The only way of mastering any topic in Organic Chemistry is doing lots of practice problems. And I know, seeing my students, that starting to work on a practice problem may be the hardest part as you don’t know where to start. It is difficult to visualize what where the double bond would be moved if you follow the five curved arrows crammed in one step. Here is the trick:
We are always told to think before doing something. Fair enough. But let me tell you, it is also strangely enough, that in Organic Chemistry, it is often better to draw and then think about what you did (not in the lab though). It is much easier to have a structure in front of you and check for errors and improvements.
Do the first step, take the pencil and you will see that the ball gets rolling.
You have all these Organic Chemistry Practice Problems waiting to be solved!
We have seen, in the alpha halogenation and aldol condensation reactions, that enolates are good nucleophiles capable of attacking halogens and carbonyl groups. In addition to these, enolates can also be alkylated when reacted with alkyl halides via the SN2 mechanism: … Read more
If a compound has two carbonyl groups (dicarbonyl compound), it undergoes an intramolecular aldol reaction if a five- or six-membered ring can be formed: What happens is one of the carbonyls is deprotonated at the ɑ position, thus … Read more
Carboxylic acids with α-hydrogen atoms can be brominated in the presence of catalytic amounts of phosphorus (or a phosphorus tribromide), forming α-bromo carboxylic acids. This is known as the Hell–Volhard–Zelinski (or HVZ) reaction: Now, let’s understand how this happens. First, … Read more
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
