Abstract The synthesis of protic ionic liquids based in carboxylate anions, too often admitted as being straightforward, is actually challenging and must be carefully addressed. This review discusses the importance of oligomeric anions, in particular those based on carboxylates, in the behavior and nature of protic ionic liquids. There is strong evidence in the literature that the synthesis, and subsequent purification, of protic ionic liquids involving carboxylic acids, leads to structures in the liquid phase with an acid:base proportion different from the expected 1:1 stoichiometry. The formation of the oligomeric anions, mostly dependent on the proton transfer from the Bronsted acid to the Bronsted base, may lead to a higher ionicity that suggests the formation of a more ionic liquids. It is here stressed the relevance of deepening the understanding of the interactions between the species and the speciation of the liquid phase, combining experimental and theoretical approaches to establish foundations for insightful advances in the area.

中文翻译：

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低聚阴离子对质子离子液体形态的影响

摘要 基于羧酸根阴离子的质子离子液体的合成通常被认为是简单的，但实际上具有挑战性，必须仔细解决。这篇综述讨论了低聚阴离子，特别是那些基于羧酸盐的阴离子在质子离子液体的行为和性质中的重要性。文献中有强有力的证据表明，涉及羧酸的质子离子液体的合成和随后的纯化导致液相中的结构具有不同于预期的 1:1 化学计量比的酸:碱比例。低聚阴离子的形成，主要依赖于从布朗斯台德酸到布朗斯台德碱的质子转移，可能导致更高的离子性，这表明形成了更多离子液体。