Patent ID: 6184309
Filing Date: 2001-02-06
Classification: C08C,C08F

Abstract:
A process for removing protecting groups from polymers, comprising treating a polymer having at least two dissimilar protecting groups, one of said protecting groups having the formula --[A(R.sup.1 R.sup.2 R.sup.1)] in which A is carbon and R.sup.1, R.sup.2, and R.sup.3 are each independently selected from the group consisting of hydrogen, alkyl, substituted alkyl groups containing lower alkyl, lower alkylthio, and lower dialkylamino groups, aryl or substituted aryl groups containing lower alkyl, lower alkylthio, and lower dialkylamino groups, and cycloalkyl and substituted cycloalkyl containing 5 to 12 carbon atoms, in the presence of an acid catalyst capable of removing at least one of said dissimilar protecting groups without removing other dissimilar protecting groups, said acid catalyst comprising a compound selected from the group consisting of organic acids selected from the group consisting of para-toluenesulfonic acid, trifluoroacetic acid, acetic acid, and methanesulfonic acid, mineral acids selected from the group consisting of hydrochloric acid, phosphoric acid and sulfuric acid; heterogeneous acid systems selected from the group consisting of acid ion exchange resins and acid clays; Lewis acids selected from the group consisting of trimethylsilyl iodide, iron (III) chloride with acetic anhydride, and boron trihalides; and fluoride ion sources selected from the group consisting of tetraalkylammonium fluoride, potassium fluoride, sodium fluoride, cesium fluoride, lithium fluoride, lithium tetrafluoroborate, hydrogen fluoride, and pyridine hydrogen fluoride complex.