kats12 - 23-9-2009 at 10:45
Hi
Does anybody know how to synthesize diethyl phthalate.
I couldn't find it anywhere on the web
I know it involves phthalic anhydride and ethanol but I couldn't find the whole procedure...?
Thanks in advance 
[Edited on 23-9-2009 by kats12]
Picric-A - 23-9-2009 at 12:18
hmm if the phthalic anhydride acts like normal anhydrides meerly boiling 2 moles of ethanol with 1 mole of phthalic anhydride will produce diethyl
pthalate.
i would use 2 moles of the phthalic anhydride and 2 moles of ethanol to increase yield.
panziandi - 23-9-2009 at 12:36
Phthalic anhydride acts like any other anhydride, the anhydride splits into two acid residues, one forms the ester the other forms the carboxylic
acid. Such as:
Ac2O + EtOH => EtOAc + AcOH
phthalic anhydride will react as below:
C6H4(CO)2O+ EtOH => C6H4(COOH)COEt
i.e. the "acid ester"
In order to get the second COOH esterified, you will have to probably reflux with H2SO4 and EtOH. Alternatively use phthaloyl chloride. You could make
di-silver phthalate and treat with ethyl iodide, thought I'd throw an odd method in for old time sake!
JohnWW - 23-9-2009 at 14:47
Diethyl phthalate? What do you want to use it for? Dimethyl phthalate (DIMP), which should be an acceptable substitute, was for many years made and
sold as a mosquito repellant, until superseded by other (but MUCH more expensive) substances several years ago. There should still be large stocks of
DIMP lying around in various industrial chemical warehouses.
kats12 - 24-9-2009 at 23:40
Thanks for suggetions.
I need it as a solvent for reaction TCPO/H2O2 - chemiluminescence. I think it would be perfect. As a solvent the reaction would last 2-10 hours.
Sauron - 8-2-2010 at 10:08
Well, all of you are basically wrong.
PA reacts with anhydrous ethanol in two steps
Step 1 (Fast and goes to completion) Alcoholysis of anhydride to ethyl hydrogen phthalate
Step 2: (slow and reversible) Esterification to diester and water.
The reaction is comducted between 1 eq PA and 2.5 eq absolute ethanol and an acid catalyst e.g, conc H2SO4, methanesulfonic acid or p-toluenesulfonic
acid. Reaction is at reflux and equilibrium of step 2 is shifted to right by distilling off the ethanol-water azeotrope while assing more absolute
ethanol at same rate.
The most common lab use of DEP is as a drying reagent for ethanol in comjunction with Na metal. See Vogel Section II, 47.
So for that application DMP is useless unless you want MeOH in uour "super dry" ethanol, as required for malonic ester and acetoacetic ester
reactions.
[Edited on 9-2-2010 by Sauron]