By Kolio D. Troev
Polyphosphoesters are a multifunctional, environmentally pleasant, and reasonably-priced fabric, making them an immense topic. The layout of this kind of fabric performs a key function within the growth of undefined, agriculture, and medication. This e-book introduces the chemistry, characterization and alertness of polyphosphoesters together with finished insurance of poly(alkylene H-phosphonate)s, poly(alkylene phosphate)s, poly(alkyl or aryl phosphonate)s, and poly(alkyl phosphite)s and poly(alkyl phosphinite)s. each one polymer is mentioned intimately together with equipment, houses, and applications.
This ebook turns out to be useful for college students and practitioners getting ready to paintings, or within the technique of operating, within the intriguing box of polymer chemistry.
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Extra resources for Polyphosphoesters: chemistry and application
The second stage, called the “high-temperature stage,” is performed under relatively deep vacuum (10À3 mmHg) as the temperature is gradually increased from 165 C to 185 C for a total of 5 h. 2, curve C). The formation of a high-molecular-weight poly(alkylene H-phosphonate) is accompanied by dialkyl H-phosphonate elimination. The two-stage process allows the formation of high-molecular-weight poly(alkylene H-phosphonate)s because at the second stage hydroxyl groups did not exist, and their dehydration or other side reactions are mostly eliminated.
O O Base RO - P - OR + CCl4 RO - P - OR + H CHCl3 Cl This reaction requires basic activation or basic catalysis to generate reactive trivalent phosphorus intermediates. The latter interact further with the corresponding substrates as strong nucleophiles. The formation of these reactive intermediates is often described in terms of simple phosphite salt formation in basic media. ðROÞ2 PðOÞH 1 B :! 8) . The initial step of this process involves deprotonation of dialkyl H-phosphonate (RO)2P(O)H by a base B to give the dialkyl phosphite anion, (RO)2POÀ.
13) reveals the following: (1) Hydrolysis under slightly basic conditions proceeds by a random scissoring of the polymer main chain and in a predominantly primary mode. 35 ppm (1), confirming the presence of CH3OP(O)(H)OCH2-phosphonate end groups. 6482 44 5 P NMR of a partially hydrolyzed poly(oxyethylene H-phosphonate). explained with their low concentration, the result of which is that the rate of hydrolysis of methoxy group is very low. 75 ppm (4) assigned to the phosphonic acid (HO)2P(O)(H), is in agreement with the primary mode of hydrolysis.