At present, biodiesel remains an untapped fuel source while crude oil reserves are being depleted. Extensive efforts are necessary to achieve efficient biodiesel production, but catalytic activity in methyl palmitate production remains unsatisfactory. In this study, we report the synthesis and organocatalyst activity of C‐arylcalix[4]‐2‐methylresorcinarene sulfonic acids for biodiesel production. The presence of a methyl group on an aromatic ring is expected to disturb the intramolecular hydrogen bonds; thus, each hydroxyl group could be utilized for the catalytic process. C‐arylcalix[4]‐2‐methylresorcinarene sulfonic acids were prepared from cyclocondensation and sulfonation reactions yielding compounds 1–6 at rates of 66.7%–86.6%. By evaluating the organocatalytic activity of the C‐arylcalix[4]‐2‐methylresorcinarene sulfonic acids, we found that 4 mol% of compound 5 exhibited the highest yield (97.8%) of methyl palmitate at 338 K for 6‐h reaction time, which is remarkable. These findings show that C‐arylcalix[4]‐2‐methylresorcinarene sulfonic acids are promising heterogeneous catalyst materials for biodiesel production.

中文翻译：

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基于C-芳基杯[4] -2-甲基间苯二甲磺酸磺酸材料的生物柴油生产中有机催化剂活性的初步研究

目前，在原油储备枯竭的情况下，生物柴油仍是未开发的燃料来源。为实现有效的生物柴油生产需要付出大量的努力，但是棕榈酸甲酯生产中的催化活性仍然不能令人满意。在这项研究中，我们报告了用于生物柴油生产的C- arylcalix [4] -2-甲基间苯二甲磺酸磺酸盐的合成和有机催化剂活性。预期芳环上甲基的存在会干扰分子内的氢键；因此，每个羟基都可用于催化过程。Ç -arylcalix从环化缩合和磺化反应，得到化合物制备[4] -2-methylresorcinarene磺酸1 - 6的比率为66.7％–86.6％。通过评估C- arylcalix [4] -2-甲基间苯二甲磺酸的有机催化活性，我们发现4 mol％的化合物5在338 K下反应6 h时，棕榈酸甲酯的最高收率（97.8％），这很了不起。这些发现表明，C-芳基杯[4] -2-甲基间苯二甲磺酸是有前途的生物柴油生产的多相催化剂材料。