Alkylation of adamantane and 1,3-dimethyladamantane using alumina catalysts

Abstract

ALKYLATIO~ of adamantane with olefms and alcohols is an important method of obtaining alkyladamantanes with different side chain lengths. Existing methods of alkylation, however, are not effective enough. Thus, alkylation of adamantane with olefins over aluminium halides even at low temperatures is accompanied by marked isomerization and oligomerization, as a result of which fairly complex product mixtures are formed [1]. In some cases, for example, during alkylation with cyclopentene, when isomerization cannot produce new substances, the yield of the end product (cyclopentyladamantane) reaches 65% with high selectivity [2]. Although alkyladamantanes of the same molecular weight can be obtained by alkylation of adamantanes with alcohols and olefins over sulphuric acid, the overall yield of reaction products does not exceed 9-25% of reacted adamantane [3, 4]. In a previous paper we proposed to use paraffin as alkylating agent [5]. Conjugate reactions of breakdown of paraffin and alkylation of adamantanes by fragments formed take place in this case over aluminium halides. When using, for example, 2,2,4-trimethylpentane, isomeric monobutyl-and dibutyladamantanes can be obtained in one stage with an overall yield of approximately 80%. The composition of reaction products obtained by this method depends on features of decomposition of the paraffin hydrocarbon. In order to develop more efficient methods for the synthesis of alkyladamantanes, particularly of high molecular weight, alkylation of adamantane and its lower homologues was examined over acid catalysts prepared using alumina. I t is well known that by isomerization catalysts of this type activate saturated tricyclic hydrocarbons, including alkyladamantanes [6, 7]. Results are given in this paper obtained by alkylation of adamantane and 1,3-dimethyladamantanc over alumina activated with sulphurie acid, a Houdry type aluminosilicate catalyst and Zeokar-2 and AShNTs-3 industrial catalysts containing zeolite. C2-Cs alkylating agents and some alcohols and alkyl halides were used as alkylating agents.