Methanol → Calix[4]arene

Participants

Reaction Conditions

Reaction Steps

A portion of the tetraketone containing pendant discotic moieties (0.01 mole) prepared in the manner of I) above, 1,3-bis(4-phenylethynylphenyl)-2-propanone (0.021 mole), 2-propanol (200 milliliters) and toluene (133 milliliters), are added to a 1 liter four neck Morton flask. The reactor is additionally outfitted with a chilled (2° C.) condenser, a thermometer with thermostatically controlled heating mantle, a Claisen adaptor with addition funnel and nitrogen sparge tube, and a glass stirring shaft with a turbine-type polytetrafluoroethylene stirrer which is coupled to a variable speed motor to provide mechanical stirring. The addition funnel is charged under a dry nitrogen atmosphere with 1M tetrabutylammonium hydroxide in methanol (0.53 milliliter) diluted into 2-propanol (10.5 milliliters). Stirring, sparging with nitrogen (0.3 liter per minute) and heating commences, and once the stirred slurry reaches 80° C., the sparge tube is removed and replaced with an overhead inlet for the nitrogen. Dropwise addition of the solution in the addition funnel to the refluxing stirred slurry commences and is completed over the next 20 minutes, during which time, the yellow slurry is transformed to a deep red solution. HPLC analysis is employed to determine conversion of the reactants, concurrent with optimum formation of the desired double Aldol condensation product and minimum coproduct formation. At the completion of the reaction, heating ceases, the heating mantle is removed from the reactor, additional 2-propanol (180 milliliters) is added to the reactor and the reaction mixture is cooled using a cooling fan on the reactor exterior. Once the stirred slurry cools to 30° C., the product is recovered via filtration through a coarse fritted glass funnel. The crystalline product on the funnel is washed with 2-propanol until a visually clear filtrate is obtained. Drying in a vacuum oven at 60° C. provides a 90 percent isolated yield of the A4B2M2 monomer as a purple colored crystalline powder. HPLC analysis demonstrates the presence of greater than 95 area percent of the desired monomer product:

Provenance & Evidence