destroyer roadmap q's

[yumi43]

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1) in roadmap 1, why does Cl2/H3O+ add to the cyclohexanone the way that it does? what is the mechanism?

2) in roadmap 3, they show two elimination reactions, where the one with the tertbutoxide forms a less substituted double bond. i know this is because of sterics, but i thought in any elimination reaction, the more substituted double bond was favored? if this situation comes up on the DAT, do we take sterics into account and choose the less substituted double bond? my kaplan book clearly states that the more substituted double bond is the major product. 😕

3) in roadmap 5, the reagents for one of the reactions uses Cl2 (excess) and OH- and forms a haloform. how does this reaction work?

thank you!!!

 

[ckmonster]

1) in roadmap 1, why does Cl2/H3O+ add to the cyclohexanone the way that it does? what is the mechanism?
is a Halogenation Reaction - Chlorination is not very selective so it would take any hydrogen. The ketone on the ring is an Electron Withdrawing Group and para- director so that's why Cl adds to the the para position on the ring

2) in roadmap 3, they show two elimination reactions, where the one with the tertbutoxide forms a less substituted double bond. i know this is because of sterics, but i thought in any elimination reaction, the more substituted double bond was favored? if this situation comes up on the DAT, do we take sterics into account and choose the less substituted double bond? my kaplan book clearly states that the more substituted double bond is the major product. 😕
You are right! Elimination would tend to give the most substituted product. But this is one exception to the rule. Whenever you have a Strong Bulky base (such as T-butoxide) and a tertiary leaving group you will form the Hoffman product due to sterics.

3) in roadmap 5, the reagents for one of the reactions uses Cl2 (excess) and OH- and forms a haloform. how does this reaction work?
I kinda have an idea but im not sure how to explain this one! Sorry!

Hope I could help you! 😉

thank you!!!

 

[yumi43]

1) in roadmap 1, why does Cl2/H3O+ add to the cyclohexanone the way that it does? what is the mechanism?
is a Halogenation Reaction - Chlorination is not very selective so it would take any hydrogen. The ketone on the ring is an Electron Withdrawing Group and para- director so that's why Cl adds to the the para position on the ring

thanks for your reply!! but doesn't this only work with aromatic rings? this is just a regular cyclohexane so i don't think o/p has anything to do with it...

 

[ckmonster]

yeah I think your right! SORRY about that! And I also just noticed that is not para but meta! Opps!
But for the other explanation Im sure! sorry again for the confusion! I must be so tired!

 

[yumi43]

1) in roadmap 1, why does Cl2/H3O+ add to the cyclohexanone the way that it does? what is the mechanism?

can anyone help me with this one please?

 

[agt621]

the cl adds on to the ortho position

 

[biomolecmed]

When you treat a ketone with halogen and acid, all you do is substitute an alpha hydrogen with a halogen. Alpha hydrogens are those that are attached to alpha carbons. Alpha carbon is the one that is attached to c=o.

 

[biomolecmed]

Haloform reaction only works on METHYL ketones. T-butoxide always favors less substituted alkene for eliminations. Hope it helped. Good luck.