Retrosynthetic reactions in mass spectrometry. Deacylation of ortho phthalamic acids under electron impact

Ortho Phthalamic acids under electron impact show a retrosynthetic reaction leading to both phthalic anhydride and amine complementary ions, the corresponding neutrals of which are the usual synthetic precursors of the original compounds. The single case of a primary amine derivative is examined, which shows the formation of [M? H₂O]^+˙ ions having the structure of the related N-substituted imide, by a process which parallels a well known thermal reaction. It also gives the species [C₈H₆NO₂]⁺ (of the same nominal mass as phthalic anhydride), the structure of which is still under study. Ionic structures are supported by collision induced mass analyzed ion kinetic energy spectra.     

Cooperative nucleophilic-electrophilic organocatalysis by ionic liquids

The anionic and the cationic partners of ionic liquids may act cooperatively and independently as nucleophilic and electrophilic catalysts. This ambiphilic propensity was demonstrated by kinetically discriminating the contributions of the anion (nucleophilic catalyst) and of the cation (electrophilic catalyst) to the solvent-free Baylis-Hillman dimerization of cyclohexenone catalysed by ionic liquids.     

Synthesis, characterization and reactivity of tetranuclear ruthenium hydrido clusters containing chiral phosphine ligands

The chiral clusters [H(4)Ru(4)(CO)(12-n)(L)(n)] (n = 1, 2; L = NMDPP), 1,1-[H(4)Ru(4)(CO)(10)(L-L)] (L-L = DUPHOS, DIPAMP), 1,2-[H(4)Ru(4)(CO)(10)(DIOP)] and [{H(4)Ru(4)(CO)(10)(DIOP)}(2)] have been synthesized by derivatizing the parent carbonyl cluster [H(4)Ru(4)(CO)(12)] with the appropriate mono- or didentate chiral phosphine ligand. The phosphine-substituted clusters were found to be able to catalyze the (asymmetric) hydrogenation of tiglic acid albeit with relatively low selectivity (enantiomeric excesses varying from 0 to 23%). It was found that the stability of the chiral ruthenium hydride clusters and the product distribution obtained in the catalytic reactions are dependent on the nature of the chiral phosphine. The crystal structures of [H(4)Ru(4)(CO)(12-n)(L)(n)] (n = 1, 2; L = NMDPP), 1,1-[H(4)Ru(4)(CO)(10)(L-L)] (L-L = DUPHOS, O-DUPHOS (partially oxygenated ligand), DIPAMP), 1,2-[H(4)Ru(4)(CO)(10)(DIOP)] and [{H(4)Ru(4)(CO)(10)(DIOP)}(2)] are presented.     

Carbonate, acetate and phenolate phosphonium salts as catalysts in transesterification reactions for the synthesis of non-symmetric dialkyl carbonates

Methyl trioctylphosphonium methyl carbonate [P(8881)](+)[MeOCO(2)](-) was prepared by the alkylation of trioctyl phosphine with the non-toxic dimethyl carbonate. This salt was a convenient source to synthesize different ionic liquids where the methyl trioctylphosphonium cation was coupled to weakly basic anions such as bicarbonate, acetate, and phenolate. At 90-220 °C, all these compounds [P(8881)](+)X(-); X = MeOCO(2); HOCO(2); AcO; PhO were excellent organocatalysts for the transesterification of dimethyl and diethyl carbonate with primary and secondary alcohols, including benzyl alcohol, cyclopentanol, cyclohexanol, and the rather sterically hindered menthol. Conditions were optimized to operate with very low catalyst loadings up to 1 mol% and to obtain non-symmetric dialkyl carbonates (ROCO(2)R'; R = Me, Et) with selectivity up to 99% and isolated yields >90%. The catalytic performance of the investigated ionic liquids was discussed through a cooperative mechanism of simultaneous activation of both electrophilic and nucleophilic reactants.     

Analysis of the role of the calculator in Brazilian textbooks

This paper presents the results of an investigation in which 48 textbooks have been analysed, to observe whether and how primary school textbooks approved by the Brazilian national textbook programme (Programa Nacional do Livro Didático—PNLD) consider the use of calculators. It has been noticed that many textbooks recommend the use of calculators in the classroom and suggest specific activities. In the PNLD teacher’s guide, only in the analysis of some textbooks is there clear information on calculator usage in the classroom. Calculator usage is mainly encouraged in the textbooks of the final years in primary school, mostly with multiplication and division, and distributed in four types of activities: conceptual development, verification of results, results calculation and calculator tool manipulation. Many textbooks have considered the recommendation to use modern technological devices to aid the learning of mathematics, while others still have to assess the value of the calculator as a valid instrument in developing mathematical knowledge.     

Triphasic liquid systems: generation and segregation of catalytically active Pd nanoparticles in an ammonium-based catalyst-philic phase

A triphasic liquid system fabricated from isooctane, aqueous base, and trioctylmethylammonium chloride/decanol promoted the formation of Pd-nanoparticles in the size range of 2-4 nm which remained immobilised in the onium phase, catalysed organic reactions, and could be recycled.     

GCA-EoS: A SAFT group contribution model—Extension to mixtures containing aromatic hydrocarbons and associating compounds

GCA-EoS is the first equation of state that takes into account association using a SAFT-like group contribution term. It has been recently upgraded to deal simultaneously with multiple associating and solvating groups. In this work a review of applications and parameters revisions are presented and the GCA-EoS extension to aromatic hydrocarbons is discussed. These compounds are important in different industrial fields (textile, fine chemicals, pharmaceutical, petrochemicals, materials, etc.). Moreover, compounds like phenol play a major role not only in several polymers syntheses but also in biomass processing mixtures. Specifically, the extension to systems containing aromatic hydrocarbons (BETX and alkylbenzenes), water and alkanols is discussed.     

A logic‐mathematical point of view of the truth: Reality,perception, and language

In this article, the authors propose a theory of the truth value of propositions from a logic‐mathematical point of view. The work that the authors present is an attempt to address this question from an epistemological, linguistic, and logical‐mathematical point of view. What is it to exist and how do we define existence? The main objective of this work is an approach to the first of these questions. We leave a more thorough treatment of the problem of existence for future works. © 2014 Wiley Periodicals, Inc. Complexity 20: 58–67, 2015     

Coulomb repulsion versus Hubbard repulsion in a disordered chain

We study the difference between on site Hubbard and long range Coulomb repulsions for two interacting particles in a disordered chain. The system size L (in units of the lattice spacing) is of the order of the one particle localization length and the energies are taken near the band center. In the two cases, the limits of weak and strong interactions are characterized by uncorrelated energy levels and are separated by a crossover regime where the states are more extended and the spectra more rigid. U denoting the interaction strength and t the kinetic energy scale, the crossovers take place for interaction energy to kinetic energy ratios U/t and U/(2tL) of order one, for Hubbard and Coulomb repulsions respectively. While Hubbard repulsion can only yield weak critical chaos with intermediate spectral statistics, Coulomb repulsion can drive the two particle system to quantum chaos with Wigner-Dyson spectral statistics. The interaction matrix elements are studied to explain this difference. Received 21 March 2000 and Received in final form 5 February 2001