Thioester Isomer Count: ${C}_{4}{H}_{8}OS$ - 4 Possibilities

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Discussion Overview

The discussion revolves around the number of isomers for thioesters with the molecular formula ${C}_{4}{H}_{8}OS$. Participants explore the definition of thioesters and the validity of certain structures as isomers.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • Some participants initially identify two structures as thioesters but question the total count of four isomers suggested by an answer key.
  • There is a discussion about the definition of thioesters, specifically the requirement for an R group to be attached to the carbon that is double-bonded to oxygen.
  • One participant cites a source to clarify that thioesters can have both an R group at the double-bonded carbon and another R' group at the sulfur.
  • Another participant questions whether hydrogen (H) can be considered an R group in this context.
  • Several participants confirm that hydrogen does count as an R group, which resolves some confusion regarding the validity of the isomers presented.

Areas of Agreement / Disagreement

Participants express differing views on the validity of certain structures as thioesters, leading to a debate about the definition and requirements for R groups. While some confusion is resolved regarding hydrogen as an R group, the overall count of isomers remains contested.

Contextual Notes

There are unresolved aspects regarding the interpretation of isomer structures and the definitions applied to thioesters, particularly concerning the attachment of R groups.

MermaidWonders
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How many isomers are there with the following description?
- Thioesters with the formula ${C}_{4}{H}_{8}OS$?

I was able to draw 2 of them, but apparently, the answer key showed and stated that there are 4. I am confused about why the following two are possibliities:

View attachment 8117

I thought that thioesters are the functional groups where a C double-bonded to O is attached to both an R group and S, with S itself being attached to an R group. So, I was wondering how the 2 structures in the above attachment could be thioesters when the C that is double-bonded to O isn't attached to an R group but is instead to an H?
 

Attachments

  • Screen Shot 2018-05-19 at 20.25.17.png
    Screen Shot 2018-05-19 at 20.25.17.png
    4.3 KB · Views: 138
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MermaidWonders said:
How many isomers are there with the following description?
- Thioesters with the formula ${C}_{4}{H}_{8}OS$?

I was able to draw 2 of them, but apparently, the answer key showed and stated that there are 4. I am confused about why the following two are possibliities:
I thought that thioesters are the functional groups where a C double-bonded to O is attached to both an R group and S, with S itself being attached to an R group. So, I was wondering how the 2 structures in the above attachment could be thioesters when the C that is double-bonded to O isn't attached to an R group but is instead to an H?

Hi MermaidWonders!

From https://en.wikipedia.org/wiki/Thioester:

In chemistry thioesters are compounds with the functional group R–S–CO–R'.
View attachment 8118​


So we can have both an R-group at the double-bonded C, and we can have another R'-group at the S.
 

Attachments

  • 150px-Thioester-2D-A.svg.png
    150px-Thioester-2D-A.svg.png
    816 bytes · Views: 135
I like Serena said:
Hi MermaidWonders!

From https://en.wikipedia.org/wiki/Thioester:

In chemistry thioesters are compounds with the functional group R–S–CO–R'.
​


So we can have both an R-group at the double-bonded C, and we can have another R'-group a the S.


Right. So doesn't it mean that there must be an R group attached to the double-bonded C, which means that the above isomers in the attached image are not valid structures since C is attached to H in both?
 
Wait... does H count as an R group?
 
Yep. H counts as an R-group. (Nod)
 
I like Serena said:
Yep. H counts as an R-group. (Nod)

Makes sense now. Thanks! :)
 

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