309919-92-4

Upstream product

• 50-00-0 formaldehyd 
• 2409-55-4 2-tert-Butyl-4-methylphenol 
• 110-70-3 N,N`-dimethylethylenediamine 
• 96-76-4 2,4-di-tert-Butylphenol 

Relevant academic research and scientific papers

Modulating the thermal properties of poly(hydroxybutyrate) by the copolymerization of: Rac -β-butyrolactone with lactide

Biobased poly(hydroxybutyrate) is produced by microorganisms under controlled conditions. It is a linear, high molecular weight, fully isotactic and highly crystalline polymer. However, it has poor mechanical and thermal properties. We have modulated the thermal properties of this material by ring-opening co-polymerization of rac-β-butyrolactone (BL) with lactide (LA) in the presence of salan-based yttrium and aluminum catalysts. The prepared poly(hydroxybutyrate-co-lactide) copolymers were characterized by proton and carbon nuclear magnetic resonance (1H and 13C NMR), size exclusion chromatography (SEC) and differential scanning calorimetry (DSC) analyses. The salan-yttrium compound was a more effective catalyst compared to the aluminum compound, affording high molecular weight copolymers with higher monomer conversion and a monomodal distribution of the molecular weights. The kinetic experiments showed a higher rate of polymerization for the LA with respect to the BL. The copolymers were amorphous and DSC showed unique transition temperatures for all of the samples. The formation of a gradient copolymer is proposed.

Steric and solvation effects on polymerization kinetics, dormancy, and tacticity of Zr-Salan catalysts

1-Hexene polymerization using four zirconium-based amine bis(phenolate) catalysts, Zr[2-R-4-tBu-ONNO]Bn2 (where R = methyl (1), ethyl (2), isopropyl (3), and tert-butyl (4)), was examined to establish the effect of ligand sterics on kinetics and stereocontrol of olefin polymerization. For each catalyst, a rich data set was obtained including monomer consumption, molecular weight evolution, end-group analysis, and active site counts. A set of reaction specific rate constants was determined for catalysts 2-4. In addition to the standard elementary reaction steps of initiation, propagation, mis-insertion, and chain transfer, these catalysts undergo isomerization leading to dormancy. This isomerization is particularly prominent in bromobenzene and for less sterically hindered complexes. Across the series 2-4, ligand steric properties have a systematic effect on both insertion and chain transfer rate constants. This relationship was rationalized using the Sterimol steric parameters. The rates of propagation and mis-insertion were found to be similarly sensitive to steric effects with sensitivities of 0.9 and 0.76 ?-1, respectively, while initiation was found to be slightly more sensitive (0.99 ?-1) and chain transfer to be considerably less sensitive (0.58 ?-1) owing to the reduced steric demand for monomer independent chain termination compared to bimolecular insertion. The rates of propagation and mis-insertion in bromobenzene were found to be more sensitive to sterics (1.24 and 0.98 ?-1, respectively). In addition, ligand sterics play a significant role in the tacticity of the resulting polymer, the difference in polymers resulting from catalysts 1-4 was also systematic and could be compared to the Sterimol steric parameters. All kinetic data were critical in the determination of the full mechanism for this series; thus, this study illustrates the importance of obtaining a complete kinetic data in order to confidently establish quantitative structure-activity relationships (QSARs).

Cytotoxic heteroleptic heptacoordinate salan zirconium(IV)-bis-chelates-synthesis, aqueous stability and X-ray structure analysis

Herein we report the synthesis and structural characterization of a series of novel Zr(iv)salan complexes. The initial metalation product [(L1)2Zr] is highly water sensitive while ligand exchanged [L1Zr(dipic)] hydrolyses slowly with a bis-hydroxo Zr(iv) species identified by MS as an intermediate. [L1Zr(dipic)] is cytotoxic in the range of cisplatin against two human carcinoma cell lines.

Diamine bis(phenolate) and pendant amine bis(phenolate) ligands: Catalytic activity for the room temperature palladium-catalyzed Suzuki-Miyaura coupling reaction

A series of amine bis(phenolate) ligands bearing aryl substituents of varying steric bulk are reported and characterized using single-crystal X-ray diffraction, NMR spectroscopy and high-resolution mass spectrometry experiments. Palladium complexes derived in situ from these ligands are evaluated as catalysts for the Suzuki-Miyaura coupling of phenylboronic acid and aryl bromides. High conversions are observed for these reactions in methanol solvent at low catalyst loadings (0.01 mol%), short reaction times (30 min) and mild temperatures (30°C). Conversion is observed for a range of substrates, and is found to depend on the nature of the external base and solvent employed. These findings demonstrate the utility of catalysts derived from late transition metal complexes of amine bis(phenolate) ligands, particularly those bearing bulky cumyl substituents.

