GENERATION OF RADICAL CATIONS——A FACILE GENERATION OF RADICAL CATIONS VIA THE ACTION OF AN OXOAMMONIUM TRIFLUOROACETATE

The reaction between a stable nitroxide, 2, 2, 6, 6-tetramethyl-4-chloropiperidinyl-1-oxy, la and aromatic amines and heterocycles, 3—9, in methylene chloride in the presence of trifluoroacetic acid, has been investigated. The corresponding radical cations of the amines and the heterocycles were readily generated by this reaction, which could persist for a long period of time in the system. Kinetic ESR studies were performed to elucidate the reaction mechanism and the results showed that the formation of the radical cations involves one-electron transfer reaction between the active oxidant, the oxoammonium trifluoroacetare, 2a, which results from the disproportionation of the nitroxide in the presence of trifluoroacetic acid, and the substrates studied. This affords a facile method for the generation of radical cations from aromatic amines and heterocyclics by the action of an organic oxidant.     

DIRECT CONVERSION OF METHANE TO METHANOL——THE EFFECT OF SENSITIZERS ON THE YIELD OF METHANOL AND THE KINETIC STUDY

The partial oxidation of methane to methanol was studied. The effectof various homogeneous "sensitizers" on the oxidation of pure methane was e-valuated at 433℃ and under a pressure of 5.0MPa. It was found that CH_3NO_2was the best one among them. A kinetic study in the presence of CH_3NO_2 wascarried out and the reaction mechanism was discussed.     

SYNTHESIS OF POLYMER—SUPPORTED PALLADIUM CATALYSTS AND THEIR CATALYTIC BEHAVIOR FOR THE SELECTIVE HYDROGENATION OF MESITYL OXIDE

Copolymer of styrene-divinylbenzene in bead from was made by suspension polymerization.After chloromethylation and amination,five kinds of polymeric amines were thus obtained.These polymers were reacted with palladium chloride,and were then reduced.The polymer-supported catalysts synthesized above were used to catalyze the selective hydrogenation of mesityl oxide under reaction conditions of 80℃ and 10kg/cm^2,using methanol as a solvent.The catalytic activity and MIBK(methyl isobutyl ketone) formation selectivity of the catalysts were examined.     

ENDOR AND ESR STUDIES OF RADICALS FORMED IN FRIEDEL-CRAFTS REACTIONS

The present study deals with the study of some Friedel-Crafts alkylating system and the accurate measurement of hyperfine coupling constants by ESR and ENDOR techniques. The results indicate that the observed ESR spectra are due to polycyclic aromatic radical cations formed from their parent hydrocarbons.It is suggested that benzyl halides produced in the Friedel-Crafts alkylating reaction undergo Scholl condensation reaction to give polycyclic aromatic hydrocarbons, which were converted into the corresponding polycyclic aromatic radical cations in the presence of aluminum chloride.     

THE CATALYTIC EFFECTS OF OXYGEN AND AMINES IN THE REDOX-INITIATED DIMERIZATION OF N-VINYLCARBAZOLE*

The redox reaction between N-vinylcarbazole (NVC) and various oxidants including Ce(Ⅳ), Fe(Ⅲ)and benzoylperoxide in methanol proceeds via the initial formation of the NVC N-cation radical which in turn leads to the formation of the NVC cyclic dimer, trans-1,2-dicarbazylcyclobutane. Molecular oxygen and a few arylamines are able to accelerate the rate of the formation and increase the yield of the dimer. The mechanism of this process and the functions of oxygen and arylamines are presented as follows: The participation of molecular oxygen is to facilitate the dissociation of the resulting reduced metal ion and the NVC N-cation radical ion pair or charge transfer complex, thereby releasing the free NVC N-cation radical and increase the rate of the formation and yield of the dimer. The arylamine in this reaction between NVC and oxidants can be viewed as electron transfer agent between NVC and the oxidant. Because the amines are present in small amount relative to the oxidants and can be regenerated in pr     

THE SOLID STATE CONTROLLED CONDENSATION REACTION OF FERROCENEALDEHYDE AND INDOLE

The ZnCl_2-catalyzed condensation reaction of ferrocenealdehyde and indole in the solid state gave a new product (di-3-indolyi)-methylferrocene(3). The crystal structure of product 3 was determined by X-ray diffraction method. Reactions in solution and photochemical reactions were also carried out.     

Propylphosphonic anhydride(T3P~) catalyzed one-pot synthesis of α-aminonitriles

The Strecker reaction was performed via a one-pot three component condensation of hetero aromatic/aromatic aldehydes, secondary amines and trimetylsilyl cyanide in the presence of propylphosphonic anhydride(T3P~) to accomplish the corresponding a-aminonitriles. The main advantages of this method are very short reaction time and excellent yields.     

