Tetrabromophthalate

COLORANTS FORFOOD,DRUGS,COSTffiTICS AND TffiDICALDEVICES] (Vol 6) Disodium salt of tetrabromophthalate... 

TetrabromophthalicAnhydride. Tetrabromophthalic anhydride [632-79-1] (TBPA) is widely used as a reactive flame retardant in unsaturated polyesters as weU as the precursor to a number of other fine retardants. Polyesters prepared from this compound have relatively poor photochemical stabiUty and tend to discolor upon exposure to light. This tendency to discolor can be reduced, but not eliminated, by the use of uv stabilizers. 

Diester/Ether Diol of Tetrabromophthalic Anhydride. This material [77098-07-8] is prepared from TBPA in a two-step reaction. First TBPA reacts with diethylene glycol to produce an acid ester. The acid ester and propylene oxide then react to give a diester. The final product, a triol having two primary and one secondary hydroxyl group, is used exclusively as a flame retardant for rigid polyurethane foam (53,54). 

The and e values of the aHyl group in DAP have been estimated as 0.029 and 0.04, respectively, suggesting that DAP acts as a fairly typical unconjugated, bifunctional monomer (42). Cyclization affects copolymerization, since cyclized radicals are less reactive in chain propagation. Thus DAP is less reactive in copolymerization than DAIP or DATP where cyclization is stericaHy hindered. Particular comonomers affect cyclization, chain transfer, and residual unsaturation in the copolymer products. DiaHyl tetrachloro- and tetrabromophthalates are low in reactivity. 

Diallyl terephthalate [1026-92-2] is utilized less, but lenses made of copolymers with triaHyl cyanurate and methacrylates have been suggested (62). Diallyl tetrabromophthalate and tetrachlorophthalate polymers have been proposed for electronic circuit boards of low flammabiUty (63). They are uv-curable and solder-resistant. Copolymers with unsaturated polyester, vinyl acetate and DAP have been studied (64). 

Various additives show considerable extraction resistance, such as impact modifiers (polyacrylates and polyblends PVC/EVA, PVC/ABS, etc.), highpolymeric processing aids (PMMA-based), elastomers as high-MW plasticisers, reactive flame retardants (e.g. tetrabromobisphenol-A, tetrabromophthalic anhydride, tetrabromophthalate diol, dibromostyrene). Direct measurement of additives by UV and IR spectroscopy of moulded films is particularly useful in analysing for additives that are difficult to extract, although in such cases the calibration of standards may present a problem and interferences from other additives are possible. 

The pyrolysis of a number of compounds at temperatures around 600— 800° and at pressures of the order of 10 2 mm. has been shown to give rise to benzyne. These compounds include for example indanetrione 29>, and phthalic anhydride 30 38>. The dimerisation of benzyne to yield biphenylene has been used preparatively 31 33>, an(j the pyrolysis of tetrafluorophthalic anhydride 34>, and tetrachlorophthalic anhydride 3i-33) gave the corresponding octahalobiphenylenes. In the case of the pyrolysis of tetrachlorophthalic anhydride some hexachlorobenzene is also formed, while the pyrolysis of tetrabromophthalic anhydride results in the formation of hexabromobenzene but no octabromobiphenylene. The disproportionation of tetrabromobenzyne to form carbon and bromine is a function of the high temperature involved and, as we shall see later, both tetrabromo- and tetraiodo-benzyne behave normally in solution. 

The first fire retardant polyester containing a reactive fire retardant monomer was introduced by the Hooker Electrochemical Corporation in the early 1950 s containing chlorendic acid as the reactive monomer (6). This pioneering development rapidly led to the introduction of variety of reactive halogen and phosphorus containing monomers, such as tetrabromophthalic anhydride, chlorostyrene and tetrabromobisphenol A, which found application in a wide variety of condensation polymer systems. 

