Yellow-orange S (manufacture)
ID: 185544 | No.: 639 | Institut für Chemieinformation
School experiment from Year 5 onwardsCategory: Flavourings and colourings
Reaction mechanism analogous to https://de.wikipedia.org/wiki/Azokupplung; the phenolic O-H group acts as the directing electron donor.
Solution 1
Suspend 1 g of sulphanilic acid in 50 ml of deionised water and add 10 ml of hydrochloric acid (w = 25 %).
The volume is then made up to approximately 200 ml with water.
Solution 2
0.1 g of sodium nitrite is dissolved in 20 ml of deionised water in the 50-ml flask.
Experimental procedure
0.5 mmol of Schäffer’s acid is weighed out and transferred to two labelled test tubes.
Add 2 ml of deionised water to each, so that suspensions are formed.
A fourth test tube, also filled with 2 ml of water, serves as a blank.
Now, 8 ml of solution 1 is mixed with 4 drops of solution 2 in a 25-ml Erlenmeyer flask, and the mixture is divided between the four test tubes.
Shake gently to ensure everything is well mixed.
After adding 2 ml of 10% ammonia solution to each, yellow, orange and orange-red colourations can be observed in the solutions.
2 x 250 mL & 1 x 25 mL Erlenmeyer flasks
2 dropper pipettes & 1 measuring pipette (5 mL)
50 mL bottle & 4 test tubes
| Name | Formula | CAS no. | H-statements | P-statements | Pictograms |
|---|---|---|---|---|---|
| Sulfanilsäure | NH₂C₆H₄SO₃H | 121-57-3 6101-32-2 |
H315
– Causes skin irritation.
German original: Verursacht Hautreizungen.
H317
– May cause allergic skin reactions.
German original: Kann allergische Hautreaktionen verursachen.
H319
– Causes serious eye irritation.
German original: Verursacht schwere Augenreizung. |
P261
– Avoid inhaling dust, fumes, gas, mist, vapour or aerosols.
German original: Einatmen von Staub/Rauch/Gas/Nebel/Dampf/Aerosol vermeiden.
P264
– After use … wash thoroughly.
German original: Nach Gebrauch ... gründlich waschen.
P272
– Do not wear contaminated work clothes outside the workplace.
German original: Kontaminierte Arbeitskleidung nicht außerhalb des Arbeitsplatzes tragen.
P280
– Wear protective gloves / protective clothing / eye protection / face protection.
German original: Schutzhandschuhe / Schutzkleidung / Augenschutz / Gesichtsschutz tragen.
P302+P352
– IF IT COMES INTO CONTACT WITH THE SKIN: Wash with plenty of water / ...
German original: BEI BERÜHRUNG MIT DER HAUT: Mit viel Wasser / ... waschen.
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 |
| Ammoniak, wässrige Lösung 10% | NH₃·aq |
H314
– Causes severe skin burns and serious eye damage.
German original: Verursacht schwere Verätzungen der Haut und schwere Augenschäden.
H335
– May irritate the respiratory tract.
German original: Kann die Atemwege reizen.
H410
– Very toxic to aquatic organisms, with long-term effects.
German original: Sehr giftig für Wasserorganismen mit langfristiger Wirkung. |
P261
– Avoid inhaling dust, fumes, gas, mist, vapour or aerosols.
German original: Einatmen von Staub/Rauch/Gas/Nebel/Dampf/Aerosol vermeiden.
P271
– Use only outdoors or in well-ventilated areas.
German original: Nur im Freien oder in gut belüfteten Räumen verwenden.
P280
– Wear protective gloves / protective clothing / eye protection / face protection.
German original: Schutzhandschuhe / Schutzkleidung / Augenschutz / Gesichtsschutz tragen.
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, GHS07, GHS09 | |
| Salzsäure 25% | HCl·aq |
H290
– May be corrosive to metals.
German original: Kann gegenüber Metallen korrosiv sein.
H314
– Causes severe skin burns and serious eye damage.
German original: Verursacht schwere Verätzungen der Haut und schwere Augenschäden.
H335
– May irritate the respiratory tract.
German original: Kann die Atemwege reizen. |
P234
– Store only in the original container.
German original: Nur im Originalbehälter aufbewahren.
P261
– Avoid inhaling dust, fumes, gas, mist, vapour or aerosols.
German original: Einatmen von Staub/Rauch/Gas/Nebel/Dampf/Aerosol vermeiden.
P271
– Use only outdoors or in well-ventilated areas.
German original: Nur im Freien oder in gut belüfteten Räumen verwenden.
P280
– Wear protective gloves / protective clothing / eye protection / face protection.
German original: Schutzhandschuhe / Schutzkleidung / Augenschutz / Gesichtsschutz tragen.
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, GHS07 | |
| Natriumnitrit 0,5 % | |||||
| Schäffersäure | C₁₀H₈O₄S | 93-01-6 | |||
| Dinatrium-6-hydroxy-5-((4-sulfonatophenyl)azo)naphthalin-2-sulfonat | C₁₆H₁₀N₂Na₂O₇S₂ | 2783-94-0 |
H/P statements: machine translation, with the German original below (authoritative). Name, formula, CAS no. and pictograms are not translated.
Yellow Orange S is considered a safe food colouring. Reductive cleavage produces harmless products
https://www.dguv.de/medien/ipa/publikationen/ipa-reporte/09-02-27_bgfa-report2_azofarbstoffe.pdf
Yellow-orange S
Klemeyer, Horst (2026) Yellow-orange S, experimental procedure for synthesis. doi: 10.5281/zenodo.21889206
Tami, Kristi; Popova, Anastasia; Proni, Gloria (2017) Engaging Students in Real-World Chemistry through the Synthesis and Confirmation of Azo Dyes via Thin-Layer Chromatography to Determine the Dyes Present in Everyday Foods and Beverages. Journal of Chemical Education, 94(4), 471–475. doi:10.1021/acs.jchemed.6b00334