OChem Tosylation Reaction: Predicting Major Product with p-TsOH Catalyst

  • Thread starter Thread starter Adsit_Deus
  • Start date Start date
Click For Summary

Discussion Overview

The discussion revolves around predicting the major product of a tosylation reaction involving a compound with multiple hydroxyl groups when treated with p-TsOH and heat. The focus is on understanding the role of the hydroxyl groups in the reaction and the implications of their structural context.

Discussion Character

  • Homework-related
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • One participant expresses uncertainty about whether the tosyl acid will replace the -OH group of the carboxylic acid, the standalone -OH group, or both, suggesting that only one replacement is likely for stability reasons.
  • Another participant reiterates the same uncertainty and emphasizes the need to consider the stability of the resulting products when determining which -OH group is replaced.
  • A later reply clarifies that the -OH group of the carboxylic acid should be treated as part of that functional group rather than as a separate alcohol, which may influence the reaction outcome.
  • One participant acknowledges their confusion regarding the treatment of the carboxylic acid's -OH group and expresses relief after receiving clarification on its role in the reaction.

Areas of Agreement / Disagreement

Participants generally agree on the need to clarify the role of the -OH groups in the reaction, but there remains uncertainty about which group will be replaced and how to approach the problem given the lack of prior examples in their coursework.

Contextual Notes

Participants note limitations in their prior learning, specifically the absence of examples involving multiple -OH groups and the complexities that arise from having both alcohol and carboxylic acid functional groups in the same molecule.

Adsit_Deus
Messages
15
Reaction score
0

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.
 
Physics news on Phys.org
Adsit_Deus said:

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
 

Attachments

  • Screen Shot 2015-01-17 at 2.08.22 PM.png
    Screen Shot 2015-01-17 at 2.08.22 PM.png
    30.1 KB · Views: 535
Adsit_Deus said:
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?
 
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.
 
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?
 
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.
 

Similar threads

  • · Replies 28 ·
Replies
28
Views
5K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 1 ·
Replies
1
Views
5K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 3 ·
Replies
3
Views
8K
  • · Replies 3 ·
Replies
3
Views
8K
Replies
8
Views
4K
  • · Replies 4 ·
Replies
4
Views
3K
Replies
2
Views
5K
  • · Replies 1 ·
Replies
1
Views
3K