3.7.1 Cleavage Gas Chromatography

Several mixed anhydrides of carboxylic and sulfonic acids, as proposed by Karger and Mazur [90], act as reagents for the cleavage of ether linkages, particularly that of acetic anhydride toluene- p-sulfonic acids, which is not only a powerful reagent for the cleavage of ether linkages but is also an active acetylating agent. For example, when the propylene oxide adduct of glycerol is treated with this reagent, the polyether is split, thus giving glycerol triacetate and propylene glycol which are easily identified by gas chromatography. Tsuji and Konishi [91] extended this method to the identification of base compounds and the determination of their oxyethylene and oxypropylene group contents.

In this method the cleavage reagent comprises a solution of acetic anhydride (80 g) in 120 g of p-toluene sulfonic acid. This mixture is refluxed at 120 C for 30 minutes. The product obtained is used as the reagent without removal of the acetic acid produced and the excess of acetic anhydride.

Figure 3.9(a) shows gas chromatograms obtained with reaction products of several polyurethane polyethers.

Figure 3.9: Reaction of polyethers with p-toluene sulfonic acid gas chromatography. Gas chromatogram of reaction products of polyurethane polyethers (1) propylene glycol diacetate; (2) glycerol triacetate; (3) trimethylpropane triacetate; (4) triethylanolamine triacetate; (5) pentaerythritol tetracetate. Gas chromatographic conditions: column 1 m 3 mm, coated with 15% FFAQ on Uniport B, oven 170 C; chart speed 1 cm/s. (b) Gas chromatogram of reaction products of polyurethane polyethers...