Synthesis and characterization of rare-earth metal guanidinates stabilized by amine-bridged bis(phenolate) ligands and their application in the controlled polymerization of rac-lactide and rac-β-butyrolactone

Eight rare-earth metal guanidinates supported by a versatile family of chelating amine-bridged bis(phenolate) ligands were synthesized. Metathesis reactions of rare-earth metal chlorides [LnClL1(THF)] stabilized by amine-bridged bis(phenolate)

Catalytic oxidation of aromatic hydrocarbons by mono-oxido- alkoxidovanadium(V) complexes of ONNO donor ethylenediaminebis(phenolate) ligands

Two oxidovanadium(V) complexes, [VVO(L1)(OMe)] (1) and [VVO(L2)(OMe)] (2), with ONNO donor ethylenediamine-bis(phenolate) ligands (H2L1 and H2L2) have been readily synthesized by the reaction between the ligand precursors and VOSO4·5H2O in MeOH, and characterized by physico-chemical techniques and single crystal X-ray diffraction studies. Both complexes 1 and 2 are hexa-coordinated with a pseudo-octahedral geometry in an N2O4 coordination environment and are found to catalyze the oxidation of toluene to benzoic acid and isomers of xylene to the corresponding hydroxy acids, with turnover numbers (TON) over 200, except for o-xylene. On changing the ligand fragments and coordination geometry around the metal centre there is an improvement in the catalytic efficiency, selectivity and also TON of the reaction as compared with the previously reported systems. The reactions were monitored using 51V NMR spectroscopy. Based on mass spectra analysis and 51V NMR studies, the mechanism of the catalytic process has been proposed, employing the formation of oxido-hydroperoxido/hydroxido-peroxido [V(ONNO)(O)(OOH)] ? [V(OH)(ONNO)(O2)] intermediates.

Iron(III) complexes of ethylenediamine derivatives of aminophenol ligands as models for enzyme-substrate adducts of catechol dioxygenases

In the present work, six N,N'-dimethylethylenediamine derivatives of substituted aminophenol ligands (H2LNEX, X: C, B, M, BM, Bu and OB) were synthesized by a convenient, green procedure. The mentioned ligands were characterized by 1

Highly cytotoxic vanadium(v) complexes of salan ligands; Insights on the role of hydrolysis

Vanadium(v) oxo complexes with tetradentate diamine bis(phenolato) "salan" ligands of the type LVO(OiPr) (L is salan) with different steric and electronic substitutions at the ortho and para positions to the binding phenolato moiety were synthesized and t

Structure/properties relationship for bis(phenoxyamine)Zr(IV)-based olefin polymerization catalysts: A simple DFT model to predict catalytic activity

The productivity of a number of bis(phenoxyamine)Zr(IV)-based catalysts (bis(phenoxyamine) = N,N′-bis(3-R1-5-R2-2-O-C 6H2CH2)-N,N′-(R3) 2-(NCH2CH2N)) in eth

Synthesis, structure, and C-C cross-coupling activity of (amine)bis(phenolato)iron(acac) complexes

A series of (amine)bis(phenolato)iron(III)acac complexes has been prepared and characterized. Reaction of Fe(acac)3 with the diprotonated linear tetradentate proligand N,N′-bis(4,6-di-tert-butyl-2-methylphenol)-N, N′-dimethyl-1,2-diaminoethane, H2[L1], and tripodal tetradentate ligand precursors dimethylaminoethylamino-N,N-bis(2-methylene-4,6- di-tert-butylphenol), H2[L2], dimethylaminoethylamino-N,N-bis(2- methylene-4-methyl-6-tert-butylphenol), H2[L3], 2-methoxyethylamino- N,N-bis(2-methylene-4,6-di-tert-butylphenol), H2[L4], 2-methoxyethylamino-N,N-bis(2-methylene-4-methyl-6-tert-butylphenol), H 2[L5], and 2-methoxyethylamino-N,N-bis(2-methylene-4,6- dimethylphenol), H2[L6], produces the distorted octahedral Fe III complexes [L1]Fe(acac) (1), [L2]Fe(acac) (2), [L3]Fe(acac) (3), [L4]Fe(acac) (4), [L5]Fe(acac) (5), and [L6]Fe(acac) (6). In all of these complexes, the phenolato oxygen atoms are cis-oriented. The paramagnetic Fe III complexes 1-6 were also characterized by UV/Vis and IR spectroscopy, mass spectrometry, cyclic voltammetry, and magnetic measurements. Single crystal X-ray molecular structures have been determined for complexes 1, 2, 3, 5, and the proligand H2[L6]. Preliminary investigations of complexes 1-6 for catalytic cross-coupling reactions of aryl Grignard reagents with cyclic and acyclic secondary alkyl halides and benzyl halides were performed. While the activity for cyclohexyl chlorides and bromides was high, cross-coupling of benzyl halides was moderate and 2-bromo- and 2-chlorobutane gave poor yields of cross-coupled product.