Destroyer Orgo #31

[famousbanker]

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On Question #31 in the 2010 Destroyer Orgo section, Why is the terminal hydrogen most acidic in the Carbonyl? I understand that alpha carbons are acidic, but why is the terminal alpha more so in this compound??

 

[GoBlue24]

On Question #31 in the 2010 Destroyer Orgo section, Why is the terminal hydrogen most acidic in the Carbonyl? I understand that alpha carbons are acidic, but why is the terminal alpha more so in this compound??

Huh? Question #31 is a grignards reagent reaction. If you're talking about question #32, that's an aldol condensation reaction. I'm not sure where you're getting a terminal alpha hydrogen from... do you mean terminal hydrogen which is on beta carbon?

 

[mario0923]

On Question #31 in the 2010 Destroyer Orgo section, Why is the terminal hydrogen most acidic in the Carbonyl? I understand that alpha carbons are acidic, but why is the terminal alpha more so in this compound??

can you at least post the question so that we can see it...?

 

[famousbanker]

http://s1174.photobucket.com/albums/r603/famousbanker/?action=view&current=2butanone.jpg

This is not the question from destroyer, but it will at least demonstrate the type of compound I am referring to.

Even though both carbons #1 and #3 have alpha hydrogens, my assumption is that the hydrogen attached to the #1 Carbon is more acidic because it does not have the additional electron donating group(i.e. Carbon #4) that the #3 Carbon has attached.

Is this correct? Thank you in advance for your help.

 

[jrub]

On Question #31 in the 2010 Destroyer Orgo section, Why is the terminal hydrogen most acidic in the Carbonyl? I understand that alpha carbons are acidic, but why is the terminal alpha more so in this compound??

i think i know what question u are talking about, usually terminal H are better bc acid/base reactions like to be very quick and if there are 2 H with similar pH then the reaction will favor the one which is easier to get to (terminal)

 

[famousbanker]

i think i know what question u are talking about, usually terminal H are better bc acid/base reactions like to be very quick and if there are 2 H with similar pH then the reaction will favor the one which is easier to get to (terminal)

Thanks man. Good information. I am going to try and fix my scanner this weekend so I can upload images a little easier.

 

[famousbanker]

By the way, can anyone give me an explanation why on the #2 road map, in the second reaction going to the right where the nitroarene gets reduced to the primary aryl amine by Sn,HCl, the 2) step of the reaction calls for OH-?

I know it is common for Nitroarenes to get reduced by Sn/H+, Fe/H+, and even H2/Pd etc down to the primary aryl amine, but I dont understand the role OH- serves in this 2nd reaction step.

Does anybody know? I just have never seen the reaction written this way.