C asymmetric

Fig. 15. Mechanically agitated columns (a) Scheibel column (b) rotating-disk contactor (RDC) (c) asymmetric rotating-disk (ARD) contactor (d) Oldshue-Rushton multiple-mixer column (e) Kuhni column and (f) reciprocating-plate column.

Hadjichristidis, N, Pispas, S.t Pitsikalis, MIatrou, H Vlahos, C. Asymmetric Star Polymers Synthesis and Properties, VoL 142, pp, 71428. 

The system Ru(PPh3)(H20)2(SB )/Phl0/CH3Cy4°C asymmetrically epoxidised styrene [917]. Related complexes made from L-histidine with salicylaldehyde, 5-chloro and 5-methoxysalicylaldehyde as Ru(PPh3)(H30)3(SB )/(PhIO/CH2Cl2 epoxidised non-functionalised styrenes at unspecified low temperatures in the dark. Possible mechanisms were discussed [918]. 

When the above-mentioned ring expansion with diazomethane 74) of trimethyl-dioxo[2.2]metacyclophane 65 (methylation was necessary to increase the inversion barrier to > 130 kJ) was performed in the presence of optically active alcohols at —60 °C, asymmetric induction occurred to an extent of ca. 40% ee (enantiomeric excess as determined by nmr-spectroscopy in the presence of chiral shift reagents)85). (+)-DibutyI tartrate favoured the dextrorotatory diketone 66 ([a]D 160° for the optically pure product) — the isomeric 67 was formed only with 3% ee (—)-ethyl lactate on the other hand led to an excess of (+)-67 ([a]D +240°) but gave (+)-66 with only 10% ee85). 

Fig. 9. Dependence of -type or p-type organic photoconductors on trapping, (a) Symmetric trapping (b) Asymmetric trapping -type (c) Asymmetric trapping p-type pt, nr — empty and filled centers, respectively = Fermi energy...

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