Integrated SequencePhysics Chemistry Organic Biology

Web Resources

Virtual Textbook of Organic Chemistry - Hydration and Hemiacetal Formation

Virtual Textbook of Organic Chemistry - Acetal Formation

Purdue University - Nucleophilic Attack by an Alcohol
Good coverage of the mechanism with some nice supplementary discussion of the importance of hemiacetal and acetal formation in biochemistry.

  click if a link is broken

Special points of emphasis

Chemical Kinetics

Organic Acids and Bases

Reactions of Aldehydes and Ketones

Acid catalysis occurs twice in acetal formation. First, the carbonyl group is activated for nucleophilic attack by protonation, and, later, the hydroxyl group of the tetrahedral intermediate is protonated, making it a better leaving group.

This is the kind of little fact that isn't so much in itself, but is really helpful for remembering the mechanism. The more networked your knoledge is with associations, the more you will retain the fundamentals.

Reactions of Aldehydes and Ketones


Nucleic Acids

Hemiacetal formation is the mechanism by which pentoses and hexoses assume their cyclic forms. Nucleophilic attack by typically the #4 or #5 carbon's hydroxyl group onto the carbonyl group (the anomeric carbon) of the noncyclic form leads to hemiacetal formation. Another nucleophile can act out the second part of the acetal formation mechanism upon the anomeric carbon forming a mixed acetal, termed a glycoside. The nucleophile may be adenine, guanine, cytosine, thymine, or uracil, in which case the glycoside product is a nucleoside, a fundamental building block of the nucleic acids DNA and RNA. If the nucleophile is another sugar, the process leads to the formation of a disaccharide (or polysaccharide). In other words, disaccharides are glycosides with the nucleophile being another sugar molecule.

The WikiPremed MCAT Course is a free comprehensive course in the undergraduate level general sciences. Undergraduate level physics, chemistry, organic chemistry and biology are presented by this course as a unified whole within a spiraling curriculum.

Please read our policies on privacy and shipping & returns.  Contact Us.
MCAT is a registered trademark of the Association of American Medical Colleges, which does not endorse the WikiPremed Course.

Creative Commons License
The work of WikiPremed is published under a Creative Commons Attribution Share Alike 3.0 License. There are elements of work here, such as a subset of the images in the archive from WikiPedia, that originated as GNU General Public License works, so take care to follow the unique stipulations of that license in printed reproductions. You can use the resources here for commercial or non-commercial purposes, but please give attribution and a link to the production credits and edit history of the resource. For the works here which began as my individual work, please attribute "John Wetzel, an author at".