Condensation Of Benzene Research Articles

Triply bridged (1,3,5) cyclophanes from cystine and lanthionine linkers—a comparison

The condensation of benzene 1,3,5-tricarbonylchloride with cystine-di-Me [H 2N–CH(COOMe)–CH 2–S–S–CH 2–CH(COOMe)–NH 2] yielded triply bridged (1,3,5) cyclophane 1, which was shown by detailed spectral studies and molecular orbital calculations to have a D 3 symmetry with conformationally identical linkers and a spherical topology. In sharp contrast, the (1,3,5) cyclophane 2 from the rarely studied lanthionine di-Me [H 2N–CH(COOMe)–CH 2–S–CH 2–CH(COOMe)–NH 2], showed only a equatorial twofold symmetry. This work highlights the special properties of the –S–S– bridge in cystine, which makes it an exceptional synthon in nature and organic synthesis.

Green Synthesis of Benzylated Aromatics Using Iron Loaded Mesoporous Materials

Syntheses of benzylated aromatics like diphenylmethane and its derivatives by the condensation of benzene or toluene or o‐xylene with benzylchloride or 4‐methylbenzylchloride in the presence of a catalytic amount of various iron loaded mesoporous solid acid catalysts such as Fe/Al‐MCM‐41 (Si/Al=25), Fe/Al‐MCM‐41 (Si/Al=50) and Fe/Al‐MCM‐41 (Si/Al=100) are reported.

Pyrolysis mechanism of carbon matrix precursor cyclohexane—The formation of condensed-ring aromatics and the growing process of molecules

Based on the experiments, the UAM1 method was adopted to investigate benzene condensation of an important intermediate and the molecule growing mechanism during the cyclohexane pyrolysis process. The conclusions were drawn as follows: (1) from the viewpoint of thermodynamics, the condensation of benzene and C 4H 5 is a spontaneous reaction and the rising temperature will increase the spontaneous tendency of the reaction. (2) From the viewpoint of kinetic, the condensation of benzene and C 4H 5 is a two-step reaction. The rate-determining step is step 2 of hydrogen removal from intermediate C 10H 10 (I1) with the activation energy of 350.61 kJ/mol below 1473 K while the rate-determining step is step 1 that free radical C 4H 5 attacks benzene to form intermediate C 10H 10 (I1) with the activation energy Δ E 0 ≠ θ = 31.74 kJ/mol above 1473 K. (3) The space structure, electronic structure and thermodynamics parameters of molecular reaction of dense-ring aromatizing compounds can be used to replace the resonance energy and free valence to judge the activation of thermodynamic reaction of compounds. And (4) the analysis of the space structure, electronic structure and thermodynamic parameters show that the growing process of molecules with benzene used as initial reactants becomes more easier as the multi-ring aromatizing molecular system increases.

Condensation of benzene and aqueous formaldehyde to diphenylmethane in a biphasic system consisting of an aqueous phase of heteropolyacid

Abstract Synthesis of diphenylmethane (PhCH 2 Ph) from benzene and formalin (aqueous HCHO) was investigated in a biphasic reaction system, which consisted of benzene and aqueous phases, where the latter phase contains HCHO and liquid acid as catalyst. Heteropolyacids such as H 3 PW 12 O 40 , H 3 PMo 12 O 40 , and H 4 SiW 12 O 40 exhibited significant activities for the formation of diphenylmethane, whereas typical mineral acids (H 2 SO 4 , HNO 3 , and H 3 PO 4 ), organic acids ( para -toluenesulfonic acid (PTS) and CF 3 COOH), and Sc(CF 3 SO 3 ) 3 were inactive. The yields of diphenylmethane were proportional to the concentrations of both proton and the heteropoly anion (PW 12 O 40 3− ). Consequently, it can be presumed that the critical reaction step is the attack by a benzyl cation to a benzene molecule, in which the intermediate benzyl cation is stabilized by a heteropoly anion to accelerate the reaction. Since heteropolyacids exist in the aqueous phase exclusively, and the product diphenylmethane is concentrated in the benzene phase after the reaction, H 3 PW 12 O 40 can be readily recovered from the reaction solution. It was confirmed that H 3 PW 12 O 40 in the aqueous phase, after drying at room temperature, could be reused repeatedly without significant decreases in the activity.