Samarium—promoted Chemoselective Reduction of Aromatic Nitro Compounds in Ionic Liquid

The differently substituted aromatic nitro compounds were chemoselectively reduced by Sm/HOAc system in an ionic liq-uid medium to afford aromatic amines,Under these conditions the other substituents,such as -X,-CHO,-COOH,-CN,-NHTos and -alkyl,remained intact,the notable advan-tages of this reaction are its mild conditions ,simple operation,short reaction time,high yields and easy recycling of ionic liquid.     

A facile protocol for N-Cbz protection of amines in PEG-600

正An efficient and eco-friendly protocol for the chemoselective N-benzyloxycarbonylation of amines was described.The reaction of amines with benzyl chloroformate(Cbz-Cl) in the presence of PEG-600 at room temperature afforded the corresponding N-Cbz derivatives in excellent yields.The method is applicable to the N-Cbz protection of aliphatic(acyclic and cyclic) and aromatic amines.     

Reduction of Sulphur-containing Aromatic Nitro Compounds with Hydrazine Hydrate over Iron(III) Oxide-MgO Catalyst

Sulphur-containing aromatic amines were prepared efficiently in good to excellent yields by reduction of the corresponding sulphur-containing aromatic nitro compounds with hydrazine hydrate in the presence of iron(III) oxide-MgO catalyst. The catalyst exhibited high activity and stability for the reduction of sulphur-containing aromatic nitro compounds. The yields of sulphur-containing aromatic amines were up to 91-99 % at 355 K after reduction for 1-4 h over this catalyst.     

STUDY OF THE CATALYTIC TECHNOLOGY IN THE OXIDATIVE COUPLING OF METHANE

The temperature of the catalyst bed in the oxidative coupling ofmethane would rise and be higher than the wall temperature when the amountof catalyst, the space velocity and the ratio of oxygen to methane wereincreased. Various aspects of the catalytic technology including the thickness ofthe catalyst bed, the mode of catalyst charge, the ratio of CH_4 to O_2 and thespece velocity were studied. An optimum temperature of the catalyst bed forhigher methane conversion and C_2 selectivity was investigated. It was foundthat the burning of methane in the gas phase to form CO occurred at certaintemperatures with some ratios of oxygen to methane. Additionally, the effectof adding water to the reaction feed gas was studied.     

THE THEORETICAL STUDY OF THE TRANSITION STATE OF THE REACTION H_2C=N=N—■H_2 AND ITS REACTION PATH

By means of energy gradient, the optimized geometries of diazomethane, diazirine and the transitionstate of the unimolecular reaction are discussed on the ground potential energy surface calculated byMINDO/3 SCF method. The nine vibrational normal modes in the transition state and the reaction pathcalculated with Fukui's IRC equation are also studied. The symmetry of the C_s point group of thereaction system is conserved throughout the reaction path. The MO correlation diagram shows that thisunimolecular reaction is symmetry admitted.     

Reduction of Sulphur-containing Aromatic Nitro Compounds with Hydrazine Hydrate over Iron（Ⅲ） Oxide-MgO Catalyst

Sulphur-containing aromatic amines were prepared efficiently in good to excellent yields by reduction of the corresponding sulphur-containing aromatic nitro compounds with hydrazine hydrate in the presence of iron（Ⅲ） oxide-MgO catalyst. The catalyst exhibited high activity and stability for the reduction of sulphur-containing aromatic nitro compounds. The yields of sulphur-containing aromatic amines were up to 91-99 % at 355 K after reduction for 1-4 h over this catalyst.     

MCSCF STUDIES ON THE IRC AND REACTION RATE CONSTANTS FOR THE DEHYDROGENATION REACTION OF VINYL RADICAL

The transition state(TS) and Intrinsic Reaction Coordinate (IRC) for the titled reaction were traced by means of MCSCF/6-31G (210 configurations). The reaction activation energy of this reaction is 140.2KJ/mol. The reaction rate constants of five temperetures were calculated by CVT involving the tunneling effects.     

THE REACTION OF ETHYL AROYLACETATES AND o-PHENYLENEDIAMINE

Instead of 2-(aroylmethylene)benzimidazolines 3 or 2-(aroyl-methyl)benzimidazoles 4, 4-aryl-2, 3-dihydro-1H-1, 5-benzodiazepin-2-ones 5 were obtained exclusively from the reaction of o-phenylenediamine (1) and ethyl aroylacetates 2 in the presence of a catalytic amount of potassium hydroxide.     

