To develop reliable models for the densities and viscosities of biodiesel fuel, reliable data for the pure fatty acid esters are required. Densities and viscosities were measured for seven ethyl esters and eight methyl esters, at atmospheric pressure and temperatures from (273.15 to 363.15) K. A critical assessment of the measured data against the data previously available in the literature was carried out. It is shown that the data here reported presents deviations of less than 0.15 % for densities and less than 5 % for viscosities. Correlations for the densities and viscosities with temperature are proposed. The densities and viscosities of the pure ethyl and methyl esters here reported were used to evaluate three predictive models. The GCVOL group contribution method is shown to be able to predict densities for these compounds within 1 %. The methods of Ceriani and Meirelles (CM) and of Marreiro and Gani (MG) were applied to the viscosity data. It is shown that only the first of these methods is able to provide a fair description of the viscosities of fatty acid esters.

Density is an important biodiesel parameter, with impact on fuel quality. Predicting density is of high relevance for a correct formulation of an adequate blend of raw materials that optimize the cost of biodiesel fuel production while allowing the produced fuel to meet the required quality standards. The aim of this work is to present new density data for different biodiesels and use the reported data to evaluate the predictive capability of models previously proposed to predict biodiesel or fatty acid methyl ester densities. Densities were measured here for 10 biodiesel samples, for which detailed composition is reported, at atmospheric pressure and temperatures from 278.15 to 373.15 K. Density dependence with temperature correlations was proposed for the biodiesels, and isobaric expansivities are presented. The new experimental data presented here were used along with other literature data to evaluate predictive density models, such as those based on Kay’s mixing rules and the GCVOL group contribution method. It is shown that Kay’s mixing rules and a revised form of the GCVOL model are able to predict biodiesel densities with average deviations of only 0.3%. A comparison between biodiesel densities produced from similar vegetable oils, by different authors, highlights the importance of knowing the detailed composition of the samples. An extension of GCVOL for high pressures is also proposed here. It is shown that it can predict the densities of biodiesel fuels with average deviations less than 0.4%.

Biodiesels have several known components in their composition. The majority of components is well described in the literature, but a minority of components are poorly characterized. These are however required to develop reliable models to predict the biodiesel behavior. This work considers minor components of biodiesel: the polyunsaturated compounds (in C18), the monounsaturated (in C16, C20, and C22), and the long-chain saturated esters. In this work, densities and viscosities of pure fatty acid ester minor components of biodiesel fuel were measured (three ethyl esters and seven methyl esters), at atmospheric pressure and temperatures from (273.15 to 373.15) K. Correlations for the densities and viscosities with temperature are proposed. Three predictive models were evaluated in the prediction of densities and viscosities of the pure ethyl and methyl esters here reported. The GCVOL group contribution method is shown to be able to predict densities for these compounds within 1.5 %. The methods of Ceriani et al. (CM) and of Marrero et al. (MG) were applied to the viscosity data. The first show a better predictive capacity to provide a fair description of the viscosities of the minority esters here studied.

The synthesis and structural characterisation of some new derivatives of dehydroabietic acid, oxidised in the 6 and 7 positions of ring B, are described. Other known derivatives were exhaustively characterised for the Ðrst time and the previous NMR assignments for three compounds are corrected.

The synthesis of some new chalcone and pyrazole type derivatives of methyl dehydroabietate is described. All compounds were exhaustively characterized using NMR and MS techniques. In order to con®rm the information obtained by those techniques, the X-ray single crystal structures of methyl 12-acetyldehydroabietate and methyl 12-(4-methoxycinnamoyl)-dehydroabietate were determined. Molecular mechanics calculations were performed in order to evaluate the steric in¯uence of the bulk of the C-12 substituent on the conformational preference of the isopropyl group in these derivatives. The energy barriers of 52.3 and 53.6 kJ/mol found for the two compounds indicated that the C-12 substituent hinders the free rotation of the isopropyl group in both cases.

No abstract

Os desastres naturais são eventos que podem afetar fortemente o ambiente natural e antropogénico, excedendo a capacidade de autorrecuperação da comunidade local, e que geralmente apresentam consequências trágicas, com perdas de vidas humanas, prejuízos socioeconómicos e impactes ambientais consideráveis. Assim, para prevenir e minimizar estes impactes negativos vários estudos e projetos têm sido desenvolvidos, promovendo uma educação para um desenvolvimento sustentável, contribuindo para a formação de comunidades mais resilientes e com um baixo nível de vulnerabilidade. Este trabalho baseou-se na realização de um inquérito para avaliar o nível de conhecimento dos estudantes no ensino superior sobre procedimentos gerais em caso de emergência, e no caso específico de ocorrência de um sismo, envolvendo 2035 estudantes do Instituto Politécnico de Leiria (IPLeiria) em cursos de diferentes áreas. Os dados obtidos revelaram que a maioria dos estudantes conhece o número nacional de emergência, sabe identificar as zonas de concentração, contudo apenas 25% demonstra saber como reagir corretamente em caso de sismo. Os resultados são importantes para desenvolver novas estratégias, para a redução da vulnerabilidade das comunidades, promovendo a compreensão do seu papel na redução do risco dos desastres naturais, e a interação e pertinência da proteção ambiental e fortalecimento dos ecossistemas para alcançar este objetivo.

Terpenes U 0200 Synthesis of Flavonoid-Type Compounds from Methyl Dehydroabietates (I) -[via a sequence of formylation, aldol condensation and cyclodehydrogenation reactions]. -(MONTEIRO, S. M. C. S.; SILVESTRE, A. J. D.; SILVA, A. M. S.; CAVALEIRO*, J. A. S.; Monatsh. Chem. 139 (2008) 9, 1119-1126; Dep. Chem., Univ. Aveiro, P-3810 Aveiro, Port.; Eng.) -H. Haber 51-175