Isobutylene Reacting w Cl2: Mechanism, Structure, Radioactive Carbon

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Discussion Overview

The discussion centers on the reaction of isobutylene with chlorine (Cl2) under specific conditions, exploring the mechanism, structure of products, and the role of radioactive carbon in the reaction. The scope includes theoretical aspects of organic chemistry, reaction mechanisms, and the influence of reaction conditions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants note that isobutylene reacts with Cl2 to produce more methallyl chloride than addition products, with specific observations regarding the presence of radioactive carbon in chloroacetone.
  • There is a question about whether the reaction proceeds via an ionic or free radical mechanism, with some suggesting it is ionic due to the lack of effect from oxygen.
  • One participant proposes that the chlorine attacks the double bond, forming a cation that subsequently eliminates to form the alkene.
  • Another participant raises the point that the presence of a vinylic t-butyl group in isobutylene may influence its reactivity compared to 1-butene and 2-butene.
  • There is uncertainty regarding the minor product formation in the presence of oxygen and whether direct elimination of the addition product's 2-chloro group is feasible.

Areas of Agreement / Disagreement

Participants generally agree on the initial observations of the reaction products but disagree on the mechanism and the influence of structural factors. The discussion remains unresolved regarding the exact nature of the mechanism and the reasons for the observed product distributions.

Contextual Notes

Participants express uncertainty about the nomenclature and specific details of the reaction products, indicating potential limitations in their understanding of the underlying chemistry.

Who May Find This Useful

Readers interested in organic chemistry mechanisms, reaction conditions, and the effects of molecular structure on reactivity may find this discussion relevant.

pardesi
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it was found that when isobutylene reacts with [tex]Cl_{2}[/tex] under [tex]0^{o}C[/tex] 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
 
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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?
 

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