Preface

Why another organic chemistry textbook?

McMurry's Organic Chemistry — the tenth edition, revised by leading chemists worldwide — is now free. It is an excellent book, and its existence changed what is worth writing.

Until recently, a major reason to write an organic chemistry textbook was the $300 price tag attached to the competition. If a student had to choose between paying for McMurry, Wade, Klein, or Solomons, there was real value in offering a free alternative of comparable quality. That reason no longer applies. McMurry OpenStax is free, rigorous, and readable. Competing with it on those terms would mean writing the same book without the reputation of the original — a losing strategy.

So the question becomes: what would make a new organic chemistry textbook different enough to justify writing in 2026?

The problem we are trying to solve

The standard organic chemistry textbook — McMurry, Wade, Klein, Solomons, Bruice, Carey — organizes its content by functional group. Chapter 10 is "Alkenes." Chapter 16 is "Aldehydes and Ketones." Chapter 22 is "Carboxylic Acids." Students learn two hundred or more reactions, organized by what type of molecule is involved.

The result, for most students, is memorization. They memorize two hundred reactions for the exam, forget them after, and never develop the ability to predict reactivity for a molecule they have never seen. The second-semester organic professor who asks "and what would happen if you treated this unfamiliar compound with lithium diisopropylamide?" is met with silence, even from students who earned A's the first semester. The skill of thinking through a mechanism has not been built, because the course was optimized for something else.

There is a better way.

A different organization

This book is organized by mechanism. Nucleophilic addition is one chapter, not fifteen. Once you understand how a nucleophile attacks an electrophilic carbon — what happens to the electrons, what the geometry of the transition state looks like, what controls the rate — you can predict what happens when any nucleophile meets any electrophilic carbon, whether the carbon is part of an aldehyde, a ketone, an ester, an acid chloride, a Michael acceptor, or a carbocation.

The mechanism-first approach is not new. David Klein's Organic Chemistry uses a skills-based framework that moves in this direction. Clayden, Greeves, and Warren's Organic Chemistry — the British standard — is mechanism-first and revered by chemists. Both are excellent. Neither is free.

This book takes the best of both and makes it free under Creative Commons.

Five things we do that standard textbooks do not

  1. Mechanism-first organization. Chapters are structured by reactivity principles — nucleophilic addition, electrophilic addition, elimination, radical substitution, pericyclic, oxidation, reduction — not by functional group catalogs. Functional groups appear as consequences of the electronic structure that drives the mechanism.

  2. Skills-based, not content-based. Every chapter builds a thinking tool. The $S_{N}2$/$S_{N}1$/$E2$/$E1$ decision framework of Chapter 13 is not a fact to memorize but a diagnostic procedure the student will use for the rest of the book. The retrosynthetic analysis of Chapter 31 is not a topic but a skill the student is rehearsing every chapter from Chapter 14 onward.

  3. Computational chemistry integrated from the start. We use free software — Avogadro for molecular modeling, WebMO or GAMESS for energy calculations — so students see what they are learning. Build a molecule, compute the HOMO, predict where a nucleophile will attack, then watch the reaction happen. This costs nothing and replaces hand-waving with empirical validation.

  4. Biology threaded through every chapter. Instead of one biochemistry chapter at the end that most courses never reach, every chapter has a Biological Connection that shows the same mechanism happening in metabolism, drug action, or biosynthesis. Organic chemistry is the chemistry of life. We refuse to hide that fact.

  5. Spectroscopy as a continuous storyline. Infrared spectroscopy and mass spectrometry enter in Chapter 6. NMR enters in Chapter 9. From there onward, every chapter uses spectra as problem-solving tools — here is a spectrum of your product, what is the structure? — rather than saving them for two crammed chapters near the end that students face with dread.

Who this book is for

Undergraduate students in the two-semester organic chemistry sequence: pre-med, pre-dental, pre-pharmacy, biology majors, chemistry majors, biochemistry majors, chemical-engineering students, and materials-science students. You have finished one year of general chemistry. You are now facing the course that is widely considered the hardest in the undergraduate science curriculum. This book is for you if you want to understand organic chemistry rather than merely survive it.

Three things this book is not:

  • It is not a compressed review. It is a full two-semester textbook with the depth a good course requires. Expect 8,000 to 12,000 words per chapter and substantial exercise sets.
  • It is not an easier organic chemistry. Organic chemistry is hard, and nothing in this book pretends otherwise. We believe the difficulty is real and worthwhile, but we also believe the difficulty lies in building new intuition, not in memorizing large volumes. The book is organized to help you build that intuition.
  • It is not a laboratory manual. Lab technique, running reactions, and synthetic procedures belong in a separate resource tailored to your institution's equipment and safety protocols.

How we use this book's recurring structure

Six repeating callouts appear throughout every chapter. Each has a specific purpose — learn to recognize them, and the book becomes easier to navigate:

Mechanism Map: A conceptual diagram showing how a mechanism principle applies across multiple functional groups. When you see this, ask yourself: what is the pattern here, and where else have I seen it?

Worked Problem: A problem solved step by step, with the reasoning explicit. These are not optional. Work through them with a pencil in hand.

Biological Connection: The same mechanism happening in a cell. These are not asides — they are half of what makes organic chemistry worth learning.

Computational Exercise: A short activity in Avogadro, WebMO, or GAMESS. The software is free; the experience of seeing an orbital is irreplaceable.

Spectroscopy Clue: How to recognize this functional group or reaction in a spectrum. These callouts accumulate into a practical diagnostic toolkit.

Common Mistake: An error students often make, what goes wrong mechanistically, and how to avoid it. These are the product of many office-hours conversations with many students.

On the voice of this book

We try to write the way a good professor teaches: clearly, warmly, without condescension, and without flattery. You will not find passages that promise this will be easy. You will not find passages that tell you how smart you are for reading them. You will find passages that take the difficulty seriously and lay out the path through it.

If something is confusing, it is probably our fault, not yours. Open an issue on the repository and we will try to rewrite it.

A request

This book is free under Creative Commons. Anyone can copy it, adapt it, translate it, reuse it, or build on it. What we ask in return is simple: if you find an error, tell us. If you find a better way to explain something, send the improvement. The repository is on GitHub. The license is CC-BY-SA-4.0. The book belongs to everyone who uses it.

Welcome to organic chemistry.

— The Open Organic Chemistry Project 2026