Print version Print setup

Methanolysis of phthalic anhydride; Phthalic acid monomethyl ester

SyntheticPage 428
DOI: 10.1039/SP428
Submitted Jul 01, 2010, published Jul 05, 2010
Christopher Cooksey (rsc@chriscooksey.demon.co.uk)
A contribution from R J H Clark Group, UCL


			Reaction Scheme: Methanolysis of <SPAN class=csm-chemical-name id=csm1285705409922 title="phthalic anhydride">phthalic anhydride</SPAN>

Chemicals Used

phthalic anhydride (Aldrich)
methanol

Procedure

Powdered phthalic anhydride (74 g, 0.5 mol) and methanol (100 cm3, 2.47 mol) were heated under reflux with magnetic stirring on an oil bath for 8 h. The clear solution was distilled to remove most of the methanol. Toluene (100 cm3) was added to the residue and distillation was continued until the still-head temperature reached 110 ºC. After cooling to 30 ºC, the resulting thick white precipitate was filtered and the residue washed with toluene (50 cm3). Petroleum ether (30/40, 100 cm3) was added to the combined filtrates to give a dense oil which crystallised as long white needles after standing overnight. Filtration and washing with petroleum ether (60/80, 50 cm3) gave the product, 44.5 g, 49% yield.

Author's Comments

A subsequent perusal of the literature reveals a much simpler procedure, 0.5 h reflux and no toluene: "Under a nitrogen atmosphere, a mixture of 75.0 grams (0.506 mole) of phthalic anhydride in 120.0 grams (3.75 moles) of methanol was stirred and heated under reflux for 30 minutes. During this time a complete solution was attained. The reaction mixture was concentrated under reduced pressure to a residual oil. The oil was placed in a refrigerator where it solidified to yield when dried, 93.0 grams of phthalic acid, mono-methyl ester; m.p. 80-81.5 ºC." in quantitative yield.

Chang Jun H, Baum J S, US 4892578 (9 Jan 1990)

Data

δH (CDCl3, 200 MHz) 7.68m (1H), 7.61m (1H), 7.56m (2H), 3.92s (3H)

Lead Reference

E L Eliel, A W Burgstahler, J Amer Chem Soc, 1949, 71, 2251-2252. doi: 10.1021/ja01174a509

Other References

Chang Jun H, Baum J S, US 4892578 (9 Jan 1990)

This page has been viewed approximately 10824 times since records began.

Get structure file (.cdx, .sk2, .mol)

Keywords: addition, alcohols, carboxylic acids, esters, nucleophilic

Post new comment
Loading ...