Hydrochloric Acid → 1,2,3,4-Tetrahydro-isoquinolin-7-ylamine dihydrochloride

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Reaction Steps

7-Nitro-1,2,3,4-tetrahydroisoquinoline hydrochloride (2) from Example 1, is placed in a Parr shaker bottle (15.0 g, 69.9 mmol) dissolved in 95% EtOH (100 mL), and to the Parr shaker bottle is added concentrated HCl (10 mL), water (25 mL), and PtO2 (0.5 g). The mixture is hydrogenated at 50 psi until no further drop in pressure was observed (about 4 hours). The yellowish suspension is filtered through Celite and evaporated to dryness to afford a yellowish solid which is made basic with 10% NaOH solution (adequate care is exercised in catalyst disposal). Extraction of the basic solution with CHCl3 (three times), followed by drying over anhydrous Na2SO4 and evaporation of the solvent, yields a reddish yellow solid (9.54 g, 92.2%): mp=110-112. 7-Amino-1,2,3,4-tetrahydroisoquinoline dihydrochloride (3) is recrystallized from aqueous MeOH as buff colored needles, mp=290° C.

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