RU_KLO
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Amyl alcohol from amyl acetate
I need amyl alcohol and the only product I can get OTC is amyl acetate.
From this post: https://www.sciencemadness.org/whisper/viewthread.php?tid=29...
it should be reacted with NaOH.
Now the questions:
1) how much NaOH? (for 250 ml amyl acetate) grs or if solution, molarity.
2) NaOH should be pellets or a solution of...
3) Does this reaction is exothermic? Should be a icebath be used?
from the post, maybe the alcohol separated from the water (I dont know where the water is from if pellets of NaOH are used - maybe from the reaction.
As the amyl alcohol should be pure - stated in the label)
4) If separation is needed, destillation is the way?
5) the remaining solution/salt is sodium acetate?
6) any dangers or things to be looked upon?
7) is there any cleanup needed (or water to be removed)? If yes, how?
Thanks
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DraconicAcid
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You'd probably have to reflux the ester with a solution of sodium hydroxide. You can use solid sodium hydroxide to dry the alcohol afterwards.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Sulaiman
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#2 is easy, from the discussion pointed to :
"You could react it with a NaOH solution,"
also
dissolving NaOH in water is very exothermic (more than 40 kJ/mole = 1 kJ/g)
it is generally better to add an NaOH solution that has cooled down,
rather than adding solid NaOH,
to an aqueous solution,
espcially if there are volatile or heat sensitive chemicals in the mix.
CAUTION : Hobby Chemist, not Professional or even Amateur
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RU_KLO
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thanks, Ive used sodium hydroxide before (known the dangers)
regarding this:
"You'd probably have to reflux the ester with a solution of sodium hydroxide."
Which molarity (sodium hydroxide)?
From what I found on internet (probably wrong because of IA)
1M amyl alcohol reacts 1M of NaOH
1 pentanol (amyl alcohol) : 88.1482 g/mol (density 0.811 g/mL)
250ml : 202.75 grs / 88.15g/mol = 2.3M
So at least 3M NaOH solution is required? better 5M (aprox. double)?
(Is my thinking correct?)
How long should be refluxed?
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DraconicAcid
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1 mol (not M, which is molarity) of sodium hydroxide will react with one mole of amyl acetate.
250 mL of amyl acetate will be less than 2.3 moles, so 2.5 moles of sodium hydroxide (about 100 g) will be plenty. You'd probably want at least 250
mL of water to dissolve that, because 50% NaOH will corrode glass.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Keras
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If you fear for the glass, either use sodium carbonate instead of sodium hydroxide, or use an acid catalyst instead of a base (you need to distill off
the water to get the hydrolysis to completion, though)
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chempyre235
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Quote: Originally posted by Keras  | | If you fear for the glass, either use sodium carbonate instead of sodium hydroxide, or use an acid catalyst instead of a base (you need to distill off
the water to get the hydrolysis to completion, though) |
I've found that sodium carbonate works very quickly for saponifying oil or fat, even without added water. Of course, some heat speeds things up quite
a bit.
@RU_KLO:
(5) Yes, the byproduct of hydrolysis with NaOH or Na2CO3 will be sodium acetate.
(7) If sodium carbonate is added to warm amyl acetate, there shouldn't be any water. The flash point of amyl acetate is 77°F (25°C) (CDC.gov), so
take care not to heat past this if using flame.
"However beautiful the strategy, you should occasionally look at the results." -Winston Churchill
"I weep at the sight of flaming acetic anhydride." -@Madscientist
"...the elements shall melt with fervent heat..." -2 Peter 3:10
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RU_KLO
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Try to found some paper regarding how much hydroxide is needed, but all papers talks about kinetics.
in a paper:
The maximum conversion of 96% was achieved for a residence/reaction time of five minutes at optimum initial concentrations of sodium hydroxide
(0.01mol/L) and ethyl acetate (0.07mol/L) in batch and plug flow reactor
"A Comparative Study of Alkaline Hydrolysis of Ethyl Acetate Using Design of Experiments"
Afzal Ahmad; Muhammad Imran Ahmad*+; Muhammad Younas; Hayat Khan; Mansoor ul Hassan Shah
Department of Chemical Engineering, University of Engineering and Technology, Peshawar, PAKISTAN"
found this video:
https://www.youtube.com/watch?v=8Vs87DsTUF0
could this be applied to amyl acetate?
Also no reflux was used, but I think that reflux is needed for better yield.
It seems that there is no best hydroxide concentration for better yield, but "use as concentrated as you can, without hurting your glass". in the
video they use 65% KOH.
Also strong stirring is needed because of phase separation. (from another paper - lost the reference)
from:
"If you fear for the glass, either use sodium carbonate"
"I've found that sodium carbonate works very quickly for saponifying oil or fat, even without added water. Of course, some heat speeds things up quite
a bit."
Could I add directly the carbonate salt to the ester? or water is needed because is a hydrolisis reaction?
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chempyre235
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You need at least 1 mole of bicarbonate for every mole of ester. It may be added directly to the ester, and this process isn't properly hydrolysis,
but saponification. Carbonate or bicarbonate is not as strong of a base as hydroxide, so heating is necessary to drive the reaction. There will be
some foaming from effervescence.
The reaction reads like this:
CH3(CH2)3OAc + NaHCO3 --> AcONa + CH3(CH2)OH + CO2
[Edit]: When I tried it with hot oil, I immediately got lots of effervescence, even with washing soda. After a couple of minutes (with stirring), I
got a water-soluble liquid with very little remaining oil. I took this to be glycerin and mixed sodium fatty acid salts, though I did no further
experimentation. It worked on spent canola oil and with bacon grease; with either baking soda (bicarbonate) or washing soda (carbonate), I got similar
results.
[Edited on 9/24/2025 by chempyre235]
"However beautiful the strategy, you should occasionally look at the results." -Winston Churchill
"I weep at the sight of flaming acetic anhydride." -@Madscientist
"...the elements shall melt with fervent heat..." -2 Peter 3:10
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Fery
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NaHCO3 is very weak, I use its solution to wash esters.
Na2CO3 works.
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