Diazotisation - A2 Chemistry Watch

allieRAWR!
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Hi, I'm not too confident with this so if I could run over what I think happens, and you could tell me if I'm right and wrong (and where) that's be great. And a few general questions on it at the end. Thanks.

Temperature has to be less then 10 degrees.

Phenylamine is dissolved in HCl and left in a beaker surrouded by ice.
NaN02 that has been left in another beaker of ice is slowly added to the phenylamine mixture.

NaNO2 + HCl --> HONO + NaCl

Then:

HCl + HONO + phenylamine --> http://img.photobucket.com/albums/v7...satan/Salt.jpg + 2H20 + Cl-

(Question: HCl isn't a product of the first equation...does this just come from the original phenylamine/HCl mixture??)

Second Question, I'm confused by this:
http://www.chemguide.co.uk/organicprops/aniline/bdc.gif

Is that a compund between Cl- and the other compund? Is so, would it be acceptable for me to draw it like this instead:

http://img.photobucket.com/albums/v7...atan/Salt2.jpg

And lastly, what happens/ where is the sodium? I'd of thought that might've formed a salt with the Cl-?? Sorry, I found it
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deadgenius
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(Original post by allieRAWR!)
Hi, I'm not too confident with this so if I could run over what I think happens, and you could tell me if I'm right and wrong (and where) that's be great. And a few general questions on it at the end. Thanks.

Temperature has to be less then 10 degrees.

Phenylamine is dissolved in HCl and left in a beaker surrouded by ice.
NaN02 that has been left in another beaker of ice is slowly added to the phenylamine mixture.

NaNO2 + HCl --> HONO + NaCl

Then:

HCl + HONO + phenylamine --> http://img.photobucket.com/albums/v7...satan/Salt.jpg + 2H20 + Cl-

(Question: HCl isn't a product of the first equation...does this just come from the original phenylamine/HCl mixture??)

Second Question, I'm confused by this:
http://www.chemguide.co.uk/organicprops/aniline/bdc.gif

Is that a compund between Cl- and the other compund? Is so, would it be acceptable for me to draw it like this instead:

http://img.photobucket.com/albums/v7...atan/Salt2.jpg

And lastly, what happens/ where is the sodium? I'd of thought that might've formed a salt with the Cl-??
Move the first Cl- next to the benzenediazonium ion, like in the diagram off chemguide. No need for a plus sign.

In green: I think all that is done here is more HCl is added.

In red: I don't know what you're on about lol. the first equation you show clearly has Cl forming a salt with Na. After that, you needn't worry about the Na.
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rincy2890
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hey.. can I ask why is there a need to cool the system in diazotisation?? pls.. answer me... thanks...
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Rubs
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Taken from George Facer, A2 Chemistry, pg 252:

- Phenylamine and concentrated hydrochloric acid are mixed and the mixture is cooled to 5ºC in an ice bath
- A solution of sodium nitrite (cooled to 5ºC is slowly added, making sure that the temperature neither rises above 10ºC nor falls below 5ºC
- The solution is kept at 5ºC and used as necessary
Just stick to drawing the compound how chemguide show it. You don't have to draw in the Cl-. If you draw the compound out you have to make sure that you have the + charge in there, and on the nitrogen attatched to the benzene.

(Original post by rincy2890)
hey.. can I ask why is there a need to cool the system in diazotisation?? pls.. answer me... thanks...
The N2+ is a good leaving group, so above 10ºC the compound would decompose and you'd get N2 gas coming off.
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