Why does 2-propanethiol have a lower boiling point than 1-propanethiol

In summary, the question discusses the boiling points of 1-propanethiol and 2-propanethiol and asks which one would be higher. After researching, it was found that 2-propanethiol has a lower boiling point, possibly due to the interruption of hydrophobic interactions or Van der Waals forces within the molecule. Another factor that may contribute is the difference in contact surface between the two molecules when lying side by side.
  • #1
jonahsaltzman
3
0

Homework Statement


Consider 2-propanethiol, shown below. Would you expect its boiling point to be higher or lower than that of 1-propanethiol? Why?

Homework Equations


1-propanethiol:
SHD5hNw.png
2-propanethiol:
Hydzs5F.png

The Attempt at a Solution


I looked it up, and 2-propanethiol does have a lower boiling point than 1-propanethiol, I just can't figure out why. I would have said that moving the S-H group to the middle of the molecule "interrupts" the hydrophobic region of the compound, but the question is referring to pure solutions, so there's no water to not interact with. My next best guess is basically the same thing, but instead of hydrophobic interactions, its Van der Waals forces. Meaning, instead of the entire hydrocarbon chain acting as one unit with a large number of electrons to be displaced, it is broken up into two units with fewer electrons each. But that really doesn't seem like a good explanation. Any ideas? Thanks so much!

Jonah
 
Last edited:
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  • #2
It might have something to do with surface area of the molecule
 
  • #3
To add to Woopydalan comment: try to imagine two molecules lying side by side - their interactions should be proportional to the "contact surface".
 

Related to Why does 2-propanethiol have a lower boiling point than 1-propanethiol

1. Why does 2-propanethiol have a lower boiling point than 1-propanethiol?

The boiling point of a substance is determined by its intermolecular forces, which are the attractive forces between molecules. In the case of 2-propanethiol and 1-propanethiol, the difference in the arrangement of atoms results in different intermolecular forces. 2-propanethiol has a branched structure, which leads to weaker intermolecular forces compared to 1-propanethiol's linear structure. This results in a lower boiling point for 2-propanethiol.

2. Can the difference in boiling point between 2-propanethiol and 1-propanethiol be explained by their molecular weight?

No, the molecular weight alone cannot fully explain the difference in boiling point between these two compounds. While 2-propanethiol has a slightly lower molecular weight than 1-propanethiol, the main factor affecting boiling point is the intermolecular forces, which are determined by the molecular structure.

3. Are there any other factors that can influence the boiling point of 2-propanethiol and 1-propanethiol?

Yes, there are other factors that can affect the boiling point. For example, the presence of impurities can alter the boiling point of a substance. Additionally, external factors such as altitude and atmospheric pressure can also impact the boiling point of a compound.

4. Does the difference in boiling point between 2-propanethiol and 1-propanethiol have any practical applications?

Yes, the difference in boiling point between these two compounds has practical applications in industries such as petroleum and chemical manufacturing. 2-propanethiol, with its lower boiling point, can be separated from 1-propanethiol through distillation, allowing for the production of pure compounds for specific purposes.

5. Can 2-propanethiol and 1-propanethiol be used interchangeably in chemical reactions?

No, the different structures and properties of these two compounds make them unsuitable for interchangeable use in chemical reactions. The reactivity of a molecule is determined by its functional groups and molecular structure, so using one instead of the other could lead to different outcomes in a reaction.

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