Flow Friedel–Crafts alkylation of 1-adamantanol with arenes using HO-SAS as an immobilized acid catalyst

In this communication flow Friedel–Crafts alkylation was studied using hydroxy-substituted sulfonic acid-functionalized silica as a catalyst and 1-adamantanol as a model substrate. The reaction of 1-adamantanol ( 1a ) with toluene ( 2a ) proceeded well with 5 min of residence time at 120°C to give good yield of 1-tolyladamantane ( 3a ) as a 1:9 mixture of meta and para isomers. When the flow synthesis was carried out over 2.5 hr of running time, the collected five fractions contain the product 3a in 97–92% yields, suggesting the durability of the catalyst.     

Universal behaviour of a wave chaos based electromagnetic reverberation chamber

In this article, we present a numerical investigation of three-dimensional electromagnetic Sinai-like cavities. We computed around 600 eigenmodes for two different geometries: a parallelepipedic cavity with one half-sphere on one wall and a parallelepipedic cavity with one half-sphere and two spherical caps on three adjacent walls. We show that the statistical requirements of a well operating reverberation chamber are better satisfied in the more complex geometry without a mechanical mode-stirrer/tuner. This is due to the fact that our proposed cavities exhibit spatial and spectral statistical behaviours very close to those predicted by random matrix theory. More specifically, we show that in the range of frequency corresponding to the first few hundred modes, the suppression of non-generic modes (regarding their spatial statistics) can be achieved by reducing drastically the amount of parallel walls. Finally, we compare the influence of losses on the statistical complex response of the field inside a parallelepipedic and a chaotic cavity. We demonstrate that, in a chaotic cavity without any stirring process, the low frequency limit of a well operating reverberation chamber can be significantly reduced below the usual values obtained in mode-stirred reverberation chambers.