Hydrochloric Acid → 2,6-Bis(2-carboxyethyl)naphthalene

First, 228 mg of metallic sodium was dissolved in 10 ml of absolute ethanol, and after adding 3.02 g of diethyl malenate, the mixture was refluxed for 5 minutes and cooled. After adding 504 mg of diethyl malonate and then 1.41 g of 2,6-bis(bromomethyl)naphthalene at once, the mixture was refluxed 2 hours. After cooling and adding 20 ml of ice water, the reaction mixture was adjusted to pH 6.0 with 1N hydrochloric acid and extracted twice with 100 ml of benzene. The extracts were combined, washed with water and a saturated sodium chloride aqueous solution, dried over magnesium sulfate, filtered, and evaporated under a reduced pressure. To the resulting pale yellow oil were added 15 ml of acetic acid and 15 ml of concentrated hydrochloric acid, and the mixture was refluxed for 23 hours, cooled and concentrated. After adding 5 ml of water, the resulting crystal was collected by filtration, washed with water and dried in air and then under a reduced pressure to obtain 1.136 g of the title compound as colorless crystal.