Activation of C_H bonds of hydrocarbons by the ArH_alkali metal systems in THF (ArH _ naphthalene, biphenyl, anthracene, phenanthrene, trans-stilbene, pyrene). Alkylation of naphthalene and toluene with ethene

摘要

Systems based on naphthalene and alkali metals (Li, Na, K) in THF are able to induce the alkylation of naphthalene with ethene at room temperature and atmospheric pressure. The highest activity in this reaction is exhibited by the naphthalene_potassium system which converts naphthalene into 1-ethylnaphthalene (1) and small amounts of two isomeric dihydro derivatives of 1 in a yield of 85% (24 h,K:C_(10)H_8 = 2:1). The same alkylation products are formed when metallic sodium is used instead of potassium.The interaction of ethene with the naphthalene_lithium system (24 h, Li:C_(10)H_8 = 2:1) affords 1 together with 1-n-butylnaphthalene (4), 1-n-hexylnaphthalene (5),1-n-oktylnaphthalene (6) and dihydro derivatives of 5 and 6 in a total yield of 60%. Alkylation of toluene with ethene in the naphthalene_alkali metal systems leads to the formation of higher monoalkylbenzenes. The greatest toluene conversion (48%, 24 h) is observed on using the lithium-containing system (Li:C_(10)H_8 = 2:1), in the presence of which a mixture of n-propylbenzene (11), n-pentylbenzene (12), 3-phenylpentane (13) and 3-phenylheptane (14) is produced from ethene and toluene. On the replacement of lithium by sodium or potassium, only 11 and 13 are obtained. A treatment of biphenyl, phenanthrene, trans-stilbene, pyrene and anthracene with alkali metals in THF also gives systems capable of catalyzing the alkylation of toluene with ethene at 22 C. Of particularly active is the stilbene_lithium system (Li:stilbene = 3:1) which converts toluene into a mixture of 11_14, n-heptylbenzene and 5-phenylnonane in a yield of 58%. In all cases, the rate of the alkylation considerably increases in the presence of the solid phase of alkali metal.The mechanism of the reactions found is discussed.