Khan Academy
Khan Academy: Cyclic Hemiacetals and Hemiketals
Provides a discussion of cyclic hemiacetals and hemiacetals and how they are formed.
Other
Frostburg State University: Organic Chemistry Help
This site is designed to be a supplement for students of organic chemistry. Its tutorials and self-grading tests are interactive and extremely helpful.
CK-12 Foundation
Ck 12: Functional Groups
[Free Registration/Login may be required to access all resource tools.] In this module, students explore functional groups and their importance to organic chemistry. They relate the properties of organic compounds to their structures and...
Wolfram Research
Wolfram Science World: Organic Chemistry
This site from ScienceWorld provides a brief look at some of the more common organic functional groups. The carboxylic acid group is also given. Quite a few links are provided at the bottom of the page for additional information.