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The solubility of haloalkanes in water
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+ Solubility
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Kaori Kitao
The solubility of haloalkanes in water
The haloalkanes are only very slightly soluble in water. In order for a
haloalkane to dissolve in water, energy is required to overcome the
attractions between the haloalkane molecules and break the hydrogen
bonds between water molecules. Less energy is released when new
attractions are set up between the haloalkane and the water molecules
as these are not as strong as the original hydrogen bonds in water. As a
result, the solubility of haloalkanes in water is low. However, haloalkanes
tend to dissolve in organic solvents because the new intermolecular
attractions between haloalkanes and solvent molecules have much the
same strength as the ones being broken in the separate haloalkane and
solvent molecules.
The haloalkanes are only very slightly soluble in water. In order for ahaloalkane to dissolve in water, energy is required to overcome theattractions between the haloalkane molecules and break the hydrogenbonds between water molecules. Less energy is released when newattractions are set up between the haloalkane and the water moleculesas these are not as strong as the original hydrogen bonds in water. As aresult, the solubility of haloalkanes in water is low. However, haloalkanestend to dissolve in organic solvents because the new intermolecularattractions between haloalkanes and solvent molecules have much thesame strength as the ones being broken in the separate haloalkane andsolvent molecules.
You are not answering the question... as to why a flouroalkane doesnot dissolve (appreciably) in water.More
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Anything that dissolves in water must overcome the inter-molecular forces (H-bonding here) between water molecules first.
The insolubility of fluoroalkanes can be explained on the basis that energy required to break the bonds between water molecules is higher than the energy released when new bonds are formed between fluoroalkanes and water.
Anything that dissolves in water must overcome the inter-molecular forces (H-bonding here) between water molecules first.
The insolubility of fluoroalkanes can be explained on the basis that energy required to break the bonds between water molecules is higher than the energy released when new bonds are formed between fluoroalkanes and water.
I think the answer lies with the fact that alkanes are basically non-polar, even if they have halogen substituents. Water, on the other hand, is polar, so the solvent and solute are incompatible.
I think the answer lies with the fact that alkanes are basically non-polar, even if they have halogen substituents. Water, on the other hand, is polar, so the solvent and solute are incompatible.
@Joe, in the case of methanol, the hydroxyl group is both an H-bond donor and an H-bond acceptor. Haloalkanes can only function as acceptors. Furthermore, in the case of fluoroalkanes specifically, the small atomic radius and high electronegativity of fluorine makes it very weakly polarizable. Also, the short C-F bond length lowers the dipole moment (by comparison to, e.g., C-Cl bonds), since dipole moment is a function not just of charge but also separation distance.More
Come to think of it, this is not quite obvious. Organics with oxygen bound to carbon seem to be able to form hydrogen bonds; acetone, for example, is infinitely miscible with water. One might think that fluorine in similar compounds (being more electronegative and thus bearing higher negative charge) would be even better at accepting hydrogen bonds. This is not the case, though.More
What is it about alkanes that makes them non-polar? Wouldnt the asymmetric distribution of electronegativity, especially with fluorine, create a permanent dipole?More
Alkanes are saturated carbon chains. The geometry about each carbon is tetrahedral and tetraheral shaped molecules can be non-polar if all their attachments are the same. Yes, adding a fluorine will create a dipole, but theres more than there just being a dipole; we must ask how significant is the dipole. The answer is usually not that significant.More
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The simple truth is that the only molecule where F forms hydrogen bonds is H-F. In C-F bonds, the F does not form hydrogen bonds. We may argue on the explanations, but those are the facts. Just remember what happens when a drop of water falls on a clean pan coated with Teflon.
The simple truth is that the only molecule where F forms hydrogen bonds is H-F. In C-F bonds, the F does not form hydrogen bonds. We may argue on the explanations, but those are the facts. Just remember what happens when a drop of water falls on a clean pan coated with Teflon.
Perhaps you could elaborate on why this is. This sounds like an interesting answer but at the moment it is lacking in detail.More
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I felt that fluorine would be able to form hydrogen bond only when it is initially bonded to hydrogen atom so that it gets significant electron cloud, in our case alkyl group is attached to fluorine so it becomes difficult for fluorine to hogg electrons now when fluoroalkane is dissolved in $\ce{H2O}$ attractive interactions between fluoroalkane and $\ce{H2O}$ is not strong enough to break hydrogen bond which binds $\ce{H2O}$ molecules. Thus fluoroalkene is not much soluble in water as it won't be able to form bonds with $\ce{H2O}$ molecules.
