41 research outputs found
The Hydrolysis of 4-Amino- and 4-Dimethylaminobenzene Sulfonyl Chlorides: An Unprecedented Case of Independence of Reactivity from pH
No full textThe reactivity-pH profile for the hydrolysis of 4-aminobenzenesulfonyl chloride 1 has a sigmoid shape with a plateau extending from pH 2 to 11; reactivity of N,N-dimethyaminobenzenesulfonyl chloride 4 is invariant over an even wider pH range (0-14.7). These results, together with the activation data determined at selected pH's for compound 1, are interpreted in light of the occurrence of a reaction mechanism that is dissociative in nature, in which nucleophilic assistance by solvent molecules is given to the amino group of 1 acting as an "internal nucleophile"
Ionic Liquids Can Significantly Improve Textile Dyeing: An Innovative Application Assuring Economic and Environmental Benefits
No full textOwing to economic reasons, the textile dyeing industry generally employs traditional and absolutely no-eco-friendly processes: very large quantities of water are indeed required together with a large number of added chemicals which represent dramatic environmental issues. In order to improve the sustainability of the process, we have investigated the dyeing of wool, polyester, and cotton with disperse Red 13 using ionic liquids as the sole additive. The results obtained in isothermal dyeing at 95 C show an outstanding effect of the ionic liquid 1-(2-hydroxyethyl)-3-methylimidazolium chloride. This ionic liquid assures efficient dyeing of polyester and wool in open vessels, in the absence of whichever auxiliary agent with total dyebath exhaustion, thus allowing in principle the recycling of the dye bath! The environmental benefits arising from the substitution of a number of usually employed auxiliary agents with only an ionic liquid are highlighted together with the economic ones. This article reports for the first time, to the best of our knowledge, dyeing processes for several kinds of fibers (cotton, wool, and polyester) employing exclusively three components: pure disperse dye, water, and an appropriate ionic liquid. (Figure Presented)
ChemInform Abstract: Are Ionic Liquids a Proper Solution to Current Environmental Challenges?
No full textOn mooring line tension and fatigue prediction for offshore vertical axis wind turbines: A comparison of lumped mass and quasi-static approaches
No full textA general method for the enantiospecific synthesis of optically active aliphatic sulfenyl chlorides and thiophthalimides
No full textCyclic tetramers from 3,5-disubstituted 4-hydroxybenzenesulfonyl chlorides. A conformational study
No full textAna em Veneza: ex-cêntricos antimodernos
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão. Programa de Pós-Graduação em LiteraturaAna em Veneza (1994), romance escrito por João Silvério Trevisan, apresenta um conjunto bem vasto de características que apontam para o tempo e o texto de agora, como a intertextualidade, o discurso paródico e irônico, a fragmentação do sujeito, tempo e espaço, a presença dos "ex-cêntricos" e discussões acerca da modernidade. O que propomos é um estudo da modernidade a partir da ótica do pensador Walter Benjamin e seus interlocutores, como o italiano Giorgio Agamben. Nossa análise parte de premissas baseadas em uma leitura antimoderna, que se revela em forma de oposição à modernidade. O discurso de negação é construído, essencialmente, a partir do personagem Alberto Nepomuceno. Por fim, temos o intuito de armar um pequeno diálogo intertextual entre Ana em Veneza e a obra de Thomas Mann Morte em Veneza, atendo-nos principalmente aos personagens Alberto Nepomuceno e Gustav von Aschenbach.Ana em Veneza (1994), novel written by João Silvério Trevisan, presents a very broad set of characteristics that indicate the time and the text now, as intertextuality, parody and ironic speech, the fragmentation of the subject, time and space, the presence of "ex-centric", discussions of modernity. We propose a study of modernity from the perspective of philosopher Walter Benjamin and his interlocutors as the Italian Giorgio Agamben. Our analysis is based on assumptions based on an anti-modernist reading, which reveals itself in the form of opposition to modernity. The discourse of denial is built mainly from the character Alberto Nepomuceno. Finally, our aim is to set an intertextual dialogue between Ana em Veneza and work by Thomas Mann Death in Venice, sticking mainly to the characters Alberto Nepomuceno and Gustav von Aschenbach
Catalysis and inhibition of ester hydrolysis in the presence of resorcinarene hosts functionalized with dimethylamino groups
