Strong nucleophile or no?

[DentalLonghorn2014]

Hey y'all,

So, a phosphorus with 3 R groups and N with 3 R groups. Chad said that P can be a strong base but in a Q&A they said a P with 3 R groups is not a good nucleophile due to it being too "fat". Also, what about N?

Thank you!!

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[clutchfans]

Even though N is smaller than P, NR3 is still going to be pretty bulky making it a poor nucleophile.

 

[DentalLonghorn2014]

Even though N is smaller than P, NR3 is still going to be pretty bulky making it a poor nucleophile.

I see. Thank you.

 

[DAT Destroyer]

Hey y'all,

So, a phosphorus with 3 R groups and N with 3 R groups. Chad said that P can be a strong base but in a Q&A they said a P with 3 R groups is not a good nucleophile due to it being too "fat". Also, what about N?

Thank you!!

Phosphorus is among our VERY BEST nucleophiles. We use them in many reactions such as the Wittig and Gilbert reaction. Even a sterically hindered nucleophile works great.....the Phosphorus -atom distance is reasonably long, the electrons are very loosely held. Although, not as common as S, N, or O nucleophiles,,,,,,these reagents are AMAZING !!!! I have read many books on Phosphorus Chemistry, and count it as one of my favorite elements !!!!

Hope this helps

Dr. Romano

Here are a few examples.......

 

[DentalLonghorn2014]

Phosphorus is among our VERY BEST nucleophiles. We use them in many reactions such as the Wittig and Gilbert reaction. Even a sterically hindered nucleophile works great.....the Phosphorus -atom distance is reasonably long, the electrons are very loosely held. Although, not as common as S, N, or O nucleophiles,,,,,,these reagents are AMAZING !!!! I have read many books on Phosphorus Chemistry, and count it as one of my favorite elements !!!!

Hope this helps

Dr. Romano

Here are a few examples.......

View attachment 195361

Thank you Dr. Romano. What about N with 3 R groups? Would that be a weak nucleophile but decent base?

 

[DAT Destroyer]

Thank you Dr. Romano. What about N with 3 R groups? Would that be a weak nucleophile but decent base?

A nitrogen with 3 R groups is usually the Kiss of Death when it comes to nucleophilicity,,,,,,just too damn big ! As far as basicity goes,,,,,we usually see an increase in its strength. For reasons still debated, steric effects dont count as heavily when basicity is concerned, likely because we are capturing a simple hydrogen ion. Interestingly, quinuclidine is a tertiary amine, that is a decent nucleophile. Can you tell me why ?

Here is a picture of the compound......

 

[DentalLonghorn2014]

A nitrogen with 3 R groups is usually the Kiss of Death when it comes to nucleophilicity,,,,,,just too damn big ! As far as basicity goes,,,,,we usually see an increase in its strength. For reasons still debated, steric effects dont count as heavily when basicity is concerned, likely because we are capturing a simple hydrogen ion. Interestingly, quinuclidine is a tertiary amine, that is a decent nucleophile. Can you tell me why ?

Here is a picture of the compound......
View attachment 195375

Is it because there's less hinderance? This may sound dumb but there's more "free " space in the front with the nitrogen than the back?