Golden cascades: Two diastereoselective gold‐catalyzed cascade processes in which propargyl acetates react with alkenes or 1,4‐dienes afford highly substituted five‐ and seven‐membered rings, respectively (see scheme). The concerted nature of the gold‐catalyzed Cope rearrangement has been used in the formal enantioselective synthesis of marine norsesquiterpenoids Frondosins A and B.

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The chemical vapor deposition (CVD) of some heterocyclic compounds was examined to control the porosity and surface functionality of the active carbon fiber (ACF). The deposition took place only on the pore wall of the ACF, when the heterocyclic compound as the precursor and the deposition temperature were selected carefully to be thermally stable and around 700 °C, respectively. Moderately activated ACFs modified with pyridine, pyrrole, and thiophene demonstrated molecular sieving activity for selective adsorptions of CO 2/CH4 and O2/N2 through selective CVD. In contrast, furan decomposed at this temperature, failing to provide molecular sieving activity. The thermal stability of the depositing molecules is a key factor to obtain the molecular sieving performance after CVD. Pyridine, pyrrole, and thiophene produced amorphous carbon within the pore which appears to implant the nitrogen and sulfur atoms over the surface of the ACF, respectively.

Catalytic activity of a series of pitch-based activated carbon fibers (ACFs) was examined at room temperature for the oxidative removal of SO 2 as aqueous H 2 SO 4 which was continuously recovered at steady state. Calcination up to 900 °C in an inert atmosphere increased the activity very markedly regardless of the ACF; however, higher temperatures up to 1200 °C increased the activity of ACFs with larger surface area (1000 m 2 /g) while the ACFs with smaller surface area lost activity very sharply. ACF with the largest surface area and calcined at 1100 °C resulted in the complete capture of 1000 ppm SO 2 by ACF weigh/flow rate (W/F) 1 × 10 -3 g‚min/mL under 10% H 2 O. Lower humidity reduced the activity, although larger W/F allowed complete removal of SO 2 . TPDE measurements revealed CO evolution from the ACF in the range of 400-1100 °C, the amount and the range depending on the ACF. ACF with the highest activity appeared to be obtained when the major CO-evolving groups were removed before marked reduction of the surface area took place. ACF that evolved CO more exhibited higher activity. The active site produced by CO evolution is discussed briefly.

A variety of cokes formed in the reactor and transfer lines of a commercial ethylene dichloride pyrolysis process producing a vinyl chloride monomer were characterized by optical and electron scanning microscopies to determine the mechanism by which they were formed and to find means for suppressing this coke formation. Typical columnar pyrolytic carbon was found on the reactor wall, which was anisotropic carbon of granular appearance. Deposits of carbon found in the transfer lines of product and feed varied in amount and composition, depending on the location of the deposition. The latter carbon appeared to be formed through a mechanism similar to refluxing carbonization of reactive species such as chloroprene and acetylene, which are easily oligomerized, can precipitate on the wall, and finally yield carbon after the repeated dissolution and precipitation. The temperature and kinds of reactive species in the product and feed may define the extent of adhesion, coalescence, and growth of carbon primary granules and may induce their softening during carbonization.