Room-temperature catalytic fluorination of C1 and C2 chlorocarbons and chlorohydrocarbons on fluorinated Fe3O4 and Co3O4
作者:James Thomson
DOI:10.1039/ft9949003585
日期:——
A study of the room-temperature reactions of a series of C1 and C2 chlorohydrocarbon and chlorocarbon substrate molecules with fluorinated iron (II, III) oxide and cobalt (II, III) oxide has been conducted. The results show that fluorinated iron(II, III) oxide exhibits an ability to incorporate fluorine into the following substrates in the order: Cl2CCCl2 > H2CCCl2 > CH3CCl3 > CHCl3 > CH2Cl2 > CH2ClCCl3 > CCI4 > CHCl2CHCl2. The fluorinated cobalt(II,III) oxide gave the reactivity series CHCl3 > CCl4 > H2CCCl2 > CHCl2CHCl2 > CH2CI2 > CH3CCl3 > CCl2CCl2 > CH2ClCl3. Reactions of C1 chlorohydrocarbon or chlorocarbon probe molecules with fluorinated Fe3O4 gave predominately C1 chlorofluorohydrocarbon and chlorofluorocarbon products, respectively, whereas fluorinated cobalt(II, III) oxide produced predominately C2 chlorofluorohydrocarbon and chlorofluorocarbons. For fluorinated Co3O4 the distribution of C2 products obtained from C1 chlorohydrocarbon precursor molecules is consistent with the formation of radical intermediates at strong Lewis acid surfaces. C2 chlorohydrocarbons exhibit a fluorine for chlorine (F-for-Cl) exchange reaction through the catalytic dehydrochlorination of the substrate to the alkenic intermediate. The F-for-Cl exchange process was dependent upon the ability of the substrate material to undergo dehydrochlorination; the inability of a substrate to undergo dehydrochlorination results in the fluorination process proceeding through the formation of chlorocarbon or chlorohydrocarbon radical intermediates.
对一系列C1和C2氯代烃和氯代碳基底分子室温下与氟化铁(II,III)氧化物和钴(II,III)氧化物的反应进行了研究。结果表明,氟化铁(II,III)氧化物具有将氟引入以下基质的能力,顺序为:Cl2CCCl2 > H2CCCl2 > CH3CCl3 > CHCl3 > CH2Cl2 > CH2ClCCl3 > CCl4 > CHCl2CHCl2。氟化钴(II,III)氧化物给出的反应活性系列为:CHCl3 > CCl4 > H2CCCl2 > CHCl2CHCl2 > CH2Cl2 > CH3CCl3 > CCl2CCl2 > CH2ClCl3。C1氯代烃或氯代碳探针分子与氟化Fe3O4反应分别主要生成C1氯氟烃和氯氟碳产物,而氟化钴(II,III)氧化物主要生成C2氯氟烃和氯氟碳。对于氟化Co3O4,从C1氯代烃前体分子获得的C2产物的分布与在强路易斯酸表面形成自由基中间体一致。C2氯代烃通过催化脱氯化氢生成烯烃中间体,进行氟氯(F-for-Cl)交换反应。F-for-Cl交换过程取决于基质材料进行脱氯化氢的能力;基质不能进行脱氯化氢将导致氟化过程通过形成氯代碳或氯代烃自由基中间体进行。