As of my knowledge cutoff in September 2021, there are several popular organic chemistry MOOCs (Massive Open Online Courses) available. It’s important to note that the “best” MOOC for organic chemistry may vary depending on your learning style, preferences, and background knowledge. However, here are a few highly regarded organic chemistry MOOCs:

1. “Introduction to Chemical Science” (Harvard University): This introductory course covers various topics, including organic chemistry. It provides a solid foundation in the principles and techniques of chemistry. The course is offered through edX.

1. “Principles of Organic Chemistry” (University of Illinois at Urbana-Champaign): This course covers the fundamental principles of organic chemistry, including nomenclature, reactions, and spectroscopy. It is available on Coursera.

1. “Organic Chemistry” (University of California, Irvine): This course is designed as an introductory-level organic chemistry course. It covers topics such as molecular structure, reactivity, and reaction mechanisms. It is available on Coursera.

1. “Advanced Organic Chemistry” (University of Tokyo): This course is designed for students who have already completed introductory organic chemistry. It delves into more advanced topics, including synthesis, stereochemistry, and organometallic chemistry. It is available on Coursera.

When choosing a MOOC, it’s beneficial to read the course descriptions, syllabi, and reviews to determine which one aligns with your goals and learning preferences. Additionally, consider factors such as instructor expertise, course format, and any associated costs.