Isobutylene Reacting w Cl2: Mechanism, Structure, Radioactive Carbon

  • Thread starter Thread starter pardesi
  • Start date Start date
  • Tags Tags
    Mechanism
Click For Summary
SUMMARY

The reaction of isobutylene with Cl2 at 0°C in the absence of light predominantly yields methallyl chloride (3-chloro-2-methyl propene) rather than the addition product. The use of 14C-labeled isobutylene revealed that approximately 97% of the radioactive carbon was found in chloroacetone after ozonolysis. The reaction mechanism is ionic, as the presence of oxygen does not alter product formation. Isobutylene is more reactive than 1-butene due to the presence of a vinylic t-butyl group, which stabilizes the carbocation intermediate.

PREREQUISITES
  • Understanding of organic reaction mechanisms, specifically ionic mechanisms
  • Familiarity with chlorination reactions of alkenes
  • Knowledge of ozonolysis and its applications in organic chemistry
  • Concept of isotopic labeling in chemical reactions
NEXT STEPS
  • Study the mechanism of ionic reactions in organic chemistry
  • Research the effects of substituents on carbocation stability
  • Learn about the process and applications of ozonolysis in organic synthesis
  • Investigate the reactivity of different alkenes with halogens
USEFUL FOR

Chemistry students, organic chemists, and researchers interested in reaction mechanisms and the behavior of alkenes under halogenation conditions.

pardesi
Messages
337
Reaction score
0
it was found that when isobutylene reacts with Cl_{2} under 0^{o}C in the absence of light it gives more methallyl chloride(3-chloro,2-methyl propene) than the addition product.bubbling oxygen through the reaction mixture doesn't affect the product formation.
thsi reaction is carried with labelled iso-butylene with the C-1 labelled as 14C.now the reaction product was made to go through ozonolysis and it was found that the majority of radioactive carbon was present in chloroacetone(about 97%) and very few in formaldehyde.

a)give the structure of methallyl chloride obtained and mention the position of the radioactive carbon.

b)is the reaction ionic or free radical?

c)outline a mechanism

d)suggest a reason why isobutylene is more prone than 1-2-butene?

e)under similar conditions in the presence of oxygen 3,3-dimethyl-1-butene yeilds more addition product but also a small yield of 4-chloro-2,3-dimethyl-1-butene.how do you fit this fact with the mechanism u proposed and also account for the minor product
 
Physics news on Phys.org
any clue anyone
 
What do you think will happen when chlorine reacts with isobutene? Which functionality is reactive with chlorine? The mechanism is either an ionic one or a free radical one. What effect would oxygen have on an ionic reaction? A free radical one? The question states that no change is observed when it is conducted in the presence of oxygen...

For part d), it is helpful to recognize that there is a vinylic t-butyl group in the starting material.
 
yes i got the first two and yes it is an ionic one since oxygen has no effect
about the third i think first the chlorine attacks the double bond and forms the cation and then cation forms the alkene by elimantion...but i can't satisfy myself with the ans of d and e

sorry for not having posted this before:cry:
 
pardesi said:
yes i got the first two and yes it is an ionic one since oxygen has no effect
about the third i think first the chlorine attacks the double bond and forms the cation and then cation forms the alkene by elimantion...but i can't satisfy myself with the ans of d and e

sorry for not having posted this before:cry:

I don't know what 1-2-butene is so I can't help with that one. Correct the nomenclature and you will probably see the answer.

For e), is direct elimination of the addition product's 2-chloro group possible from the adjacent t-butyl group?
 
tahnks
by that i meant 1-butene and 2-butene
 
What mechanism do you propose?
 

Similar threads

Rising Carbon Dioxide Levels Don’t Increase Earth’s Temperature
  • · Replies 28 ·
Replies
28
Views
28K