CH610B Sophomore Organic II

Dr. Brian Pagenkopf

All nucleophiles add to aldehydes the same way!

Four addition reactions to aldehydes and ketones. In each case, the nucleophilic site of the molecule (electron rich, red or orange color) interacts with the carbonyl carbon atom that has a partial positive charge (blue color). Note that in the case of CN- and the Grignard reaction it is not so obvious which nucleophilic site reacts with the carbonyl. Each has more than one partial negative charge. The site that reacts is not always the one with the most electron density, it is the one that can form the most stable bond. Reactions need a motive to react, namely stable products (lower in energy than starting materials) as well as the opportunity (nucleophile reacts with electrophile). In the case of the Grignard and CN- reaction, the more stable bonds by far are the carbon-carbon bonds, so these are what form in the reactions.

Sources http://www.cm.utexas.edu/academic/courses/Spring2001/CH610B/Iverson/index.html