Mesitylacetic acid

C. Mesitylacetic acid. To 900 ml. of water in a 3-1. threenecked flask is added 750 ml. of concentrated sulfuric acid.When the mixture has cooled to about 50°, 127 g. (0.80 mole) of mesityl-acetonitrile is added (Note 9), and the mixture is refluxed and stirred mechanically for 6 hours. At the end of this period, a large amount of mesitylacetic acid has precipitated from the solution. The contents of the flask are cooled and poured into 3 1. of ice water. The acid is collected on a Buchner funnel and washed well with water. A solution of the acid in dilute alkali is boiled with Norite, and the acid is precipitated from the filtered solution by acidifying with dilute hydrochloric acid. The mesitylacetic acid is collected on a filter, washed well with water, and dried in an oven at about 80°. The yield of mesitylacetic acid melting at 163-166° is 123 g. (87%). After recrystallization from dilute alcohol or ligroin, the acid melts at 167-168°. 

Mesitylacetic acid has been prepared from 2,4,6-trimethyl-acetophenone by treatment with yellow ammonium sulfide and hydrolyzing the resulting amide with alkali,6 by the dry distillation of 2,4,6-trimethylmandelic acid,7 by heating 2,4,6-trimethyl-phenylglyoxylic acid with hydriodic acid and red phosphorus,8 and by treating mesitylacetonitrile with potassium hydroxide.4... 

Several possibilities for a large-scale synthesis of mesitylacetic acid 12, a central building block in the synthesis of spiromesifen 8a, were examined (Scheme 28.4.2). Using the classical standard route, mesitylene 13 is transferred into mesityl acetonitrile 14 via chloromethylation and cyanide exchange, which is then saponified to the aryl acetic acid. Another route examined is the Friedel-Crafts alkylation of mesitylene with 1,3-dichloro-propene to the adduct 15, which is ozo-nolyzed to the corresponding aldehyde in the form of its dimethyl acetal and than further oxidized with hydrogen peroxide under acidic conditions to mesityl acetic... 

A solution of 3.56 g mesitylacetic acid (20 mmol), 0.6 mL triethylamine, and 30 mL DMF was electrolyzed at 35-50°C at a current density of 16.7-2.5 mA/cm (140-150 V) for 6 h. A total of 0.670 g CO2 was collected (76%). The solvent was removed imder reduced pressure. No acid was recovered by extraction with Na2C03. The reaction mixture was placed on an alumina column and eluted with n-hexane to yield 1.17 g 1,2-dimesitylethane,... 

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