Search results for "imine"

Design principles for learning analytics information systems in higher education

2020

This paper reports a design science research (DSR) study that develops, demonstrates and evaluates a set of design principles for information systems (IS) that utilise learning analytics to support learning and teaching in higher education. The initial set of design principles is created from theory-inspired conceptualisation based on the literature, and they are evaluated and revised through a DSR process of demonstration and evaluation. We evaluated the developed artefact in four courses with a total enrolment of 1,173 students. The developed design principles for learning analytics information systems (LAIS) to establish a foundation for further development and implementation of learning…

Flow-injection spectrophometric determination of propoxur with p-aminophenol

1992

Abstract The spectrophotomeric determination of propoxur [2-(1-methyxlthoxy)phenyl methyl carbamate] was carried out with p -aminophenol (PAP) in a flow system. The method involves the on-line hydrolysis with NaOH of propoxur to 2-isopropoxyphenol and the oxidation of PAP to its relative quinone imine with KIO 4 and the reaction between the phenolate and the quinone imine. A four-channel flow manifold was employed to carry out all the different steps of the reaction considered, monitoring the indo dye formed at 600 nm. The developed procedure provides a typical calibration line of A = 0.000 7 + 1.8 × 10 3 C ( A = absorbance; C = concentration in M) with a regression coefficient of 0.9998 an…

La teoria dell’associazione-rinforzo differenziale di Robert L. Burgess e Ronald L. Akers

2017

Il saggio analizza gli sviluppi compiuti da Robert L. Burgess e Ronald L. Akers dell’associazione differenziale a partire dagli approcci psicologici dell’apprendimento maturati in ambito comportamentista.

Dalle teorie del labeling alla costruzione dei problemi sociali

2017

Il saggio analizza gli studi sulla devianza e sul crimine di derivazione interazionista chiamati in vario modo: «teoria» dell’etichettamento o labelling theory o anche «prospettiva interazionista della devianza», «teoria della reazione sociale» o «nuova teoria della devianza». Si tiene conto di approcci e applicazioni diversificate accomunati dall'analisi della reazione sociale alle condotte devianti e criminali e nei confronti dei processi di definizione «che li costruiscono» e li «costituiscono».

Voimaantumisen mahdollisuuksia verkko-opiskeluympäristöissä

2002

Assessing (for) Understanding in the CLIL Classroom

2020

In this chapter, we conceptualise CLIL assessment as a dialogic activity in which teachers and learners share the responsibility for building learners’ understanding of subject-specific issues. We illustrate such a conceptualisation by first studying how secondary school CLIL teachers perceive classroom assessment in interviews collected in Finland and Austria. Then, by examining video data from a CLIL lesson, we show how opportunities for assessing to support learning can emerge in routine instructional interaction, and how a teacher can attend to learner talk both to develop his or her own understanding of the learner’s abilities and to promote these same abilities. Our data suggest that,…

Chiral α-P,N Ligands From a Diastereoselective Ph2PH Addition to (η6-Benzaldimine)tricarbonylchromium Complexes

1999

International audience; Chiral α-aminophosphane (α-P–C–N) ligands have been prepared by reversible addition of Ph2PH to tricarbonylchromium benzaldimine complexes (CO)3Cr[η6-o-C6H4(Y)(CH=NR)] (with Y, R = CH3, CH3 or CH2COOCH3; CH3O, CH3 or p-CH3OC6H4; Cl, C6H5), with complete diastereoselectivity. These complexes are stabilized in solution by electron-withdrawing group(s) on the imine.

Addition of dianions of carboxylic acids to imines. Influence of the acid in the outcome of the reaction

2009

The addition of different carboxylic acids dianions to N-benzylidenebenzeneamine have been studied. The outcome of the reaction depends on the acid. Saturated ones lead to β-aminoacids with good yields and syn-selectivity whereas α,β-unsaturated ones lead to α− and γ− regioisomers with a regioselectivity that depends on the steric hindrance around the reactive centre. From some of these unsaturated acids, polyunsaturated carboxylic acids can be obtained as a change in the reaction conditions lead to the in situ elimination of aniline. From o-methyl aromatic acids δ-aminoacids are isolated with uneven results. Those derived from six member arene carboxylic acids give, on standing, dihydro-2-…

The influence of substitution in the quinoxaline nucleus on 1,3-dipolar cycloaddition reactions: A DFT study

2013

Abstract The reaction mechanism of 1,3-dipolar cycloadditions of both symmetric and unsymmetric benzo-condensed diazines with a nitrilimine dipole, to give two different mono- and bis-cycloadducts, in tetrahydrofuran (THF) solution, was studied by DFT calculations. The results obtained show that each 1,3-dipolar cycloaddition reaction always proceeds by a two steps mechanism, in which the first intermediate shows only one covalent bond between the beta carbon of the nitrilimine and the aromatic nitrogen of the diazine molecule. The structure and energy content of the two transition states of the two cycloaddition steps, in the case of the unsymmetric benzo-condensed diazine, nicely explains…

Mechanismus der Umsetzung von 1,1-Diphenylhydrazin mit Azodicarbonsäure-diethylester

1979

Bei der Umsetzung von 1,1-Diphenylhydrazin (1a) mit Azodicarbonsaure-diethylester (2a) uber-lagern sich funf Reaktionsmechanismen: A und B) Oxidation des Diphenylhydrazins 1a durch den Azodicarbonsaureester 2a zum Aminonitren 8; Bildung des Tetrazens 10 entweder durch Dimerisierung von 8 oder uber das Tetrazan 11; Zerfall von 11 in N2 und Diphenylamin. — C) Addition des Aminonitrens 8 an den Azodicarbonsaureester 2a zum Aminoazimin 3a; Zerfall von 3a in das Urethan 4a und den Azidoameisensaureester 5a. — D) Isomerisierung des Aminoazimins 3a zu 13 und Reduktion von 13 durch 1a zum Tetrazen 14; Spaltung von 14 in Diphenylamin und das Azid 15; Zerfall von 15 in Ethylcyanat (17) und den Kohlen…