Models of simple teichoic acids were prepared by using a ring-opening polymerization. Thus a cyclic phosphite, 4-(acetoxymethyl)-2-oxo-l,3,2X6-dioxaphospholane, was ionically polymerized under anhydrous conditions, giving the corresponding high molecular weight polyphosphite. The polyphosphite was directly oxidized, preferably with N204, to the corresponding poly(dialkyl phosphate) (Mn up to 10000), having the structure of a simple model of a teichoic acid: poly[4-(acetoxymethyl)-2-hydroxy-2-oxo-l,3,2-dioxaphospholane] [poly(l-acetyl-2,3-glycerol phosphate)]. An alternative method, in which 4-(acetoxymethyl)-2-methoxy-2oxo-l,3,2-dioxaphospholane was first polymerized to the corresponding polyester and then dealkylated to the polyacid, gave less promising results because of the incompleteness of the dealkylation step.

Polycondensation of diols with phosphonic bis(dialky1amide)s leads to high-molecular-weight polyphosphites (a, up to 4 . lo4). Model reactions of 1-butanol, 2-butanol and phenol with phosphonic bis(diethy1amide) (1) were studied and it was established, that these reactions exhibit characteristic induction periods. Linearization of the kinetic curves after addition of amines prior to reaction enabled us to postulate the mechanism of esterification, involving activation of 1 by hydrogen-bonding to amines. However, the major side reaction lowering the degree of polymerization was found to be dealkylation of the formed ester units by added and/or evolved amine. Therefore, in order to increase the rate of polycondensation and to prevent the formed polymer chain from breaking down by dealkylation, the process was conducted at increased temperature (90°C) in a nonsolvent for the polymer of higher molecular weight. Thus, the polymer separates from the major solution and becomes less prone to dealkylation.

SynopsisThe microstructure of polyphosphites and polyphosphates obtained by the ring-opening polymerization of asymmetrically substituted 5-membered cyclic phosphites wasstudied. It has been established, using 31P NMR, that 4-substituted 2-hydro-2-oxo-1,3,2-dioxaphospholanes underwent polymerization giving polymers with head-to-tail dyads as well as head-to-head and tail-to-tail structures. Analyses of 31P NMR spectra of racemic and optically active poly(2-hydro-4-methyl-2oxo-1,3,2-dioxaphospholane) and model compounds estimated the statistical mode of ring scission of cyclic phosphites. Similar results were obtained for the polymerization of 4-acetoxymethyl-2hydro-2-oxo-1,3,2-dioxaphospholane, which provided the simplest model of teichoic acid, namely poly(l,2-glycerol phosphate).

2-Ethylhexylpoly(trimethylene 1,3-phosphate) (3). poly(l,2-glycerol phosphate) (1) and poly-(l-acetoxy-2,3-glycerol phosphate) (2) were synthesized and used as synthetic analogues of teichoic acids. Their properties as a carrier of magnesium and calcium ions were examined in the competitive exchange diffusion process with the countertransport of hydrogen or sodium ions. It turned out that polymers with 1,2-glycerol phosphate units (1,2) exhibit lower ability to transport preferentially magnesium ions than poly(l,3-alkylene phosphate+ (3). In all cases the efficiency of polyphosphates in preferential transport of magnesium ions is higher when transport is coupled with proton counterflow. 0 1990, Hitthig & Wepf Verlag, Basel CCC 0025-1 16X/90/$03.00