OChem Issue: Tosylation

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  • #1
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Homework Statement



Predict the major product in the following reaction (Hint: Consider intra-molecular reaction)

Homework Equations



HO2C-(CH2)3-CH(OH)-CH3 ------------cat. p-TsOH, heat----------> ???

The Attempt at a Solution



Essentially what I cannot figure out is if the tosic acid is going to replace the -OH group of the carboxylic acid, the other standalone -OH group, or both. I would assume that it would only replace one since the molecule would likely be more stable, and for that same reason I would also assume that it would replace the 2 prime -OH rather than the -OH attached to the carboxylic acid group.
 

Answers and Replies

  • #2
16
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Homework Statement



Predict the major product in the following reaction (Hint: Consider intra-molecular reaction)

Homework Equations



HO2C-(CH2)3-CH(OH)-CH3 ------------cat. p-TsOH, heat----------> ???

The Attempt at a Solution



Essentially what I cannot figure out is if the tosic acid is going to replace the -OH group of the carboxylic acid, the other standalone -OH group, or both. I would assume that it would only replace one since the molecule would likely be more stable, and for that same reason I would also assume that it would replace the 2 prime -OH rather than the -OH attached to the carboxylic acid group.


A screenshot of the molecule in Marvin Sketch is attached
 

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  • #3
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and for that same reason I would also assume that it would replace the 2 prime -OH rather than the -OH attached to the carboxylic acid group.
And, your doubts regarding your assumption are what?
 
  • #4
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My original thought was stability, but I am not sure. We were never shown an example problem where there was any more than one -OH group in class, nor were we shown what could happen if there are two oxygen-centric functional groups. I just do not know how to go about dealing with them since we only worked one or two problems with run-of-the-mill 1 and 2 prime alcohols.
 
  • #5
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The second "-OH" group you're worried about doesn't work as such; it's part of the carboxylic acid functional group and has to be treated as being part of that group rather as another alcohol group. Feel a little more comfortable?
 
  • #6
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Extremely, thank you. I was mainly unsure of that exact point. "Is is still treated as a lone hydroxyl group, or is it treated as a part of a group that does not necessarily obey that tosylate rule?" That clears everything up.
 

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