Radical intermediates in organic chemistry lack a full octet of electrons and, thus, are commonly said to be electron deficient. By denotation, such a statement is technically correct; however, in modern literature, the term ‘electron deficient’ carries a connotation of electrophilicity. This lexical quirk leads one to predict that all radicals should behave as electrophiles, when this is not the case. Indeed, practitioners of radical chemistry have known for decades that many radicals behave as nucleophiles, sometimes strongly so. This Review aims to establish guidelines for understanding radical philicity by highlighting examples from recent literature as a demonstration of general reactivity paradigms across a series of different carbon-based and heteroatom-based radicals. We present strategies for predicting the philicity of a given radical on the basis of qualitative features of the radical’s structure. Finally, we discuss the implications of radical philicity to selective hydrogen atom transfer.

有机化学中的自由基中间体缺少完整的八位电子，因此通常被称为缺电子。通过外延，这样的陈述在技术上是正确的；然而，在现代文学中，“缺电子”一词带有亲电性的含义。这种词汇上的怪癖导致人们预测所有的自由基都应该表现得像亲电试剂，但事实并非如此。事实上，几十年来自由基化学的实践者都知道许多自由基表现为亲核试剂，有时甚至是强烈的。本综述旨在通过突出近期文献中的示例作为一系列不同的碳基和杂原子基自由基的一般反应范式的证明，来建立理解自由基亲和性的指南。我们提出了根据部首结构的定性特征预测给定部首亲和性的策略。最后，我们讨论了亲自由基对选择性氢原子转移的影响。