No full textComplexation and catalysis of two calixresorcinarene (RES) derivatives with nucleophilic N,N-dimethylamino functions attached to their upper rims in the hydrolysis of carboxylate and sulfonate esters of 4-nitrophenol and 2,4-dinitrophenol have been investigated. Rate constants obey the complexation equation: k(obs) = k(b) x K-s + k(c) [Host] / K-s + [Host] Values of the dissociation constant (K-s) of the complexes are within the range exhibited by other systems such as cyclodextrins-ester complexes. The reactions of sulfonate esters only exhibit inhibition by the macrocyclic hosts. The reactions of the carboxylate esters exhibit catalysis and inhibition depending on the pH of the system. It is proposed that the dimethylamino function in RES3 and RES5 behaves as a nucleophile to form a reactive acylammonium species which subsequently decomposes and regenerates the catalytic amine. In the reaction of substituted phenyl acetates with RES3 the effective charge on the leaving oxygen in the complexed state (+0.88) is slightly more positive than that in the free ester (+0.70). The effective charge on the leaving oxygen in the transition structure is substantially more positive (+0.04 units) than in a model intramolecular reaction of tertiary dimethylamines with aryl esters (-0.53 units). The influence of the host on the reaction in the complex includes an electronic component which is ascribed to solvation of the transition structure of the rate-limiting step by water molecules located within the cavity of the host. It is suggested that this solvation is stronger than that occurring in the transition state for the model intramolecular reaction
On the estimation of landslide intensity, hazard and density via data-driven models
No full textMaps that attempt to predict landslide occurrences have essentially stayed the same since 1972. In fact, most of the geo-scientific efforts have been dedicated to improve the landslide prediction ability with models that have largely increased their complexity but still have addressed the same binary classification task. In other words, even though the tools have certainly changed and improved in 50 years, the geomorphological community addressed and still mostly addresses landslide prediction via data-driven solutions by estimating whether a given slope is potentially stable or unstable. This concept corresponds to the landslide susceptibility, a paradigm that neglects how many landslides may trigger within a given slope, how large these landslides may be and what proportion of the given slope they may disrupt. The landslide intensity concept summarized how threatening a landslide or a population of landslide in a study area may be. Recently, landslide intensity has been spatially modeled as a function of how many landslides may occur per mapping unit, something, which has later been shown to closely correlate to the planimetric extent of landslides per mapping unit. In this work, we take this observation a step further, as we use the relation between landslide count and planimetric extent to generate maps that predict the aggregated size of landslides per slope, and the proportion of the slope they may affect. Our findings suggest that it may be time for the geoscientific community as a whole, to expand the research efforts beyond the use of susceptibility assessment, in favor of more informative analytical schemes. In fact, our results show that landslide susceptibility can be also reliably estimated (AUC of 0.92 and 0.91 for the goodness-of-fit and prediction skill, respectively) as part of a Log-Gaussian Cox Process model, from which the intensity expressed as count per unit (Pearson correlation coefficient of 0.91 and 0.90 for the goodness-of-fit and prediction skill, respectively) can also be derived and then converted into how large a landslide or several coalescing ones may become, once they trigger and propagate downhill. This chain of landslide intensity, hazard and density may lead to substantially improve decision-making processes related to landslide risk
The Hydrolysis of 4-Amino- and 4-Dimethylaminobenzene Sulfonyl Chlorides: An Unprecedented Case of Independence of Reactivity from pH
No full textThe reactivity−pH profile for the hydrolysis of 4-aminobenzenesulfonyl chloride 1 has a sigmoid shape with a plateau extending from pH 2 to 11; reactivity of N,N-dimethyaminobenzenesulfonyl chloride 4 is invariant over an even wider pH range (0−14.7). These results, together with the activation data determined at selected pH’s for compound 1, are interpreted in light of the occurrence of a reaction mechanism that is dissociative in nature, in which nucleophilic assistance by solvent molecules is given to the amino group of 1 acting as an “internal nucleophile”
