HW 6C.17 Which is the stronger base?

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Charysa Santos 4G
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HW 6C.17 Which is the stronger base?

Postby Charysa Santos 4G » Thu Dec 05, 2019 12:28 am

How do we find out which base is stronger -- either BrO- or C17H19O3N -- without knowing the pKb value?

Mashkinadze_1D
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Re: HW 6C.17 Which is the stronger base?

Postby Mashkinadze_1D » Thu Dec 05, 2019 1:39 am

I believe for something like this we would need the pKb value but we can also use a rule of thumb that most compounds with N are going to be a weak base and also due to the negative charge on hypobromite we can figure it will be a stronger acid as this allows it readily accept a proton.

Jielena_Bragasin2G
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Re: HW 6C.17 Which is the stronger base?

Postby Jielena_Bragasin2G » Sat Dec 07, 2019 7:49 pm

You can also look at the stability of the conjugate acid to see which one is stronger. The more stable one will be the stronger base.

Eugene Chung 3F
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Re: HW 6C.17 Which is the stronger base?

Postby Eugene Chung 3F » Sat Dec 07, 2019 8:14 pm

We know that BrO- is stronger base since it has a negative charge. This means that when it accepts a proton H+, it will become neutral whereas for C17H19O3N, it will become positively charged. Neutral charge is more favorable.

Edmund Zhi 2B
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Re: HW 6C.17 Which is the stronger base?

Postby Edmund Zhi 2B » Sat Dec 07, 2019 8:21 pm

BrO- is more likely to pick up a hydrogen because it is the conjugate base of a weak acid and equilibrium will be more likely to lie the left. This makes it a STRONGER base than C17H19O3N since it is considered a weak base and is not too likely (but still can) pick up a proton with the lone pair on nitrogen.

Jacquelyn Challis 2B
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Re: HW 6C.17 Which is the stronger base?

Postby Jacquelyn Challis 2B » Fri Dec 11, 2020 4:47 pm

the textbook's answer says, "the smaller the pKb of a base, the stronger the base. pKb (morphine)= 5.79. pKb (BrO-)= pKw-pKa=14-8.69=5.31." This reasoning is confusing me because I don't know how they calculated pKb and pKa. Can anyone explain how they got those numbers?


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