The Basics

Abstract

If science is a language that is used to describe the universe, then Lewis structures— the sticks, dots, and letters that are used to represent organic compounds—are the vocabulary of organic chemistry, and reaction mechanisms are the stories that are told with that vocabulary. As with any language, it is necessary to learn how to use the organic chemistry vocabulary properly in order to communicate one’s ideas. The rules of the language of organic chemistry sometimes seem capricious or arbitrary; for example, you may find it difficult to understand why RCO₂Ph is shorthand for a structure with one terminal O atom, whereas RSO₂Ph is shorthand for a structure with two terminal O atoms, or why it is so important that ↔ and not ⇄ be used to indicate resonance. But organic chemistry is no different in this way from languages such as English, French, or Chinese, which all have their own capricious and arbitrary rules, too. (Have you ever wondered why I, you, we, and they walk, but he or she walks?) Moreover, just as you need to do if you want to make yourself understood in English, French, or Chinese, you must learn to use proper organic chemistry grammar and syntax, no matter how tedious or arbitrary it is, if you wish to make yourself clearly understood when you tell stories about (i.e., draw mechanisms for) organic reactions. The first section of this introductory chapter should reacquaint you with some of the rules and conventions that are used when organic chemistry is “spoken.” Much of this material will be familiar to you from previous courses in organic chemistry, but it is worth reiterating.