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Pupils’ free-hand synthesis of heptyl acetate

ID: 69612  |  No.: 134  |  Institut für Chemieinformation

School experiment from Year 5 onwards

Category: Esters, fats, surfactants

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Permanent archiving (DOI)

No permanent DOI has been generated for this experiment yet.

Procedure

The pupils add approximately 2 mL of heptanol and three boiling stones to a test tube containing a mixture of 3 mL of concentrated acetic acid and 0.5 mL of concentrated sulphuric acid, using a pipette fitted with a Pileus ball. The test tube is then sealed with the stopper and rising tube and clamped into a test tube holder
. The hot-air blower is placed upright on the student experiment table and switched on. The test tube is now held at an angle in the hot-air stream for short intervals of 10–20 s at a time, whilst being shaken gently. This procedure is repeated twice at intervals of approximately 30 s.
Clean-up:
Once the test tube has cooled to room temperature, the reaction mixture is carefully poured into the beaker, which has been pre-filled with 20 mL of cold water. After one minute, the contents of the beaker can be poured back into the test tube. The resulting ester separates as a water-clear oily phase above the aqueous phase.

Notes:

The aqueous acid solution can be coloured by adding a drop of the indicator methyl orange. The phase boundary between the ester and the aqueous phase, now coloured red, is then easier to identify. Alternatively, it is possible to neutralise the aqueous phase before separating the ester by adding magnesium oxide, causing the colour to change from red to yellow.

Equipment & materials

Test tube rack,
test tube (with rim),
50 mL beaker,
test tube holder,
rubber stopper with rising tube (l = approx. 20 cm),

pipette with Pileus bulb

Pasteur pipette,

Hot-air blower (e.g. Steinel HL 1810 S),
boiling stones,

Disposable gloves,

Safety goggles

Hazardous substances
Name Formula CAS no. H-statements P-statements Pictograms
Essigsäure CH₃COOH 64-19-7
H226 – The liquid and vapour are flammable.
German original: Flüssigkeit und Dampf entzündbar.
H314 – Causes severe chemical burns to the skin and serious eye damage.
German original: Verursacht schwere Verätzungen der Haut und schwere Augenschäden.
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.
P280 – Wear protective gloves / protective clothing / eye protection / face protection.
German original: Schutzhandschuhe / Schutzkleidung / Augenschutz / Gesichtsschutz tragen.
P310 – Call the POISON INFORMATION CENTRE / a doctor ... immediately.
German original: Sofort GIFTINFORMATIONSZENTRUM / Arzt ... anrufen.
P301+P330+P331 – IF SWALLOWED: Rinse out the mouth. DO NOT induce vomiting.
German original: BEI VERSCHLUCKEN: Mund ausspülen. KEIN Erbrechen herbeiführen.
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.
GHS02, GHS05
1-Heptanol C₇H₁₅OH 111-70-6
H319 – Causes serious eye irritation.
German original: Verursacht schwere Augenreizung.
P264 – After use … wash thoroughly.
German original: Nach Gebrauch ... gründlich waschen.
P280 – Wear protective gloves / protective clothing / eye protection / face protection.
German original: Schutzhandschuhe / Schutzkleidung / Augenschutz / Gesichtsschutz tragen.
P337+P313 – If eye irritation persists: seek medical advice / seek medical attention.
German original: Bei anhaltender Augenreizung: Ärztlichen Rat einholen / ärztliche Hilfe hinzuziehen.
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.
GHS07
Schwefelsäure 96% H₂SO₄ 7664-93-9
H290 – May be corrosive to metals.
German original: Kann gegenüber Metallen korrosiv sein.
H314 – Causes severe chemical burns to the skin and serious eye damage.
German original: Verursacht schwere Verätzungen der Haut und schwere Augenschäden.
P234 – Store only in the original container.
German original: Nur im Originalbehälter aufbewahren.
P280 – Wear protective gloves / protective clothing / eye protection / face protection.
German original: Schutzhandschuhe / Schutzkleidung / Augenschutz / Gesichtsschutz tragen.
P363 – Wash contaminated clothing before wearing it again.
German original: Kontaminierte Kleidung vor erneutem Tragen waschen.
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.
P304+P340+P310 – IF INHALED: Move the person to fresh air and ensure they can breathe freely. Call a POISON INFORMATION CENTRE or a doctor immediately.
German original: BEI EINATMEN: Die Person an die frische Luft bringen und für ungehinderte Atmung sorgen. Sofort GIFTINFORMATIONSZENTRUM oder Arzt anrufen.
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
Wasser, entionisiert H₂O 7732-18-5
Heptylacetat C₉H₁₈O₂ 112-06-1

H/P statements: machine translation, with the German original below (authoritative). Name, formula, CAS no. and pictograms are not translated.

