Synthesis of 4,4′-bis(dichloroamino)- and 4,4′-bis(chloroamino)-3,3′-azofurazans,the first representatives of dichloroamino- and chloroaminofurazans

First representatives of dichloroamino- and chloroaminofurazans, viz., 4,4′-bis(dichloroamino)- and 4,4′-bis(chloroamino)-3,3′-azofurazans, were synthesized by the chlorination of 4,4′-diamino-3,3′-azofurazan with sodium hypochlorite in the CH₂Cl₂—H₂O mixture.     

Practical and theoretical study on the α-substituent effect on α-diimine Nickel(II) and Cobalt(II)-based catalysts for polymerization of ethylene

The Late transition metal catalysts based on Ni(II) and Co(II) were synthesized and their structure and activity in polymerization of ethylene were compared. Methylaluminoxane (MAO) was used as a co-catalyst. To discover the optimum polymerization conditions, the effect of polymerization temperature, monomer pressure, [Al]: [Ni] molar ratio and time of polymerization were studied. Activity of the catalysts was promoted by increasing of the monomer pressure. The viscosity average molecular weights M_v of the synthesized polymers using 1,2-bis(2,4,6-trimethyl phenyl imino) acenaphthene Nickel(II) dibromide were increased with increasing of the monomer pressure from 1 up to 6 bar which studied. Explicitly, the ortho-substituent has a significant effect on the catalyst behavior. Melting point and crystallinity of the obtained polyethylene using 1,2-bis(2,4,6-trimethyl phenyl imino) acenaphthene Nickel(II) dibromide catalyst were increased with enhancing monomer pressure. The optimum and stable structures were computed and some factors related to the activity were studied. Catalyst 1,2-bis(2,4,6-trimethyl phenyl imino) acenaphthene Nickel(II) dibromide had the highest activity with the highest quantities of dipole moment (18.29 Debye), charge of Mullikan on metal atom (1.48) and Sum of electronic and thermal Energies (–7906.52 e.u.).     

A low-symmetry nickel(II) α-diimine complex for homopolymerization of ethylene: study of interactive effects of polymerization parameters

A low-symmetry nickel(II) α-diimine complex [(2,4,6-trimethylphenyl)imino)-((2,6-diisopropylphenyl)imino)-acenaphthene nickel(II) dibromide] (C1) was synthesized and characterized crystallographically. Response surface method (RSM) was employed to study the interactive effects of critical factors on ethylene polymerization. The maximum activity of C1, when activated by methylaluminoxane (MAO) cocatalyst {4960 kgPE [(mol Ni)^?1 h^?1]} was achieved at 10 °C, 7 bar and CC (cocatalyst-to-catalyst ratio) equal to 1550, which is higher than most similar counterparts. Considering surface plots of MW, it is concluded that at high levels (>1000) of CC, there is competition between chain transfer to aluminum and reinsertion of macromonomer to newly formed metal-methyl bonds.     

Dual catalysis with an N-heterocyclic carbene and a Lewis acid: Thermally latent precatalyst for the polymerization of ε-caprolactam

So far, the earlier reported strong correlation between basicity of an N-heterocyclic carbene (NHC) and its reactivity in poly(ε-caprolactam) (PA6) synthesis resulted in a substantial limitation of applicable carbenes. Here, to overcome this issue, 1,3-dimethylimidazolium-2-carboxylate, an easily accessible, air and moisture-stable NHC, was applied as thermally latent initiator. In order to compensate for its low basicity, reactivity was enhanced by the addition of both a Lewis acid and an activator to ease the initial polymerization step. The resulting mixtures of ε-caprolactam, the CO₂-protected NHC, a Lewis acid and N-acylazepan-2-one constitute homogeneous, thermally fully latent “single-component” blends for the anionic polymerization-based synthesis of PA6. They can be stored both in the liquid and solid state for days and months, respectively, without any loss in activity. The role of the Lewis acid as well as technical implications of the prolonged pot-times are discussed.     

Development of technique for synthesis of methyl(β-oxyethyl) sulfide by the reaction of ethylene oxide with methyl mercaptan

Reaction of ethylene oxide with methyl mercaptan in the presence of a catalyst, a solution of potassium hydroxide in methyl(β-oxyethyl) sulfide, was studied. Various technological procedures for synthesis of methyl(β-oxyethyl) sulfide were analyzed. The process conditions providing a 98–99% conversion of the starting reagents at a selectivity of 97–98% were suggested.     

