Fery
National Hazard
Posts: 990
Registered: 27-8-2019
Location: Czechoslovakia
Member Is Offline
|
|
butyl butyrate
90,0 g butyric acid + 83,2 g 1-butanol (slight excess) + 5 ml conc. H2SO4 (added dropwise !!! while stirring) + 35 ml hexane (at least 2x the volume
of empty Dean-Stark trap adapter)
rfx for 1 h using Dean-Stark trap adapter (very good device to see the reaction progress), at the end the amount of trapped water ceased so totally
19,5 ml of H2O collected, it had very slight odor of 1-butanol (that's why slight excess of 1-butanol used)
cooled down to room temperature
using 500 ml separatory funnel washed 2x200 ml of cold water, 2x100 ml of 5% NaHCO3 (! a little of CO2 evolution !), 2x200 ml of cold water
dried by freezing in freezer at -18 C overnight, then further drying using anh. Na2SO4
simple distillation using oil bath, first fraction distilled was the hexane which was discarded, the main fraction collected at 163-168 C (lit. 166 C)
yield 112,3 g
   
|
|
|
Cou
National Hazard
Posts: 958
Registered: 16-5-2013
Member Is Offline
Mood: Mad Scientist
|
|
epic x)
according to this chart, it should smell like pineapple
fruity banana pineapple green cherry fruit tropical fruit fruit ripe fruit juicy fruit
|
|
|
DraconicAcid
International Hazard
Posts: 4278
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline
Mood: Semi-victorious.
|
|
I find it one of the "generic tutti-frutti" esters, rather than a specific fruit.
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.
|
|
|
Cou
National Hazard
Posts: 958
Registered: 16-5-2013
Member Is Offline
Mood: Mad Scientist
|
|
Uh, you can use hexane as a dean-stark solvent? this is surprising. It doesn't even form an azeotrope with water. the boiling point of hexane is also
substantally lower than the boiling point of water.
A suitable solvent for dean-stark fischer esterification should have a boiling point well below the boiling point of both reactants. e.g. toluene
doesn't work here b/c it boils at 110 C, which is too close to the boiling point of 1-butanol (117 C).
[Edited on 19-5-2020 by Cou]
|
|
|
Fery
National Hazard
Posts: 990
Registered: 27-8-2019
Location: Czechoslovakia
Member Is Offline
|
|
DraconicAcid is right, I recognize butyl butyrate as tutti-frutti, very pleasant. Best pineapple scent for me are ethyl hexanoate (very pleasant),
then allyl valerate (in very low concentrations only, otherwise slightly irritating). Though there are certainly better pineapple scents based on
sulfur organocompounds (occuring naturally in ripe pineapple fruit) which I cannot synthesize in my home lab (yet).
Cou - hexane really works to remove water by distillation (but is not very efficient) and by some extent it also reduces loses of the ester dissolved
in water (in the water captured in Dean-Stark trap and during the workup). The ester table is not 100% correct. There are also differences in
perception of scents among people.
Another mistake I found here in different thread claiming walnut scent for ethyl valerate:
Ethyl valerate has fruity scent for me, not walnut at all.
The best experience is usually to synthesize the ester and then try its scent by yourself.
[Edited on 19-5-2020 by Fery]
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
