Redox catalysis in a ball mill Mixing solid reactants in a ball mill is a promising means of avoiding the copious solvent waste associated with most chemical syntheses. Kubota et al. now report that adding a piezoelectric catalyst to the mix can promote bond formation through apparent electron transfer cycles (see the Perspective by Xia and Wang). Specifically, barium titanate activates aryl diazonium salts toward borylation and coupling with heterocycles in a manner reminiscent of solutionphase photoredox catalysis. The reactions are insensitive to air and were demonstrated up to gram scale. Science, this issue p. 1500; see also p. 1451 A piezoelectric material appears to act as an electron-transfer catalyst to activate aryl diazonium salts under solid-state agitation. Over the past decade, photoredox catalysis has harnessed light energy to accelerate bond-forming reactions. We postulated that a complementary method for the redox-activation of small organic molecules in response to applied mechanical energy could be developed through the piezoelectric effect. Here, we report that agitation of piezoelectric materials via ball milling reduces aryl diazonium salts. This mechanoredox system can be applied to arylation and borylation reactions under mechanochemical conditions.

中文翻译：

---

使用球磨和压电材料的小有机分子的氧化还原反应

球磨机中的氧化还原催化 在球磨机中混合固体反应物是避免与大多数化学合成相关的大量溶剂浪费的有前途的方法。久保田等人。现在报告说，在混合物中添加压电催化剂可以通过明显的电子转移循环促进键的形成（参见 Xia 和 Wang 的观点）。具体而言，钛酸钡以类似于液相光氧化还原催化的方式激活芳基重氮盐进行硼酸化并与杂环偶联。该反应对空气不敏感，并被证明达到克级。科学，这个问题 p。1500；另见第。1451 一种压电材料似乎作为电子转移催化剂在固态搅拌下激活芳基重氮盐。在过去的十年，光氧化还原催化利用光能来加速成键反应。我们假设可以通过压电效应开发一种补充方法，用于响应施加的机械能而氧化还原小有机分子。在这里，我们报告了通过球磨搅拌压电材料可以减少芳基重氮盐。该机械氧化还原系统可应用于机械化学条件下的芳基化和硼化反应。