Eduardo Miguez

Characterization of amide bond conformers for a novel heterocyclic template of N-acylhydrazone derivatives.

Herein we describe NMR experiments and structural modifications of 4-methyl-2-phenylpyrimidine-N-acylhydrazone compounds (aryl-NAH) in order to discover if duplication of some signals in their 1H- and 13C-NMR spectra was related to a mixture of imine double bond stereoisomers (E/Z) or CO-NH bond conformers (syn and anti-periplanar). NMR data from NOEdiff, 2D-NOESY and 1H-NMR spectra at different temperatures, and also the synthesis of isopropylidene hydrazone revealed the nature of duplicated signals of a 4-methyl-2-phenylpyrimidine-N-acylhydrazone derivative as a mixture of two conformers in solution. Further we investigated the stereoelectronic influence of substituents at the ortho position on the pyrimidine ring with respect to the carbonyl group, as well as the electronic effects of pyrimidine by changing it to phenyl. The conformer equilibrium was attributed to the decoplanarization of the aromatic ring and carbonyl group (generated by an ortho-alkyl group) and/or the electron withdrawing character of the pyrimidine ring. Both effects increased the rotational barrier of the C-N amide bond, as verified by the ΔG≠ values calculated from dynamic NMR. As far as we know, it is the first description of aryl-NAH compounds presenting two CO-NH bond- related conformations.

Discovery of Novel Orally Active Anti-Inflammatory N-Phenylpyrazolyl-N-Glycinyl-Hydrazone Derivatives That Inhibit TNF-α Production

Herein, we describe the synthesis and pharmacological evaluation of novel N-phenylpyrazolyl-N-glycinyl-hydrazone derivatives that were designed as novel prototypes of p38 mitogen-activated protein kinase (MAPK) inhibitors. All of the novel synthesized compounds described in this study were evaluated for their in vitro capacity to inhibit tumor necrosis factor α (TNF-α production in cultured macrophages) and in vitro MAPK p38α inhibition. The two most active anti-TNF-α derivatives, (E)-2-(3-tert-butyl-1-phenyl-1H-pyrazol-5-ylamino)-N’-((4-(2-morpholinoethoxy)naphthalen-1-yl)methylene)acetohydrazide (4a) and (E)-2-(3-tert-butyl-1-phenyl-1H-pyrazol-5-ylamino)-N’-(4-chlorobenzylidene)acetohydrazide (4f), were evaluated to determine their in vivo anti-hyperalgesic profiles in carrageenan-induced thermal hypernociception model in rats. Both compounds showed anti-inflammatory and antinociceptive properties comparable to SB-203580 used as a standard drug, by oral route at a dose of 100 µmol/kg. This bioprofile is correlated with the ability of NAH derivatives (4a) and (4f) suppressing TNF-α levels in vivo by 57.3 and 55.8%, respectively.

Caracterização do Sistema Éter Diglicidílico do Bisfenol A/Poliaminas Alifáticas

Diglycidyl ether of the bisphenol A (DGEBA), product DER 331 and hardener 24 system marketed by Chemical Dow of Brazil were characterized by spectroscopic, calorimetric and determination of functional groups methods. The hardener 24 is constituted by triethylenetetramine (60 % molar) and a mixture of ethylene polyfunctional amines with linear, ramified and cyclic structures. The epoxy equivalent of the resin corresponds to 187 g eq -1 . The functionality average, equivalent amine, and the concentration of the hardener that satisfy the stoichiometry corresponds to 5.54, 27.5 g eq -1 , and 14.7 phr, respectively. The epoxy system displayed an enthalpy of reaction of 486 J g -1 (106.6 kJ eq -1 ), and a glass transition temperature (Tg ¥ ) of 124 °C. Also presented in this work is a cure program in two stages where the maximum conversion was reached.

