All the aldol reactions we discussed so far were between identical partners, meaning the same carbonyl compound served as an electrophile and a nucleophile in the form of an enolate: An aldol reaction between two different carbonyl compounds … Read more
We have seen that the product of the aldol reaction is a β-hydroxy carbonyl compound: One can look at it as an alcohol, and what is interesting about this alcohol is that it undergoes an elimination when heated … Read more
We have seen, in the halogenation of aldehydes and ketones, that enolates are quite good nucleophiles: This reaction shows that the ɑ position of a carbonyl compound is a potential nucleophilic site. So, keep this in mind and remember … Read more
Ketones and aldehydes react with halogens at the alpha position when an acid or a base catalyst is used. The halogenation works with Cl2, Br2, and I2: Let’s start discussing the mechanism of the acid-catalyzed halogenation. The reaction … Read more
This is a comprehensive practice problem on the alpha carbon/enolate chemistry. The topics covered range from the simple halogenation reactions of enols to multistep synthetic transformations. To correctly answer these questions, you need to review the main principles of enolate … Read more
In the previous post, we talked about the Claisen condensation reaction and went over the mechanism as well as some details regarding the importance of at least two α hydrogens. Check those if you need to, before working on the … Read more
In the previous post, we learned that the crossed aldol condensation is the aldol reaction between two different carbonyl compounds. This is also known as a mixed aldol reaction. Crossed aldol reactions have the advantage of controlling which carbonyl compound serves … Read more
In the previous post, we discussed the acetoacetic ester synthesis, which is a method for preparing substituted methyl ketones via alkylation of the acetoacetic ester followed by hydrolysis and decarboxylation. Below are some practice problems on the acetoacetic ester synthesis … Read more
In the previous post we discussed the alkylation reactions of enolates, which are one of the most important transformations in carbonyl chemistry. Enolates are typically formed from carbonyl compounds, but they are not limited to aldehydes and ketones. Similar enolate-type … Read more
In the previous two posts, we went over the introduction, mechanism of aldol reaction and its difference from the aldol condensation. There are also shortcuts discussed there that you can use to work on the following practice problems.
