Claisen
Hazard to Self
Posts: 70
Registered: 10-12-2010
Member Is Offline
Mood: No Mood
|
|
Benzyne Mechanism
What is the major product obtained when meta bromo anisole is treated with KNH2 in liquid NH3
[img] http://u.spig.in/forum/65223072.jpg [/img]
[img] http://u.spig.in/forum/65223268.jpg [/img]
Notice the change in the position of the double bonds.
I have a confusion. According to me it should depend on the structure given.
P.S. How do I insert a subscript/superscript ?
|
|
|
Nicodem
Super Moderator
Posts: 4230
Registered: 28-12-2004
Member Is Offline
Mood: No Mood
|
|
Check DOI:10.1016/S0040-4020(02)01563-6. There should be something on regioselectivity of benzyne formation and nucleophilic addition, but I don't have
the time to read that.
|
|
|
Claisen
Hazard to Self
Posts: 70
Registered: 10-12-2010
Member Is Offline
Mood: No Mood
|
|
That is a paid site.
I have a book which explains the regioselectivity but it does not say anything about major/minor product.
|
|
|
DDTea
National Hazard
Posts: 940
Registered: 25-2-2003
Location: Freedomland
Member Is Offline
Mood: Degenerate
|
|
Looking at this, I'm really tempted to say that m-methoxyanisole ought to be the major product because a) it forms from both pathways and b)
it is the major product in one of those pathways. Of course, this assumes a 50/50 split at the beginning regarding the location of the benzyne triple
bond.
"In the end the proud scientist or philosopher who cannot be bothered to make his thought accessible has no choice but to retire to the heights in
which dwell the Great Misunderstood and the Great Ignored, there to rail in Olympic superiority at the folly of mankind." - Reginald Kapp.
|
|
|
TheOrbit
Hazard to Self
Posts: 59
Registered: 4-4-2009
Location: deepth point of a black hole
Member Is Offline
Mood: manic bipolar science dis/order
|
|
-OCH3 by mesomeric effect place -ve charge on O- & P- so it hinder the attack of the -ve NH2 on this position make m- more stable
[img] http://img254.imageshack.us/img254/5039/37404454.jpg [/img]
|
|
|
DDTea
National Hazard
Posts: 940
Registered: 25-2-2003
Location: Freedomland
Member Is Offline
Mood: Degenerate
|
|
Orbit, that drawing and explanation are great, but it's m-bromoanisole undergoing this reaction. Only the ortho and para position are adjacent to the
bromide-subsituted carbon. Which proton would be preferentially attacked by -NH2?
"In the end the proud scientist or philosopher who cannot be bothered to make his thought accessible has no choice but to retire to the heights in
which dwell the Great Misunderstood and the Great Ignored, there to rail in Olympic superiority at the folly of mankind." - Reginald Kapp.
|
|
|
TheOrbit
Hazard to Self
Posts: 59
Registered: 4-4-2009
Location: deepth point of a black hole
Member Is Offline
Mood: manic bipolar science dis/order
|
|
DDTea , we apply the same principle of O- , P- -ve charge . so m- NH2 will be preferable
|
|
|
Claisen
Hazard to Self
Posts: 70
Registered: 10-12-2010
Member Is Offline
Mood: No Mood
|
|
I too think that meta product will be major.
Actually my book says that ortho is the major & para is minor but now I believe that its wrong.
|
|
|
spirocycle
Hazard to Others
Posts: 197
Registered: 29-9-2010
Member Is Offline
Mood: No Mood
|
|
^call the publishing company and you can get some cash
|
|
|
Claisen
Hazard to Self
Posts: 70
Registered: 10-12-2010
Member Is Offline
Mood: No Mood
|
|
lol I will 
|
|
|
Nicodem
Super Moderator
Posts: 4230
Registered: 28-12-2004
Member Is Offline
Mood: No Mood
|
|
Quote: Originally posted by Claisen  | That is a paid site.
I have a book which explains the regioselectivity but it does not say anything about major/minor product. |
Scientific books have references, so check the reference!
I also gave you a reference for a review paper, yet you did not even bother checking it. I find your "That is a paid site" excuse offensive, because
we are all in the same boat and someone has to get it in some way or the other, either via proxy servers, VPN's or by going to the library. Find it here.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