Nickel(II)-α-diimine complexes containing naphthyl substituents for ethylene polymerization under low ethylene pressure

Two new α-diimine containing Ni(II) complexes, {bis[N,N′-(2,6-dimethyl-4-naphthylphenyl)imino]-1,2-dimethylethane}dibromonickel 3a and {bis[N,N′-(2-methyl-4-naphthylphenyl)imino]-1,2-dimethylethane}dibromonickel 3b were synthesized and characterized. The crystal structures of representative ligand 2a and its complex 3a were determined by X-ray crystallography. Complex 3a bearing 2,6-dimethyl and 4-naphthyl groups, activated by diethylaluminum chloride (DEAC), shows high catalytic activity for the polymerization of ethylene [4.43 × 10⁶ g PE/(mol Ni h bar)]. Interestingly, complexes 3a and 3b bearing the naphthyl substituent in the para-aryl position produced dendritic polyethylenes (branching degree, 3a: 112, 118, and 147; 3b: 113, 127, and 151 branches/1,000 C at 20, 40, and 60 °C, respectively). The dendritic polyethylene particle size obtained by 3a and 3b/DEAC can be controlled in the 1–20 nm range under low ethylene pressure (diameter, 3a: 18.31, 14.44, and 11.09; 3b: 12.29, 8.98 and 6.27 nm at 20, 40, and 60 °C, respectively) and could be expected to produce a nano-targeted drug carrier after modification with water-soluble oligo(ethylene glycol).     

General features of the reaction of 4,4′-difluorobenzophenone with potassium diphenoxide of 2,2-bis (4-hydroxyphenyl)propane

The major factors determining molecular weights of polyarylene-ether ketones formed by the reaction of 4,4-difluorobenzophenone with 2,2-bis(4-hydroxyphenyl)propane in the presence of K₂CO₃ were revealed. The optimum conditions for the preparation of high-molecular-weight polymers were found, and it was demonstrated that it is possible to control their molecular weights ( from 10 000 to 200 000).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2526–2530, October, 1996.     

Synthesis and properties of α, α′ -bis -(p-benzylphenyl)xylene

Summary ,-bis-(p-Benzylphenyl)xylene was synthesized for the first time and its UV and infrared spectra determined.     

Cyclocondensation of β-(aryl/heteroaryl)methylaminoenones with thionyl chloride: a facile general approach for the synthesis of 2,4-bis(het)aryl-5(het)aroylthiazoles

An efficient, regioselective route to 2,4-bis(het)aryl-5(het)aroylthiazoles has been developed by cyclocondensation of thionyl chloride with novel β-(het)arylmethylaminoenones which are readily accessible by the reaction of (het)arylmethylamines with 1,3-bis(het)arylmonothio-1,3-diketones. The method allows entry to 2,4,5-trisubstituted thiazoles, with full control for the introduction of either a (het)aryl group at 2,4 positions or a (het)aroyl group at 5 position of the thiazole ring.     

Chemical modification of expanded glass aggregate with N-Benzoyl-N′-(4-methylphenyl) thiourea (TTU) for the adsorptive removal of Cr(III) ion

In this study, the silylant agent 3-aminopropyl trimethoxysilane (APTES) was anchored on expanded glass aggregate (GA) to prepare a new adsorbent. N-Benzoyl-N′-(4-methylphenyl) thiourea (TTU) bonded to amino-functionalized GA adsorbent with reflux. Developed adsorbent (GA-APTES-TTU) was characterized using thermal analysis (TGA) and scanning electron microscopy (SEM). TGA and SEM studies indicated that modification of the glass aggregate (GA) surfaces was successfully performed. The adsorption studies exhibited that the GA-APTES-TTU could be efficiently used for the removal of Cr(III) from aqueous solutions. The effects of pH, adsorbent dosage, ion concentration, time, and temperature were investigated as adsorption parameters. The maximum removal of Cr(III) was observed at pH 4. The adsorption equilibrium was achieved in 120 min and adsorption of Cr(III) followed the Langmuir isotherm model. The maximum adsorption capacity for Cr(III) was 0.4305 mmol/g with GA-APTES-TTU. Thermodynamic parameters such as the standard free energy (ΔG^o), enthalpy change (ΔH°) and entropy change (ΔS°) were calculated in order to explain the mechanism of adsorption process. The thermodynamic data showed that Cr(III) adsorption was spontaneous, endothermic, and a physisorption reaction. In addition, the adsorption kinetic data fitted to the pseudo-second order model.     

