Crystal structure of the monoglycidyl ether of isoeugenol.

The title compound, C13H16O3 [GE-isoEu; systematic name: 2-({2-meth-oxy-4-[(E)-1-propen-1-yl]phen-oxy}meth-yl)oxirane], which crystallizes in the triclinic P space group, was synthesized in one step from iso-eugenol, a bio-based phenyl-propanoid, with an excess of epi-chloro-hydrin. Colourless prismatic crystals suitable for X-ray diffraction were obtained from a mixture of ethyl acetate and cyclo-hexane, during purification by column chromatography on silica gel. GE-isoEu, which corresponds to the trans isomer of the monoglycidyl ether of iso-eugenol, is based on a 1,2,4-tris-ubstituted benzene ring by diglycidyl ether, meth-oxy and 1-(E)-propenyl groups, respectively. In the crystal, mol-ecules are organized through offset π-stacking inter-actions. Chemically, GE-isoEu constitutes an inter-mediate in the synthesis protocol of 2-[3-meth-oxy-4-(2-oxiranylmeth-oxy)phen-yl]-3-methyl-oxirane (GEEp-isoEu), a di-epoxy-dized monomer used in the manufacturing of thermosetting resins and intended for the elaboration of bio-composites.

New Eco-Friendly Synthesized Thermosets from Isoeugenol-Based Epoxy Resins.

Epoxy resin plays a key role in composite matrices and DGEBA is the major precursor used. With the aim of favouring the use of bio resources, epoxy resins can be prepared from lignin. In particular, diglycidyl ether of isoeugenol derivatives are good candidates for the replacement of DGEBA. This article presents an effective and eco-friendly way to prepare epoxy resin derived from isoeugenol (BioIgenox), making its upscale possible. BioIgenox has been totally characterized by NMR, FTIR, MS and elemental analyses. Curing of BioIgenox and camphoric anhydride with varying epoxide function/anhydride molar ratios has allowed determining an optimum ratio near 1/0.9 based on DMA and DSC analyses and swelling behaviours. This thermoset exhibits a Tg measured by DMA of 165 °C, a tensile storage modulus at 40 °C of 2.2 GPa and mean 3-point bending stiffness, strength and strain at failure of 3.2 GPa, 120 MPa and 6.6%, respectively. Transposed to BioIgenox/hexahydrophtalic anhydride, this optimized formulation gives a thermoset with a Tg determined by DMA of 140 °C and a storage modulus at 40 °C of 2.6 GPa. The thermal and mechanical properties of these two thermosets are consistent with their use as matrices for structural or semi-structural composites.

Crystal structure of the diglycidyl ether of eugenol.

The diep-oxy monomer, C13H16O4 {DGE-Eu; systematic name: 2-[3-meth-oxy-4-(oxiran-2-ylmeth-oxy)benz-yl]oxirane}, was synthesized from eugenol by a three-step reaction. It consists of a 1,2,4-tris-ubstituted benzene ring substituted by diglycidyl ether, a meth-oxy group and a methyl-oxirane group. The three-membered oxirane rings are inclined to the benzene ring by 61.0 (3) and 27.9 (3)°. The methyl-ene C atom of one of the two terminal epoxide rings is positionally disordered [refined occupancy ratio = 0.69 (1):0.31 (1)]. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds, forming layers parallel to the ab plane. The layers are linked by C-H⋯π inter-actions, forming a three-dimensional network.

ß-Aminobutyric acid (BABA)-induced resistance in Arabidopsis thaliana: link with iron homeostasis.

ß-Aminobutyric acid (BABA) is a nonprotein amino acid inducing resistance in many different plant species against a wide range of abiotic and biotic stresses. Nevertheless, how BABA primes plant natural defense reactions remains poorly understood. Based on its structure, we hypothesized and confirmed that BABA is able to chelate iron (Fe) in vitro. In vivo, we showed that it led to a transient Fe deficiency response in Arabidopsis thaliana plants exemplified by a reduction of ferritin accumulation and disturbances in the expression of genes related to Fe homeostasis. This response was not correlated to changes in Fe concentrations, suggesting that BABA affects the availability or the distribution of Fe rather than its assimilation. The phenotype of BABA-treated plants was similar to those of plants cultivated in Fe-deficient conditions. A metabolomic analysis indicated that both BABA and Fe deficiency induced the accumulation of common metabolites, including p-coumaroylagmatine, a metabolite previously shown to be synthesized in several plant species facing pathogen attack. Finally, we showed that the protective effect induced by BABA against Botrytis cinerea was mimicked by Fe deficiency. In conclusion, the Fe deficiency response caused by BABA could bring the plant to a defense-ready state, participating in the plant resistance against the pathogens.

1-n-Butyl-3-methylimidazolium-2-carboxylate: a versatile precatalyst for the ring-opening polymerization of ε-caprolactone and rac-lactide under solvent-free conditions.

The ring-opening polymerization of ε-caprolactone (ε-CL) and rac-lactide (rac-LA) under solvent-free conditions and using 1-n-butyl-3-methylimidazolium-2-carboxylate (BMIM-2-CO2) as precatalyst is described. Linear and star-branched polyesters were synthesized by successive use of benzyl alcohol, ethylene glycol, glycerol and pentaerythritol as initiator alcohols, and the products were fully characterized by (1)H and (13)C{(1)H} NMR spectroscopy, gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). BMIM-2-CO2 acts as an N-heterocyclic carbene precursor, resulting from in situ decarboxylation, either by heating under vacuo (method A) or by addition of NaBPh4 (method B). Possible catalytic and deactivation mechanisms are proposed.

Tantalum-Gold and Tantalum-Copper Trihydride Complexes [Cp'(2)TaH(3)MPPh(3)][PF(6)] (Cp' = C(5)H(4)C(CH(3))(3)). Structure Determination from (1)H T(1) Relaxation Studies.

The reaction of Cp'(2)TaH(3) (Cp' = C(5)H(4)C(CH(3))(3)) with [MPPh(3)][PF(6)] yields the bimetallic complexes [Cp'(2)TaH(3)MPPh(3)][PF(6)] (M = Au (1),M = Cu (2)). The detailed NMR study of 1 and 2 showed the structure with two bridging hydride ligands. The mutual orientation of the Cp' rings has been determined by NOE experiments. The variable-temperature NMR data showed an intramolecular exchange between two outer hydride ligands. The exchange is faster in 1 (DeltaG()(210 K) = 9.3 kcal/mol) than in 2 (DeltaH() = 8.6 +/- 0.2 kcal/mol, DeltaS() = - 5.0 +/- 0.4 eu, DeltaG() (210 K) = 9.6 +/- 0.2 kcal/mol). In contrast, complex 2 undergoes the faster intermolecular PPh(3)/PPh(3) exchange. It has been demonstrated that T(1min), T(1), T(1sel) and T(1bis) measurements are a powerful instrument for quantitative localization of the hydride ligands in solutions of bimetallic complexes. The determined hydride-hydride and metal-hydride distances reproduce well the structural tendencies in the related niobium trihydride [{Nb(C(5)H(3)RR')(2)H(3)}(2)Au][PF(6)] (R = R' = Si(CH(3))(3)) established by the X-ray method. Tantalum-gold complex 1 showed weak exchange couplings.