethyl tert-butyl ether (ETBE) synthesis reaction on macroreticular acid ion-exchange resins

Ethyl tert-butyl ether (ETBE) production is one of the industrial processes of major importance today in Europe. However, the study of side reactions in this synthesis reaction appears scarcely in the open literature. Side reactions take place along with the etherification of C4 olefinic cuts with ethanol, catalyzed by acidic ion-exchange resins. In this work, byproducts formation is studied in a batch reactor. The presence of diethyl ether (DEE), ethyl sec-butyl ether (ESBE), dimers of isobutene (2,4,4-trimethyl-1-pentene (TMP-1) and 2,4,4-trimethyl-2-pentene (TMP-2)) and tert-butyl alcohol (TBA) has been studied in terms of production and selectivity. The effect of temperature, ranging from 323 to 383K, and the influence of initial molar ratio ethanol/isobutene (R°A/O), ranging from 0.5 to 2.0, on byproducts formation have been analyzed. All byproducts formation was favored by high temperatures. A low initial molar ratio ethanol/isobutene favored the formation of DEE, ESBE, TMP-1 and TMP-2, whereas high molar ratios favored TBA formation.

H(OEt2)2[P(1,2‐O2C6Cl4)3]: Synthesis, Characterization, and Application as a Single‐Component Initiator for the Carbocationic Polymerization of Olefins

The development of novel Brønsted acids featuring the hexacoordinate phosphorus(V) anion [TRISPHAT](-) {[1](-)=[P(1,2-O2C6Cl4)3](-)} are reported. The title compound, H(OEt2)2[1], was synthesized from 1,2-(HO)2C6Cl4 (3 equiv) and PCl5 in the presence of diethyl ether. This compound was fully characterized by (1)H, (31)P and (13)C NMR spectroscopy, X-ray crystallography and elemental microanalysis. Dissolution of H(OEt2)2[1] in acetonitrile results in the slow precipitation of crystalline H(OEt2)(NCMe)[1], which was characterized by X-ray diffraction; however, in CD2Cl2 solution the [TRISPHAT](-) anion protonated and ring-opened. The weighable, solid H(OEt2)2[1] was found to be a competent initiator for the polymerization of n-butyl vinyl ether, α-methylstyrene, styrene and isoprene at a variety of temperatures and monomer-to-initiator ratios. At low temperatures, polymers with M(n) >10(5) were obtained for n-butyl vinyl ether and α-methylstyrene whereas slightly lower molecular weights were obtained with styrene and isoprene (10(4) < M(n) <10(5)). The poly(α-methylstyrene) synthesized at -78 °C is syndiotactic-rich (ca. 87% rr) whereas the polystyrene obtained at -50 °C is atactic. The polyisoprene obtained possessed all possible modes of enchainment as well as branched and/or cyclic structures that are often observed in polyisoprene.

Effects of Fuel Additives on the Thermal Cracking of n-Decane from Reactive Molecular Dynamics

Thermal cracking of n-decane and n-decane in the presence of several fuel additives are studied in order to improve the rate of thermal cracking by using reactive molecular dynamics (MD) simulations employing the ReaxFF reactive force field. From MD simulations, we find the initiation mechanisms of pyrolysis of n-decane are mainly through two pathways: (1) the cleavage of a C-C bond to form smaller hydrocarbon radicals, and (2) the dehydrogenation reaction to form an H radical and the corresponding decyl radical. Another pathway is the H-abstraction reactions by small radicals including H, CH(3), and C(2)H(5). The basic reaction mechanisms are in good agreement with existing chemical kinetic models of thermal decomposition of n-decane. Quantum mechanical calculations of reaction enthalpies demonstrate that the H-abstraction channel is easier compared with the direct C-C or C-H bond-breaking in n-decane. The thermal cracking of n-decane with several additives is further investigated. ReaxFF MD simulations lead to reasonable Arrhenius parameters compared with experimental results based on first-order kinetic analysis. The different chemical structures of the fuel additives greatly affect the apparent activation energy and pre-exponential factors. The presence of diethyl ether (DEE), methyl tert-butyl ether (MTBE), 1-nitropropane (NP), 3,6,9-triethyl-3,6,9-trimethyl-1,2,4,5,7,8-hexaoxonane (TEMPO), triethylamine (TEA), and diacetonediperodixe (DADP) exhibit remarkable promoting effect on the thermal cracking rates, compared with that of pure n-decane, in the following order: NP > TEMPO > DADP > DEE (∼MTBE) > TEA, which coincides with experimental results. These results demonstrate that reactive MD simulations can be used to screen for fuel additives and provide useful information for more comprehensive chemical kinetic model studies at the molecular level.

