A Preparation of Luminol

Preparation Sign in at www.cengage.com/login to answer Pre-Lab Exercises, access videos, and read the MSDSs for the chemicals used or produced in this procedure. Review Sections 2.9, 2.10, and 2.17. 

Apparatus A 20-mm x 150-mm test tube, 25-mL Erlenmeyer flask, thermometer, 

Setting Up Combine 1 g of 3-nitrophthalic acid and 2 mL of an 8% aqueous solution of hydrazine in the test tube and carefully heat the mixture until the solid dissolves. Add 3 mL of triethylene glycol and a boiling stone and clamp the vial in a vertical position. Insert a thermometer into the solution, securing the thermometer with a clamp. 

Return the damp solid to the uncleaned test tube, add 5 mL of 3 A4 aqueous NaOH, and mix the contents until the solid is dissolved. Add 3 g of fresh sodium hydrosulfite dihydrate to the solution, rinsing any solid adhering to the walls of the test tube into the solution with a few drops of water, and heat the resulting mixture to just below boiling for 5 min, taking care to avoid bumping. 

Work-Up and Isolation Add 2 mL of glacial acetic acid to the reaction mixture, cool the test tube in a beaker of cold water, and collect the crude luminol by vacuum filtration. A second crop of product may separate from the filtrate upon standing, but do not combine it with the first crop, which is to be used in the chemiluminescence experiment. 

---