Reactions of hydroxymethyl derivatives of uric acid with oxiranes. II. An analysis of reaction course and product structure

Abstract

Polyetherols containing thermostable purine rings are obtained in reactions of hydroxymethyl derivatives of uric acid with an excess of ethylene oxide or propylene oxide. By using elementary analytical tools and 1 H-NMR spectroscopy, it was possible to follow the course of reaction at various molar ratios of reagents. A migration of formaldehyde molecules from N-hydroxymethyl groups or from oligooxymethylene bridges to the end of oxyalkyl chains was observed. At the same time, the O-hydroxymethyl groups are successively blocked by oxiranes. The most probable structure of polyetherols is proposed.

Reaction of uric acid with excess of propylene carbonate

“…Reactions of hydroxymethyl derivatives of UA with oxiranes; the oxymethylene fragment (CH 2 O) containing polyetherols are formed according to the scheme below 11, 12…”

“…Similar products are formed here, in reaction between UA and PC, but without oxymethylene insert. Synthesis was conducted at UA : PC 1 : 12 molar ratio, which was previously experienced in case of PO as suitable to give the resin product with all NH groups reacted,12 in the presence of TBAH (55% aqueous solution, added in 20.0 g/mol UA; see Table I), which was an effective catalyst for the reaction between isocyanuric acid and PC18 at 185°C. At this temperature, the reaction progressed fast enough without considerable degradation of product(s), which were brownish, dense liquids.…”

“…Those hydroxymethyl derivatives obtained from the mixtures at UA:CH 2 O 1:>6 molar ratio are resin semisolids after removal of water. They are miscible with oxiranes and react with them at elevated temperatures to give polyetherols according to the scheme below 11, 12…”

Polyetherols from isocyanuric acid and propylene carbonate

“…17,18 (10) The methyl protons of the normal products have different chemical shifts than those in the abnormal products; 19 thus, it was possible to calculate the per- centages of the products in the postreaction mixtures (Table II). As shown by these data, for the reaction performed in acidic conditions, where the acidic protons of imide groups were present, the product was mostly abnormal [cf.…”

Polyetherols with purine ring

“…Rozpuszczanie to ma charakter reakcji chemicznej prowadz¹cej do otrzymania N-hydroksymetylowych pochodnych KM [10]. Pochodne takie, otrzymane w warunkach stosunku molowego KM:CH 2 O = 1:>6, po oddestylowaniu wody s¹ pó³sta³ymi ¿ywicami dobrze mieszaj¹cymi siê z oksiranami i reaguj¹cymi z nimi ³atwo w podwy¿szonej temperaturze z utworzeniem polieteroli z pieroecieniem purynowym [11,12]:…”