Hydrosilylation of α,β-unsaturated nitriles and esters catalyzed by tris (triphenylphosphine)chlororhodium

The hydrosilylation of α,β-unsaturated nitriles and esters such as acrylonitrile, crotononitrile, cinnamonitrile, ethyl and methyl acrylate, ethyl and methyl crotonate and ethyl and methyl methacrylate using tris(triphenylphosphine)chlororhodium as a catalyst is described. The hydrosilylation of α,β-unsaturated nitriles provided α-adduct exclusively in high yield except in the case of trichlorosilane which afforded β-adduct with acrylonitrile. On the other hand, the hydrosilylation of α,β-unsaturated esters gave rather complex results. The selectivity of the reactions was dramatically affected by the substituent of the ester group and that on the β-carbon. Thus, the hydrosilylation of ethyl acrylate with triethylsilane afforded a β-adduct, but, that of ethyl crotonate using the same hydrosilane gave a 1,4-adduct exclusively. Possible mechanisms for these reactions are discussed.     

A longitudinal view of mathematics achievement of primary students: case studies from Japan, Singapore, and the United States

This paper shares results from a secondary analysis of data from the participation of Japanese, Singaporean, and U.S. students in the International Project on Mathematical Attainment (IPMA). IPMA was a longitudinal study to assess the mathematics achievement of primary students from their first year of schooling through the end of fifth grade. Tests were constructed to enable achievement on the same items to be assessed over multiple years, thus permitting the assessment of growth in achievement throughout primary school. Achievement is compared to the grade at which the content is introduced so that achievement can be related to students’ opportunity to learn.     

An analytical method for measuring α‐amylase activity in starch‐containing foods

The quality of starch‐containing foods may be significantly impaired by contamination with very small amounts of α‐amylase, which can enzymatically hydrolyze the starch and cause viscosity loss. Thus, for quality control, it is necessary to have an analytical method that can measure low amylase activity. We developed a sensitive analytical method for measuring the activity of α‐amylase (from Bacillus subtilis) in starch‐containing foods. The method consists of six steps: (1) crude extraction of α‐amylase by centrifugation and filtration; (2) α‐amylase purification by desalting and anion‐exchange chromatography; (3) reaction of the purified amylase with boron‐dipyrromethene (BODIPY)‐labeled substrate, which releases a fluorescent fragment upon digestion of the substrate, thus avoiding interference from starch derivatives in the sample; (4) stopping the reaction with acetonitrile; (5) reversed‐phase solid‐phase extraction of the fluorescent substrate to remove contaminating dye and impurities; and (6) separation and measurement of BODIPY fluorescence by HPLC. The proposed method could quantify α‐amylase activities as low as 10 mU/mL, which is enough to reduce the viscosity of starch‐containing foods. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis of Substituted Phenyl Esters of Amino Acids and Polycondensation in Langmuirblodgett Films

Long-alkyl-chain phenyl esters of β-alanine, glycine, and L-valine were prepared, and their monolayer properties were correlated with their molecular structures. These compounds formed stable monolayers on acidic subphases. In particular, the p-hexadecylphenyl esters of β-alanine and glycine were remarkably stable, and their monolayers could be deposited on calcium fluoride plates as Y-type film by Blodgett's technique. The polycondensation of multilayers under an atmosphere saturated with triethylamine was investigated by changes in the IR spectra. It was determined that the polycondensation proceeded by a first-order reaction mechanism in the initial stage and that the rate in multilayers was faster than that in the bulk crystalline powder. These results suggest that the polycondensation is accelerated by a regular arrangement of the monomer in the multilayers, where the active sites are concentrated and located better for the polycondensation. In the case of the polycondensation in multilayers of the glycine ester, two kinds of condensation proceeded to afford poly(glycine) and 2,5-piperazinedione.     

Synthesis of L-Lysine and L-Glutamic Acid Derivatives with Long Alkyl Chains and Polycondensation of Langmuir-Blodgett Films

Two esters of L-lysine and L-glutamic acid containing long alkyl groups were synthesized and their polycondensation in monolayers and multilayers was investigated. The pressure-area isotherms of the ester of L-lysine depend markedly on the time of residence at the air-water interface. The change of FT-IR spectra of the deposited film, which can be lifted as a Z-type film, indicates that polycondensation can occur in the monolayer at 10°C without any treatment. The spectrum of the film cast from chloroform hardly changed with time. These results lead to the conclusion that a regular arrangement of monomer molecules in the monolayer, where the amino and ester carbonyl groups are concentrated, is more suitable for the polycondensation. The ester of L-glutamic acid can also form stable monolayers which can be easily deposited on a hydrophobic plate as a Y-type film by the Blodgett technique. The polycondensation of multilayers under an atmosphere of triethylamine was investigated by IR spectroscopy. It indicates that the condensation in multilayers proceeds via intermolecular and intramolecular reactions, by which poly(L-glutamate) derivatives and 2-pyrrolidone derivatives are formed, respectively. The condensation in the bulk crystalline powder gives exclusively the 2-pyrrolidone derivative by intramolecular reaction. These results suggest that the monomer molecules in the multilayers are favorably aligned for the intermolecular reaction, in contrast to the situation in the bulk crystalline powder.     

The Polymerization of 1,3-Dioxolane Catalyzed by Ion Exchange Resin (Polystyrene Sulfonic Acid)

Polystyrene sulfonic acid resin (Amberlyst 15) was found to initiate the cationic polymerization of 1,3-dioxolane easily in bulk at 0 to 50° C, and polymers with a reduced viscosity of 0.1 were obtained. However, this resin showed only low initiator activity for the polymerizations of 2-methyl-1, 3-dioxolane and trioxane.