Process for the preparation of 5-(2',4'difluorophenyl)-salicylic acid in pure form II
AssigneeZambon Group S.p.A.
InventorsClaudio Giordano, Maurizio Paiocchi
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Abstract
A crystallization process of crude 5-(2',4'-difluorophenyl)-salicylic acid from a mixture of an aromatic hydrocarbon and an aliphatic ketone for preparing 5-(2',4'-difluorophenyl)-salicylic acid in form II substantially pure is described.
Claims5
A process for preparing 5-(2',4'-difluorophenyl)-salicylic acid in form II substantially pure, consisting in dissolving a mixture of polymorphous crystals of 5-(2',4'-fidluorophenyl)-salicylic acid in a mixture of solvents consisting of an aromatic hydrocarbon and an aliphatic ketone at the reflux temperature, in adding a seed of 5-(2',4'-difluorophenyl)-salicylic acid in pure form II, in removing by distillation at least 90% by volume of the aliphatic ketone, in cooling to a temperature comprised between 10.degree. and 20.degree. C. and in filtering the suspension.
5-(2',4'-difluorophenyl)-salicylic acid in form II substantially pure characterized by bulk density values comprised between 0.20 and 0.40 g/ml, tamped apparent density values comprised between 0.30 and 0.50 g/ml and a surface area comprised between 4.0 and 6.0 m.sup.2 /g.
Dependencies are inferred from the claim text.