A-level Organic Chemistry

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Yes, I know there probably is a thread on just A-level Chemistry. But I wanted to dedicate a thread just to this d*amned topic anyway.

My question: How do you turn nitrobenzene into 1,3 - dinitrobenzene? And then from that to 1,3,5 trinitrobenzene (?)? I'm not sure if I'm naming the compounds right. Hence, the '?' in brackets.

EDIT: I know you need to add NO2+ ions... But what's the reagent? Conditions?
 
Hmmm, I wondered that too...

The conditions you need for the nitration of benzene to simply (1-)nitrobenzene is concentrated nitric acid & sulphuric acid, and 50-60 degrees C.... and according to my textbook:
"Careful temperature control is needed to minimize the formation of dinitrobenzene".
What I understood from this is that to add more nitro groups to the benzene ring, you just increase the temperature further...all the other reagents required probably stay the same.

I'm pretty sure you're right about all the naming. :thumbs_up
 
Salam
I have done this but dont need to do again but use a chemistry revision guide, should help :D x
 
~Raynn~ said:
Hmmm, I wondered that too...

The conditions you need for the nitration of benzene to simply (1-)nitrobenzene is concentrated nitric acid & sulphuric acid, and 50-60 degrees C.... and according to my textbook:
"Careful temperature control is needed to minimize the formation of dinitrobenzene".
What I understood from this is that to add more nitro groups to the benzene ring, you just increase the temperature further...all the other reagents required probably stay the same.
Click to expand...

I understand, but what temperature exactly? What range of temperatures?

I have done this but dont need to do again but use a chemistry revision guide, should help
Click to expand...

Since you've already done this, perhaps you could help? (^_^) I don't own an A2 chemistry revision guide. Poverty exists even in a Ruler's life.
 
Achh, hopefully you won't need to know any exact values, but maybe this'll give you some idea...

http://www.patentstorm.us/patents/5488187/description.html

"When a mononitrobenzene product is desired, the reaction is suitably conducted at a reaction temperature not exceeding 80° C, preferably between 0° C. and 60° C, more preferably between 10° C. and 60° C.....
The process for producing dinitrobenzene is suitably conducted at a reaction temperature of between about 30° C. and about 70° C, preferably between about 50° C. and about 70° C, more preferably about 65° C."

I couldn't find anything for trinitrobenzene...it all seems pretty vague... :hmm:
 
^Thank you. Did you ever have to do organic plannings? They're assessments that count towards your final grade. I have one on Tuesday, but am slightly clueless as to what exactly it's about.
 
Lol, I kinda remember having to do some really confusing thing about identifying which functional group was present in an organic sample...what exactly do you have to plan??
 
Identifying functional groups isn't so bad. But planning an organic synthesis, such as esterification is what we're supposed to do.

Could you tell me about the separating funnel? About the densities of the soluted and things like that? I've been reading my notes... But I don't fully understand.
 
All I can remember is that it involves the base hydrolysis of an ester, under reflux, to give a carboxylate salt (the soap) and an alcohol. The soap is present in solution, and you precipitate it out by adding excess sodium chloride.

What syllabus do you follow for chemistry, by the way?? Because I can't remember ever even carrying out an esterification, letting alone having to plan it! (so I don't have a clue about the coursework...sorry!)
 
It's not coursework. It's an assessment. We follow the Edexcel syllabus.

I got the summary from my summary sheets. But what I need to know are the steps to it... You know? Like heat under reflux; separating funnel (I don't know if we use it); Buchner funnel + flask (yet again, unsure whether we have to use it) and other apparatus that one might need to carry out stupid saponification.
 
OK... Scrap saponification. Could you help me with the stages of recrystallisation?
 
Recrystallization...okay, basically, you have the sample of (impure) crystals, in a beaker or whatever...you add to it the minimum amount of boiling water needed to completely dissolve the crystals, then allow the mixture to cool (you can scratch the sides of the beaker to promote the growth of crystals from the glass particles you dislodge, but make sure you don't destroy the crystals that do form, lol). The slower you cool it, the larger the crystals'll be.

After it's completely cooled, you need to filter it (that's where you'd use a Buchner funnel...suction filtration) and dry it, to get rid of the excess water. The whole process can be repeated if you want to purify the sample further. That's pretty much it, I think...
 
^Yah, thanks. Because everything seemed hopeless, I ended up memorising the steps. But your explanation makes sense.
 
Thanks... It's laughable really. I just finished 3 hours of studying... And I don't feel any more wiser than I was. *sigh*
 
I forgot all about 2,4 DNP. And thus, probably lost a few marks that way. It was totally different to what I'd expected... So I was a little surprised. I finished the 2 hour thing in 30 minutes and then did a second draft (more so that I'm not the first one out than anything else really). I think that pretty much sums it all up.

It went bad.
 
Aww...don't worry about it. I'm certain it couldn't have gone too badly...do they give you any kind of second chance, at a similar assessment or something, btw?

And hmmm... 2,4-dnp?? That doesn't seem to be linked to esterification or ester hydrolysis in any way, lol...
 
No... Not esterification, but recrystallisation.

Nope, I don't get a second chance. Wouldn't it be wonderful if I did? *Sigh*
 

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