Sandra A. Hernández

• Universidad Nacional del Sur

The extraction of sweet almond oil at room temperature and reflux is an easy and accessible procedure to obtain natural oil in a laboratory scale for undergraduates' courses in chemistry and related areas. In this paper we show how the utilization of Fourier Transform Infrared (FTIR) spectroscopy can be interesting in the qualitative analysis of th...

The extraction of sweet almond oil at room temperature and reflux is an easy and accessible procedure to obtain natural oil in a laboratory scale for undergraduates' courses in chemistry and related areas. In this paper we show how the utilization of Fourier Transform Infrared (FTIR) spectroscopy can be interesting in the qualitative analysis of th...

The substituent steric and electronic effects on mesophase stability and glass-forming properties of a series of 1,4-bis-(4-n-alkyloxybenzoyloxy)-2-N-(p-Y-aryl)azomethinebenzenes were evaluated. The diesters showed a typical though mild dependence of the monotropic nematic–isotropic transition temperatures on the substituent size that was attribute...

Summary The synthesis and thermotropic behavior are reported for a series of polyesters, 1, and its model compounds, 2, which bear a N-arylazomethine pendant group with para-substituents in order to evaluate electronic and steric effects on mesophase stability of segmented LCP with Y-shaped mesogens. Substituent effects on these polymer series and...

Although the bis-sulfonium salt precursor route is one of the most versatile procedures available for the synthesis of conjugated polymers, little effort has been made to explore the scope of this polymerization reaction. In this study, a series of bis-sulfonium salts were synthesized and in order to assess their polymerizability, isotopic exchange...

The thermal conversion of dialkylsulfonium polyelectrolyte precursor polymers 1b−e to poly(p-arylene vinylene)s was studied by direct pyrolysis mass spectrometry in order to elucidate the mechanism of the sulfonium elimination reaction. The temperature dependence of the single ion currents of the four more abundant volatile products was correlated...

Two series of diesters with bend-rod shapes were synthesized and their thermal properties characterized by POM and DSC. The central group conformational mobility and polarity as well as the length of the mesogenic groups were varied in order to correlate these parameters with mesophase stability. Results indicate that series II diesters are enantio...

A series of arylene vinylene copolymers containing either unsubstituted or phenyl-monosubstituted arylene units and 2,5-dialkoxy-1,4-phenylene units was prepared from water soluble, sulfonium salt precursor polymers. Doping of the polymer films with iodine vapor led to faster increases in conductivity for the phenyl-substituted copolymers compared...

Three-dimensional molecular models are powerful tools used in basic courses of general and organic chemistry when the students must visualize the spatial distributions of atoms in molecules and relate them to the physical and chemical properties of such molecules. This article discusses inexpensive, easily carried, and semipermanent molecular model...