Synthesis of n-alkylalkanoates by transesterification of triglycerides: the example of propyl propionate
ID: 126520 | No.: 429 | Institut für Chemieinformation
Pupil experiment from Year 5 onwardsCategory: Esters, fats, surfactants
As the propyl propionate formed evaporates from the reaction mixture immediately after its formation, a reverse reaction is not possible. An equilibrium cannot be established. Image: Wikipedia
In a spot plate, approximately 2 drops of tripropionin (glycerol tripropionate) are mixed with 3 drops of 1-propanol and stirred in with one drop of caustic soda solution.
Propyl propionate is identified by its characteristic odour. Propyl propionate; ZVG = 510344 is highly volatile, with a vapour pressure (pD) of 13.5 hPa at 20°C, and has a strong smell of grapes and pineapple.
The test procedure can be adapted to the synthesis of corresponding volatile ethyl esters (fruit esters), whereby only the amount of the alkanol needs to be increased accordingly in line with the rising molar mass.
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Glycerol esters |
Name |
Ethanol |
1-propanol |
1-Butanol |
1-Pentanol |
1-hexanol |
1-Heptanol |
1-Octanol |
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Wikipedia |
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ZVG / ECHA |
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TheGoodScents |
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Wikipedia |
Hexyl propionate |
Heptyl propionate |
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ZVG / ECHA |
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TheGoodScents |
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Wikipedia |
Heptyl butyrate |
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ZVG / ECHA |
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TheGoodScents |
A porcelain or glass test plate and a glass rod
| Name | Formula | CAS no. | H-statements | P-statements | Pictograms |
|---|---|---|---|---|---|
| Glycerin | HOCH₂CH(OH)CH₂OH | 56-81-5 | |||
| Natriumhydroxid 50% | NaOH·aq |
H290
– May be corrosive to metals.
German original: Kann gegenüber Metallen korrosiv sein.
H314
– Causes severe chemical burns to the skin and serious damage to the eyes.
German original: Verursacht schwere Verätzungen der Haut und schwere Augenschäden. |
P280
– Wear protective gloves / protective clothing / eye protection / face protection.
German original: Schutzhandschuhe / Schutzkleidung / Augenschutz / Gesichtsschutz tragen.
P308+P310
– IN THE EVENT OF EXPOSURE OR IF AFFECTED: Call the POISON INFORMATION CENTRE or a doctor immediately.
German original: BEI Exposition oder falls betroffen: Sofort GIFTINFORMATIONSZENTRUM oder Arzt anrufen.
P303+P361+P353
– IF IN CONTACT WITH THE SKIN (or hair): Remove all contaminated clothing immediately. Wash the skin with water or take a shower.
German original: BEI BERÜHRUNG MIT DER HAUT (oder dem Haar):Alle kontaminierten Kleidungsstücke sofort ausziehen. Haut mit Wasser abwaschen/duschen.
P305+P351+P338
– IF IN EYES: Rinse gently with water for several minutes. Remove any contact lenses if possible. Continue rinsing.
German original: BEI KONTAKT MIT DEN AUGEN: Einige Minuten lang behutsam mit Wasser spülen. Vorhandene Kontaktlinsennach Möglichkeit entfernen. Weiter spülen. |
GHS05 | |
| Propylpropionat | C₆H₁₂O₂ | 106-36-5 |
H226
– The liquid and vapour are flammable.
German original: Flüssigkeit und Dampf entzündbar.
H332
– Harmful if inhaled.
German original: Gesundheitsschädlich bei Einatmen. |
P210
– Keep away from heat, hot surfaces, sparks, open flames and other sources of ignition. No smoking.
German original: Von Hitze, heißen Oberflächen, Funken, offenen Flammen und anderen Zündquellen fernhalten. Nicht rauchen.
P261
– Avoid inhaling dust, smoke, gas, mist, vapour or aerosols.
German original: Einatmen von Staub/Rauch/Gas/Nebel/Dampf/Aerosol vermeiden.
P312
– If you feel unwell, call the POISON INFORMATION CENTRE / a doctor ...
German original: Bei Unwohlsein GIFTINFORMATIONSZENTRUM / Arzt ... anrufen.
P304+P340
– IF INHALED: Move the person to fresh air and ensure they can breathe freely.
German original: BEI EINATMEN: Die Person an die frische Luft bringen und für ungehinderte Atmung sorgen.
P403+P233
– Store the container tightly sealed in a well-ventilated place.
