Indium-mediated reaction of nitroethane and aldehydes: characterization of the nucleophilic organoindium species

A novel method for the preparation of 2-nitroalkan-1-ols by an indium-promoted reaction of bromonitromethane and 2-bromonitropropane with a variety of aldehydes was recently reported. Extension of the procedure to 1-bromo-1-nitroethane, which gives rise to a new chiral centre, was considered. On the basis of the diastereoselectivity of the nitroalkanols formed and NMR studies on the reaction mixtures, a mechanistic proposal for the indium-promoted reaction of bromonitroalkanes and aldehydes is discussed. The proposed mechanism allows the prediction of the stereochemical outcome of the present reaction.     

Fibrant extensions of free G-spaces

We show that any equivariant fibrant extension of a compact free G-space is also free. This result allows us to prove that the orbit space of any equivariant fibrant compact space E is also fibrant, provided that E has only one orbit type.     

Indium-mediated allylation and Reformatsky reaction on glyoxylic oximes under ultrasound irradiation

A novel and more convenient method for the indium-promoted allylation of glyoxylic oximes based on the use of ultrasonic waves is reported. A similar procedure was used to develop the first example reported in the literature of an indium-mediated Reformatsky reaction on oxime ethers.     

Structures of d4 MH3X: a computational study of the influence of the metal and the ligands

Density functional theory (DFT, PBE0, and range separated DFT, RSH + MP2) and coupled-cluster with single and double and perturbative triple excitations (CCSD(T)) calculations have been used to probe the structural preference of d(4) MH(3)X(q) (M = Ru, Os, Rh(+), Ir(+), and Re(-); X = H, F, CH(3), CF(3), SiH(3), and SiF(3)) and of MX(4) (M = Ru; X = H, F, CH(3), CF(3), SiH(3), and SiF(3)). Landis et al. have shown that complexes in which the metal is sd(3) hybridized have tetrahedral and non-tetrahedral structures with shapes of an umbrella or a 4-legged piano stool. In this article, the influence of the metal and ligands on the energies of the three isomeric structures of d(4) MH(3)X and MX(4) is established and rationalized. Fluoride and alkyl ligands stabilize the tetrahedral relative to non-tetrahedral structures while hydride and silyl ligands stabilize the non-tetrahedral structures. For given ligands and charge, 4d metal favors more the non-tetrahedral structures than 5d metals. A positive charge increases the preference for the non-tetrahedral structures while a negative charge increases the preference for the tetrahedral structure. The factors that determine these energy patterns are discussed by means of a molecular orbital analysis, based on Extended Hückel (EHT) calculations, and by means of Natural Bond Orbital (NBO) analyses of charges and resonance structures (NRT analysis). These analyses show the presence of through-space interactions in the non-tetrahedral structures that can be sufficiently stabilizing, for specific metals and ligands, to stabilize the non-tetrahedral structures relative to the tetrahedral isomer.     

Dynamic phase profile of phase objects based in the use of a quasi-common path interferometer

In this paper, we propose a quasi common-path interferometer based on a two beams configuration (TBC) using simultaneous phase shifting interferometry modulated by polarization that shows insensitivity against external vibration. Due to the fact that the configuration is capable of obtaining two beams whose separation can be varied, according to the characteristics of the grid used, to obtain the interference patterns. It can be used to implement a quasi-common path interferometer that allows the measurement of dynamic events with high accuracy. For demodulate the fringe patterns generated by the optical system we using the conventional four step phase shifting method. Experimental results are also given.     