Hydroxyalkylation of benzene derivatives by benzaldehyde in the presence of acid zeolites

Condensation of benzene, anisole and N, N-dimethylaniline with benzaldehyde has been carried out in the presence of a USY zeolite (Si/Al 17.5). A combined study of the product distribution present in the liquid phase (di- and triarylmethanes together with N-benzylated byproducts in the case of dimethylaniline) as well as the organic material entrapped inside the zeolite micropores (triphenylmethane or trityl ions) has established that there is a direct relationship between the reactivity of the arene and the conversion of benzaldehyde, percentage of diarylmethanes in the liquid phase and population of trityl cations. A hydride transfer from triarylmethanes to diarylmethyl cation intermediates has been proposed as a key step for the simultaneous presence of trityl cations adsorbed in the solid and diarylmethanes in the liquid phase.

SANS investigations of benzene adsorption on porous silica gel

The mechanisms of the adsorption and condensation of benzene in a mesoporous silica gel at 310 K have been investigated by SANS. Measurements have been made in situ during an adsorption/desorption isotherm cycle with a specially constructed cell using contrast matching conditions for the condensed fluid. The results are in accordance with a process of multilayer formation and subsequent capillary condensation, which develops around the zones of particle contact in the gel structure.

Neutron scattering studies of the structure and mechanisms of adsorption in porous oxide gels

The mechanism of the adsorption and condensation of benzene at 310 K in two mesoporous silica gels with different pore structure was investigated by SANS. Measurements have been made in situ during an adsorption/desorption isotherm cycle with a specially constructed cell using contrast matching conditions for the condensed fluid. Results are in accord with a process of multilayer formation and subsequent capillary condensation, which develops around the zones of particle contact in the gel structure.

Adsorption and Diffusion of Benzene in Activated Carbon at High Pressures

The adsorption isotherms and the effective diffusivities of benzene in activated carbon pellets in the presence of subcritical and supercritical carbon dioxide were measured from the sorption curves in a spinning basket autoclave at temperatures 308, 318, and 328 K and pressures up to 163 bar. The adsorption isotherm data showed that no condensation of benzene in activated carbon occurred at the given temperatures and pressures. The effective diffusivities measured were observed to be concentration-dependent and to decrease with increasing pressure. At high-pressure operations, the effective diffusivities were found to be invariant with temperature.

Study on thermotropic liquid crystalline polymers—I. Synthesis and properties of poly(azomethine-urethane)s

A series of novel azomethinediols, benzene 1,4-di(4-iminohydroxyphenoxy-n-alkanol)s was prepared from 4-[4-(4-hydroxybenzylideneamino)phenyliminomethyl] phenol with 2-chloroethanol, 3-bromopropanol, 6-bromohexanol, respectively. A series of poly(azomethine-urethane)s was prepared by condensation of benzene 1,4-di(4-iminohydroxyphenoxy-n-alkanol) with hexamethylene-diisocyanate (HMDI), isophorone-diisocyanate (IPDI), 4,4'-methylene-di(phenyl-diisocyanate) (MDI) and 2,4-toluylene-diisocyanate (2,4 TDI), respectively. Thermotropic liquid crystalline properties of these synthesized poly(azomethine-urethane)s were examined by differential scanning calorimetry (DSC), optical photomicroscopic observation, X-ray diffraction and thermogravimetric analysis (TGA). All of the polymers, except polymers P2, P3 and P7, exhibit thermotropic liquid crystalline properties.

