Sciencemadness Discussion Board - propyl octanoate

propyl octanoate

Fery - 20-8-2021 at 21:37

propyl octanoate is the only one ester claimed to have coconut scent I've found in database
http://www.thegoodscentscompany.com/data/rw1049811.html

Quote:

propyl octanoate
octanoic acid, propyl ester

Specific Gravity: 0.86100 to 0.86700 @ 25.00 °C
Boiling Point: 225.00 to 226.00 °C @ 760.00 mm Hg

Organoleptic Properties:
Odor Type: coconut
Odor Strength: medium
coconut cocoa cognac winey fatty
Odor Description at 100.00 % coconut caco gin

Suppliers:
Alfrebro
n-PROPYL OCTANOATE NATURAL
Odor: Wine, Slightly Fatty

I synthetized it but I do not scent it as coconut and also Alfrebo supplier does not describe it as coconut...

here the synthesis at 0,5 mol scale:

72,1 g octanoic acid (0,5 mol, M = 144,214 g/mol)
45 g 1-propanol (0,75 mol, M = 60,096 g/mol, must be slight excess as some of it will distill out into Dean-Stark trap apparatus with water as ternary azeotrope mixture)
0,2 ml 96% H2SO4 (yeah it is enough, cca 5 drops, it is just a catalyst, no need to use few ml of it)
30 ml isohexanes mixture, b.p. 60-65 C

refluxed in 250 ml RBF with Dean-Stark trap apparatus
11,5 ml water phase collected in 1 hour (should be 0,5 mol H2O = 9,0 ml + the rest is n-propanol), refluxed for extra 1 hour, no more water trapped
cooled down in cold water bath
transferred into 250 ml separatory funnel
washed:
twice with 100 ml cold water
twice with 100 ml of 5% NaHCO3
twice with 100 ml cold water
dried with anhydrous Na2SO4, magnetically stirred for 1 hour, then let to sit overnight
filtered through funnel with small piece of cotton plug into 250 ml RBF
distilled out isohexanes on oil bath (it also removed remaining water, few tiny drops visible on bottom of receiver flask), then vacuum applied using water aspirator to remove the rest of solvent
vacuum distilled, b.p. 71-73 C, vacuum level uknown (2 stage rotary oil vacuum pump), yield 79,0 g = 85% (0,5 mol = 100% = 93,1 g)

synthesis

washing

vacuum distillation

video of the vacuum distillation:

https://youtu.be/mlR67g03YUM

[Edited on 21-8-2021 by Fery]

happyfooddance - 21-8-2021 at 20:05

There are many esters that smell like coconut! Check out the database at goodscents:

http://www.thegoodscentscompany.com/search3.php

An easy way to make coconut esters is to take coconut oil, about 10-20 molar equivalents of methanol, and a slight molar excess of potassium hydroxide (or NaOH, but it's less soluble), and reflux for a few hours.

This is a transesterification, the methanol replaces glycerol from the oil, and the products smell like a tropical paradise!

UC235 - 21-8-2021 at 20:26

Quote: Originally posted by happyfooddance

There are many esters that smell like coconut! Check out the database at goodscents:

http://www.thegoodscentscompany.com/search3.php

An easy way to make coconut esters is to take coconut oil, about 10-20 molar equivalents of methanol, and a slight molar excess of potassium hydroxide (or NaOH, but it's less soluble), and reflux for a few hours.

This is a transesterification, the methanol replaces glycerol from the oil, and the products smell like a tropical paradise!

Having made coconut oil biodiesel before the scent is a horrible mishmash of pineapple, orange-adjacent, and "fatty."

Probably the "fatty" note is what made them list propyl octanoate under coconut.

If you're looking for a coconut scent, you want gamma-nonalactone, called "aldehyde C-18" for deeply confusing reasons in the fragrance industry.

Here is a prep: http://www.sciencemadness.org/talk/viewthread.php?tid=11202

Heptanal can be produced by thermal cracking of castor oil or preferentially biodiesel made from it (primarily methyl ricinoleate).

Fery - 21-8-2021 at 23:00

Hi guys, as I wrote, that was the only one ester which I found in databases with claimed coconut scent. If you know another one, please post its name. Posting links to search engines is helpful but personal experience is better. The lactone is also known to me, aldehydes too. I checked documents concerning analysis of natural coconut water and pulp, like this where nonanal and nonanol seems to be the most abundant compounds present https://agritrop.cirad.fr/563900/1/document_563900.pdf
I wanted to synthesize this ester to check how much is it coconut (week/strong, whether not only pure coconut but also another scents recognized etc).
But I did not recognize the claimed coconut scent in it at all. Maybe waxy, oily, fatty but also this only very week. It has almost no scent for me, no matter concentrated / diluted. Also Alfrebo supplier declares something else (only wine and slightly fatty).
If it had coconut scent I would suggest it here to other forumers, but I can't. It also could be a variability in my scent receptors? If anyone here has positive experience with this ester and find its coconut scent, please post your personal experience. Rewriting only theoretical information is helpful, but personal experience is better. Even more, sometimes there are controversies like between table:
https://jameskennedymonash.files.wordpress.com/2013/12/table...
which declares also another coconut ester - butyl heptanoate, but if you lookup other databases like good scents company they declare something else
http://www.thegoodscentscompany.com/data/rw1013461.html
I wanted to find coconut ester to suggest here as the fisher esterification synthesis is more suitable to home chemists than other more complicated synthesis. My goal was not to find any coconut compound, but to find coconut ester and suggest it here. But I did not succeeded in this, I succeeded only in the ester preparation itself.
Castor oil cracking into heptanal if possible to do at home lab would be cool (but that would suit into the posted thread started by Klute). Malonic acid available at chemcraft.su and for amberlyst 15 we can ask our suppliers like chemship1978.