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Organic chemistry butene

  • Thread starter chewchun
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  • #1
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Homework Statement


But-2-ene reacts with bromine in the presence of concentrated aqueous sodium nitrate to give the following compound
CH3-C(H)(ONO2)-C(H)(Br)-CH3

Which of the following statement is correct.
a.the electrophile is NO2+
b.Only 2,3-dibromobutane is formed.
c.Resultant solution shows optical activity.
d.Mechanism involves an initial electrophilic attack followed by nucleophilic attack

Homework Equations





The Attempt at a Solution


I know that B is out cause you can have -Br and -OH instead of just 2-Br.
C is also out because the compound can be attacked from both side(Trigonal planar)
A or D is correct.D makes sense to me but isnt NO2+ a electrophile. In this case i would presume NO2+ is somehow formed which attacks OH group....If not what is the case???
 

Answers and Replies

  • #2
AGNuke
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See, the halide molecule also polarize and form halide electrophile, in this case, Br+ can form. NaNO3 cannot give NO2+ ion, as it is obtained by "protonation" of nitric acid, which is not a simple task, considering nitric acid itself is very strong acid. That's what I feel.
 
  • #3
chemisttree
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Name these ions... NO3- and NO2+

Which one is present in your proposed mixture?
 
  • #4
AGNuke
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CH3-C(H)(ONO2)-C(H)(Br)-CH3

Care to elaborate, as chemisttree asked?

UPDATE: I have formed on paper the compound H3C-CH(ONO2)-CHBr-CH3, considering Nitrate group, albeit I am afraid I may have have bent some rules (which looks like the case, forming acid out of aqueous nitrate ions) And I have reached to following answers: C, D.
 
Last edited:
  • #5
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CH3-C(H)(ONO2)-C(H)(Br)-CH3

Care to elaborate, as chemisttree asked?

UPDATE: I have formed on paper the compound H3C-CH(ONO2)-CHBr-CH3, considering Nitrate group, albeit I am afraid I may have have bent some rules (which looks like the case, forming acid out of aqueous nitrate ions) And I have reached to following answers: C, D.
The answer was given to be D only.
The carbon is directly bonded to oxygen,and the oxygen directly bonded to NO2.So it seems to be O- and NO2+???And i presume the O- to be created from a alcohol group and the H+ is removed....
Answer is not C as the compound is trigonal planar and can be attacked from both sides,hence a racemic mixture..
But i don't understand how C(O)(NO2) is formed as it seems impossible to form NO2+ from this reaction....
 
  • #6
AGNuke
Gold Member
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Esterification I guess.
 

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