Characterization of the raw essential oil eugenol extracted from <Emphasis Type="Italic">Syzygium</Emphasis> <Emphasis Type="Italic">aromaticum</Emphasis> L.

Eugenol is the main volatile compound extracted oil from clove bud, Syzygium aromaticum L., and used in traditional medicine, as a bactericide, fungicide, anesthetic, and others. Its extraction was performed using hydrodistillation which is the most common extraction technique. Its components and thermal behavior were evaluated using gas chromatography (GC) and differential scanning calorimetry (DSC), which provide a better characterization of these natural compounds. This extracted product was compared to the standard eugenol results. The GC results suggested ~90% eugenol was found in the total extracted oil, and some of its boiling characteristics were 270.1 °C for peak temperature and 244.1 J g⁻¹ for the enthalpy variation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Thermal behavior and structural properites of plant-derived eugenyl acetate

Eugenol is an allyl chain-substituted guaiacol in the biosynthesized phenylpropanoid compound class derived from Syzygium aromaticum L. and widely used in folk medicine. Nonetheless, its pharmacological use is limited by some problems, such as instability when exposed to light and high temperature. In order to enhance stability, the eugenol molecule was structurally modified, resulting in eugenyl acetate. The eugenyl acetate’s thermal behavior and crystal structure was then characterized by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) and compared to a commercial sample.     

Spectrophotometric study of complex formation equilibria of Ni(II) ion with benzyl-, phenyl- and dibutyldithiocarbamates

Complex formation equilibria between Ni(II) with benzyldithiocarbamate, phenyldithiocarbamate and dibutyldithiocarbamate have been studied spectrophotometrically at (25±0.1)°C in 0.1M diethanolamine/diethanolamonium ionic strength and pH 8.8 that prevents ligand decomposition, frequent in acid medium. The stability constants and molar absorptivity coefficients have been evaluated for the three complex species obtained in each case.     

Influence of different extraction methods on the yield and linalool content of the extracts of Eugenia uniflora L

This work has been developed using a sylvestral fruit tree, native to the Brazilian forest, the Eugenia uniflora L., one of the Mirtaceae family. The main goal of the analytical study was focused on extraction methods themselves. The method development pointed to the Clevenger extraction as the best yield in relation to SFE and Soxhlet. The SFE method presented a good yield but showed a big amount of components in the final extract, demonstrating low selectivity. The essential oil extracted was analyzed by GC/FID showing a large range of polarity and boiling point compounds, where linalool, a widely used compound, was identified. Furthermore, an analytical solid phase extraction method was used to clean it up and obtain separated classes of compounds that were fractionated and studied by GC/FID and GC/MS.     

Gamma radiation effects on mechanical properties and morphology of a polyurethane derivate from castor oil

In this study, an adhesive of a polyurethane derivate from castor oil was irradiated with gamma radiation from a ⁶⁰Co source, at doses from 0.2 to 25 kGy. This adhesive polyurethane is considered for use in hospital furniture because it does not liberate dangerous solvents. Hardness and elastic modulus were measured by instrumented indentation with a pyramidal Berkovich indenter, using loads from 0.08–40 mN with a nanoindenter XP. The instrumented indentation hardness was 110 MPa for an untreated sample, increasing to 124 MPa after irradiation with 25 kGy, at penetration depths of about 5 μm. The increases in elastic modulus induced by radiation were less pronounced. This polyurethane is naturally cross-linked and the relative modifications in the hardness are attributed to an additional cross-linking process induced by radiation. X-ray diffraction indicates a slight increase in crystallinity. The roughness measured by atomic force microscopy increases after gamma irradiation.     

Analytical data: Potentiometric study of the association constant of isothiocyanic acid

The association constant of isothiocyanic acid, HNCS, has been determined potentiometrically and found to be 0.135 +/- 0.007 and 0.168 +/- 0.007 at ionic strengths (NaClO(4)) of 2.0 and 4.0M respectively. The indicator electrode was Hg(SCN)(2-)(4)/Hg. For accuracy and precision the metal phase was used in the form of a dropping electrode. Because the association constant is so low, liquid-junction potentials would cause significant errors, since a strong acid was added to the working solutions in the procedure, and an estimate of this effect was taken into account.     

The stepwise formation of complexes in the uranyl/azide system in aqueous medium

The use of an indirect potentiometric method with the glass electrode in a ₃?/HN₃/UO₂2+ solution leads to ligand number $\text{n}\text{?}$, at several azide concentrations, at 2.0M ionic strength (NaClO₄), aqueous medium and 25.0±0.1°C. The analysis of data under conditions where hydrolysis is avoided leads to the six overall stepwise constants: β₁ = 1.39 × 10²M^?1; β₂ = 8.26 × 10³M^?2; β₃ = 4.9 × 10⁵M^?3; β₄ = 7.1 × 10⁵M^?4; β₅ = 2.3 × 10⁶M^?5; β₆ = 1.2 × 10⁷M^?6.     

Elimination of the copper-zinc interference in anodic stripping voltammetry by addition of a complexing agent

The addition of cyanide and Triton X-100 suppress the formation of the CuZn intermetallic compound in ASV making it possible to determine traces of zinc(II) in the presence of an excess of copper ions. The precision of the method (5%) and the accuracy (error of 1.4%) in sea water are satisfactory.     

Correlation between i.r. spectra and thermal decomposition of cobalt(II), nickel(II), copper(II) and mercury(II) complexes with piperidinedithiocarbamate and pyrrolidinedithiocarbamate

The thermal decomposition of pyrrolidinedithiocarbamate and piperidinedithiocarbamate complexes of Co^II, Ni^II, Cu^II and Hg^II have been studied by thermogravimetry and differential scanning calorimetry. The decomposition intermediates and final products were identified by their X-ray diffraction patterns. The i.r. spectra are discussed in terms of the thermal decomposition pathways.     

Crystal Structure Determination for Eugenyl Acetate

Abstract  Essential oils are good candidates for the substitution of conventional medicinal treatments. Many articles and patents for their use have been published in recent years. The most attractive aspects of using essential oils as medicaments are their natural source and rapid permeability. Besides permeability, the solubility behavior of a drug is a key determinant of its oral bioavailability. Based on these characteristics, the aim of this study was to synthesize an essential oil derivative compound, using the raw oil extracted from Syzygium aromaticum L., without previous purification. The Eugenol molecular modification may diminish the problems of water solubility and bioavailability. The Eugenyl acetate molecule was characterized and its molecular modification investigated, including its structural properties and stereochemistry. This study was performed applying techniques, such as carbon-13 nuclear magnetic resonance spectroscopy (C-13 NMR), X-ray crystallographic analysis (XRD), powder X-ray diffraction (PXRD) and microscopic recording. Graphical Abstract  Eugenol and its structure have been known for many years, where as Eugenyl acetate’s structure has never been elucidated nor confirmed until now.