The replacement of mineral acids by sulfonic resins in the synthesis of rac-5-(4-hydroxyphenyl)hydantoin from p-hydroxymandelic acid and urea comparison of alternative methods

Elsevier 2004

The sulfonic acid resin Dowex® 50W × 8 can be used to replace mineral acids in the reaction between p-hydroxymandelic acid and urea in water or NaCl solutions. The synthesis of p-hydroxymandelic acid is efficiently carried out using NaOH to promote the reaction between phenol and glyoxylic acid. Alternatively, KF/alumina can be used to obtain methyl p-hydroxymandelate by reaction of phenol with methyl 2-hydroxy-2-methoxyacetate, although, this process is carried out in an organic solvent and gives a lower yield. A comparison between the three alternative methods for the synthesis of 5-(4-hydroxyphenyl)hydantoin shows that the direct route from glyoxylic acid, urea and phenol is the most efficient method, although the p-hydroxymandelic acid route would be an interesting alternative if its heterogeneous synthesis were optimized.

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English

CTK oai:digital.csic.es:10261/272894
Applied Catalysis A: General 274(1-2): 9-14 (2004)
0926-860X
10.1016/j.apcata.2004.04.033
1333188071

CSIC
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