Overview of Organic Reactions (and Electrophilic Addition Reactions)

what are four types of organic reactions?

1. Addition reaction

2. Elimination reaction

3. Substitution reaction

4. Rearrangements

what is a nucleophile?

• has high electron density

• is attracted to an electrophile

• donates electron pair to electrophile

• acts as a Lewis base

what makes a stronger nucleophile?

• has a full negative charge

• has more localized lone pairs (less resonance)

• is more polarizable (electron cloud is more able to distort from an external influence) → larger atoms are more polarizable

• π bonds are not very nucleophilic if they are spread out via resonance

what is an electrophile?

• low electron density

• accepts an electron pair from nucleophile

• acts as a Lewis acid

• has either a partial positive charge or an empty p orbital to accept electron density

what are the four mechanism patterns?

1. Proton transfer

2. Nucleophilic attack

3. Loss of leaving group

4. Rearrangements

• nucleophiles can be negatively charged or ___

• electrophiles can be positively charged or ___

neutral

what is Markovnikov’s Rule?

in the addition of H-X to an alkene, the more substituted carbocation is formed as the intermediate (the H goes to the C w/ fewer substituents) rather than the less substituted carbocation

what is the order of carbocation stability? what are inductive effects?

• tertiary > secondary > primary >> methyl

• inductive effects: alkyl groups donate electron density to stabilize the carbocation (coming from sigma bond b/t C and carbocation)

what is hyperconjugation?

neighboring electrons in a sigma bond can donate into the p orbital of the carbocation to stabilize it (from an orbital perspective)

• they are not fully transferring, but just helping to stabilize

• no movement, just overlap

what happens if both carbocations are equally substituted?

there is no way to distinguish, so the result is a mixture of constitutional isomers as products

the more stable carbocation leads to the ___ product

major

whenever a carbocation forms, what do we do?

evaluate whether it can rearrange to a more stable carbocation

• can be a hydride shift or a methyl shift

• generally a mixture of products is observed w/ the product from the more substituted carbocation usually being the major product