Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

The reaction of o-carborane with 13 alkylation agents in CS₂ over AlCl₃ using different ratios of reactants was investigated. Alkylation succeeded with CH₃X, C₂H₅X and i-C₃H₇X whereas other used agents failed. Only i-C₃H₇Br alkylated in nitromethane. A rich mixture resulted even with o-carborane: RX 1 : 1 ratio. In the presence of H₂SO₄ o-carborane was isopropylated with i-C₃H₇OH, no other alcohols or olefins reacted. Alkyls enter stepwise B-9(12) > B-8(10) > B-4(5,7,11) positions, facilitating always the introduction of further alkyl into the skeleton. On ethylation, the most ethylated product was 4,5,7,8,9,10,12-(C₂H₅)₇-1,2-C₂B₁₀H₅. Seven B-alkyl and polyalkyl derivatives were isolated as individua. With C₆H₅Br-AlCl₃ no reaction occurred at 27 °C, while only a transfer of Br into 9-position was observed at 127 °C. Possible mechanisms of B-substitution under electrophilic conditions are discussed.