Thermal, Catalytic Conversion of Alkanes to Linear Aldehydes and Linear Amines

Abstract

Alkanes, the main constituents of petroleum, are attractive feedstocks for producing value-added chemicals. Linear aldehydes and amines are two of the most important building blocks in the chemical industry. To date, there have been no effective methods for directly converting n-alkanes to linear aldehydes and linear amines. Here, we report a molecular dual-catalyst system for production of linear aldehydes via regioselective carbonylation of n-alkanes. The system is comprised of a pincer iridium catalyst for transferdehydrogenation of the alkane using t-butylethylene or ethylene as a hydrogen acceptor working sequentially with a rhodium catalyst for olefin isomerization-hydroformylation with syngas. The system exhibits high regioselectivity for linear aldehydes and gives high catalytic turnover numbers when using ethylene as the acceptor. In addition, the direct conversion of light alkanes, npentane and n-hexane, to siloxy-terminated alkyl aldehydes through a sequence of Ir/Fe-catalyzed alkane silylation and Ir/Rhcatalyzed alkane carbonylation, is described. Finally, the Ir/Rh dual-catalyst strategy has been successfully applied to regioselective alkane aminomethylation to form linear alkyl amines.

n -Alkanes to n -alcohols: Formal primary C─H bond hydroxymethylation via quadruple relay catalysis

“…In addition to n-alkanes, the alkyl chains of aryl-substituted alkanes with dimethyl substitution at the benzyl position underwent the terminal-selective hydroxymethylation (5g to 5i). Substitution of the benzyl H atoms is essential because it prevents the formation of styrene derivatives, which are reluctant toward the ISO because of thermodynamic reason (32). Consistent with the observed selectivity in the reactions with n-alkanes, the shorter alkyl chain (5g, >50 n/i) afforded a higher linear selectivity than the longer chains (5h, n/i: 26; 5i, n/i: 16).…”

Transition-metal complex-catalyzed alkane functionalization

“…最近, 本课题组 [78] 基于烷烃脱氢反应, 设计了 烷烃先进行脱氢, 生成的内烯烃混合物经由异构氢 甲酰化反应生成直链醛的策略, 从而实现了从直链 烷烃到直链醛的转化(图4(b)). 在烷烃脱氢步骤还是 使用本课题组 [34] 报道的高活性的PSCOP型铱催化剂 3.…”

“…在第二步铑催化烯烃异构氢甲酰化的配体筛选中, 我 们 发 现 美 国 联 合 碳 化 公 司 发 展 的 biphephos 配 体 [90,91] 在脱氢后的体系中可以兼容, 表现较好直链 选择性, 同时产率优秀. 以此为最佳配体, 对底物的 [78] . 乙烯作为比叔丁基乙烯更便宜也更实用的氢气 接收体, 在该体系中也得到应用.…”

“…乙烯作为比叔丁基乙烯更便宜也更实用的氢气 接收体, 在该体系中也得到应用. 在正辛烷转化成正 壬醛的反应中, 我们 [78] 以乙烯为氢气接收体, 在最 优条件下, 对于铱和铑的催化TON可以分别达到577 和1110.…”

“…原料制备直链胺化合物的反应. 通过对反应条件的 考察, 发现Beller课题组 [92,93] [78] . Figure 4 Terminal selective alkane functionalization via alkane dehydrogenation 3 烷烃复分解和聚乙烯可控降解 早期Burnett和Hughes [94] 报道了在非均相条件下, 以氧化铝负载的铂作为脱氢催化剂, 二氧化硅负载 的氧化钨作为烯烃复分解催化剂, 实现了丁烷的复 分解反应.…”