Pentaerythritol, cleavage

The above mechanism of intramolecularly catalyzed cleavage is possible only for compounds with a N02 group close to the departing NO group. In other words, it can be postulated to follow nitro reduction in erythritol tetra-nitrate (9.8), mannitol hexanitrate (9.9), pentaerythritol tetranitrate (9.10), and perhaps trolnitrate (9.14), but not in isosorbide dinitrate (9.11). 

The alcohol pentaerythritol, C(CHjOH)4, forms tetragonal crystals, with the structure77 shown in Figure 12-9. The hydrogen bonds, with the O—H---0 distance 2.69 A, bind the molecules into layers. The crystal shows a correspondingly good basal cleavage. 

Molecules of this form are linked in the crystal by hydrogen bonds of length approximately 2 95 A to form two-dimensional sheets (fig. 14.07 b), and the three-dimensional structure is built up by a superposition of these sheets. As in pentaerythritol, the crystals are very stable (they decomposite at 420 °C without melting) and possess a perfect cleavage parallel to the sheets. 

Results of gas chromatographic analysis of the hydrolysis products, presented in Fig. 7, show two major peaks due to the diol and pentaerythritol dipropionate and two minor peaks, identified as the monoesters of 1,6-hexanediol and pentaerythritol. When the area under the peaks is corrected for unequal detector response, the area corresponding to the monopropionate of 1,6-hexanediol corresponds to about 4.5% of the total area. According to these results, 95.5% of the hydrolysis proceeds via initial protonation and cleavage of the exocyclic alkoxy group. 

In contrast, the hydrolysis of Alkanox P-24 starts with the cleavage of the exo-cyclic sterically more shielded P-O bond (Scheme 2.113) [144c,d]. The second phenol unit is subsequently released 2,4-di-fert-butyl phenol, phosphoric acid, and pentaerythritol were found only at the very end. 

---