German original: Behälter dicht verschlossen an einem gut belüfteten Ort aufbewahren.
P303+P361+P353
– IF IT COMES INTO CONTACT WITH THE SKIN (or hair): Remove all contaminated clothing immediately. Wash the skin with water or take a shower.
German original: BEI BERÜHRUNG MIT DER HAUT (oder dem Haar):Alle kontaminierten Kleidungsstücke sofort ausziehen. Haut mit Wasser abwaschen/duschen. |
GHS02, GHS07 |
| Ethanol | C₂H₅OH | 64-17-5 |
H225
– Liquid and vapour are highly flammable.
German original: Flüssigkeit und Dampf leicht entzündbar.
H319
– Causes serious eye irritation.
German original: Verursacht schwere Augenreizung. |
P210
– Keep away from heat, hot surfaces, sparks, open flames and other sources of ignition. Do not smoke.
German original: Von Hitze, heißen Oberflächen, Funken, offenen Flammen und anderen Zündquellen fernhalten. Nicht rauchen.
P233
– Keep the container tightly closed.
German original: Behälter dicht verschlossen halten.
P240
– Earth the container and the equipment to be filled.
German original: Behälter und zu befüllende Anlage erden.
P241
– Use explosion-proof electrical equipment / ventilation systems / lighting /...
German original: Explosionsgeschützte elektrische Betriebsmittel / Lüftungsanlagen / Beleuchtung /... verwenden.
P242
– Use only non-sparking tools.
German original: Nur funkenfreies Werkzeug verwenden.
P305+P351+P338
– IF IN EYES: Rinse gently with water for several minutes. Remove contact lenses, if possible. Continue rinsing.
German original: BEI KONTAKT MIT DEN AUGEN: Einige Minuten lang behutsam mit Wasser spülen. Vorhandene Kontaktlinsennach Möglichkeit entfernen. Weiter spülen. |
GHS02, GHS07 |
| Glycerintripropionat | C₁₂H₂₀O₆ | 139-45-7 |
H/P statements: machine translation, with the German original below (authoritative). Name, formula, CAS no. and pictograms are not translated.
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Safety goggles must be worn.German originalEine Gestellschutzbrille ist zu tragen.
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Disposable nitrile gloves are used as splash protection.German originalAls Spritzschutz dienen Nitril-Einmalhandschuhe.
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through skin contactGerman originaldurch Hautkontakt
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through eye contactGerman originaldurch Augenkontakt
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Fire hazardGerman originalBrandgefahr
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Risk of explosionGerman originalExplosionsgefahr
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Start-up firesFight fires in their early stages using a fire extinguisher. Pupils must keep a safe distance. If the fire cannot be extinguished immediately, leave the room straight away and alert the fire brigade and the school management. Immediately tackle fires on people using a hand-held hose or, if necessary, a fire extinguisher – every second counts!German originalEntstehungsbrände mit Feuerlöscher bekämpfen. Schülerinnen und Schüler halten sicheren Abstand. Können diese nicht sofort gelöscht werden, Raum unverzüglich verlassen und Feuerwehr sowie Schulleitung alarmieren. Personenbrände mit Handbrause oder ggf. Feuerlöscher unverzüglich bekämpfen, hier zählt jede Sekunde!
There are no known hazardous properties of the substances or other risks that would, in principle, preclude the experiment from being carried out by pupils or teachers. The list of substances in DGUV Information 213-098 at degintu.dguv.de has been taken into account.
Owing to the minimal reaction volume, the fact that the reaction is carried out at room temperature, and the absence of volatile free carboxylic acids, this experimental procedure is significantly less hazardous than acid esterification.
This is a method for synthesising propyl propionate without having to handle propionic acid, which is highly volatile and corrosive. The caustic soda solution used as a catalyst is classified as ‘skin corrosive, Category 1A’, which corresponds to a high level of hazard. The substitution test using the less hazardous methanesulphonic acid (acid catalysis) was unsuccessful.
Figure: Spot plate with twelve ‘reaction wells’ Image: Klüver & Schulz GmbH
Experimental procedure: Synthesis of n-alkylalkanones by transesterification of triglycerides, example: propyl propionate (2026) Klemeyer, H. DOI: 10.5281/zenodo.22832401
School experiments on the synthesis of nature-identical, odour-active esters on a micro-scale by alkali-catalysed transesterification of glycerides (2026); DOI: 10.1002/ckon.70023