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Methyl ester hydrolysis; 2-(2,3,5-Trimethoxy-4-methylbenzoyl)benzoic acid

SyntheticPage 442
DOI: 10.1039/SP442
Submitted Jul 21, 2010, published Jul 22, 2010
Christopher Cooksey (rsc@chriscooksey.demon.co.uk)
A contribution from R J H Clark Group, UCL


			Reaction Scheme: Methyl ester hydrolysis

Chemicals Used

Methyl 2-(2,3,5-trimethoxy-4-methylbenzoyl)benzoate page 441

NaOH

Procedure

Methyl 2-(2,3,5-trimethoxy-4-methyl-benzoyl)-benzoate page 441 (9 g, 26 mmol) was heated under reflux with NaOH (2 g) dissolved in water (30 cm3) and methanol (20 cm3) for 4 h. After cooling, concentrated HCl (5 cm3) was added to give a white crystalline precipitate which was filtered and washed with water to give 2-(2,3,5-trimethoxy-4-methyl-benzoyl)-benzoic acid (8.2 g, 95%), mp. 148.8 ºC.

Author's Comments

Evaporation of the filtrate and refrigeration gave a further 257 mg of product. Some product (464 mg) was recrystallised from methanol (5 cm3) and water (15 cm3) to give white crystals (379 mg), mp. 149.3 ºC.

Raistrick H, Robinson R, Todd AR, J Chem Soc 1937, 80-88, doi: 10.1039/JR9370000080, obtained a product with a very different m.p. 205-208 ºC, from 2,3,6-trimethoxytoluene, phthalic anhydride, AlCl3 in CS2, perhaps the alternative isomer, 2-(2,4,5-trimethoxy-3-methyl-benzoyl)-benzoic acid.

A reaction using 28.2 g of starting material gave a 99% yield.

Using the same procedure, 2-(2,3,5-trimethoxy-benzoyl)-benzoic acid methyl ester was hydrolysed to give 71% of the corresponding acid.

Data

δH (CDCl3) 8.02d (7.9), 7.60t (7.2), 7.52t (7.3), 7.39d (7.6), 7.24s, 3.88s, 3.86s, 3.27s, 2.16s.

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

Keywords: carboxylic acids, esters, hydrolysis

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