Solubility of alkanols in water

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Discussion Overview

The discussion revolves around the solubility of alkanols, specifically comparing propan-1-ol and propan-2-ol in water. Participants explore factors influencing solubility, including hydrogen bonding and molecular structure, while also considering broader trends in solubility among longer-chain alkanols.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant suggests that propan-1-ol may be more soluble than propan-2-ol due to its ability to form hydrogen bonds with water, influenced by the number of electron-donating alkyl groups.
  • Another participant counters that the accessibility of propan-2-ol to water is lower, which could negatively impact its solubility despite its potential for hydrogen bonding.
  • It is noted that both propan-1-ol and propan-2-ol are soluble in water in all proportions, although the conditions under which this holds may vary.
  • Discussion shifts to pentanols, with participants indicating that more highly branched alkanols tend to be more soluble than their extended chain isomers, suggesting a trend that could be explored further.

Areas of Agreement / Disagreement

Participants express differing views on the factors affecting the solubility of propan-1-ol and propan-2-ol, indicating that the discussion remains unresolved regarding which factors are most significant. There is also a general agreement that both propanols are soluble in water, but the nuances of their solubility are debated.

Contextual Notes

Participants mention the influence of molecular structure and hydrogen bonding, but the discussion lacks specific quantitative data or conditions under which solubility may change, such as temperature or carbon chain length.

Who May Find This Useful

This discussion may be of interest to those studying organic chemistry, particularly in the context of solubility and molecular interactions in solutions.

ioioio7777
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Is propan-1-ol more soluble than propan-2-ol in water?
Propan-2-ol has 2 alkyl group, which is electron donating.
Since the formation of H-bonding is due to the elecrionegativity difference of O atom and H atom is the hydroxl group. I think think that the O atom in propan-2-ol can gain electrons from two alkyl groups while propan-1-ol can gain electrons from one alkyl group only and thus the ability of propan-1-ol to form H-bonding is greater than that of propan-2-ol.

Sorry for my poor English and thanks a lot
 
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But another factor is accessibility to water which is less for propan-2-ol, so that factor is in the opposite direction. Around hydrophobic (-CH3) groups water takes up a more structured form, more like ice and less able to form the H-bonds.

Which effect is more important? My sense is that solvent effects are always more important. I can't justify this sense so let's wait see if anyone who knows what he's talking about happens along.

But these are sorts of things you have to think about or find out about. Not enough to be looking at just one molecule but have a sense of the solution. Or rather, the solution versus the separate bulk liquids. Not easy.
 
Last edited:
Both of those propanols are soluble in water in all proportions.
 
chemisttree said:
Both of those propanols are soluble in water in all proportions.

Now I remember. :biggrin:

However there would be some number of carbon atoms and some temperature at which the question would arise?
 
Probably better to talk about pentanols or 5-carbon alcohols. There are definite trends. More highly branched alkanols are more soluble than the extended chain isomers.
 
chemisttree said:
Probably better to talk about pentanols or 5-carbon alcohols. There are definite trends. More highly branched alkanols are more soluble than the extended chain isomers.

I said it was not easy. :biggrin:

Can you say why that tendency is?
 

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