6‐Deoxyhexoses from l‐Rhamnose in the Search for Inducers of the Rhamnose Operon: Synergy of Chemistry and Biotechnology

In the search for alternative non‐metabolizable inducers in the l ‐rhamnose promoter system, the synthesis of fifteen 6‐deoxyhexoses from l ‐rhamnose demonstrates the value of synergy between biotechnology and chemistry. The readily available 2,3‐acetonide of rhamnonolactone allows inversion of configuration at C4 and/or C5 of rhamnose to give 6‐deoxy‐d ‐allose, 6‐deoxy‐d ‐gulose and 6‐deoxy‐l ‐talose. Highly crystalline 3,5‐benzylidene rhamnonolactone gives easy access to l ‐quinovose (6‐deoxy‐l ‐glucose), l ‐olivose and rhamnose analogue with C2 azido, amino and acetamido substituents. Electrophilic fluorination of rhamnal gives a mixture of 2‐deoxy‐2‐fluoro‐l ‐rhamnose and 2‐deoxy‐2‐fluoro‐l ‐quinovose. Biotechnology provides access to 6‐deoxy‐l ‐altrose and 1‐deoxy‐l ‐fructose.     

Rubbery wound closure adhesives. II. initiators for and initiation of 2‐octyl cyanoacrylate polymerization

The polymerization of 2‐octyl cyanoacrylate (OctCA) initiated by five N‐bases [N,N‐dimethyl‐p‐toluidine (DMT), pyridine (Pyr), triethyl amine (Et₃N), azobicyclo[2.2.2]octane (ABCO), and diazobicylo[2.2.2]octane (DABCO)] was investigated. Our main objective was to assess the suitability and relative reactivity of these initiators for neat OctCA polymerization as wound closure adhesives. Methodologies were developed to determine stir‐stop and set times of OctCA polymerization and to use these quantities to assess initiation reactivity. According to these studies Et₃N, ABCO, DABCO, and Pyr are most reactive initiators, while DMT is much less reactive. Polymerizations were much faster in the presence of small amounts of tetrahydrofuran than toluene, indicating solvent polarity effects. Initiator reactivity is discussed in terms of structural parameters. NMR and MALDI‐TOF analyses of low molecular weight P(OctCA) prepared with DMT did not show evidence for the expected aromatic head group proposed by earlier investigators, which suggests complex initiation mechanism. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1652–1659     

Breathable rubbery skin protectors: Design,synthesis, characterization,and properties of cyanoacrylated silicone rubber networks

We extended our investigations of rubbery wound closure adhesives and created novel flexible networks by crosslinking cyanoacrylated silicone rubbers (i.e., commercial methylhydrosiloxane‐dimethylsiloxane copolymers, PMHS‐co‐PDMS) with N,N‐dimethyl‐p‐toluidine in tetrahydrofuran and hexamethyldisiloxane solvents at room temperature. Cyanoacrylation was achieved by hydrosilating (anthracene‐protected) allyl cyanoacrylate with PMHS‐co‐PDMS. Steric hindrance and the molecular weight of the copolymer strongly affect the extent of hydrosilation. The rate of crosslinking is proportional with the number of cyanoacrylate groups in the copolymer and networks form in seconds with appropriate amounts of initiator. Networks on porcine skin yield well‐adhering flexible optically‐transparent colorless conformal coatings of good “feel” appropriate for clinically useful non‐occlusive “breathable” skin or wound protectors. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1367‐1372     

Fracture detection by grating moiré and in-plane ESPI techniques

Optical interferometry techniques have been used for high-precision displacement measuring. Commonly, in-plane sensitive arrangements use two symmetrical collimated wavefronts for object surface illumination. However, this is a limitation when large object surface, has to be analyzed. In this case spherical illumination is needed. As a consequence of using non-collimated symmetrical dual-beams the sensitivity vector varies with the local position on the surface target. Then, this kind of illumination is also capable of detecting a lightly and systematic out-of-plane component of deformation. In this paper a theoretical analysis of the sensitivity vector components behavior is made. Each component of the sensitivity vector to minimize the required displacement component uncertainty is calculated. This study is important in the stage of planning any interferometric measurement experiment, particularly, for moiré grating interferometric technique, which has been used only in collimated illumination. By using a spherical dual-beam optical setup, the present work shows results of fracture measuring by using moiré and speckle interferometric methods. As a result, advantages and disadvantages of both techniques are discussed and an accuracy study is reported.