Enhanced hydrogen generation from hydrolysis of LiBH4 with diethyl ether addition for micro proton exchange membrane fuel cell application

LiBH4 has a high hydrogen storage capacity and could potentially serve as a superior hydrogen storage material. However, in its hydrolysis process, incomplete hydrolysis caused by the agglomeration of LiBH4 and its hydrolysis products limits its full utilization. In the present paper, a novel enhancement method to completely release the theoretical amount of hydrogen from LiBH4 hydrolysis is presented by the addition of diethyl ether. The results show that in the presence of diethyl ether, hydrolysis of LiBH4 can fully release 4 equivalents of hydrogen, and the agglomeration can be avoided. The enhanced performance can be attributed to the new phase LiBH4·[Et2O]x which is formed through the combination of LiBH4 with Et2O molecules. Hydrolysis of this new phase shows a complete hydrolysis process with a slow kinetics. The method discussed in this paper presents a novel strategy to enhance the hydrolysis of borohydrides and other hydrides that have the same agglomeration problems. LiBH4 diethyl ether suspension might be applied as a hydrogen generation source of micro proton exchange membrane fuel cells.

Hydrogen evolution performance of magnesium alanate prepared by a mechanochemical metathesis reaction method

Solvent-free magnesium alanates were prepared by a mechanochemical metathesis reaction method (ball milling method) with a variation of milling time. For the purpose of comparison, magnesium alanate was also prepared by metathesis reaction method in the presence of diethyl ether. The formation of magnesium alanate (Mg(AlH4)2) and magnesium alanate-diethyl ether (Mg(AlH4)2·Et2O) adduct was confirmed by XRD measurements. In both magnesium alanates, hydrogen evolution occurred in the first step decomposition. The starting temperature for hydrogen evolution of the solvent-free magnesium alanates decreased with increasing milling time, whereas the amount of hydrogen evolution of the solvent-free magnesium alanates increased with increasing milling time. The maximum amount of hydrogen evolution of the Mg(AlH4)2·Et2O adduct was slightly larger than that of the solvent-free Mg(AlH4)2, but the starting temperature for hydrogen evolution of the Mg(AlH4)2·Et2O adduct was much higher than that of the solvent-free Mg(AlH4)2. The addition of a small amount of titanium to the solvent-free Mg(AlH4)2 greatly reduced the hydrogen evolution temperature of titanium-doped Mg(AlH4)2. However, the maximum amount of hydrogen evolution of the titanium-doped Mg(AlH4)2 was smaller than that of the solvent-free Mg(AlH4)2.

Mononucleating Bis(β-diketonate) Ligands and Their Titanium(IV) Complexes

Novel bis(beta-diketones) linked by 2,2'-biphenyldiyl, 2,2'-tolandiyl, and 2,2'-bis(methylene)biphenyl moieties have been prepared. All are metalated readily by titanium(IV) isopropoxide, but the nature of the complexes formed depends on the linker structure. The biphenyl-bridged ligand gives only traces of a mononuclear complex, which is thermodynamically unstable with respect to oligomerization. The tolan-bridged ligand does form mononuclear complexes, but only as a mixture of geometric isomers. In contrast, the substituted 2,2'-bis-(2,4-dioxobutyl)biphenyl ligands, R2BobH2 (R = tBu, p-Tol), react with Ti(OiPr)4 to give, initially, a mixture of monomer and oligomers, which is converted quantitatively to monomer upon heating in the presence of excess Ti(OiPr)4. Only a single relative configuration of the biphenyl and bis(chelate) titanium moieties, established by crystallography of (tBu2Bob)Ti(O-2,6-iPr2C6H3)2 to be the (R)-/(S)- diastereomer, is observed. The kinetic and thermodynamic robustness of the (R2Bob)Ti framework is confirmed by reactions with Lewis acids. For example, (Tol2Bob)Ti(OiPr)2 reacts with trimethylsilyl triflate or triflic acid to substitute one or both of the isopropoxide groups with triflates without any redistribution or loss of the diketonate ligands. Cationic complexes can be prepared by abstraction of triflate from (Tol2Bob)Ti(OiPr)(OTf) with Na[B(C6H3(CF3)2)4]. For example, in the presence of diethyl ether, the crystallographically characterized [(Tol2Bob)Ti(OiPr)(OEt2)][B(C6H3(CF3)2)4], containing a rapidly dissociating ether ligand, is formed.

