The effect of Fenton chemistry on the properties of microfibrillated cellulose

A fully bleached birch kraft pulp was treated with acidic hydrogen peroxide in the presence of ferrous ions (Fenton’s reagent) and thereafter treated mechanically in a colloid mill to produce a product containing microfibrillated cellulose (MFC). The produced MFC products were chemically and morphologically characterized and compared with MFC products produced without pretreatment as well as with enzymatic hydrolysis. Fenton treatment resulted in an increase in total charge and number of carbonyl groups while the intrinsic viscosity decreased. The Fenton treated pulps were easier to process mechanically i.e. they reached a higher specific surface area at a given mechanical treatment time and the MFC produced had a stable water-fibre suspension for at least 8 weeks compared to enzymatic pretreated pulps and pulps not subjected to any pretreatment.     

Immobilization and Continuous Recycling of Photoredox Catalysts in Ionic Liquids for Applications in Batch Reactions and Flow Systems: Catalytic Alkene Isomerization by Using Visible Light

A catalytic (E)‐ to (Z)‐isomerization of olefins using a photoredox catalyst under mild reaction conditions is presented. A variety of (Z)‐alkenes can be prepared in the presence of visible light. A new reaction system allows an easy and efficient scale‐up, as well as a continuous flow process in which the photocatalyst is immobilized in an ionic liquid and continuously recycled by simple phase separation.     

Scalable Synthesis of Piperazines Enabled by Visible‐Light Irradiation and Aluminum Organometallics

The development of more active C? H oxidation catalysts has inspired a rapid, scalable, and stereoselective assembly of multifunctional piperazines through a [3+3] coupling of azomethine ylides. A combination of visible‐light irradiation and aluminum organometallics is essential to promote this transformation, which introduces visible‐light photochemistry of main‐group organometallics and sets the basis for new and promising catalysts.     

Ortho‐Quinone Methides as Reactive Intermediates in Asymmetric Brønsted Acid Catalyzed Cycloadditions with Unactivated Alkenes by Exclusive Activation of the Electrophile

An efficient method for the highly enantioselective synthesis of chiral chromanes bearing multiple stereogenic centers was developed. A chiral BINOL‐based N‐triflylphosphoramide proved to be an effective catalyst for the in situ generation of ortho‐quinone methides (o‐QMs) and their subsequent cycloaddition reaction with unactivated alkenes provided chromanes with excellent diastereo‐ and enantioselectivity.     

Intracellular transport and localization of microsomal cytochrome P450

The cytochrome P450 (P450) enzymes are mainly localized to the endoplasmic reticulum (ER), where they function within catalytic complexes metabolizing xenobiotics and some endogenous substrates. However, certain members of families 1–3 were also found in other subcellular compartments, such as mitochondria, plasma membrane, and lysosomes. The physiological function of these enzymes in non-ER locations is not known, although plasma-membrane-associated P450s have been described to be catalytically active and to participate in immune-mediated reactions with autoantibody formation that can trigger drug-induced hepatitis. Several retention/retrieval mechanisms are active in the ER retention of the P450s and inverse integration of the translated P450 into the ER membrane appears to be responsible for transport to the plasma membrane. Furthermore, hydrophilic motifs in the NH₂-terminal part have been suggested to be important for mitochondrial import. Phosphorylation of P450s has been described to be important for increased rate of degradation as well as for targeting into mitochondria. It was also suggested that the mitochondria-targeted P450s from families 1–3 could be active in drug metabolism using an alternative electron transport chain. In this review we present an update of the field emphasizing studies concerning localization, posttranslational modification, such as phosphorylation, and intracellular transport of microsomal P450s.     

