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Author: Subject: heptyl butanoate - fruity and little of chamomile scent
Fery
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[*] posted on 1-7-2020 at 02:01
heptyl butanoate - fruity and little of chamomile scent


1,00 mol 1-heptanol 116,2 g
+
butyric acid 1,25 mol 110,1 g (slight excess)
+
40 ml redistilled medical petrolether (hydrogenated alkanes), fraction b.p. 60-80 C (hexane + isomers of hexane)
+
5 ml 96% H2SO4 (catalyst) added dropwise while stirring

placed into 1 L RBF, added boiling chips, attached Dean-Stark trap adapter + condenser, refluxing, in less than 1 hour 18,5 ml H2O collected (very likely water with some small amount of butyric acid) so esterification seemed to be complete (at the end some carbonization appeared)

cooled down to 4 C

using 1 L separatory funnel:
washed 2x 750 ml ice cold water (necessary to allow separatory funnel to stay in a lab. stand for 1 hour for the separation to complete, bottom water layer got rid of most of carbon/tar from to upper organic layer)
washed 2x with 150 ml of saturated NaHCO3 solution, only the first washing produced CO2, the second one almost no effervescence (seems the washing with water already removed most of butyric acid)
washed with 500 ml ice cold water (later it was necessary to add 50 ml of saturated solution of NaCl to facilitate sharp layers separation)

put into freezer to -18C overnight to freeze out water, then further dried using anhydrous pulverous Na2SO4

filtered into 500 ml RBF, on oil bath distilled out approx 20 ml of hexane which drove out remainders of water, let to cool down, changed distillation head to new clean dry one and attached an air condenser, continued distillation, hexane and forerun discarded, main fraction collected 219-224 C (due to too much high b.p. I should rather use vacuum distillation), yield 141,4 g (0,76 mol)

it has fruity + slightly chamomile scent
I synthesized it because it is wasp / yellowjacket attractant, but I did not yet have any opportunity to test it, last 2 months were rainy and colder than usually


http://www.thegoodscentscompany.com/data/rw1025801.html
Name: heptyl butanoate
CAS Number: 5870-93-9
Molecular Weight: 186.29474000
Specific Gravity: 0.86000 to 0.86400 @ 25.00 °C
Melting Point: -58.00 to -57.00 °C. @ 760.00 mm Hg
Boiling Point: 225.00 to 226.00 °C. @ 760.00 mm Hg
Odor Type: fruity
Odor Strength:medium
Substantivity:6 hour(s) at 100.00 %
fruity tropical chamomile tea green tea sweet floral clean honey
Odor Description:at 100.00 %. fruity tropical chamomile green tea sweet floral clean
Luebke, William tgsc, (2009)



apparatus with reactants

IMG_20200629_090523_0_sm.jpg - 32kB



first 4 ml of H2O collected

IMG_20200629_091509_1_sm.jpg - 30kB



H2SO4 seems not to be much soluble in the ester, perhaps 1 ml instead of 5 ml would be enough as an catalyst

IMG_20200629_093303_2_sm.jpg - 97kB



when almost all H2O trapped and H2SO4 became concentrated again, a carbonization started and a strange phenomenon - small droplets floating at the surface

IMG_20200629_094509_2_sm.jpg - 100kB IMG_20200629_094531_4_sm.jpg - 77kB IMG_20200629_094556_0_sm.jpg - 75kB



17 ml of H2O trapped, not yet expected 1 mol = 18 ml (previously it was already drained out 10 ml of H2O)

IMG_20200629_094817_0_sm.jpg - 21kB



18,5 ml of H2O trapped, slightly more than 1 mol, I expected a little of H2O in reactants + this is certainly not only H2O but contains a little of butyric acid too

IMG_20200629_095959_9_sm.jpg - 23kB



washing with H2O removed most of carbon + tar so the ester in upper layer became less dark :)

IMG_20200629_150253_9_sm.jpg - 34kB



simple distillation using air condenser (I should use vacuum distillation due to too high b.p.), main fraction collected 219-224 C

IMG_20200701_101237_2_sm.jpg - 14kB IMG_20200701_102736_3_sm.jpg - 14kB IMG_20200701_105247_4_sm.jpg - 16kB




If there is a heaven, it seems not to be materially based. Does chemistry exist there and if yes, how does it look like? Are there good souls well supplied with laboratory equipment, glass, chemicals and information?
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Tsjerk
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[*] posted on 1-7-2020 at 03:39


Nice prep, but please use a water or a sand bath next time, you don't want a big fire when the flask breaks. Also you would probably have avoided that carbonization when using a water bath.
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Fery
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[*] posted on 1-7-2020 at 04:38


Hi Tsjerk, you are right, that should help at the small cost that it won't be so well visible what happened at the bottom of the reaction flask. The carbonization occurred when H2SO4 became again concentrated at the end of reaction when last 2 ml of H2O trapped in the Dean-Stark trap adapter during last 20 minutes (first 16 ml was collected fast in 30 minutes). Also better for safety not to heat flammable chemicals using direct flame, I know.
So everyone repeating this experiment should do it as Tsjerk suggested, no need to observe the bottom of the flask, you already know, shown on the pictures.
The only annoying problem I encountered was fuming oil bath on the final distillation, I had to close both doors and open both windows in the lab so fume blew out and did not spread inside my house - vacuum distill is better.
I forgot to mention that 20 ml of dark ester remained in the 500 ml distillation flask as a distillation residue which I'll use for attracting yellowjackets so the main fraction = pure ester will stay for me to smell it or to offer some of it to anyone interested in esters/scents/yellowjackets etc.




If there is a heaven, it seems not to be materially based. Does chemistry exist there and if yes, how does it look like? Are there good souls well supplied with laboratory equipment, glass, chemicals and information?
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Tsjerk
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[*] posted on 1-7-2020 at 05:17


I like to use sand baths instead of oil baths, lot less smoke!
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