Chlorophosphazene

The steric bulk of steroid structures prevents their use as the only organic side group present. However, mixed-substituent polymers that contain both steroidal side groups and amino acid ester or other cosubstituent units can be readily synthesized. If a saturated A ring is present in the steroid, linkage to the polymer chain is complicated by side reactions that result from dehydration of the steroid (chlorophosphazenes are powerful dehydrating agents). 

Many typical reactions of chlorophosphazenes, R(CO N=PCl3)2 [R = -CCI2- or -CCl2(CH2)5CCl2-] with nucleophiles have been reported ... 

The factors affecting the preparation of the cyclic chlorophosphazenes from phosphorus pentachloride and ammonium chloride continue to receive attention. For example, the yields and reaction times for the preparation of the series, (NPCla) ( — 3—7), varied with the fineness of the ammonium chloride, the nature and volume of the solvent, and added catalysts such as phosphoryl chloride. A procedure, giving due consideration to these factors, was described for the preparation of N3P3CI6 in good yield (88% of cyclic products) and in a relatively short time (2J h). The cyclic chlorophosphazenes can be obtained in even shorter times ca. 10 min) by addition of four moles of pyridine to remove the hydrogen chloride formed ... 

There is little mention in the literature of the use of amide salts in substitution reactions on chlorophosphazene precursors. The anilide anion was shown to be a powerful nucleophile in substitution reactions on various trimer derivatives, but investigations of such reactions with the high polymer have not been reported.22 Where strong nucleophiles (such as amide salts) with low steric requirements are employed, the usual pentacoordinate transition state (Scheme 1), may be a viable reaction intermediate which can undergo alternative modes of decomposition, perhaps involving chain cleavage and/or cross-linking. 

Chlorophenols, manufacture of, 23 654 Chlorophenoxy acid herbicides, 73 304 (E) -(RS) -1 -(4-Chlorophenyl) -4,4-dimethyl-2-(lH- l,2,4-triazol-l-yl)-pent-l-en-3-ol, 73 47—48. See also 4-Chlorophenyl-4,4- dimethyltriazol pentenol 4-Chlorophenyl-4,4-dimethyltriazol pentenol, 73 40t, 47 48 Chlorophosphazenes, 19 55, 56 in silicone polymerization, 22 556... 

Chlorophosphazenes (NPCI2), in the form of hexachlorocyclotriphos-phazene (m.p. 112-113°C, Inabate Co., Japan) as well as cyclic oligomers (m.p. 87-91°C, Poland) and terephthaloyl chloride (Merck, FRG), served as reactive modifiers. 

The lignin modifications in solid (C) were carried out using lignins (1.0 g) mixed with corresponding amounts of hydrogen chloride acceptor and chlorophosphazenes. The reaction was carried out by heating at a temperature of 100°C, i.e., above the melting point of chlorophosphazene. The reaction mixture was poured into ice water, and then the solid product was purified as described before (9). 

The modification of lignins with chlorophosphazenes allows the manufacture of products characterized by flame resistance and thermal stability. This can be attributed to the aromatic structure of the lignin-phosphazene polymer as well as to the presence of such flame inhibiting elements as phosphorous, nitrogen and sulfur. Other useful properties may also result from this combination. It has previously been reported (8-13) that the modification provides crosslinked products with suitably low chlorine content. This is a consequence of incomplete substitution of the phosphazenes cycles. Additional modification of the reaction products by chemical compounds with reactive hydroxyl or amine groups reduces the unreacted chlorine content and improves product properties (8-13). Some properties of the derivatives obtained are presented in Table I. 

The modification of lignins by chlorophosphazenes allows the formulation of polymeric materials characterized by ... 

Continuous improvements of chlorophosphazene-modified lignins, allowing the evaluation of a wide range of applications. 

The modification of lignins with chlorophosphazenes results in changes of E that correspond to the degree of substitution and the phosphorous content (Table V). 

Lignin modification with chlorophosphazenes is an example of how this renewable resource may be utilized in special polymeric materials. 

Stokes was the first person to prepare a polymeric form of these species. He reported that any of the small-molecule cyclic chlorophosphazene compounds, when heated, were transformed into a rubbery material that was later called inorganic rubber. 11 This material swelled in organic solvents such as benzene but it did not dissolve. Stokes also described how inorganic rubber decomposed to reform the cyclic compounds when heated to high temperatures under reduced pressure. His accomplishments at that time are all the more remarkable because these compounds are sensitive to a moist atmosphere in which they are hydrolyzed to ammonium phosphate and hydrochloric acid. 

The earliest synthesis method, which involves a ring-opening polymerization of a cyclic chlorophosphazene followed by replacement of the chlorine atoms in the polymer by organic groups, is the most extensively developed route to the preparation of poly(organophosphazenes). It is summarized in reaction sequence (3). 

As discussed, condensation reactions form the basis of the synthesis of the cyclic trimer, (NPC12)3. The reaction between phosphorus pentachloride and ammonia or ammonium chloride proceeds in a stepwise fashion, as shown in reaction sequence (18), by elimination of hydrogen chloride first to form a monomer (3.40), then a linear dimer (3.41), trimer (3.42), tetramer, and so on. Cyclization could occur to give cyclic chlorophosphazenes at any stage beyond the dimer, but in practice is less likely as the chains grow beyond a certain length. Several authors have extended this process to produce relatively low molecular weight poly(dichlorophosphazene).36-39... 

A great deal of basicity data is available on substituted chlorophosphazenes. None has hitherto been published on fluoro-phosphazenes. A priori, one surmises a greater electron-withdrawing inductive effect for fluorine, which oould be compensated for by the greater potential of fluorine to back-donate by a mesomsric effect. Data is new compared on structurally related chloro- and... 

Fluorination of chlorophosphazenes, especially the trimeric phos-phazene, has been the subject of studies primarily to understand the... 

Also found in Table I are the P—N stretching frequencies obtained from the infrared spectra of the cychc phosphazenes. These values fall in the range 1297-1408 cm . For the chlorophosphazenes, (NPCl2)n n — 3-6), this frequency is observed in the range 1218-1354 cm (3). 

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