I felt that fluorine would be able to form hydrogen bond only when it is initially bonded to hydrogen atom so that it gets significant electron cloud, in our case alkyl group is attached to fluorine so it becomes difficult for fluorine to hogg electrons now when fluoroalkane is dissolved in $\ce{H2O}$ attractive interactions between fluoroalkane and $\ce{H2O}$ is not strong enough to break hydrogen bond which binds $\ce{H2O}$ molecules. Thus fluoroalkene is not much soluble in water as it won't be able to form bonds with $\ce{H2O}$ molecules.
The haloalkanes are only very slightly soluble in water. In order for a haloalkane to dissolve in water, energy is required to overcome the attractions between the haloalkane molecules and break the hydrogen bonds between water molecules. Less energy is released when new attractions are set up between the haloalkane and the water molecules as these are not as strong as the original hydrogen bonds in water. As a result, the solubility of haloalkanes in water is low. However, haloalkanes tend to dissolve in organic solvents because the new intermolecular attractions between haloalkanes and solvent molecules have much the same strength as the ones being broken in the separate haloalkane and solvent molecules.
The haloalkanes are only very slightly soluble in water. In order for ahaloalkane to dissolve in water, energy is required to overcome theattractions between the haloalkane molecules and break the hydrogenbonds between water molecules. Less energy is released when newattractions are set up between the haloalkane and the water moleculesas these are not as strong as the original hydrogen bonds in water. As aresult, the solubility of haloalkanes in water is low. However, haloalkanestend to dissolve in organic solvents because the new intermolecularattractions between haloalkanes and solvent molecules have much thesame strength as the ones being broken in the separate haloalkane andsolvent molecules.
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The insolubility of fluoroalkanes can be explained on the basis that energy required to break the bonds between water molecules is higher than the energy released when new bonds are formed between fluoroalkanes and water.
The insolubility of fluoroalkanes can be explained on the basis that energy required to break the bonds between water molecules is higher than the energy released when new bonds are formed between fluoroalkanes and water.
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I think the answer lies with the fact that alkanes are basically non-polar, even if they have halogen substituents. Water, on the other hand, is polar, so the solvent and solute are incompatible.
I think the answer lies with the fact that alkanes are basically non-polar, even if they have halogen substituents. Water, on the other hand, is polar, so the solvent and solute are incompatible.
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The simple truth is that the only molecule where F forms hydrogen bonds is H-F. In C-F bonds, the F does not form hydrogen bonds. We may argue on the explanations, but those are the facts. Just remember what happens when a drop of water falls on a clean pan coated with Teflon.
The simple truth is that the only molecule where F forms hydrogen bonds is H-F. In C-F bonds, the F does not form hydrogen bonds. We may argue on the explanations, but those are the facts. Just remember what happens when a drop of water falls on a clean pan coated with Teflon.
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I felt that fluorine would be able to form hydrogen bond only when it is initially bonded to hydrogen atom so that it gets significant electron cloud, in our case alkyl group is attached to fluorine so it becomes difficult for fluorine to hogg electrons now when fluoroalkane is dissolved in $\ce{H2O}$ attractive interactions between fluoroalkane and $\ce{H2O}$ is not strong enough to break hydrogen bond which binds $\ce{H2O}$ molecules. Thus fluoroalkene is not much soluble in water as it won't be able to form bonds with $\ce{H2O}$ molecules.
I felt that fluorine would be able to form hydrogen bond only when it is initially bonded to hydrogen atom so that it gets significant electron cloud, in our case alkyl group is attached to fluorine so it becomes difficult for fluorine to hogg electrons now when fluoroalkane is dissolved in $\ce{H2O}$ attractive interactions between fluoroalkane and $\ce{H2O}$ is not strong enough to break hydrogen bond which binds $\ce{H2O}$ molecules. Thus fluoroalkene is not much soluble in water as it won't be able to form bonds with $\ce{H2O}$ molecules.
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