Orgo Destroyer Complete the Product Question

[DetroitDentistry]

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Hi everyone,

I was going through the Orgo Destroyer and ran into a question that I still do not understand despite going over the answer a few times. It is number 266 in the 2015 DAT Destroyer.

The initial reactant is a 1,4 benzene ring with a bromine & nitro group attached. First reaction is with Sn, Hcl, & OH- which reduces the nitro group; makes sense. Next reaction is with Cl2 & H2O, adding Chlorines ortho to the NH2 group; I am guessing the chlorines were added oath to the NH2 because it is activating group versus the deactivating Bromine. Next is where I get a little confused, the reaction is with NaNO2, HCL, 5 degrees celsius which kicks off the hydrogens and adds another Nitrogen to the NH2. I do not remember seeing this reaction anywhere. Finally, H3PO2 is reacted with the product to form a 1-bromo 3,5-dichloro benzene.

I know this is pretty confusing with the way I wrote it, I will try and upload a picture. Any clarification would be greatly appreciated.

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Good luck to everyone, and study hard!

Cheers,

Christofer

 

[FeralisExtremum]

These are just reactions you probably haven't been exposed to prior to Destroyer. The tin chloride reduction turns the NO2 group into an NH2 group. The followup with NaNO2, HCl, 5 degrees celsius turns the NH2 group into diazonium (N2). The diazonium group is useful because it can be easily displaced with a number of reactions (see here) to place different groups there instead. Using H3PO2 will result in the N2 group being replaced by an H.

Long story short: nitro group got replaced by an H by turning it into an intermediate that could easily be swapped.

 

[pulltheleverkronk]

The part where you get confused is the critical part of this- actually making the diazonium salt. It's just a salt because of the Cl- attached to it. Any time you see HNO2 or NaNO2 combined with an acid (can be HCl, H2SO4... whatever) you'll form that salt from NH2. You can do whatever you want when you have that salt. H3PO2 just rips off the leaving group, attaching an H to the ring and making it "normal" again (N2 compound will be released with that). Adding H2O plus heat will add an OH. Tip: any time you run into something like this and have no clue what attaches, consider the compound being a leaving group. This reaction isn't super uncommon. I'd learn it. Hope this helped, somewhat! Sometimes you just have to remember what happens with certain solvents and try to find patterns. I'm sure Dr. Romano could do a far better job of explaining the WHY, though.

 

[pulltheleverkronk]

Side note: this might help you out 🙂

 

[DetroitDentistry]

Thanks for the quick responses everyone, explanations helped a lot. I will never forget the diazonium rxns now after this 🙂 Taking my DAT this Thursday; now I pray that a Diazonium rxn comes up 🙂

 

[DAT Destroyer]

Hi everyone,

I was going through the Orgo Destroyer and ran into a question that I still do not understand despite going over the answer a few times. It is number 266 in the 2015 DAT Destroyer.

The initial reactant is a 1,4 benzene ring with a bromine & nitro group attached. First reaction is with Sn, Hcl, & OH- which reduces the nitro group; makes sense. Next reaction is with Cl2 & H2O, adding Chlorines ortho to the NH2 group; I am guessing the chlorines were added oath to the NH2 because it is activating group versus the deactivating Bromine. Next is where I get a little confused, the reaction is with NaNO2, HCL, 5 degrees celsius which kicks off the hydrogens and adds another Nitrogen to the NH2. I do not remember seeing this reaction anywhere. Finally, H3PO2 is reacted with the product to form a 1-bromo 3,5-dichloro benzene.

I know this is pretty confusing with the way I wrote it, I will try and upload a picture. Any clarification would be greatly appreciated.

[/IMG]


Good luck to everyone, and study hard!

Cheers,

Christofer

This is a vital problem !!! Review Diazonium salts !!!! Diazonium salts are utilized in a wide range of reactions. We use them to introduce groups such as D, F, I, CN, OH, OR, SH...directly onto the benzene ring. N2 is an excellent leaving group...one of our BEST !!!! Any Organic text will review this reaction. Review this material.....then come back and ask me another !

Keep hammering away !

Dr. Romano

 

[DetroitDentistry]

This is a vital problem !!! Review Diazonium salts !!!! Diazonium salts are utilized in a wide range of reactions. We use them to introduce groups such as D, F, I, CN, OH, OR, SH...directly onto the benzene ring. N2 is an excellent leaving group...one of our BEST !!!! Any Organic text will review this reaction. Review this material.....then come back and ask me another !

Keep hammering away !

Dr. Romano

Dr. Romano,

I just wanted to thank you for providing all of us aspiring dentists such amazing DAT resources. I finished my DAT today and absolutely destroyed Orgo, 30... 🙂 could not have done it without you!

Best,

Christofer

 

[DAT Destroyer]

Dr. Romano,

I just wanted to thank you for providing all of us aspiring dentists such amazing DAT resources. I finished my DAT today and absolutely destroyed Orgo, 30... 🙂 could not have done it without you!

Best,

Christofer

Congratulations! I am delighted my work helped you achieve your goal! Orgo 30, dental schools will take notice...You DESTROYED IT!!!!

Dr. Romano

 

[pulltheleverkronk]

Dr. Romano,

I just wanted to thank you for providing all of us aspiring dentists such amazing DAT resources. I finished my DAT today and absolutely destroyed Orgo, 30... 🙂 could not have done it without you!

Best,

Christofer

YOOOOOOOOOO

great scores! enjoy applying this cycle 🙂