Orgo questions about - hydrogen bonding and solubility

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JFK90787

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OK two questions I'm having a hard time finding clarification for, maybe these will help others:

1. Does the ability to H-bond = solubility in water? I.E. Something like a phenol has 6 carbons, and I always learned that anything with >5 carbons is supposed to kill solubility, but it is still able to H-bond. So does the ability to H-bond make phenol soluble despite having 6 carbons?

2. Are non-polar things like O2 and CO2 able to be H-bond acceptors? I thought O2 couldn't

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OK two questions I'm having a hard time finding clarification for, maybe these will help others:

1. Does the ability to H-bond = solubility in water? I.E. Something like a phenol has 6 carbons, and I always learned that anything with >5 carbons is supposed to kill solubility, but it is still able to H-bond. So does the ability to H-bond make phenol soluble despite having 6 carbons?

2. Are non-polar things like O2 and CO2 able to be H-bond acceptors? I thought O2 couldn't

Questions are best placed in the Question and Answer forum. I'm moving so that you might get some repsonses.
 
OK two questions I'm having a hard time finding clarification for, maybe these will help others:

1. Does the ability to H-bond = solubility in water? I.E. Something like a phenol has 6 carbons, and I always learned that anything with >5 carbons is supposed to kill solubility, but it is still able to H-bond. So does the ability to H-bond make phenol soluble despite having 6 carbons?

2. Are non-polar things like O2 and CO2 able to be H-bond acceptors? I thought O2 couldn't

I think this is right, so someone correct me if I'm wrong.

Solubility is all about being similar or having similar qualities. H-bonding doesn't tell us much about a molecule, as it could just be a small portion of the molecule that H bonds. While this still may be true, I would use the idea that water is a polar molecule and therefore other polar molecules will tend to be soluble. Straight from wikipedia:

Phenol has a limited solubility in water (8.3 g/100 ml). It is slightly acidic: the phenol molecule has weak tendencies to lose the H+ ion from the hydroxyl group, resulting in the highly water-soluble phenolate anion C6H5O−, also called phenoxide anion

You can see the anion is highly soluble, which is likely due to the increased polarity in the molecule. If you drew the dipole it is much greater. Your 5 or 6 carbon rule just lends more to this idea, the longer the hydrocarbon chain the MORE nonpolar the molecule and the less like water it is.

For CO2, as you said it is nonpolar. There is no polarity to attract a hydrogen atom and therefore it will not hydrogen bond. O2 is the same, non polar and therefore will not H bond.
 
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Here's my guess:
I'm pretty sure C02 dissolves in water. I think a molecule needs only polar bonds (not polar overall) with either Nitrogen, Oxygen, Fluorine (an hydrogen bond acceptor). The carbon-oxygen bond is polar so there is a slight negative charge on the oxygen, even though the molecule overall is not polar.

Phenol is slightly soluble due to its polarity and acidic proton. However, it's not very soluble because of the aromatic ring.

Just my guess...
 
Oops, acceptor. I don't, and couldn't find one. Comparing the solubility of carbon disulfide and carbon dioxide is corroborating though.
 
With CO2 in water the story looks like it is convertes to carbonic acid like
CO2 + H2O -> H2CO3.
Carbonic acid partially disassociates to ions:
H2CO3 <--> H+ + HCO3-
I guess in this form it can make H-bonds to other water molecules.
 
With CO2 in water the story looks like it is convertes to carbonic acid like
CO2 + H2O -> H2CO3.
Carbonic acid partially disassociates to ions:
H2CO3 <--> H+ + HCO3-
I guess in this form it can make H-bonds to other water molecules.

agreed. CO2 has good solubility in water because it becomes carbonic acid. I just wanted to find some info on CO2 (not carbonic acid or bicarb) H-bonding.

My feeling is that it can't because it is a nonpolar molecule, but I am not 100% sure and would like to know if this idea is incorrect.

This knowledge is beyond the MCAT though, so at this point it is just curiosity.
 
Yeah, CO2 dissolution equiibrium has too much going on to consider that I suppose. At any rate, hydrogen bonding doesn't have to do with overall molecule polarity but with local polarity.
 
just a thought:
CO2 is a liner molecular and as a whole it is not polar. however in micro scale I would expect that oxygen stoles the electrons from carbon as in carbonyl bond. And the electric field across one molecule should looks like -V ++V -V ,where V is a partial electric charge. So, we have oxygen with two lone pairs and additional negative charge. I would say we have a good chance to form a H-bond with an electron deficient hydrogen in water molecule. I also would think that it is possibly a driver that forms the carbonic acid. It is just a speculation, I am not able to find any confirmation in textbook.
 
just a thought:
CO2 is a liner molecular and as a whole it is not polar. however in micro scale I would expect that oxygen stoles the electrons from carbon as in carbonyl bond. And the electric field across one molecule should looks like -V ++V -V ,where V is a partial electric charge. So, we have oxygen with two lone pairs and additional negative charge. I would say we have a good chance to form a H-bond with an electron deficient hydrogen in water molecule. I also would think that it is possibly a driver that forms the carbonic acid. It is just a speculation, I am not able to find any confirmation in textbook.

agreed. Mechanisms are just ideas on what is happening anyhow, they aren't what happens exactly.

I think your assessment would be good. The electrophilicity of that carbon is likely more "attractive" than the H-bonding though, so I wouldn't think that H-bonding is somehow setting up the carbonic acid reaction.
 
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