Summary The conversion of different types of lignin to monophenolic compounds has been studied be... more Summary The conversion of different types of lignin to monophenolic compounds has been studied between 500 and 650 K, under typical coal liquefaction conditions using 9,10-dihydroanthracene (AnH2) and 7H-benz[de]anthracene (BzH) as the hydrogen-donor solvents. The yield of phenolic compounds was found to increase with the capacity of the hydrogen donor. The application of a polar cosolvent appeared to be beneficial as well. The differences in product distribution could be related to the origin of lignin. The maximum yield amounted to 11 % after 4 h at 625 K using milled wood lignin in AnH2. It has been found that lignin itself is a hydrogen-donating substance and capable of cleaving aromatic ketones such as α-phenoxyacetophenone.
In a mixture of oil and water the interfacial tension is reduced by surfactants, amphiphilic mole... more In a mixture of oil and water the interfacial tension is reduced by surfactants, amphiphilic molecules. The influence of the structure of these surfactants on the interfacial tension is studied with the Dissi-pative Particle Dynamics (DPD) technique. It can be concluded that both increasing the length of the hydrophobic tail and hydrophilic head group of a linear surfactant has a positive effect on the decrease of the interfacial tension of an oil–water system. However, the effect of increasing tail length is less pronounced for surfactants with a large head group. Another important structure effect is that a branched sur-factant, with two hydrophobic tails, is more efficient than a linear sur-factant, because the monolayer formed by these surfactants is more ordered. The results are in agreement with experimental and other theoretical work on surfactants.
The reactivity of o-hydroxybenzyl alcohol (o-HBA, 1), as a model compound for lignin, has been st... more The reactivity of o-hydroxybenzyl alcohol (o-HBA, 1), as a model compound for lignin, has been studied in various solvents between 390 and 560 K. Both in polar and apolar solvents the benzylic cation is the reactive intermediate. In alcoholic solvents, the benzylic cation reacts with the solvent to give the corresponding ethers. Relative reaction rates have been determined for different alcohols; a factor of 14 is encountered between the most (methanol) and least (tert-butyl alcohol) reactive ones. The etherification is reversible, in contrast to the electrophilic aromatic substitution with phenol and anisole, for which k(PhOH) = 1 x 10(5) M(-)(1) s(-)(1) and k(anisole) = 1 x 10(4) M(-)(1) s(-)(1), at 424 K. In apolar hydroaromatic solvents, 7H-benz[de]anthracene, 9,10-dihydroanthracene, and 9,10-dihydrophenanthrene, the formation of o-cresol proceeds via hydride transfer from the solvent to the benzylic cation; rate constants at 555 K are 2 x 10(6), 5 x 10(4), and 5 x 10(3) M(-)(1) s(-)(1), respectively.
Summary The conversion of different types of lignin to monophenolic compounds has been studied be... more Summary The conversion of different types of lignin to monophenolic compounds has been studied between 500 and 650 K, under typical coal liquefaction conditions using 9,10-dihydroanthracene (AnH2) and 7H-benz[de]anthracene (BzH) as the hydrogen-donor solvents. The yield of phenolic compounds was found to increase with the capacity of the hydrogen donor. The application of a polar cosolvent appeared to be beneficial as well. The differences in product distribution could be related to the origin of lignin. The maximum yield amounted to 11 % after 4 h at 625 K using milled wood lignin in AnH2. It has been found that lignin itself is a hydrogen-donating substance and capable of cleaving aromatic ketones such as α-phenoxyacetophenone.
The formation of the rippled phase in biological membranes and its relation with anomalous swelli... more The formation of the rippled phase in biological membranes and its relation with anomalous swelling are still lacking a molecular explanation. Starting from all-atom simulations we use a mapping to create a mesoscopic model of the lipid dimyristoylphosphatidylcholine (DMPC) in water. We use this model to study the phase behaviour of lipid bilayers. Depending on the lipid structure and head group, our simulations reproduce the experimental phase diagrams. The anomalous swelling is caused by conformational changes of the lipid tails but is not ...
