High temperature and high pressure extraction of lanthanofullerenes by using different solvents

The traditional Soxhlet extraction of lanthanofullerenes was improved and the high temperature and high pressure method with different extraction solvents was used. It's found that La@C-2n can be efficiently extracted with toluene and pyridine from the insoluble part of the soot after the toluene Soxhlet extraction. Pyridine can more efficiently and selectively extract lanthofullerenes, especially La@C-82, while toluene can extract La@C-74, which is a new member added to the soluble species to lanthanofullerenes.

Synthesis and crystal structure of chiral bis(cyclopentadienyl) samarium Schiff base complexes bearing intramolecular C-C bond formation and hydrogen transfer

SmCl3, reacted with CpNa (Cp = Cyclopentadienyl) in the ratio of 1:3 in THF, which then was reacted with (S)-(+)-N-1-(phenylethyl) salicylideneamine/toluene to yield the title complex, [GRAPHICS] The X-ray crystal structure determination of the title complex reveals that 1 is a dimer with intramolecular C-C bond formation and hydrogen transfer, which leads to the configuration turnover of the carbon atom at the benzyl position of the ligand, while those of the newly formed asymmetric centers may have either Ii or S type configurations. (C) 1998 Elsevier Science Ltd. All rights reserved.

Synthesis and characterization of (phenolphthalein/4,4 '-thiodiphenol) PES copolymers

Copolymers based on monomers phenolphthalein (PP)/4,4'-thiodiphenol (Bis-T)/4,4'-dichlorodiphenylsulfone (DCDPS) were prepared by a route involving the toluene, N-methyl-2-pyrrolidone and anhydrous potassium carbonate synthesis. The range of optimum reaction temperature was between 185 and 195 degrees C. The copolymers were characterized by C-13 NMR, differential scanning calorimetry (DSC) and torsion braid analysis. It was found that all of the copolymers were random and homogeneous and their glass transition temperatures (T-g) decreased linearly with an increase of Bis-T contents in the copolymers. The thermal stability determined by thermogravimetry analysis in air atmosphere indicated that the copolymer had better resistance to thermo-oxidative degradation. Dynamic mechanical measurement showed that (PP/Bis-T) PES copolymers containing 0-50 mol% of Bis-T components had two secondary relaxations. (C) 1998 Elsevier Science Ltd. All rights reserved.

Synthesis, extraction and electronic structure of Ce@C-2n

In view of the growing interest in endohedral lanthanide fullerenes, Ce, as a typical +4 oxidation state lanthanide element, has been systematically studied. The synthesis, extraction and electronic structure of Ce@C-2n are investigated. Soot containing Ce@C-2n was synthesized in high yield by carbonizing CeO2-containing graphite rods and are back-burning the CeC2-enriched cathode deposit in a DC are plasma apparatus. Ce@C-2n, dominated by Ce@C-82, can be efficiently extracted from the insoluble part of the soot after toluene Soxhlet extraction by pyridine at high temperature and high pressure in a closed vessel. About 60% Ce@C-2n (2n = 82,80,78,76) and 35% Ce@C-82 can be enriched in the pyridine extract. This fact is identified by desorption electron impact mass spectrometry (DEI MS). The electronic structure of Ce@C-2n is analyzed by using X-ray photoemission spectroscopy (XPS) of pyridine-free film. It is suggested that the encapsulated Ce atom is in a charge state close to +3 and was effectively protected from reaction with water and oxygen by the enclosing fullerene cage. Unlike theoretical expectation, the electronic state of Ce@C-82 is formally described as Ce+3@C-82(3-). (C) 1997 Elsevier Science Ltd.

The polymerization of methyl methacrylate with a new Nd(O-i-Pr)(3)-Al(i-Bu)(3) catalyst system

Methyl methacrylate (MMA) was polymerized with the rare earth coordination catalyst-system of Nd(O - i-Pr)(3) in toluene. The influences of various ligands in neodymium complexes, molar ratio of Al/Nd, catalyst concentration, catalyst aging time, solvents, the third component CCl4, temperature and time on the polymerization of MMA were studied. The results showed that the polymerization conversion reached more than 80% at a catalyst concentration of 9.2 x 10(-3) mol/L. The appropriate molar ratio of CCl4/Nd was 4. Hydrocarbon was preferred for the polymerzation to obtain a high conversion and a high <(M)over bar w> of PMMA. The H-1 NMR spectra of PMMA indicated that the lower the temperature, the higher the syndiotactic content of PMMA was obtained.

Asymmetric polymerization of the mixture of TrMA and MMA initiated by chiral complexes

A mixture of triphenylmethyl methacrylate (TrMA) and methyl methacrylate (MMA) was polymerized with chiral anionic initiator, such as fluorenyl lithium-(-)-sparteine [FlLi-(-)-Sp] and fluorenyl lithium-(+)-2S,3S-dimethoxy-1,4-bis(dimethylamino) butane [FlLi-(+)-DDB] in toluene at -78 degrees C. The results show that after the stable helix formed, when FlLi-(+)-DDB was used as the initiator, TrMA and MMA could be copolymerized, whereas when FlLi-(-)-Sp was used, the two monomers tended to be selectively polymerized into two polymers. This phenomenon has been explained by the existence of helix-selective polymerization. (C) 1997 John Wiley & Sons, Inc.

