Starting from common monounsaturated fatty acids, a strategy is revealed that provides ultra-long aliphatic α,ω-difunctional building blocks by a sequence of two scalable catalytic steps that virtually double the chain length of the starting materials. The central double bond of the α,ω-dicarboxylic fatty acid self-metathesis products is shifted selectively to the statistically much-disfavored α,β-position in a catalytic dynamic isomerizing crystallization approach. “Chain doubling” by a subsequent catalytic olefin metathesis step, which overcomes the low reactivity of this substrates by using waste internal olefins as recyclable co-reagents, yields ultra-long-chain α,ω-difunctional building blocks of a precise chain length, as demonstrated up to a C₄₈ chain. The unique nature of these structures is reflected by unrivaled melting points (T_m=120 °C) of aliphatic polyesters generated from these telechelic monomers, and by their self-assembly to polyethylene-like single crystals.

中文翻译：

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脂肪酸的链增倍形成精确的螯螯状聚乙烯

从常见的单不饱和脂肪酸开始，揭示了一种策略，该策略通过两个可扩展的催化步骤的序列提供超长的脂肪族α，ω-双官能结构单元，实际上使起始原料的链长加倍。在催化动态异构化结晶方法中，α，ω-二羧酸脂肪酸自复分解产物的中心双键选择性地转移到统计学上非常不利的α，β-位置。通过随后的催化烯烃复分解步骤进行“链加倍”，该步骤通过使用废弃的内部烯烃作为可回收的共试剂克服了这种底物的低反应性，从而产生了具有精确链长的超长链α，ω-双官能团，如C _48所示链。这些结构的独特性质反映在由这些远螯单体产生的脂肪族聚酯的无与伦比的熔点（T _m = 120°C）以及它们自组装成聚乙烯状单晶的过程中。