Evaluation of Composites Miscibility by Low Field NMR

Solid state nuclear magnetic resonance (NMR) is a powerful technique to analyze polymer composites. The use of proton relaxation data to evaluate the dispersity of the dispersion phase in the composite and its homogeneity are very wide. In this work PVC/silica composites were prepared using different ratios to obtain a new material to be used in chromatograph column for separation of plant extracts. Thus, this study used proton spin–lattice and spin-spin nuclear magnetic resonance relaxation data, determined in a low field NMR spectrometer as a method to characterize those composites in relation to silica dispersion as well as PVC/silica compatibility. From the relaxation data analyses, the best ratio of PVC/silica, according to the components dispersion and consequently composite compatibility, was 80/20, according to the determined T1 values.

Syn or anti Selective Michael addition of allyl phenyl sulphone and phenyl prenyl sulphone to enoates derived from D-mannitol

Abstract Prenyl and allyl sulphones (3a,b) were deprotonated with BuLi in THF and the resulting carbanions were allowed to react with enoates prepared from D-(+)-mannitol. A major diastereomer (control at the two newly created stereogenic centers) was obtained from enoates E-1b-c (Ethyl and t-Butyl ester, respectively) in d.e. up to 90 %. Syn-stereoselectivities were observed when the reactions were stopped at r.t. while at −78° C anti-stereoselectivities predominated. Enoate E-1a (methyl ester) led to anti-addition regardless the temperature at which the reaction was quenched. However, a syn-stereoselectivity was found when the reaction was run in the presence of HMPA. The stereochemical assignments for both newly generated stereogenic centers were based on the transformation of the adducts into the corresponding β,γ-disubstituted γ-lactones, followed by measurements of 1H,1H coupling constants and nOe experiments.

Caracterización cualitativa de poliaminas libres en endurecedores de resinas epoxídicas del tipo etilenaminas por espectroscopia de resonancia magnética nuclear

The qualitative characterization of two commercial ethyneamines epoxide hardeners marketed by ACROS (U.S.A.) was carried out by using carbon-13 nuclear magnetic resonance spectroscopy. The products were triethylenetetramine (TETA) and tetraethylenepentamine (TEPA). TETA had four components, the most importante one being triethylenetetramine, an ethyleneamine of lineal structure, in a concentration of 60 mol%. Another component had ramified structure, while the other two exhibited recurrent structures of the piperazina type. TEPA had five components with similar structures. The major component was tetraethylenepentamine in an approximate concentration of 55 mol%. These results agree with the composition of similar products marketed by Dow Chemical Company, namely DEH 24 and DEH 26, respectively.

NMR Assignment of Carbonyl and Olefinic Regions of Amescla Resin

The structural assignment of amescla resin was carried out using a methodology already established in a previous work published by Tavares and Silva. From the methodology, three structural fragments were determined, allowing us to conclude that this natural resin was polymerized from the double bond localized in the middle of the aliphatic chain.

Anisotropic and hydrogen bonding effects in phenylglyoxamides and mandelamides: theoretical and NMR conformational evaluation.

Interesting anisotropic effects were observed for phenylglyoxamides and their respective mandelamides. Such effects were observed in experimental 1H and 13C NMR (in CDCl3, CD3OD, and DMSO‐d6 solvents) and in some cases with good correlation to theoretical 1H and 13C NMR DFT–GIAO (B3LYP/6‐311 + + G**//B3LYP/6‐31G*) calculations. A systematic conformational analysis of these compounds was performed in a two‐step methodology, using PM3 and DFT (B3LYP/6‐31G*) calculations; with good accomplishment and computational time economy. It was observed that intramolecular hydrogen bonding plays a significant role in the conformation of such compounds. Finally, a geminal nonequivalence of an NCH2 moiety, in one of the alkyl side chain (R1 = R2), was found for the tertiary mandelamides studied. Copyright

Model of reverse logistics by means of a logistics operator

This study describes a reverse logistics model that can be used for the disposal of waste electrical and electronic equipment (WEEE) from small businesses, which includes its collection, dismantling, sorting, storage and destination by a logistics operator. The logistics operator will only collect WEEE after the minimum volume it stipulates has been accumulated, which has proved a barrier for small businesses. This could be solved by setting up an intermediate public or private management structure that would take over responsibility for the receipt, storage and transfer of the WEEE to the logistics operator in exchange for a fee. This business model brings social, environmental and economic benefits.