High-temperature, high-pressure extraction of metallofullerenes Gd@C-2n

A high-temperature, high-pressure extraction technique with toluene and pyridine were employed for the extraction of metallofullerenes Gd@C-2n, A series of Gd@C-2n for 2n from 70 to 96 were effectively extracted by toluene. Gd@C-74 was shown to be a new stable soluble metallofullerene species. Pyridine was found to be more useful for the extraction of Gd@C-82 and Gd-2@C-80 from empty fullerenes and other metallofullerene species.

Formation and special solubility of endohedral thulium metallofullerenes

Endohedral metallofullerenes Tm@C-2n were synthesized with the carbon-arc discharge method of activating the Tm2O3-containing graphite anode in situ and back-burning technique, Toluene soxhlet extraction, toluene and pyridine high-temperature and high-pressure extraction technique were employed for the effective extraction of Tm@C-2n. The formation of Tm@C-2n was confirmed by LD-TOF and DEIMS characterization. The mass spectrometric results indicate that Tm@C-2n have a better solubility in toluene and worse solubility in pyridine than other metallofullerenes.

Two-step-method extraction of endohedral metallofullerenes

A new and efficient extraction method of endohedral metallofullerenes, especially of rare-earth elements encapsulated metallofullerenes, has been reported in this paper. Soxhlet-extraction of raw soot with toluene was used in the first step to wash away most accompanying C-60, C-70. Then pyridine was chosen as solvent to obtain high-temperature and high pressure extract. Two kinds of extract were analysed by DEI-MS and LDI-MS, the results indicate that this two-step method can provide the extract which has the highest fraction of endohedral metallofullerenes. So it will greatly simplify the following separation and purification processes of metallofullerenes.

A new method for the preparation of fullerol

Reaction of C-60 with excessive potassium in toluene at refluxing temperature results in black precipitate KaC60 with high conversion, which can completely be hydrolyzed to prepare the fullerol. Investigations including FT-IR. H-1 NMR C-13 NMR, UV-Vis and FABMS of the product were reported.

Reactions of C-60 with R(3)SnH: A new synthetic route to C-60(RH)(n) and the property of C-60 to catalyze radical reactions

A new method for the preparation of polyalkyl and polyarenefullerene derivatives C-60(RH)(n)(R=Bu,n=1-3; R=Ph,n=1-10) by the reaction of C-60 with organotin hydride in toluene is described. Another series of products of stannanes R(a)Sn(b)H(c) (R=Bu, a=3-8, b=1-4, c=0-3 R=Ph, a=3-11, b=1-5, c=0-4) were also obtained, which shows that C-60 can catalyze polymerization of organic-tin. These products were determined by mass and infrared spectrometry. And the possible reaction mechanisms are discussed.

Synthesis and extraction of lanthanofullerenes and its DEIMS, ESR characterizations

The synthesis for lanthanofullerenes was studied by activating the La2O3 containing graphite rod in situ and back-burning the carbide-rich cathode deposite, La@C-2n are efficiently extracted in high temperature toluene, among them, La@C-74 as a new species is added into the soluble lanthanofullerenes, The toluene extraction is first characterized by desorption electron impact (DEI) mass spectrometry, The ESR spectrum of the extraction at room temperature is also discussed.

The reactivity of lanthanide alkyl compounds with phenylacetylene: Synthesis and structure of [(Bu(t)Cp)(2)LnC CPh](2) (Ln=Nd, Gd)

[(Bu(t)Cp)(2)LnCH(3)](2) (Ln = Nd, Gd) react with PhC=CH to form the dimeric alkynide-bridged complexes [(Bu(t)Cp)(2)LnC=CPh](2) [Ln = Nd (I), Gd (II)]. Both compounds crystallized from toluene in the monoclinic space group C2/c. The two complexes are homologous, composed of asymmetric metal-alkynide bridges with Nd-C, Gd-C (alkynide) bond lengths of 2.602(4), 2.641(5) (I) and 2.532(6), 2.601(7) Angstrom (II), respectively. The average Nd-C (ring) and Gd-C (ring) distances are 2.746(13) and 2.703(19)Angstrom.

High-yield Synthesis and Extraction of Gd@C-2n

Endohedral metallofullerene Gd@C-2n were synthesized with high-yield using the carbon-arc discharge method of activating the Gd2O3-containing graphite anode in situ and back-burning technique. A series of Gd@C-2n for 2n from 70 to 96 were effectively extracted by toluene at high-temperature and under high-pressure condition. Gd@C-82, Gd@C-74 were considered to be fairly stable and soluble metallofullerene species.

A study of the radical reaction of C-60 with n-Bu(3)SnH

The reaction of buckministerfullerene (C-60) with tri-n-blltyltin hydride(n-Bu(3)SnH) in toluene solution has been investigated. According to mass spectrometry analysis, the products of above reaction are C-60(BuH)(n)(n = 1 similar to 3) and Bu(x)Sn(y)H(x) (x = 3 similar to 8, y = 1 similar to 4,approximate to = 0 similar to 3). The reaction maybe provide a new method for the synthesis of alkylated fullerene derivatives. Where C-60 also takes a role of a catalysis of organtic-tin polymerization. The radical reaction mechanism has been discussed.