Romix
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Propan2ol + NaOH
Added 3 spoon of NaOH to anhydrous isopropanol.
5 - 10 minuts all of it solidified, crystallized.
Added another 100ml, checked hour later, solid crystals(soluble in water)
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Romix
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Would same happen with ethanol?
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Neuro-
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Yes, as long as your ethanol was anhydrous, although yields wouldn't be great.
https://en.wikipedia.org/wiki/Sodium_ethoxide
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BromicAcid
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Dissolution of NaOH/KOH in simple alcohols is exothermic, it doesn't take much KOH to make MeOH boil on addition. Of course, as the solvent heats up
it dissolves more of the hydroxide until everything is in solution. Then your solution cools and you crash out your hydroxide. Some will form the
alkoxide in equilibrium with the alchohol but I would think that most of what you are seeing is unreacted NaOH.
What size were these spoon fulls? Heaping tablespons? How much isopropanol did you have to start out with? We all have to start somewhere but I
would recommend your next investment be in some measuring tools for liquids, preferably in milliliters, even plastic disposable beakers can have
graduations. As it stands you don't have much to work with. Wiki says solubility is 238 g/L in MeOH, less than 139 g/L in EtOH and the trend is
going to continue downward from there.
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Nicodem
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Thread Moved
2-4-2016 at 12:44 |
Romix
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Quote: Originally posted by BromicAcid  | Dissolution of NaOH/KOH in simple alcohols is exothermic, it doesn't take much KOH to make MeOH boil on addition. Of course, as the solvent heats up
it dissolves more of the hydroxide until everything is in solution. Then your solution cools and you crash out your hydroxide. Some will form the
alkoxide in equilibrium with the alchohol but I would think that most of what you are seeing is unreacted NaOH.
What size were these spoon fulls? Heaping tablespons? How much isopropanol did you have to start out with? We all have to start somewhere but I
would recommend your next investment be in some measuring tools for liquids, preferably in milliliters, even plastic disposable beakers can have
graduations. As it stands you don't have much to work with. Wiki says solubility is 238 g/L in MeOH, less than 139 g/L in EtOH and the trend is
going to continue downward from there. |
No, its not exothermic, in anhydrous alcohols.
Compare to water. Only a lil bit.
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Romix
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Ok, what will happen on decomposition of this crystals, NaOH and isopropanol?
[Edited on 2-4-2016 by Romix]
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Tsjerk
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Do you think there is a difference between lower and higher alcohols? Do you know why there is a difference between water and alcohol?
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Romix
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| Quote: Originally posted by Tsjerk |
Do you think there is a difference between lower and higher alcohols? Do you know why there is a difference between water and alcohol?
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No.
All ols I know boils at lower temperature then water.
[Edited on 3-4-2016 by Romix]
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Hegi
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I must agree with BromicAcid. It is soluble in isopropanol and it does not react. Equilibrium is shifted to the reactants. So there´s just a minimum
of isopropoxide.
There is no rule for an exothermic reaction it must boil the solvent off 
Our webpage has been shut down forever cause nobody was willing to contribute. Shame on you all!!!
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Tsjerk
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As far as I know there is a difference between binding affinity of the compounds with water, which has to do with the formation of hydrogen bonds. I
can imaging these bonds are stronger (or less hindered) with lower alcohols.
There is no reaction between water and hydroxide either, dissolving them is exothermic though. There is a difference between sodium and potassium
hydroxide however. The difference can be explained by the size and overall interaction of the ions with water.
I know that the dissolution of for example ethanol in water is exothermic, for the reason I described above. I asked the last question because I was
wondering whether the same is true for isopropanol (which I think is true). I think it is true for every alcohol that is miscible with water.
Edit: Ok, there is a reaction between hydroxide and water, but that doesn't explain the exothermic reaction.
[Edited on 3-4-2016 by Tsjerk]
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Tsjerk
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The reaction between absolute ethanol and water is stronger than the reaction between 96% and water. The difference can be explained by the fact part
of the hydrogen bonds already formed.
The reason azeotropes exist is because certain compounds like to bind (like water and ethanol like to bind). In this process disorder is gained.
Nature always looks for chaos. This way molecules are happy. Breaking the bonds costs energy, therefore they are not happy.
Nature loves losing ordering.
Chaos is the final goal.
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BromicAcid
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Of interest to this tread in terms of alkoxides using hydroxides:
http://www.sciencemadness.org/talk/viewthread.php?tid=2656
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