Search results for "Opening"

Synthesis and biological evaluation of new bicyclic fluorinated uracils through ring-closing metathesis.

2006

Two families of bicyclic fluorinated uracils have been prepared starting from a gem-difluorinated unsaturated nitrile, by means of a ring-closing metathesis reaction to form the new ring, which is fused at the C-5/C-6 or N-1/C-6 positions of the uracil moiety. The selective formation of olefin regioisomers in the metathesis process can be controlled according to the reaction conditions (catalyst, solvent, and temperature). The acaricidal activities of the resulting compounds have also been investigated.

Transition Metal Catalyzed Olefin, Cycloolefin, and Styrene Polymerization

2013

The sections in this article are History and Trends Polymerization Processes Supported Catalysts and Morphology Control Polymerization Mechanisms and Stereoselectivity History and Principles of Metallocene Catalysis Regio- and Stereoselective Polymerization of α-Olefins Polymerization of Cyclic Olefins, Cyclopolymerization, and Stereoselective Polymerization of Styrene Late Transition Metal Catalysts Transition Metal Catalyzed Copolymerization Acknowledgements

Long-Chain Branched Poly(Lactide)s Based on Polycondensation of AB2 -type Macromonomers

2012

A series of long-chain branched poly(d-/l-lactide)s is synthesized in a two-step protocol by (1) ring-opening polymerization of lactide and (2) subsequent condensation of the preformed AB2 macromonomers promoted by different coupling reagents. The linear AB2 macromonomers are prepared by Sn(Oct)2-catalyzed ROP of D- and L-lactide with 2,2-bis(hydroxymethyl)butyric acid (BHB) as an initiator. Optimization of the polymerization conditions allows for the preparation of well-defined macromonomers (Mw/Mn = 1.09–1.30) with adjustable molecular weights (760–7200 g mol−1). The two-step approach of the synthesis comprises as well the coupling of these AB2 macromonomers and hence allows precise contr…

Aliphatic Hyperbranched Copolyesters by Combination of ROP and AB2-Polycondensation

2005

Hyperbranched aliphatic copolyesters have been prepared by the copolymerization of e-caprolactone and 2,2-bis(hydroxymethyl)butyric acid (AB 2 -monomer), catalyzed by (i) HfCl 4 (THF) 2 and (ii) diphenylammonium trifluoromethanesulfonate (DPAT), respectively. In both cases, copolymerization by combined ROP/AB 2 -Polycondensation was achieved. The degree of branching (DB) and consequently the density of functional groups of the resulting copolyesters were controlled by the comonomer ratio in the feed. Molecular weights in the range M n =22 000-166 000 g mot -1 (GPC, PS standards) were obtained, with apparent polydispersity indices of 1.20 to 1.95. The DB was in the range 0.03-0.35. Remarkabl…

Soluble Hyperbranched Poly(glycolide) Copolymers

2010

A series of (hyper)branched poly(glycolide) copolymers has been prepared by copolymerization of glycolide (GA) with 2,2-bis(hydroxymethyl)butyric acid (BHB) via combined ROP/AB2-polycondensation. Polymerization was conducted in bulk and catalyzed by stanneous-2-ethyl hexanoate (Sn(Oct)2). The branched topology of the resulting polyesters was studied in detail by 1D- and 2D-NMR spectroscopy and confirmed by the synthesis and characterization of model compounds. The AB2 monomer BHB was incorporated either as a dendritic or focal unit, but hardly in linear or terminal mode. As expected for multifunctional polycondensation, SEC measurements showed polydisperse products with polydispersity index…

Hyperbranched Polylactide Copolymers

2006

A series of hyperbranched poly(l-lactide) (PLLA) copolymers were prepared by copolymerization of dilactide with 2,2-bis(hydroxymethyl)butyric acid (BHB) as an AB2 comonomer via a combined ring-open...

Arts. 34-40 EIR

2016

The comments on Arts. 34-40 of EU Regulation 2015/848 deal with opening of secondary insolvency proceedings. These comments systematically tackle the prerequisites required for the opening of secondary insolvency proceedings, the relationship between main and secondary proceedings and the duties of cooperation that are put on the courts and the insolvency practitioners of both main and secondary proceedings. A particular attention is devoted to the introduction of the so-called “Undertaking to Avoid the Opening of Secondary Insolvency Proceedings” (Art. 36).

Olefin metathesis reactions with fluorinated substrates, catalysts, and solvents.

2014

Benzoxetes and Benzothietes ¾ Heterocyclic Analogues of Benzocyclobutene

2012

Benzo-condensed four-ring heterocycles, such as benzoxetes 1 and benzothietes 3 represent multi-purpose starting compounds for the preparation of various higher heterocyclic ring systems. The thermal or photochemical valence isomerizations between the benzenoid forms 1,3 and the higher reactive o-quinoid structures 2,4 provide the basis for the synthetic applications. On the other hand, this valence isomerization impedes in particular the generation and storage of 1 because the thermal equilibrium 1 ⇆ 2 is completely on the side of 2. Thus, the number of erroneous or questionable benzoxete structures published to date is surprisingly high. On the contrary, the thermal equilibrium 3 ⇆ 4 is o…

Il mito del giudicato civile e amministrativo alla prova degli obblighi internazionali di restitutio in integrum

2019

The principles of res judicata and legal certainty in terminated civil and administrative proceedings often clash with the obligation of restitutio in integrum stemming from the violation of international law, namely of human rights provisions such as the European Convention on Human Rights (ECHR). Frequently, the European Court on Human Rights indicates the re-opening of terminated proceedings as (one of) the most appropriate form for redress. The Italian Constitutional Court, however, has recently held that the lack of specific clauses allowing for the re-opening of civil and administrative proceedings which have resulted in the violation of the ECHR does not contravene the Constitution. …