Basic doubts related to organic chemistry

Basic doubts related to organic chemistry (selectivity and stability)

Dear students, 

As per your request i  am posting  few definition and facts: 

• Chemo selectivity: Which  functional group will react. 
•  Regio selectivity: Where it will react.
• Stereo selectivity: How it will react (stereo chemistry of the product)

Let me explain them further as per the specific cases.

• If we have a substrate containing two functional group i.e carbonyl and acid derivative.Clemmsen reduction will only take place at carbonyl group, we can here use the term Chemo selectivity.
• If we have C=C in conjugation with C=O then a nucelophile can attack at  one of the double bond depending on  reaction conditions. this is categorized in Regio selectivity.
• Stereo selectivity :this is important issue in alkyl halide reactions where generally primary alkyl halide undergoes inversion of configuration with suitable nucelophile i.e Sn2 reaction but if it tertiary alkyl halide then recimization takes place i.e Sn1 reaction . This is important concept of alkyl halide.

other cases

• If  substrate has two site one  is double bond and the other one  be triple bond. If we go for Electrophilic addition reaction then  Electrophile   will attack on double bond not on triple bond.Reason behind  is the double bond is more reactive than  a triple bond .If we look into reaction mechanism, then the Electrophile (reagent) has  done  SELECTIVITY i.e it preferred the double over the triple bond due to stability of carbocation.

Stability of carbocation. 

• tertiary carbocation>benzylic carbocation>allylic carbocation>secondary carbocation>primary carbocation.

Stability of free radicals. 

• Secondary allylic radical>benzylic radical> /=primary allylic radical>tertiary radical>secondary radical>primary radical.