Activation of an aryl C [sbnd]H bond to oxygen insertion: Model for the phenoloxidase activity of tyrosinase

The reactions of dioxygen with the binuclear tricoordinate copper(I) complexes, derived from the condensation of benzene- 1,3-dicarboxaldehyde and two molecules of a diamine, give phenoxy-bridged copper(II) complexes by direct hydroxylation of the benzene ring.

Adsorption and epitaxial growth of benzene on ZnO(1010) studied by thermal desorption spectroscopy, LEED and UPS

The adsorption and condensation of benzene on ZnO(101̄0) was investigated by thermal desorption spectroscopy and LEED. The first monolayer shows an ordered c(2 × 2) super-structure. First order desorption is observed. The desorption energy and frequency factor decrease from 73 to 56 kJ mole −1 and from ~10 15 to ~10 12 s −1, respectively, with coverage increasing to 0.85. The second layer is more weakly bound. Two-dimensional (2D) island formation is deduced from peak shape analysis. Near completion, the second layer converts to a more tightly bound configuration as deduced from a sudden shift of the desorption peak and the formation of an additional c(4 × 3) LEED pattern. This pattern which can be identified as a property of bulk benzene is preserved upon epitaxial growth of the 3D benzene crystal. Angular resolved UPS measurements indicate the benzene molecules of the first layer to be arranged in an oblique position of low symmetry.

Investigation of the adsorption properties and secondary porous structure of adsorbents exhibiting a molecular sieve action Communication 11. Specific surface of secondary pores of molded synthetic type a zeolites

1. An analysis of the physical content of various methods of determining the specific surface of the secondary pores of molded zeolites is given. From experiments on the pressing in of mercury and capillary condensation of benzene, one can calculate the specific surface of the secondary pores on an equivalent model sorbent with the geometrical shape of the pores assumed. 2. Specific surfaces of the secondary pores of type A molded zeolites and outer surfaces of the zeolite crystals contained in them, close to the actual values, were determined by the use of a highly sensitive gravimetric adsorption setup. The specific surfaces of the secondary pores of molded zeolites are determined basically by the porous structure of the additions of binders. 3. The specific surfaces of secondary pores for equivalent model porous sorbents, as a rule, are considerably greater than the actual specific surfaces of the secondary pores of real molded zeolites. Hence, the methods of pressing in mercury and capillary condensation of vapors cannot be used for any exact evaluation of the specific surfaces of the secondary pores of molded zeolites. 4. The basic content of the rational approximated adsorption method for determining the specific surfaces of the secondary pores of molded type A zeolites was substantiated.

Condensation of Benzene with Unsaturated Chlorides1

Condensation of Benzene with Unsaturated Chlorides¹

ON THE OXIDATION OF 1, 1, 1-TRICHLORO-2,2-BIS- (p-TOLYL) -ETHANE

The condensation of benzene with chloral hydrate in the presence of concentrated sulphuric acid gave rise to 1,1,1-trichloro-2,2-bis-(p-tolyl)-ethane. The oxidation of this condensation product with potassium dichromate in dilute sulphuric acid at the boiling temperature yielded 1,1-dichloro-2,2-bis-(p-carboxyphenyl)-ethylene, the structure of which was shown by its oxidative degradation to 4,4′-dicarboxybenzophenone. When the oxidation of the same condensation product was carried out in the cold, with the aid of chromium trioxide in glacial acetic acid and acetic anhydride, 1,1,1-trichloro-2,2-bis-(p-carboxyphenyl)-ethane was obtained in a good yield. This last compound was converted to the dichloroethylenic-dicarboxylic acid upon refluxing with a methanolic solution of sodium hydroxide. The corresponding amide derivatives of both the dichloro and trichlorodicarboxylic acids were also prepared.

Further Observations on the Condensation of Benzene with Alloxan1

Further Observations on the Condensation of Benzene with Alloxan¹