Ochem question

[YoonS]

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Here is attachment of the question picture.

I thought both compounds are meso compound.

However, it turned out to be the first one is not meso, nor the second

was just achiral compound.

Can you explain why those two compounds are meso compound?

 

[bharat008]

Here is attachment of the question picture.

I thought both compounds are meso compound.

However, it turned out to be the first one is not meso, nor the second

was just achiral compound.

Can you explain why those two compounds are meso compound?

Its not meso because it doesn't have any chiral center. TO be meso you have to have chiral center and plane of symmetry. This one is plain achiral due to absence of chiral center...👍

 

[YoonS]

Thank you! I totally forgot about sterocenter!

Its not meso because it doesn't have any chiral center. TO be meso you have to have chiral center and plane of symmetry. This one is plain achiral due to absence of chiral center...👍

 

[bharat008]

You only have 2 more days to review.. Don't make silly mistakes...
Good Luck!! Kill it..

 

[dantemac]

Symmetry alone doesnt make something meso. Watch for stereocenters! Especially 1,2 (right next to each other).

 

[chance8]

Pls correct if my reasoning is incorrect.
1. The first one is not meso b/c there's no stereocenter
2. The second one, when the alkene adds to HCL, it forms a compound via the Markonikov' rule so you do not get a stereocenter either. Therefore, not meso.

Here is attachment of the question picture.

I thought both compounds are meso compound.

However, it turned out to be the first one is not meso, nor the second

was just achiral compound.

Can you explain why those two compounds are meso compound?

 

[bharat008]

Pls correct if my reasoning is incorrect.
1. The first one is not meso b/c there's no stereocenter
2. The second one, when the alkene adds to HCL, it forms a compound via the Markonikov' rule so you do not get a stereocenter either. Therefore, not meso.

yup..
Chiral Center + Plane of Symmetry = MESO ACHIRAL
Achiral Center + PLane of Symmetry = ACHIRAL

 

[DrHJ]

Hi,
Can anybody explain the answer of this question to me please? The correct answer is A
What is the major product of the following synthesis?

 

[DAT Destroyer]

Hi,
Can anybody explain the answer of this question to me please? The correct answer is A
What is the major product of the following synthesis?

This is a simple SN2 intramolecular reaction. The OH- displaces the Br at one end,,,,,this sets up the Oxygen to act as a nucleophile to attack the same molecule and remove the second Bromine. Intramolecular reactions occur very rapidly, especially forming a 5 membered ring.

Hope this helps.

Dr. Jim Romano

 

[plusalpha]

This is a simple SN2 intramolecular reaction. The OH- displaces the Br at one end,,,,,this sets up the Oxygen to act as a nucleophile to attack the same molecule and remove the second Bromine. Intramolecular reactions occur very rapidly, especially forming a 5 membered ring.

Hope this helps.

Dr. Jim Romano

Hi Dr. Romano,

Was the purpose of using specifically "2eq." of the alkyl dibromide to ensure that the 1eq of NaOH displaces only ONE of the bromines (in order to do the intermolecular reaction) and not both of the bromines..? If this is so, would "dilute NaOH" or "excess alkyl dibromide" be other ways of writing this same reaction?

 

[DAT Destroyer]

Hi Dr. Romano,

Was the purpose of using specifically "2eq." of the alkyl dibromide to ensure that the 1eq of NaOH displaces only ONE of the bromines (in order to do the intermolecular reaction) and not both of the bromines..? If this is so, would "dilute NaOH" or "excess alkyl dibromide" be other ways of writing this same reaction?

Hope this helps!

Dr. Romano

 

[Artdent97]

Hope this helps!

Dr. Romano
View attachment 198675

This explains a lot and clears up some of the confusions. Thank you for posting.

 

[Incis0r]

Hope this helps!

Dr. Romano
View attachment 198675

Dr. Romano and his life-saving mechanisms strike again!

 

[DAT Destroyer]

Dr. Romano and his life-saving mechanisms strike again!

Everyone needs a lifesaver every now and then😀

 

[DrHJ]

Thanks Dr. Romano