Synthesis of hyperbranched low molecular weight polyethylene oils by an iminopyridine nickel(II) catalyst

A 6-(2,6-dimethylphenyl)-2-(2,6-diisopropylphenyl)iminopyridine dibromo nickel(II) complex was synthesized, characterized by X-ray diffraction analysis and tested in ethylene polymerization using diethylaluminumchloride as the cocatalyst. Low molecular weight (Mn ∼ 103 g mol−1) polyethylene oils were obtained under a variety of reaction conditions. Detailed NMR analysis showed the formation of hyperbranched macromolecules (branching density >100 branches per 1000 carbons) with a high fraction of “branches on branch” and one unsaturation per chain, resulting in polymer features comparable to those of polymers produced by α-diimine Pd(II) catalysts. The DFT model of the catalytic species showed that the ortho-2,6-dimethylphenyl substituent of the pyridine group destabilizes the ethylene coordination to the metal centre but does not encumber both axial coordination site. So the polymerization performance of 1 can be addressed to the catalytic pocket generated by the coordinated ligand that favors both chain transfer and chain walking over propagatio

Preparation of pyrimidin-2-one derivatives via base-mediated decomposition of uracil-analogues Fischer carbene complex

A practical and efficient synthesis of pyrimidin-2-one derivatives from Fischer carbene complex uracil-analogues through base-mediated elimination reactions is described. The scope of the protocol has been explored with the preparation of a variety of pyrimidin-2-one derivatives by base mediated demetallation of N-1 and N-3 substituted uracil Fischer carbene

On the hydrolysis of the Dysprosium(III) ion

The hydrolysis of the Dysprosium (III) (Dy 3+ ) ion has been investigated at 25°C in 1, 2 and 3 molal (Na)ClO4 medium through a combined potentiometric‐coulometric methodology. At each perchlorate concentration the formation constants of the complexes DyOH 2+ , Dy2(OH)2 4+ and Dy5(OH)9 6+ have been determined. The values have then been extrapolated to zero ionic strength by using the Specific Interaction Theory. Analogies with the hydrolysis mechanism of other lanthanides are pointed out. This paper is just the first to be reported of a series of studies undertaken with the aim to prove that a single mechanism of hydrolysis applies to all the trivalent lanthanides and probably to the corresponding actinides, too radioactive to be investigated directly

Electrogenerated acid as an efficient catalyst for the preparation of 5-hydroxymethylfurfural

A new method for the synthesis of 5-hydroxymethylfurfural (HMF) with high yields in dimethyl sulfoxide (DMSO) is presented. By using constant-current electrolysis more than 90% of sucrose or fructose was converted to HMF at room temperature in DMSO in the presence of traces of water. Keywords: 5-Hydroxymethylfurfural, Electrochemical synthesis, Electrogenerated aci

First total synthesis of natural aplyolides C and E, ichthyotoxic macrolides isolated from the skin of the marine mollusc Aplysia depilans

A convergent pathway is described for the synthesis of the marine macrolides aplyolides C 4 and E 5. The key fragment 8 was prepared stereo selectively by Sharpless asymmetric dihydroxylation of eneyne 13