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!
What is a substitution reaction? In a substitution reaction, one atom (or a functional group) replaces another one. The replacing group is called a “nucleophile,” and the group being kicked out is called a “leaving group.”: These reactions … Read more
The nomenclature of alkyl halides follows the same IUPAC rules that we discussed for naming alkane. The only difference here is that one (or more) of the substituents is a halogen, and its naming is a little modified. Let’s first … Read more
Alkyl halides are molecules in which a halogen is bonded to an sp3 hybridized carbon atom. They are classified into Primary, Secondary, and Tertiary Alkyl Halides, which are especially important in nucleophilic substitution and elimination reactions. To distinguish between a primary, secondary, … Read more
E1 reactions are stereoselective – that is, when a cis or a trans alkene can be formed, the trans isomer is generally the major product: This selectivity can be explained by simply comparing the stability of alkenes. Remember, … Read more
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
