In this article, we review the recent progress that has been made in the field of Lewis-acid catalysis of carbon carbon-bond-forming reactions in aqueous solution. Since water hampers the hard hard interactions between the catalyst and the reactant, it often complicates catalysis. However, once coordination has taken place, water can have beneficial effects on rates and selectivities of Lewis acid catalysed Diels Alder reactions, aldol reactions, allylation reactions, Barbier and Mannich type reactions as well as Michael additions.
DOCUMENT
Michael additions of α-nitroesters with enones and α,β-unsaturated aldehydes result in quantitative conversions to the corresponding 1,4-adducts by performing the reactions in water in the presence of ytterbium triflate as water-tolerant Lewis acid.
DOCUMENT
The catalytic oxidation of potato starch by [MnIV2 (μ-O)3(tmtacn)2][H2O](CH3COO)2 (Mncat, with tmtacn =1,4,7-trimethyl-1,4,7-triazacyclononane) with H2O2, was recently introduced as a promising alternative to ubiquitous sodium hypochlorite (NaOCl). Here, we report an in-depth investigation into interactions of the catalyst with the starch granule. Pitted starches obtained by pre-treatment with high-frequency ultrasound (HFUS) were shown to result in a uniquely homogeneous oxidation. To study this further, fractionation of oxidised potato starch was done which showed a preference for the oxidation of smaller granules with a higher relative surface area. This result was corroborated by chemical surface gelatinisation of fractionated granules. These studies showed that the inside of the granules was oxidised, but that Mncat had a moderate preference for oxidation of the periphery. Together, these results allow for a better understanding of oxidation of starch by Mncat and how it differs from NaOCl oxidation making further optimisation of the process possible.
DOCUMENT
In mijn vorige blog schreef ik dat ik "groene chemie" niet zo'n goede term vind. Dit bericht borduurt daar enigszins op voort en is mijn persoonlijke kritische noot bij de transitie naar een groene(re) economie die momenteel in volle gang is.
DOCUMENT
The invention relates to the use of modified starch obtainable by treating amylose containing starch in aqueous medium with an enzyme from the group of the α-1,4-α-1,4-glucosyl transferases (EC 2.4.1.25) or an enzyme the activity of which corresponds to that of enzymes from the group just mentioned, as an agent for forming a thermoreversible gel. The invention also relates to products in the form of a thermoreversible gel having as gel-forming substance a modified starch as defined. The invention further relates to the use of a modified starch as defined in the form of an aqueous solution.
LINK
There is more to be learned from nature as a whole. In practice ‘nature’ is often used in teaching, training, consultancy and organisational development as a metaphor, as a source of inspiration or as an example for all kinds of processes, including leadership, cooperation, relationships and the development of organisations and society. Mainly ecological, and much less frequently biological, processes are generally involved here. The question has gradually arisen whether we can learn more from nature in the social environment than what we ‘see’ on the surface - which is often translated in metaphors. Seen more holistically, this is about the systemic side, the complexity, the context and the coherence. For example, can we demonstrate that applying fundamental ecological principles, such as cycles (learning, self-organising, selfregulating and self-sufficient capacity), succession, diversity and resilience, social and cooperative behaviour, interconnectedness and interdependency within an organisation leads to a sustainable organisation? Mauro Gallo is conducting research into the significance of technical innovation in and for the agricultural and food sector, and into the question whether biomimicry can in fact be backed up in such a way that it contributes to the social sciences domain. At the same time there is a clear teaching issue: Is it logical from the perspective of our green DNA to include biomimicry thinking in our teaching? Is it possible to learn to apply biomimicry, and can biomimicry be applied in teaching/learning? (How) can we apply biomimicry in green VMBO and MBO, pass it on to the teachers of the future in teacher training courses and include it in making current lecturers more professional? Is it conceivable that it could become an integral component of the curricula in green HBO?
DOCUMENT
There is more to be learned from nature as a whole. In practice ‘nature’ is often used in teaching, training, consultancy and organisational development as a metaphor, as a source of inspiration or as an example for all kinds of processes, including leadership, cooperation, relationships and the development of organisations and society. Mainly ecological, and much less frequently biological, processes are generally involved here. The question has gradually arisen whether we can learn more from nature in the social environment than what we ‘see’ on the surface - which is often translated in metaphors. Seen more holistically, this is about the systemic side, the complexity, the context and the coherence. For example, can we demonstrate that applying fundamental ecological principles, such as cycles (learning, self-organising, selfregulating and self-sufficient capacity), succession, diversity and resilience, social and cooperative behaviour, interconnectedness and interdependency within an organisation leads to a sustainable organisation? Mauro Gallo is conducting research into the significance of technical innovation in and for the agricultural and food sector, and into the question whether biomimicry can in fact be backed up in such a way that it contributes to the social sciences domain. At the same time there is a clear teaching issue: Is it logical from the perspective of our green DNA to include biomimicry thinking in our teaching? Is it possible to learn to apply biomimicry, and can biomimicry be applied in teaching/learning? (How) can we apply biomimicry in green VMBO and MBO, pass it on to the teachers of the future in teacher training courses and include it in making current lecturers more professional? Is it conceivable that it could become an integral component of the curricula in green HBO?
DOCUMENT
