Question

 

1. How can you tell by looking at the reaction if their will be 2 or 1 products formed.

 

2. Which way will the bond fold? When it is turned into an alkene.

 

3. How can you tell if it's an e1 or e2 reaction? Do I look at what they're mixing the compound with?

Answer 1

Ans 1,3 - In E1 the rate of the reaction depends upon the concentration of the substrate . The first step in volves the ionization of substrate. This is followed by the rapid removal of a proton from the beta carbonby the reagend in the second step. Example- Dehydrohalogenation reactionof alkyl halides by base, Dehydration of alcohols by acids.

E1 is facilitated by -

i) strong polar solvent - To aid ionization

ii) low concentration of base- the grater stabiliy of alkene over the carbocation makes the extraction of proton easy

E2 - When the rate of the reaction is dependent on both the substrate and reagends . Tjis reaction involves both the reactants in the rate deteming step ( RDS ), the reaction occurs in one step in which both the groups (proton and the leaving group) departs simultaneously through the intermediate transition scale . It is visualized that as the base abstract a proton from the beta , simultaneous departure of the nucleophile take place from the alpha carbon . In the transition state the beta C-H and alpha C-X bonds streched on the attack of whith the incipient pi-bond formation.

E2 reaction is facilitated by -

i) branching at alpha and beta - carbons since more stable olefins in formed

ii) strong base of high concentration - since a strong C-H bond has a break.

iii) Solvent of polarity

These are the chr. of elemination reactions E1 and E2 . In this wayyou can easily determine , it is E1 or E2