Watanabe, Takashi published the artcileOrganic synthesis unit process-thiochemicals and heterocyclic compounds: heterocyclic compounds (part 1), Quality Control of 636-73-7, the publication is Fain Kemikaru (2013), 42(8), 53-66, database is CAplus.
Unit processes of various heterocyclic compounds including furan derivatives, THF or its derivatives, chroman, thiophene or its derivatives, tetrahydrothiophene, pyrrole or its derivatives, pyrrolidine or its derivatives, indole derivative, pyridine derivatives, piperidine derivatives, and quinoline or its derivatives are described. Thus, 2,6-dibromo-4-nitrophenol 8, glycerin 20, and concentrated H3PO4 12 g were charged to a 3-neck flask fitted with a stirrer, a reflux condenser, and a thermometer, cooled, treated slowly with concentrated H2SO4 with stirring well, heated in a oil bath at 150-160° for 3 h with gentle refluxing, and cooled. Water (∼150 mL) was added to the flask content solidified, throughly pulverized, and filtered to sep. the insoluble residue and the filtrate. The insoluble residue was immersed in warm 5% aqueous HCl solution and left to be cooled to readily precipitate colorless needle crystals which were filtered off. The filtrate was concentrated to give addnl. crystalline salt. The combined crystalline salt (3.55 g) was added to slightly acidic aqueous Na2CO3 solution, throughly stirred, left to stand for ∼20 min, and the free amine formed (2.87 g) was filtered off and recrystallized from acetone to give 7-bromo-6-hydroxyquinoline. The filtrate from the aqueous Na2CO3 solution was neutralized with Na2CO3, followed by filtering off the precipitated free amine (0.72 g) and recrystallization from acetone to give 7-bromo-6-hydroxyquinoline in ∼62% as crude product.
Fain Kemikaru published new progress about 636-73-7. 636-73-7 belongs to pyridine-derivatives, auxiliary class Pyridine,Sulfonic acid, name is Pyridine-3-sulfonic acid, and the molecular formula is C4H7BN2O2, Quality Control of 636-73-7.
Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem