You can test for the aldehyde group by making a batch of Fehlings reagent. It's made in the following manner:
Fehling's solution is prepared just before use by mixing equal volumes of two previously prepared solutions, one containing about 70 grams cupric sulfate pentahydrate per liter of solution and the other containing about 350 grams Rochelle salt (potassium sodium tartrate tetrahydrate) and 100 grams sodium hydroxide per liter of solution. The cupric ion (complexed with tartrate ion) is reduced to cuprous ion by the aldehyde (which is oxidized) and precipitates as cuprous oxide (Cu2O).
If positive, you'll get a nice precipitate at the bottom of your testtube.
Do a burn test to check for the aromatic group. Dissolve a bit of the compound in some ethanol, drip a little on a rod and ignite it. The flame will be very blackish/yellow because of an incomplete combustion if it's aromatic.
The physical properties for the compounds are:
2,5-dimethoxybenzaldehyde:
mp:52 oC
bp:146 oC at 10 mmHg
2,5-dimethoxynitrostyrene:
mp:?
bp:?
Quite easy to identify by looking at it. It's beatifull long needleshaped orange crystals. Itch like hell if you get them on your skin with some solvent.
Good luck!
Regards
Bandil
