Trifluoroacetic Acid Hydroxylamine System as Organocatalyst Reagent in a One-Pot Salt Free Process for the Synthesis of Caprolactam and Amides of Industrial Interest

Catalysis Letters - In this work we studied the reactivity of the Trifluoroacetic acid hydroxylamine system in the one step salt free synthesis of amides from ketones. A particular regards was paid...     

Effectiveness of crystalline admixtures and lime/cement coated granules in engineered self-healing capacity of lime mortars

Recently, the use of lime mortars in the restoration of historic buildings has found a renewed interest because they can guarantee the required mechanical, chemical and physical compatibility with the existing substrate. Spontaneous occurrence of self-healing phenomena in lime-based mortars is well known; the possibility of engineering the self-healing capacity, through tailored additions, is therefore of the utmost interest with the aim of enhancing the durability of the building masonry restoration works. This work proposes a system for the evaluation of the self-healing capacity with reference to traditional and advanced lime mortars. The autogenous healing capacity of a reference lime mortar has been first of all evaluated. Then, the possibility of engineering the aforementioned capacity has also assessed, through both commercial crystalline admixtures and tailored encapsulated additives. These should work according to a twofold mechanism: first, the coated granules envelope a core of lime mortar with purpose of making it inert during the hardening phase. Secondly, once the coated granules rupture upon cracking and damage of the mortar, the reactive binder is released and undergoes a delayed hardening, which is responsible of the healing phenomena. The results show that the mortar is able to heal micro-cracks; moreover, the addition of the crystalline admixture enhances this capacity. The different kinds of employed coated granules were also able to induce a sensible self-healing, but they decrease the instantaneous compressive strength.     

Metal-assisted syntheses and NMR characterization of square-planar Pd(II) and Pt(II) complexes with tridentate nitrogen-donor chelate ligands

The complexes [PtCl(NNN^H)](OTf) (1^H), [PdCl(NNN^H)](OTf) (2^H), [PdCl(NNN^Me)](OTf) (2^Me), [PdMe(NNN^H)](OTf) (3^H), [PdMe(NNN^Me)](OTf) (3^Me) and [PdMe(NNN^Ph)](OTf) (3^Ph) {NNN^H = (pyridin-2-ylmethylene)-quinolin-8-yl-amine; NNN^Me = (1-pyridin-2-yl-ethylidene)-quinolin-8-yl-amine; NNN^Ph = (phenyl-pyridin-2-yl-methylene)-quinolin-8-yl-amine} were prepared by reacting a stoichiometric methanolic mixture of 8-aminoquinoline and an ortho-substituted aldehydo- or keto-pyridine {2-pyridinecarboxaldehyde, 2-acetylpyridine or 2-benzoylpyridine} with the proper Pt(II) or Pd(II) precursor in methanol. In the case of the 2 ^Me derivative, the addition of a stoichiometric amount of a Ag(I) salt to the reaction mixture was necessary to obtain the desired product. Information about the formation of these complexes are reported. In particular, NMR experiments allowed to observe the different reactivity of 8-aminoquinoline towards aldehydo- and keto-pyridines and the formation of the emiaminal ligand pyridin-2-yl-(quinolin-8-ylamino)-methanol NNN(H₂O)^H 4. Finally, the methanesulphonato-complex [Pd(η¹-OSO₂CH₃)(NNN^Me)](OTf) (5^Me) was obtained by reacting the chloro-derivative 2^Me with a stoichiometric amount of AgSO₃CH₃ in nitromethane.