Personal protective equipment
  • Safety goggles must be worn.
    German original
    Eine Gestellschutzbrille ist zu tragen.
  • Disposable nitrile gloves are used as splash protection.
    German original
    Als Spritzschutz dienen Nitril-Einmalhandschuhe.
Protective measures
The concentrated acetic acid and concentrated sulphuric acid are mixed under the fume cupboard. The laboratory is well ventilated. (Cross-ventilation) The prepared acid mixture is combined with the alcohol in the laboratory and heated there in a stream of hot air.
German original
Die konz. Essigsäure und konz. Schwefelsäure werden unter dem Abzug gemischt. Der Fachraum wird gut gelüftet. (Querlüftung) Das vorgelegte Säuregemisch wird im Fachraum mit dem Alkohol versetzt und dort im Heißluftstrom erwärmt.
⚠ Hazards
  • by inhalation
    German original
    durch Einatmen
  • through skin contact
    German original
    durch Hautkontakt
  • through eye contact
    German original
    durch Augenkontakt
  • Fire hazard
    German original
    Brandgefahr
  • Risk of explosion
    German original
    Explosionsgefahr
⚠ Further hazards and notes
  • Start-up fires
    Fight small fires with 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. Fight fires on people immediately using a hand-held hose or, if necessary, a fire extinguisher – every second counts!
    German original
    Entstehungsbrände 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!
⚠ Safety instructions

Note:
The ester syntheses can be carried out in a test tube with a rising tube, or alternatively within 10 minutes in a water bath heated to approximately 80°C. However, this method eliminates the errors that can occur when heating with a hot-air gun – particularly those resulting from failing to adhere to the specified temperature and time parameters – thereby ensuring that the experiment remains a hands-on activity for the pupils.

German original

Hinweis:
Die Estersynthesen können im Reagenzglas mit Steigrohr alternativ auch innerhalb von 10 Minuten in einem ca. 80°C warmen Wasserbad durchgeführt werden. Die Fehler, die beim Erwärmen mittels Heißluftgebläse insbesondere durch eine unzureichende Beachtung der Temperatur- bzw. der Zeitvorgaben gemacht werden können, werden dadurch aber zulasten der Schüleraktivität ausgeschlossen.
Substitution Substitution 1
The substitution of hazardous substances, as well as their forms of use and methods of application, has been assessed. The experiment is essential for teaching key learning content and can be carried out provided that the restrictions set out in the experiment instructions are observed and the protective measures specified therein are followed.
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.

Klemeyer, H., 2022: Risk assessment: sorting, comparing, grouping, doi: 10.1002/nadc.20224126220 

Heptyl propionate is not classified as a hazardous substance according to the read-across approach applicable under Annex XI of REACH and the classification by the trade (Source: https://msds.chemicalbook.com/Search/MSDS?cbn=CB3371541&l=EN). Nevertheless, it is still listed as such in the DEGINTU substance list (Source: https://degintu.dguv.de/chemicals/export/pdf).

It is therefore advisable to create a new entry for heptyl propionate without a GHS classification in DEGINTU for the purposes of the risk assessment.

Media & figures
Schematic illustration of the freehand experiment
Literature

Klemeyer, H. 2008, The Experiment: Free-form experiments on esters doi: 10.1002/ckon.200890017

Klemeyer, H. 2020, Safe Experimentation – Synthesis of nature-identical flavourings as an experiment in chemistry lessons: Optimising safety in chemistry lessons through systematic testing of substitutes, using the synthesis of flower, herb, vegetable and fruit flavourings as an example, doi:  10.1002/ckon.202000034 https://www.gdch.de/my/article/risikobewertung-sortieren-vergleichen-gruppieren-4126220