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Topic: Formation of alkoxides from alcohols by using strong bases  (Read 494 times)

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Offline 4gkenzy

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Formation of alkoxides from alcohols by using strong bases
« on: December 04, 2019, 05:12:21 AM »
I'm reading about making primary haloalkanes from primary alcohols. Basically, from what I understand, you protonate the alcohol to form oxonium.

But, my textbook says this:


The second sentence is what I am curious about. Basically, it says primary alcohols are subject to nucleophilic attack (for reasons that I am aware of), and that the oxonium species will be trapped by the nucleophile. However, in the chemical equation at the bottom, it clearly shows that H2O forms after reacting with HBr. So, why does it say a nucleophile will trap the oxonium yet I can clearly see that it left right there?

Offline AWK

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Re: Formation of alkoxides from alcohols by using strong bases
« Reply #1 on: December 04, 2019, 05:49:54 AM »
The next three sentences explain what the authors meant by the word "trapped".
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Offline 4gkenzy

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Re: Formation of alkoxides from alcohols by using strong bases
« Reply #2 on: December 04, 2019, 06:25:33 AM »
The next three sentences explain what the authors meant by the word "trapped".
Thanks I read that but how can it be trapped if it ends up leaving and becoming its own H2O?

Offline AWK

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Re: Formation of alkoxides from alcohols by using strong bases
« Reply #3 on: December 04, 2019, 06:43:49 AM »
Vollhardt repeatedly uses the word "trapped" when discussing the SN1 mechanism (Google Books search). Perhaps it is a transfer of words from the lecture, where you can clarify the meaning of the word used by intonation or additional explanation. But this question should be directed to the author of the textbook.
Personally, I think that textbooks should not use the "tenth" synonym or synonymous word, but without using them, spoken texts would be quite boring.
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Offline 4gkenzy

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Re: Formation of alkoxides from alcohols by using strong bases
« Reply #4 on: December 04, 2019, 07:10:15 AM »
Vollhardt repeatedly uses the word "trapped" when discussing the SN1 mechanism (Google Books search). Perhaps it is a transfer of words from the lecture, where you can clarify the meaning of the word used by intonation or additional explanation. But this question should be directed to the author of the textbook.
Personally, I think that textbooks should not use the "tenth" synonym or synonymous word, but without using them, spoken texts would be quite boring.
Then what exactly does he mean?

Offline AWK

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Re: Formation of alkoxides from alcohols by using strong bases
« Reply #5 on: December 04, 2019, 07:26:36 AM »
But this question should be directed to the author of the textbook.
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Offline 4gkenzy

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Re: Formation of alkoxides from alcohols by using strong bases
« Reply #6 on: December 04, 2019, 08:05:46 AM »
But this question should be directed to the author of the textbook.
Okay thank you. So just to clarify, the oxonium group will detach when a nucleotide attacks it right? Since it's no longer -OH (bad leaving group) but R-OH2 which I know is a good LG. I suppose my followup question would be, since secondary and tertiary alcohols are able to drop this R-OH2 group with relative ease, why is a stable group more likely to "hang onto" the oxonium group? Bit more fundamental of a question. Higher energy = more unstable = less likely to drop the oxonium group. Why?

Offline AWK

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Re: Formation of alkoxides from alcohols by using strong bases
« Reply #7 on: December 04, 2019, 08:36:12 AM »
Quote
when a nucleotide attacks
nucleotide?
Be more precise!
AWK

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