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!
The E1 is a stepwise, unimolecular – 1st order elimination mechanism: The first, and the rate-determining step, is the loss of the leaving group, forming a carbocation which is then attacked by the base: This is … Read more
Consider these E2 elimination reactions. For both, the β hydrogens are on the right side of the Br, and as expected, that’s where the double bond appears in the product: So, no problems with the regiochemistry of these … Read more
E2 reactions are stereoselective. Let’s understand the meaning of this statement by looking at the following elimination reaction: Two stereoisomers are formed – a cis and a trans alkene. The trans alkene is the major product, and this … Read more
Zaitsev’s Rule Suppose you have this alkyl halide and need to determine all the products of an E2 reaction when it is treated with a strong base such as sodium ethoxide. Remember in E2 reactions, we’re first going … Read more
E2 is the most common elimination mechanism. The “2” indicates that both the alkyl halide and the base participate in the rate equation. This is somewhat similar to the SN2 mechanism: Notice that the beta hydrogen and the bromine … Read more
What are the Fischer Projections? Fischer projections are just another way of drawing compounds containing chiral centers. They were initially proposed by Emil Fischer for making it easier to draw the structures of compounds containing multiple chiral centers, with the … Read more
In my teaching experience, I have noticed that conveying the message about meso compounds is a lot easier when Fischer projections are used. So, we will talk about it by drawing the Fischer projections of three isomers of 2,3-dichlorobutane: … Read more
Check Also in Stereochemistry: Enantiomeric excess (ee) Stereoisomerism Chirality and Enantiomers The R and S system to label chiral centers Diastereomers Optical Activity Calculating Enantiomeric Excess from Optical Activity Symmetry and Chiralty. Meso Compunds Fischer projection
When we learned about enantiomers, we mentioned that they have identical physical properties – melting point, boiling point, and solubility. So, one question you may wonder about is how we distinguish enantiomers if they all seem to be identical. Yes, … Read more
