Question Regarding Polar Protic Solvents

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In summary, polar protic solvents have active hydrogen atoms that are involved in hydrogen bonding, with compounds containing -OH, -NH2, -CO2H, and -SH functional groups being protic solvents. While there is a spectrum of grays when it comes to covalent and ionic bond character, hydrogen bonding occurs when a highly electronegative atom has a hydrogen attached to it. While sulfur can also form hydrogen bonds, oxygen is more electronegative and therefore water is a better protic solvent. Any weaker hydrogen bonds are likely prohibited in the presence of O, N, or F. Additionally, carboxylic acid groups have an -OH group and can be considered protic solvents.
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delecticious
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I'm currently studying for an organic chemistry exam and I came across polar protic solvents. I read that polar protic solvents have active hydrogen atoms that are involved in hydrogen bonding and that compounds with functional groups -OH, -NH2, -CO2H, and -SH are usually protic solvents. Then I went over a concept check question which asked whether H2O or H2S was a better protic solvent. The answer was that H2O was because it will form hydrogen bonds with the solute then it went on to say that only hydrogen atoms bonded to O, N, or F form hydrogen bonds with other atoms, thus what has confused me. If protic solvents are involved in hydrogen bonding and compounds with aforementioned functional groups are protic solvents then if the above statement is true how can compounds with the thiol and carboxylic acid functional groups be considered protic solvents?
 
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  • #2
As I recall, it's like covalent and ionic bond character; it's not black and white, but a spectrum of grays. Hydrogen bonding happens when a highly electronegative atom has a hydrogen attached to it. Sulfur is pretty electronegative relative to most of the table, so it does hydrogen bond, just to a very small degree. The more electronegative the atom trying to bond to the hydrogen, the stronger the bond will be. So since oxygen is more electronegative than sulfur, water is a better protic solvent.

It's not that O, N, and F are the only elements to form hydrogen bonds, they're just the most likely, and their presence I imagine would prohibit any weaker hydrogen bonds from forming.

And besides, a carboxylic acid group has an -OH group on it.
 
  • #3
thanks for clearing that up for me, it makes perfect sense now.
 

Related to Question Regarding Polar Protic Solvents

1. What are polar protic solvents?

Polar protic solvents are a type of solvent that contain hydrogen atoms bonded to highly electronegative atoms such as oxygen or nitrogen. These solvents have a partial positive charge on the hydrogen atom, making them highly polar and capable of forming hydrogen bonds with other molecules.

2. What are some common examples of polar protic solvents?

Some common examples of polar protic solvents include water, alcohols (such as methanol and ethanol), ammonia, and acids (such as acetic acid and hydrochloric acid).

3. How do polar protic solvents affect chemical reactions?

Polar protic solvents can greatly influence chemical reactions by stabilizing ions and polar molecules through hydrogen bonding. They can also solvate and dissolve polar molecules, making them more reactive and allowing them to undergo reactions more easily.

4. Are polar protic solvents safe to use in laboratory experiments?

Polar protic solvents can be safe to use in laboratory experiments, but it is important to handle them with caution. Some of these solvents can be flammable and toxic, so proper safety precautions should be taken when handling them.

5. Can polar protic solvents be used in nonpolar reactions?

No, polar protic solvents are not suitable for use in nonpolar reactions. These solvents are highly polar and cannot effectively dissolve nonpolar molecules or ions, making them unsuitable for use in nonpolar reactions.

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