Microflow photochemistry—a reactor comparison study using the photochemical synthesis of terebic acid as a model reaction

The continuous-microflow photochemical synthesis of terebic acid from maleic acid was investigated in two different microreactor set-ups. The results were subsequently compared to analogue experiments in a conventional chamber reactor. Based on conversion rates, reactor design and energy efficiency calculations, the simple microcapillary reactor showed the best overall performance.     

Enhanced transdermal delivery by using electrostatically interactive chitosan nanocapsules

This paper describes a useful means of noninvasively enhancing transdermal delivery efficiency. For this, chitosan nanocapsules with positive surface charges were fabricated by using the in situ precipitation method. These nanocapsules cannot only have an ability to encapsulate the drug molecule (this study used riboflavin 5′-monophosphate), but also electrotatically interact with the stratum corneum layer. To demonstrate this, fluorescence-labeled polymer nanoparticles with different particle sizes as well as surface charges were topically applied onto the skin and their distribution was directly imaged. This demonstration experiment allowed us to figure out that once the nanocapsules were provided with positive surface charges, they readily deposited into the stratum corneum layer due to the electrostatic interaction. Further quantitative characterization of the penetrating amount of riboflavin 5′-monophosphate by using the Frantz diffusion cell method showed that our chitosan nanocapsule system effectively improved transdermal delivery efficiency.     

Ferroelectric liquid crystals from banana-shaped achiral molecules with vinyl end groups

Banana-shaped achiral compounds, the 1,3-phenylene bis[4-(alkenyloxyphenyliminomethyl)benzoate]s, were synthesized with varying length of the alkenyl group; their ferroelectric properties are described. The smectic mesophases, including a switchable chiral smectic C (SmC*) phase, were characterized by differential scanning calorimetry, polarizing optical microscopy and the triangular wave method. The presence of vinyl groups at the ends of the linear side-wings in the banana-shaped achiral molecules, containing a Schiff's base mesogen, induced a decrease in melting temperature and formation of the switchable SmC* phase in the melt. The compound having the octenyloxy group exhibited a spontaneous polarization of 120 nC cm^?2 on reversal of an applied electric field.     

Highly Efficient α‐Sialylation by Virtue of Fixed Dipole Effects of N‐Phthalyl Group: Application to Continuous Flow Synthesis of α(2‐3)‐and α(2‐6)‐Neu5Ac‐Gal Motifs by Microreactor

Highly α‐selective sialylation of sialic acid N‐phenyltrifluoroacetimidate with various galactose and lactose acceptors has been achieved by introducing the C‐5 N‐phthalyl group on the donor. The “fixed dipole effect” of the N‐phthalyl group was proposed to explain the high reactivity and α‐selectivity. The microfluidic system was applied to the present α‐sialylation, which is amenable to large‐scale synthesis. The N‐phthalyl group was removed by treatment with methylhydrazine acetate, for which protocol can be readily applied to the synthesis of a variety of sialic acid‐containing oligosaccharides.