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

Join the discussion
Registration is free. Start your own thread to ask a follow-up.
Sign up Log in
5 replies · 5K views
MermaidWonders
Messages
112
Reaction score
0
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: 174
Mathematics news on Phys.org

Discussion

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: 163
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?
 
I like Serena said:
Yep. H counts as an R-group. (Nod)

Makes sense now. Thanks! :)