| 摘要 |
<p>The phosphosal or 2-phosphonoxybenzoic acid is obtained in three steps: (a) phosphorilation of salicylic acid with phosphorus pentoxide, with a molar ratio of 2-4 mol. of salicylic acid per mol. of P4O10 into toluen at reflux temperature; (b) addition in situ of the water quantity corresponding to the molar ratio of 4-12 mol. of water per mol. of P4O10; and (c) precipitation of the phosphosal, its isolation by filtration and, optionally, its purification. The step (a) also includes the formation of one or various anhydride intermediates, specially the anhydride intermediate (II) herein disclosed for the first time. It solves the environmental problem of obtaining phosphosal without having to eliminate five moles of HC1 per mol. of consumed phosphorus. It has the advantages of minor corrosion of the installations and a higher security and hygiene for personnel.</p> |
