vibbzlab - 15-9-2022 at 22:09
So I had this bottle of anthracene which I bought from a chemicak supplies store almost one year back. Now when I open it ,it has this fluorescent
like green color. When I tried to make anthracene picrate ,it gave yellow precipitate instead of the red color. So I am not sure if the compound is
anthracene itself . Can someone help me?
I have provided the photograph of anthracene powder which I took out from its box
Boffis - 15-9-2022 at 22:43
Hi Vibbzlab, That does look to bad! I have several jars of anthracene and some are very old (<1950) and some according to the label is "coal tar"
anthracene of >90% purity and is a brownish yellow crystalline powder. The "newest one" claims to >98% and doesn't say what it is from. The
former is faintly fluorescent under UV but if carefully sublimed it gives three concentric zone. The inner most and most abundant is clearly
anthracene itself and it is pale yellow with a strong bluish green fluorescence. Around this forms a less abundant white zone with a blue white
fluorescent and finally a trace of white sublimate with a dull purple fluorescence. I don't know what the two outer zones are but "coal tar
anthracene" is notoriously impure. Your material resembles my "newer" anthracene and mine is fluorescent green too (particularly under UV) and so is
probably OK.
You can try oxidizing a bit with conc. nitric acid and then recrystallising the anthraquinone from glacial acetic acid to test it. I haven't tried a
Mp test on the raw material but this might be worth it and you could also see if it sublimes.
vibbzlab - 15-9-2022 at 22:51
Thank you so much for your information. Actually I am giving some tuition classes to highschool students. There's a test in the books which helps to
differentiate between naphthalene and anthracene. It says that one adding a solution of picric acid in acetone to a solution of naphthalene in acetone
and anthracene in acetone , it gives a yellow crystallise product and red colored product respectively.
But it didnt seem to work here.