Synthesis of substituted benzene rings I | Aromatic Compounds | Organic chemistry | Khan Academy

Synthesis practice problems. Created by Jay.
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Organic Chemistry on Khan Academy: Carbon can form covalent bonds with itself and other elements to create a mind-boggling array of structures. In organic chemistry, we will learn about the reactions chemists use to synthesize crazy carbon based structures, as well as the analytical methods to characterize them. We will also think about how those reactions are occurring on a molecular level with reaction mechanisms. Simply put, organic chemistry is like building with molecular Legos. Let's make some beautiful organic molecules!
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[@carmenkapadia6049]

Is there any kind of blanket or general rule that tells us in what order to install groups onto the ring?

[@sarah57920]

For the second one, couldn't you nitrate second, then use reduction (such as Zn(Hg) HCl) to make it NH2 for an ortho/para directing then use friedal crafts third? You would have an extra step converting back to NO2 with MCPBA but is that also possible???

[@elissafatme]

how to know which reaction occured first?

[@TheMooseCaboose]

If you listen to the video, he explained with the N2O and carbonyl group that you cannot add the carbonyl with the NO2 already there because of the deactivation effect that NO2 has. Br has to be added last because it is an O/P director and you would not get the same result if you were to leave the Br on first. The final molecule has to have groups that are meta to Br, which is contradicting to where Br directs groups. Hence, this group is added last.

[@alejandrosantos1879]

Thank you for this

[@cee8ch238]

fiedel crafts always gave me problems thanks khan!

[@naluwembedamalie9983]

Tnx

[@obaidaalbitar5737]

Thanks dr Jay

[@keelumenate6271]

couldn't the acylation have occurred last in the 2nd example?
it is para to br and meta to no2...

[@stargazer4023]

The nitro group is so strongly deactivating that, in this case, it would prevent the Friedel-Crafts acylation from occuring so it makes sense to do the acylation before the nitration. However, acylation of an aromatic ring bearing a nitro group can be a possible reaction if the ring also bears a strongly activating group to counteract the deactivating effect of the nitro group.

[@ScilexGuitar]

@@stargazer4023 But doesnt it deactivate just the orto/para positions? I dont get it, the meta position is ok to be substituted??

[@nabilahaque2783]

@keel umenate
Since you asked the question 5 years ago, I got the answer already prepared, thanks a lot...

[@1BigMan.Tshepo]

W video.

[@videos-rl3by]

i love in it

[@lajasadi9406]

Thank you BUT how do we know the orders

[@TheMooseCaboose]

If you listen to the video, he explained with the N2O and carbonyl group that you cannot add the carbonyl with the NO2 already there because of the deactivation effect that NO2 has. Br has to be added last because it is an O/P director and you would not get the same result if you were to leave the Br on first. The final molecule has to have groups that are meta to Br, which is contradicting to where Br directs groups. Hence, this group is added last.