Search results for "DF"

Can Green Dimethyl Carbonate Synthesis be More Effective? A Catalyst Recycling Study Benefiting from Experimental Kinetics and DFT Modeling

2014

Dibutyldimethoxystannanes are known to catalyze the reaction between carbon dioxide and methanol leading to dimethyl carbonate. Despite similarities between din-butyl- and ditert-butyldimethoxystannane, the recycled complexes have different structural features. In the din-butyl series, a decatin(IV) complex has been characterized and is less active than the stannane precursor. Kinetic experiments likely indicate that all the tin centers are not active, which is confirmed in comparing with the related dinuclear 1,3-dimethoxytetran-butyldistannoxane complex. In the ditert-butyl series, the tritin(IV) complex isolated upon recycling features the steric effect of bulky tBu ancillary ligands. In…

Synthesis, spectroscopic characterization and in vitro antimicrobial activity of diorganotin(IV) dichloride adducts with [1,2,4]triazolo-[1,5-a]pyrim…

2006

Abstract The heterocyclic ligands [1,2,4]triazolo-[1,5-a]pyrimidine (tp) and 5,7-dimethyl-[1,2,4]triazolo-[1,5-a]pyrimidine (dmtp), react with diorganotin dichlorides giving the addition compounds Me2SnCl2(tp)2, Et2SnCl2(tp)2, Me2SnCl2(dmtp)2, Et2SnCl2(dmtp)2, Bu2SnCl2(dmtp), Ph2SnCl2(dmtp). The organotin:ligand stoichiometry goes from 1:2 to 1:1 by increasing the steric hindrance of the organic groups bound to tin. The compounds have been characterized by means of infrared, 119Sn Mossbauer and 1H AND 13C NMR spectroscopy. The ligands presumably coordinate to tin classically through the nitrogen atom at the position 3. The 1:1 complexes adopt trigonal bipyramidal structures, with the organi…

Substituent effects in trans-p,p'-disubstituted azobenzenes: X-ray structures at 100 K and DFT-calculated structures.

2014

The crystal and molecular structures of twopara-substituted azobenzenes with π-electron-donating –NEt2and π-electron-withdrawing –COOEt groups are reported, along with the effects of the substituents on the aromaticity of the benzene ring. The deformation of the aromatic ring around the –NEt2group inN,N,N′,N′-tetraethyl-4,4′-(diazenediyl)dianiline, C20H28N4, (I), may be caused by steric hindrance and the π-electron-donating effects of the amine group. In this structure, one of the amine N atoms demonstrates clearsp2-hybridization and the other is slightly shifted from the plane of the surrounding atoms. The molecule of the second azobenzene, diethyl 4,4′-(diazenediyl)dibenzoate, C18H18N2O4,…

Stereocontrol in Diphenylprolinol Silyl Ether Catalyzed Michael Additions : Steric Shielding or Curtin-Hammett Scenario?

2017

The enantioselectivity of amine-catalyzed reactions of aldehydes with electrophiles is often explained by simple steric arguments emphasizing the role of the bulky group of the catalyst that prevents the approach of the electrophile from the more hindered side. This standard steric shielding model has recently been challenged by the discovery of stable downstream intermediates, which appear to be involved in the rate-determining step of the catalytic cycle. The alternative model, referred to as Curtin-Hammett scenario of stereocontrol, assumes that the enantioselectivity is related to the stability and reactivity of downstream intermediates. In our present computational study, we examine th…

Crowdfunding as a tool to support sustainability‐oriented initiatives: Preliminary insights into the role of product/service attributes

2019

A common goal of current research seems to uncover whether crowdfunding (CF) could be considered an effective way to support sustainability-oriented initiatives in securing funding, due to diverging results emerging from literature. We claim that the objective of proving whether CF may benefit sustainability-oriented initiatives could be misplaced; rather, we deem more fruitful to understand how critical are some attributes of products/services pursued within CF campaigns to benefiting sustainability-oriented initiatives and increasing their odds of success in CF. We focus on food-related projects as in this sector, sustainability issues apply more than to any other human activities and con…

Differential Effects of Two Contemplative Practice-based Programs for Health Care Professionals

2019

The aim of the study was testing the differential effectiveness of two interventions to improve Majorcan primary care professionals' quality of life: Mindful-Based Stress Reduction Training (MBSRT) and Compassion Cultivation Training (CCT). 50 professionals participated in the study; 81% were women. We evaluated mindfulness, empathy, self-compassion, and professional quality of life. Results showed statistically significant effects of the programs on the improvement of mindfulness, self-compassion, and professional quality of life, and differential effects on two dimensions of mindfulness, acting with awareness and non-reacting to inner experience, and on the dimension of burnout of the pro…

Biological and metodological bases of muscular stretching

2008

Selective hydrogenation of 2-methyl-butyn-2-ol on Pd catalysts

2013

A new mechanism for internal nucleophilic substitution reactions

2018

A new mechanism for the classic internal nucleophilic substitution reactions SNi by means of computational studies in the gas-phase, DCM and acetonitrile is reported. Despite the importance of the SNi mechanism, since the mid-1990s this mechanism has remained unexplored. This study focused mainly on the comparison between the mechanisms postulated to date for the SNi reactions and a new mechanism suggested by us that fits better the experimental observations. This comparative study has been applied to the conversion of ethyl, neopentyl, isopropyl and tert-butyl chlorosulfites into the corresponding alkyl chlorides. This new mechanism occurs through two transition structures. For primary and…

Interacción de procesos geomórficos y distribución de componentes de la superficie del suelo en relación a la evolución de los abarrancamientos de Ta…

2009

Este artículo se ha desarrollado en el contexto de los proyectos: REN2003-045707GLO(PECOS); CGL2007-63258/BOS(PREVEA) y CGL2006-11619(PROBASE), financiados por la CICYT en el marco del Plan Nacional I+D+I