Interlayer Formation of Cyclobis(paraquat-o-phenylene) by the Reaction of Laponite-4,4'-bipyridinium Intercalates with α, α'-Dibromo-o-xylene: A One Electron Template Synthesis

Cyclobis(paraquat-o-phenylene) cyclophane can be synthesised in the form of a free radical within the gallery space of a synthetic aluminosilicate clay mineral. The interlayer formation of the cyclophane was revealed by XRD, IR and optical measurements. The mechanism of its formation is consistent with a one electron redox synthesis in which the electron donated by the clay mineral plays the role of the template towards the -electron deficient bipyridinium moieties.     

Anion ring-opening polymerization of ethylene oxide by initiation of sodium 4-amino-N-(2-pyrimidinyl)benzene sulfonamide and influence of moisture on polymerization

Polyethylene oxide with sulfadiazine and hydroxyl end groups (PEOsf) were prepared by anion ring-opening polymerization of ethylene oxide initiated by sodium 4-amino-N-(2-pyrimidinyl)benzene sulfonamide (SF-Na). The product was characterized in detail by NMR, IR, GPC and DSC. Its molecular weight and molecular weight distribution are in the range of 1200-1 500 and 1.04-1.06 respectively, and the latter is nearly monodistribution. The trace of the moisture from air could accelerate the polymerization, and the mechanism is discussed.     

Enantiospecific nucleophilic substitution of the dimethylamino group in (R)-tricarbonyl[-{(1-dimethylamino)ethyl}-η6-benzene]chromium

Treatment of (R)-tricarbonyl[-{(1-dimethylamino)ethyl}-η⁶-benzene]chromium 1 with esters of chloroformic acid leads to enantiospecific substitution of the dimethylamino group for a chloro substituent. The chloro group in turn can enantiospecifically be replaced for a diphenylphosphino group. Both reactions proceed with retention.     

Synthesis and crystal structure of nickel(Ⅱ) and zinc(Ⅱ) complexes with 2,4-bis(3,5-dimethylpyrazol-1-yl)-6-methoxyl-1,3,5-triazine

2,4-Bis(3,5-dimethylpyrazol-1-yl)-6-methoxyl-1,3,5-triazine(bpt) has been synthesized by using a new, simple and general method with high yields. Reactions of bpt with Ni(CIO4)2 · 6H2O and Zn(CIO4)2 · 6H2O in methanol gave mononuclear complex [Ni(bpt)2] · (CIO4)2 · H2O and ternary complex [Zn(mpt)2(dmp)](CIO4)2 respectively, where mpt (2,4-dimethoxy-6-(3,5-dimethyl-pyrazol-1-yl)-1,3,5-triazine) and dmp(3,5-dimethylpyrazole) are the alcoholysis products of bpt in the presence of Zn2+ ion. A possible mechanism for this catalytic reaction was proposed. X-ray crystal structure for ligand bpt, Ni and Zn complexes are reported. The protonated form of the ligand bpt crystallizes as its perchlorate salt including one molecule of water, [Hbpt · H2O · CIO4]. The proton is located on one pyrazole N-atom. [Hbpt ?H2O ?CIO4], in which [Hbpt]+ is in cis-cis conformation, are packed in slipped stacks of approximately parallel layers. The π-π overlap interactions between the non-protonized pyrazoles of the adjace     

Sequential Analysis of α-Glucooligosaccharides with α-(1→4) and α-(1→6) Linkages by Negative Ion Q-TOF MS/MS Spectrometry

Negative ion Q-TOF MS/MS spectra are shown to be very useful for sequential analysis of the glycosidic linkage in the α-gluco-oligosaccharides (DP 3-6) derived from an amylopectin molecule. The composition of the fragmentation ions generated from these compounds enabled us to distinguish two kinds of glycosidic linkage, α-(1→4) and α-(1→6), at same time to determine the glucose sequence from the reducing end of the oligosaccharide.     

Rearrangement of enol acetates of α-(3,5-dimethyl-1,2,4-triazol-1-yl)-2,4-dichloroacetophenone and α-(1,2,4-triazol-1-yl)-2,4-dichloropropiophenone

At 140 °C in acetic anhydride enol acetates of -(3,5-dimethyl-1,2,4-triazol-1-yl)-2,4dichloroacetophenone and -(1,2,4-triazol-1-yl)-2,4-dichloropropiophenone undergo 1,3and 1,5-rearrangement, respectively.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 182–184, January, 1995.