Polyfluoroorganoboron‐Oxygen Compounds. 4 [1] Lithium Pentafluorophenyltrimethoxyborate, Li[C6F5B(OMe)3], Reactions with Selected Electrophiles and Nucleophiles

AbstractLi[C6F5B(OMe)3] (1a) reacted with the electrophiles CD3C(O)CD3, CH3OD, CD3CN, CH3CN, HOC2H4OH, Br2, and I2 to give C6F5X (X = D, H, Br, I). The treatment of 1a with Me3SiCl or BF3 in CH2Cl2 and CCl3F or pentene resulted in C6F5B(OMe)2 or C6F5BF2, respectively. The attempted metathesis of 1a with KF or [Bu4N]Br in CH2Cl2 led to a mixture of M[(C6F5)2B(OMe)2] (2b,c, main product) and M[C6F5B(OMe)3] (1b,c, minor product) (M = [Bu4N], K). Even in the presence of diethyl ether, THF, DME, or TMEDA salt 1a underwent dismutation to the diarylborate salt [Li(L)n][(C6F5)2B(OMe)2] (L = Et2O, THF, DME, TMEDA) and [Li(L)n][B(OMe)4]. In subsequent reactions with aqueous K[HF2] or [Bu4N][HF2] M[(C6F5)2B(OMe)2] (M = K, [Bu4N], [Li(L)n]) yielded K[(C6F5)2BF2] (4c) or [Bu4N][(C6F5)2BF2] (4b). The molecular structure of [Li·TMEDA][(C6F5)2B(OMe)2] from single crystals showed significant cation‐oxygen interactions.

Radical Addition Approach to Asymmetric Amine Synthesis: Design, Implementation, and Comparison of Chiral N-Acylhydrazones

Intermolecular radical addition to C=N bonds with acyclic stereocontrol offers excellent potential as a mild, nonbasic carbon-carbon bond construction approach to chiral amines. Here, complete details of the first radical additions to chiral N-acylhydrazones as an approach to asymmetric amine synthesis are disclosed. Novel N-acylhydrazones were designed as chiral C=N radical acceptors with Lewis acid activation, restriction of conformational mobility, and commercial availability of precursors. Amination of 4-alkyl-2-oxazolidinones with O-(mesitylenesulfonyl)hydroxylamine or O-(p-nitrobenzoyl)hydroxylamine afforded N-aminooxazolidinones which were condensed with aldehydes to afford N-acylhydrazones 3-8. Three synthetic methods were developed, implementing these N-acylhydrazones in Lewis acid-promoted intermolecular radical additions to C=N bonds. First, additions of various secondary and tertiary alkyl iodides to propionaldehyde and benzaldehyde hydrazones (3 and 7) under tin hydride radical chain conditions in the presence of ZnCl2 gave N-acylhydrazine adducts with diastereomeric ratios ranging from 93:7 to 99:1. Radical additions to a series of N-acylhydrazones with different substituents on the oxazolidinone revealed that benzyl and diphenylmethyl were more effective stereocontrol elements than those with the aromatic ring directly attached to the oxazolidinone. Second, a tin-free method, exploiting dual functions of triethylborane for both initiation and chain propagation, enabled improved yields in addition of secondary alkyl iodides. Third, under photolytic conditions with hexamethylditin, primary radical addition could be achieved with ethyl iodide in the presence of diethyl ether as cosolvent; the 1-ethoxyethyl adduct was observed as a minor product. Chloromethyl addition was achieved under both the tin-free and photolytic conditions; in this case, the adduct bears alkyl chloride functionality with potential for further elaboration.

Bis(imino)pyridine Iron(II) Alkyl Cations for Olefin Polymerization

Treatment of the five-coordinate ferrous dialkyl complex, (iPrPDI)Fe(CH2SiMe3)2 (iPrPDI = ((2,6-CHMe2)2C6H3N=CMe)2C5H3N), with [PhMe2NH][BPh4] in the presence of diethyl ether or tetrahydrofuran furnished the corresponding alkyl cations, where the donor ligand is coordinated in the basal plane of a distorted square pyramidal iron(II) alkyl cation. Performing the same reaction with the neutral Lewis acid, B(C6F5)3, induced methide abstraction from a silicon atom followed by rearrangement to afford the base free ferrous alkyl cation, [(iPrPDI)Fe(CH2SiMe2CH2SiMe3)][MeB(C6F5)3]. This complex is active for the polymerization of ethylene and yields polymers that are of higher molecular weight and narrower polydispersity than traditional methylalumoxane-activated catalysts.

Anionic synthesis of secondary amine functionalized polymers by reaction of polymeric organolithiums with N-benzylidenemethylamine

Functionalization of poly(styryl)lithium and poly(butadienyl)lithiums (PBDLi) with N-benzylidenemethylamine was investigated in hydrocarbon solvents at room temperature. The resulting secondary amine functionalized polymers were characterized by size exclusion chromatography, titration, 1H NMR, 13C NMR, and thin-layer chromatography. No dimeric side-products were observed by SEC. The secondary amine functionalized polystyrene was obtained in high yields (96%) in benzene solvent. The functionalization reactions of PBDLi in the absence or presence of 12 vol.-% triethylamine gave high yields (≥ 96%), whereas the same reaction in the presence of 12 vol.-% diethyl ether was less efficient (yield = 61%). The low functionalization yields in the presence of diethyl ether were attributed to the increased reactivity of PBDLi in the presence of diethyl ether, which promotes side reactions such as metalation between PBDLi and N-benzylidenemethylamine.