Sodium Hydroxide → 2-Amino-1-naphthalenethiol

Reaction equation

[OH-].[Na+].NC1[S:5][C:6]2[C:12]3[CH:13]=[CH:14][CH:15]=[CH:16][C:11]=3[CH:10]=[CH:9][C:7]=2[N:8]=1>O.C(O)CO>[NH2:8][C:7]1[CH:9]=[CH:10][C:11]2[C:12](=[CH:13][CH:14]=[CH:15][CH:16]=2)[C:6]=1[SH:5]

Participants

Procedure

To a solution of 30.0 g sodium hydroxide in 30 mL of water and 140 mL of ethylene glycol was added 18.0 g of 2-aminobenzo[g]benzothiazole. The mixture was heated at reflux under nitrogen for 20 hours and diluted with 80 mL of water. After cooling, the mixture was filtered, then the filtrate was chilled in an ice-bath and neutralized with acetic acid. The aqueous suspension was extracted with ether (3×200 mL) and the combined extracts were dried (magnesium sulfate). Removal of the solvent gave the product to which heptane (3×150 mL) was added and the solvent was removed under reduced pressure. (This step removed traces of acetic acid). The yield of the 2-aminonaphthalene-1-thiol was 15.4 g (97%), mp 108°-110°. A sample of this compound was recrystallized from ethanol, mp 109°-110°. This compound is sensitive to air and therefore was used immediately in the next step of the synthetic scheme.