from first principles PP-I-1

PP-II-2Chemistry Carbcations: β-Methyl Shift – a New Rearrangement of theCarbcations Bridged Alicyclic HydrocarbonsBagrii E.I.A.V. Topchiev Institute of Petrochemical Synthesis RAS, Moscow, Russiabagrii@ips.ac.ruResults of researches on studying of the kinetics and isomerization mechanism of thealkyladamantanes in the presence of the catalysts of acid type are considered by author asdetection of a new intramolecular rearrangement of the carbcations bridged alicyclichydrocarbons – 2,4-moving of the methyl groups ( β-methyl shift, BMS). The proof ofrealization of such rearrangement is direct and primary formation 1,4-dimethyladamantane(c.1, Fig.) from 1,2-dimethyladamatane, passing a formation stage of the thermodynamicmuch stable 1,3-dimethyladamantane (c.2, Fig.); direct formation 1,3,6-trimethyladamantanefrom 1,3,4-trimethyladamantane, excepting a formation stage 1,3.5-trimethyladamantane, andalso other isomers which formation is impossible to explain by means of known 1,2-methylshift (α-methyl shift). Rearrangement BMS is realized, mainly, when sterical or electronicdifficulties arise for 1,2-movings of methyl groups. Realization of the BMS rearrangement atisomerous transformations of the higher alkyldiamondoids, such as methyldiamantanes,methyltriamantanes etc., also containing in petroleum and gase condensates is quite expected.НСН3 СН3 СН3СН3СНСН 3НН 4НН1,2-DMA-c1,4-DMA-c132