Phosphoramidic Polyols

An interesting structure of some phosphorus polyols used as reactive flame retardants is the phosphoramide. 

An interesting polyol was produced by using phosphorus oxichloride, PO and diethanolamine as raw materials (reaction 18.27). First, one mol of phosphorus oxychloride is reacted with 2 mols of PO and the resulting product is reacted with diethanolamine, in the presence of an acid acceptor  

Various substances are used as acid acceptors such as PO (which is transformed in propylene chlorohydrin), Na2C03, K2C03, NaOH, KOH and so on [36]. 

A variant for phosphoramide polyol synthesis by using dialkylphosphites and carbon tetrachloride as raw materials was developed (reaction 18.28). 

The same substances mentioned before are used as acid acceptors. The phosphorus polyol shown in 18.28 has an hydroxyl number of 490-495 mg KOH/g, a phosphorus content of 13-13.6% and a nitrogen content of 6.1-6.2%. The acidity of all phosphorus polyols presented in Section 18.2 is a maximum of 2 mg KOH/g. 

---

Smith et al. have developed a very elegant route to complex polyol structures by sequential dithiane-epoxide coupling reactions (Scheme 7) [16]. Following the work of Tietze [17], 2-silyl-1,3-dithianes 42 are deprotonated with /BuLi in ether and converted into the stable lithium alk-oxides 43 with enantiomerically pure epoxides. A fast 1,4-Brook rearrangement occurs only after the addition of 0.3 equivalents of hexamethyl-phosphoramide (HMPA) or 1,3-dimethylhexahy-dro-2-pyrimidone (DMPU) to the reaction mixture. A new lithiated dithiane 44 that can undergo... 

---