Summary The conversion of different types of lignin to monophenolic compounds has been studied be... more Summary The conversion of different types of lignin to monophenolic compounds has been studied between 500 and 650 K, under typical coal liquefaction conditions using 9,10-dihydroanthracene (AnH2) and 7H-benz[de]anthracene (BzH) as the hydrogen-donor solvents. The yield of phenolic compounds was found to increase with the capacity of the hydrogen donor. The application of a polar cosolvent appeared to be beneficial as well. The differences in product distribution could be related to the origin of lignin. The maximum yield amounted to 11 % after 4 h at 625 K using milled wood lignin in AnH2. It has been found that lignin itself is a hydrogen-donating substance and capable of cleaving aromatic ketones such as α-phenoxyacetophenone.
In a mixture of oil and water the interfacial tension is reduced by surfactants, amphiphilic mole... more In a mixture of oil and water the interfacial tension is reduced by surfactants, amphiphilic molecules. The influence of the structure of these surfactants on the interfacial tension is studied with the Dissi-pative Particle Dynamics (DPD) technique. It can be concluded that both increasing the length of the hydrophobic tail and hydrophilic head group of a linear surfactant has a positive effect on the decrease of the interfacial tension of an oil–water system. However, the effect of increasing tail length is less pronounced for surfactants with a large head group. Another important structure effect is that a branched sur-factant, with two hydrophobic tails, is more efficient than a linear sur-factant, because the monolayer formed by these surfactants is more ordered. The results are in agreement with experimental and other theoretical work on surfactants.
The reactivity of o-hydroxybenzyl alcohol (o-HBA, 1), as a model compound for lignin, has been st... more The reactivity of o-hydroxybenzyl alcohol (o-HBA, 1), as a model compound for lignin, has been studied in various solvents between 390 and 560 K. Both in polar and apolar solvents the benzylic cation is the reactive intermediate. In alcoholic solvents, the benzylic cation reacts with the solvent to give the corresponding ethers. Relative reaction rates have been determined for different alcohols; a factor of 14 is encountered between the most (methanol) and least (tert-butyl alcohol) reactive ones. The etherification is reversible, in contrast to the electrophilic aromatic substitution with phenol and anisole, for which k(PhOH) = 1 x 10(5) M(-)(1) s(-)(1) and k(anisole) = 1 x 10(4) M(-)(1) s(-)(1), at 424 K. In apolar hydroaromatic solvents, 7H-benz[de]anthracene, 9,10-dihydroanthracene, and 9,10-dihydrophenanthrene, the formation of o-cresol proceeds via hydride transfer from the solvent to the benzylic cation; rate constants at 555 K are 2 x 10(6), 5 x 10(4), and 5 x 10(3) M(-)(1) s(-)(1), respectively.
Summary The conversion of different types of lignin to monophenolic compounds has been studied be... more Summary The conversion of different types of lignin to monophenolic compounds has been studied between 500 and 650 K, under typical coal liquefaction conditions using 9,10-dihydroanthracene (AnH2) and 7H-benz[de]anthracene (BzH) as the hydrogen-donor solvents. The yield of phenolic compounds was found to increase with the capacity of the hydrogen donor. The application of a polar cosolvent appeared to be beneficial as well. The differences in product distribution could be related to the origin of lignin. The maximum yield amounted to 11 % after 4 h at 625 K using milled wood lignin in AnH2. It has been found that lignin itself is a hydrogen-donating substance and capable of cleaving aromatic ketones such as α-phenoxyacetophenone.
The formation of the rippled phase in biological membranes and its relation with anomalous swelli... more The formation of the rippled phase in biological membranes and its relation with anomalous swelling are still lacking a molecular explanation. Starting from all-atom simulations we use a mapping to create a mesoscopic model of the lipid dimyristoylphosphatidylcholine (DMPC) in water. We use this model to study the phase behaviour of lipid bilayers. Depending on the lipid structure and head group, our simulations reproduce the experimental phase diagrams. The anomalous swelling is caused by conformational changes of the lipid tails but is not ...
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