Vanilla or Vanillin

Vanilla or Vanillin
On Monday the 12th of April we made an excursion to the „Alfred-Krupp-Schülerlabor“ at
the university of Bochum with our chemistry class.We met at Cologne Central Station at 6.30
a.m. and took the train to Bochum Central Station, where we had to change for the
Underground. When we arrived, we got the keys to our lockers after signing that we knew
about the houserules of “AKS” .
We played a little bit with the science attractions in the entrance. Afterwards we were
familiarised with the topic “Vanilla or Vanillin”. The introducing lecture was easy to follow,
the English was very clear and it wasn’t tot fast. We were taught the difference between
natural flavour substance, natural identical flavour substance and artificial flavour substance.
You extract vanilla from the capsule fruit of an orchid. Vanillin is the substance you taste in
vanilla, but it’s not the only ingredient of vanilla. Vanillin was identified as the vanilla flavour
in 1872. From then they had been searching for alternatives to produce the natural flavour
substance. They were successful in 1874, only 2 years after vanillin had been identified. Now
they can extract vanillin from modifying spruce bark rubbish.
After this short introductory lecture we got a
safety briefing, which is important for working
in a laboratory. For the experiments we had to
build pairs. I worked with Jasmin. We had to
divide a text into six steps. This text told us how
to extract vanillin and prepared us for the first
experiment, in which we had to extract the
filtrate from the batch twice with diethylether.
We waited until the separation of two phases,
then we led the lower phase (liquid) into a
beaker. The upper phase (organic) went into a crystalisaton dish. Ulli and Leonie finished the
experiment.
The second experiment was about the structure of vanillin. We filled five tubes with vanillin
solution and added to four of them either iron(III)-chlorid-solution, Schiff reagent, saturated
ethanolic phloroglucin-solution or sulphuric acid and ethanol. The solution in the fifth tube
was checked for the pH-value. For controll we filled a sixth tube with acetic acid, sulphuric
acid and ethanol.
Observations:
Part 1: iron(III)-clorid-solution: blue-violett
Part 2: Schiff reagent: pink
Part 3: phloroglucin-solution: red-orange warm
Part 4: ethanol and sulphuric acid: no change
Part 5: ph: orange means ph 4
Part 6: acetic acid, ethanol ans sulphuric acid: change in
smell from acetic acid to adhesive
solvent
So we got to know the molecule structure of Vanillin:
Vanillin contains an aldehyde-group (V2), a phenolic
structure (V1), reacts with water sour (V5) but there is no
carboxylate-group (V4+V6) and it has got ligninstructure (V3).
In the third experiment we had to find differences between vanilla- and vanillin sugar. We
tried the DC-layer-chromatography. We found out that vanilla has more flavour than vanillin.
With experiment 4 we tried to find out the concentration of Vanillin in Vanillin sugar. We put
one sachet (8 gramm) with 25 ml ethanol in an erlenmeyer flask and added 3 drops of
phenolphthalein, a stirfish and put it on the magnetic stirrer. We titrated the mixture with
0,1 m sodium-hydroxid-solution until the colour switched into pink. We needed ca. 6,8 mL of
sodium-hydroxide-solution and worked out that one sachet of vanillin sucar contains only
1,2 % Vanillin.
The way home was the same as the way to Bochum. We were back at Cologne Central Station
at 6.15 p.m..
Hanna Bieniek
Hürth, 17.04.2010