Avanine-Commuter - 1-5-2007 at 20:57
So far I have:
Methanol + Sulfuric Acid + Salicylic Acid
C2H6O3 + C2H7O + H2S04
I know that methanol + sulfuric acid is dimethyl sulfate
C2H6O4S
but what is the FINAL product of all three?
Does dimethyl sulfate form before the reaction with salicylic acid or does it not even matter?
I need an answer quick please respond! THANK YOU!! 
Ramiel - 1-5-2007 at 21:18
First of all, Methanol + Sulphuric Acid + Salicylic Acid is
CH<sub>3</sub>OH + C<sub>7</sub>H<sub>6</sub>O<sub>3</sub> +
H<sub>2</sub>SO<sub>4</sub>
I wouldn't expect <a href="http://physchem.ox.ac.uk/MSDS/DI/dimethyl_sulfate.html">dimethyl sulphate</a> to be made at all... for sure
given your apparent chemistry prowess, I would hope not for your genital's safety.
I'd think this is an esterfication rxn.:
CH<sub>3</sub>OH + C<sub>6</sub>H<sub>5</sub>(OH)COOH (if you will)
--(H<sub>2</sub>SO<sub>4</sub>, Heat)--> Methyl Salicylate (oil of wintergreen) + H<sub>2</sub>O
You'd want to perform this reaction under good reflux and with good, concentrated Sulphuric acid. Possibly about 3M excess of Methanol, but now I'm
just guessing.
- Ramiel
Nicodem - 1-5-2007 at 23:20
In Fischer esterifications like this, it is best to use 0.5-2 mol. equivalents of conc. H2SO4 with 30-50 mol. excess methanol. Due to the very low
reflux temperature of methanol some acids require 24-48h for efficient conversion to the ester, but the yields are generally high (on the other hand,
with ethanol and higher boiling alcohols a couple of hours reflux is generally enough). Intermediate formation of dimethyl sulfate is possible but
completely irrelevant since after so much reaction time one isolates only the thermodynamic ester product which dimethyl sulfate certainly is not.