Thermodynamics and bending energetics of toruslike micelles

The self-assembly of surfactants forming toruslike or toroidal micelles has been investigated from a theoretical point of view, in particular the structural behaviour and stability of tori in terms of the three bending elasticity constants spontaneous curvature (H(0)), bending rigidity (k(c)) and saddle-splay constant (k(c)). It is demonstrated that the size of toruslike micelles increases with an increasing bending rigidity, but is independent of both spontaneous curvature and saddle-splay constant. Similar to conventional micelles, toruslike micelles are found to be stable over bilayers as the spontaneous curvature times the surfactant layer thickness exceeds 1/4. Moreover, it is shown that toruslike micelles, in general, are favoured at the expense of long spherocylindrical micelles as a result of elimination of the unfavourable end-caps. However, conventional micelles that are able to grow with respect to both width and length (tablets) may be stable over tori as well as spheres in much wider regimes of different bending elasticity constants. As a result, toruslike micelles are predicted to be stable over conventional micelles, including rods, at large values of the effective bending constant k(eff) identical with 2k(c)+k(c), i.e. in the same region where infinite cylinders are expected to be observed. This result is consistent with the fact that toruslike micelles have usually been observed to coexist with large networks of branched cylinders.     

Sodium trichloro­methane­sulfonate monohydrate

Sodium trichloro­methane­sulfonate monohydrate, Na⁺·CCl₃SO₃⁻·H₂O, crystallizes in P2₁/a with all the atoms located in general positions. The trichloro­methane­sulfonate (trichlate) anion consists of pyramidal SO₃ and CCl₃ groups connected via an S—C bond in a staggered conformation with approximate C_3v symmetry. The water mol­ecule is hydrogen bonded to the sulfonate O atoms, with one water H atom forming weak bifurcated O—H⋯O hydrogen bonds to two different trichlate ions. Two water O atoms and three O atoms from different SO₃ groups form a square‐pyramidal arrangement around the sodium ion.     

C–F Bond Cleavage Reactions with Beryllium,Magnesium, Gallium,Hafnium, and Thorium Halides

The work describes unexpected stoichiometric C–F bond cleavage reactions of beryllium, magnesium, gallium, hafnium and thorium halides with α,α,α-trifluorotoluene. The reaction of BeBr₂ / GaBr₃ or MgBr₂ / GaBr₃ mixtures as well as neat GaI₃ with α,α,α-trifluorotoluene in the presence of (OSi₂Me₄)₂ ( I ) yields the carbenium ion containing compounds [Ph-C(O₂Si₂Me₄)][GaX₄] (X = Br: 1 , X = I/F: 2 ). Both compounds were successfully characterized and a defluorination type reaction under incorporation of a siloxy unit was observed. Compound 1 was also characterized by single-crystal X-ray diffraction analysis. The conversion of α,α,α-trifluorotoluene with BeI₂, HfI₄ or ThI₄ turned out to be a halodefluorination-type reaction with formation of α,α,α-triiodotoluene ( 3 ). An adequate NMR spectroscopic and the X-ray crystallographic characterization of 3 were performed for the first time.     

Diphenylberyllium Reinvestigated: Structure,Properties, and Reactivity of BePh2, [(12-crown-4)BePh]+, and [BePh3]−

The first synthesis of BePh₂ was accomplished almost a century ago. However, its structure has remained unknown so far, while the corresponding aryls of the elements adjacent to beryllium in the periodic table are well investigated. Herein, we present an improved synthesis for diphenylberyllium and show by X-ray diffraction that it forms a trinuclear complex in the solid state. NMR spectroscopy revealed that this structure is also retained in solution but exhibits dynamic behavior. Its stability against heat and coordinating solvents is discussed and the possible obstacles to the synthesis of BePh₂ from BeCl₂ are examined. In the process of this study two ether adducts, BePh₂⋅Et₂O and Be₂Ph₄⋅Et₂O, have been characterized as well as the previously unknown triphenylberyllate anion. From the latter several single-crystal structures were obtained under various conditions, in which [BePh₃]⁻ is either isolated or acts as a ligand for Li⁺. Furthermore, the crown ether induced selfionization of BePh₂ is described and the resulting [(12-crown-4)BePh]⁺ cation was isolated, which shows an unusual 4+1 coordination around the Be atom.