Blends of flame retardant additives have been advocated as an approach to an optimum balance of properties in the finished products. For example, blends of tetrabromophthalate esters with de-cabromodiphenyl oxide or other flame retardants are reported to yield a V-0 rating in modified PPO and in polycarbonate resins without compromising melt processability or performance properties (23a-b). 

Bis(2-chloroethylthio)ethane, 5 816 Bis(2-chloroethylthioethyl) ether, 5 816 Bis(2-ethylhexyl)phthalate, 2 27 Bis(2-ethylhexyl)tetrabromophthalate,... 

Bis(methyl)tetrabromophthalate, physical properties of, 4 355t Bismin, 4 31... 

Dies, in bar soap manufacture, 22 752 Diester/ether diol of tetrabromophthalic anhydride, 11 478 Diester production, 10 489 Die swell, 20 172 Diet, 2 823... 

Tetrabromophthalic anhydride physical properties of, 4 357t Tetrabromophthalic anhydride/diol physical properties of, 4 357t Tetrabutylammonium bromide (TBAB), 2 550t, 76 557-558, 566 Tetrabutylphosphonium hydroxide, 22 573 Tetrabutyltin, toxicity of, 24 831 Tetrabutylurea, 2 550t Tetracalcium aluminate,... 

The resistance of polymers to flame may be increased by the addition of halogenated compounds and antimony oxide. Organic phosphate additives inhibit the glow of the char formed in burning polymers. Polymers with chlorine pendant groups, such as PVC, and those with halogen-substituted phenyl groups, such as polyesters produced from tetrabromophthalic anhydride, are more flame-resistant than hydrocarbon polymers. 

Halogenated intermediates, dibromoneopentyl glycol [3296-90-0] (DBNPG), and alkoxylated derivatives of tetrabromobisphenol A are used extensively in flame-retardant applications. Similar properties can be derived from halogenated dibasic acids, chlorendic anhydride [115-27-5] (CAN), and tetrabromophthalic anhydride [632-79-1] (TBPA). Processes can be used to produce brominated products by the in situ bromination of polymers derived from tetrahydrophthalic anhydride. 

Flame-Retardant Resins. Flame-retardant resins are formulated to conform to fire safety specifications developed for construction as well as marine and electrical applications. Resins produced from halogenated intermediates (Table 5) are usually processed at lower temperatures (180°C) to prevent excessive discoloration. Dibromoneopentyl glycol [3296-90-0] (DBNPG) also requires glass-lined equipment due to its corrosive nature. Tetrabromophthalic anhydride (TBPA) and chlorendic anhydride (8) are formulated with ethylene glycols to maximize flame-retardant properties reaction cycle times are about 12 h. Resins are also produced commercially by the in situ bromination of polyester resins derived from tetrahydrophthalic anhydride... 

Tetrachlorophthalic anhydride gave a relatively low yield of products derived from tetrachlorobenzyne. The pyrolysis tube was badly carbonized evidently extensive decomposition of the anhydride, the aryne, or the chlorinated products had occurred. Tetrabromophthalic anhydride gave a still lower yield of products. These are not listed in the table because none of them retained all four bromine atoms and could be definitely ascribed to reactions of tetrabromobenzyne, although tri-bromo- and dibromonaphthalene were present in appreciable amounts. Tetraphenylphthalic anhydride also gave low yields of products of the reaction of tetraphenylbenzyne with pyridine. This was not because of the stability of the anhydride and its reluctance to form the aryne, but rather because the aryne preferred to stabilize itself intramolecularly. The behavior of tetraphenylphthalic anhydride is discussed in another Section. 

For more demanding applications, tetrabromophthalate ester is a thermally stable liquid fire-retardant additive with a bromine content of approximately 45wt%. Decabromodiphenyl ether is used for foamed soft PVC for thermal insulation even if diphenyl ether-free systems have been developed because of environmental concerns. 

Diaryl tellurium dichlorides and disodium orthophthalate or tetrabromophthalate produced diaryl tellurium orthophthalates in 50 to 85% yields, when shaken in chloroform for 48 h at 20°4. 

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