Facile Synthesis of Ureas in lonic Liquid

The reaction of isocyanates with aliphatic and aromatic amines in the l-n-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4) ionic liquid in good to excellent yields is described.Due to its insolubility, the desired urea solids could be recovered by simple filtration from the ionic liquid after reaction.     

PEG-OSO3H as an efficient and recyclable catalyst for the synthesis of β-amino carbonyl compounds via the Mannich reaction in PEG-H2O

Sulfuric acid-modified polyethylene glycol 6000（PEG-OSO₃H） was applied as an efficient and recyclable catalyst for the synthesis ofβ-amino carbonyl compounds via the Mannich reaction between aldehydes,aromatic ketones and aromatic amines at room temperature using PEG400-H₂O（1:1） as environment-friendly solvents.The reactions were completed in short times and mild reaction conditions with good to excellent yields.     

STUDIES ON GRAFT COPOLYMERIZATION OF DL—LACTIDE ON CORN STARCH AND BIODEGRADABILITY OF THE COPOLYMERS

The starch/D,L-lactide graft copolymers were synthesized by reacting D,L-lactide with corn starch in N,N-dimethylacetamide(DMAM)in the presence of triethylamine(NEt3)and anhydrous lithium chloride.The effect of reaction time and the molar ratio of D,L-lactide to glucose structural unit of starch on monomer conversion(C%),graft(G%)and graft efficiency(GE%)were studied,The C%,G%and GE% could approach 37.3% 179.7%and 68.0%,respectively when the molar ratio of D,L-lactide to glucose structuralunit of starch is 10:1 and the graft copolymerization was carried out at 80-85℃ for 4hr under nitrogen atmosphere.The Fourier transforms infra-red (FTIR) spectroscopy.differential scanning calorimetry(DSC)and X_ray diffraction (XRD) spectroscopy were used in order to characterize the graft copolymers.FTIR spectra show that absorption band at 1740cm^-1 confirmed the formation of ester bond,indicating the starch /D,L-lactide graft copolymers were produced,the DSC characteristic results show the melting temperature of the graft copolymer were elevated slightly as the molar ratio of D,L-lactide to glucose structural units of starch increased and the X-ray diffraction spectra show the synthesized graft copolymers were amorphous.The degradability of graft copolymer was tested with the aid of acid,alkali and microbe such as bacillus subtilis and staphylococcus aureus.The results of water rsistance show the graft copolymer produced can be used as a component of impermeable coating for cardboard.     

THE ROLE OF LATTICE AND GASEOUS OXYGEN ON THE OXIDATIVE COUPLING OF METHANE STUDIED BY A PULSE REACTION TECHNIQUE

A comparative study of the role of lattice and gaseous oxygen in theoxidative coupling of methane over Na~ /Cao and Ca_xSr_(1-x)TiO_3 perovskiteoxide catalysts was performed by using a pulse reaction technique with CH_4,O_2 and mixtures of CH_4and O_2.It was found that there is an oxygen species onthe Surface of Cao which is active only for the total oxidation of methane at thereaction temperature.These oxygen species.once reacted with methane andconsumed,can be regenerated by the adsorption of oxygen molecules from thegas phase or by the migration of the lattice oxysen from the bulk onto thesurface.In contrast,no such oxygen species and no reaction can be detected bymethane pulsed over Ca_xSr_(1-x)TiO_3perovskite oxide catalysts.Na~ can heavilysuppress the non-selective oxygen species on the surface,and When 5mol%Na~ was incorporated onto the surface of Cao,the sample showed no reactivityto methane.When oxygen exists in the gas phase,or the pulse containsmethane and oxygen,the reaction over(Cao is mai     

STUDIES ON THE ACTIVITY COEFFICIENTS OF NONELECTROLYTES IN AQUEOUS SALT SOLUTIONS——Ⅱ. THE EFFECTS OF SALTS OF FATTY ACIDS AND QUATERNARY AMMONIUM SALTS ON THE SOLUBILITIES OF NAPHTHALENE IN WATER

On the assumption that the salt effect (salting-out or salting-in) representsthe balance of the electrostatic effect between the ion and the water dipole andthe dispersion effect between ion and nonelectrolyte molecule, the solubilitiesof n-valeric acid in five cobaltammimes were studied and reported in article Ⅰof this series. In the present investigation the activity coefficients of naph-thalene in two series of salts are determined spectrophotometrically. The firstseries consists of seven sodium salts of fatty acids (sodium formate to sodiumn-heptylate), differing from one another only by the number of CH_2 groups inthe anions. The second series consists of ammonium bromide and three tetra-