Antimony halogen reaction

Interference with the antimony-halogen reaction will affect the flame retardancy of the polymer. For example, metal cations from color pigments or an inert filler such as calcium carbonate or talc may lead to the formation of stable metal halides, rendering the halogen unavailable for reaction with antimony oxide. The result is that neither the halogen nor the antimony is transported into the vapor zone. Silicones have also been shown to interfere with the flame retardant action of halogenated flame retardants. 

Either mechanism can be used to describe how antimony—halogen systems operate in both the condensed and vapor phases. In the condensed phase a chat that is formed during the reaction of the polymer, antimony trioxide, and the halogen reduces the rate of decomposition of the polymer therefore, less fuel is available for the flame (16). 

J.J. Pitts, "Antimony-Halogen Synergistic Reactions in Fire Retardants, "J. Fire Flamm., 51 (1972). 

Exchange of antimony-carbon bonds with antimony-halogen bonds in triphenylantimony and antimony trichloride upon heating at 250° C for 75 hours has been utilized for the preparation of phenylantimony chlorides (108,109). Also exchange of vinyl groups with chlorine atoms on antimony has been observed (155). Recently, however, a quantitative study of the kinetics of the reaction between trimethylantimony and antimony trichloride has been reported (298), details of which have been discussed in Section IV, A,1. 

Pitts, J. J. Antimony-halogen synergistic reactions in fire retardants, Journal of Fire and Flammability, 1972, 33, 51-84. 

The HF-pentavalent antimony halide reaction is not limited to the methane series but has been applied to longer-chain saturated and unsaturated halogenated hydrocarbons, cyclic olefins, and dienes, and certain of the silica organic derivatives. 

Pitts, J.J. (1972) Antimony Halogen Synergistic Reactions in Fire Retardance. J. Fire Flammability, 3, 235. 

A complete set of trihalides for arsenic, antimony and bismuth can be prepared by the direct combination of the elements although other methods of preparation can sometimes be used. The vigour of the direct combination reaction for a given metal decreases from fluorine to iodine (except in the case of bismuth which does not react readily with fluorine) and for a given halogen, from arsenic to bismuth. 

The mechanism by which tin flame retardants function has not been well defined, but evidence indicates tin functions in both the condensed and vapor phases. In formulations in which there is at least a 4-to-l mole ratio of halogen to tin, reactions similar to those of antimony and halogen are assumed to occur. Volatile stannic tetrahaUde may form and enter the flame to function much in the same manner as does antimony trihaUde. 

Catalytic Oxidation. Catalytic oxidation is used only for gaseous streams because combustion reactions take place on the surface of the catalyst which otherwise would be covered by soHd material. Common catalysts are palladium [7440-05-3] and platinum [7440-06-4]. Because of the catalytic boost, operating temperatures and residence times are much lower which reduce operating costs. Catalysts in any treatment system are susceptible to poisoning (masking of or interference with the active sites). Catalysts can be poisoned or deactivated by sulfur, bismuth [7440-69-9] phosphoms [7723-14-0] arsenic, antimony, mercury, lead, zinc, tin [7440-31-5] or halogens (notably chlorine) platinum catalysts can tolerate sulfur compounds, but can be poisoned by chlorine. 

A number of compounds of the types RSbY2 and R2SbY, where Y is an anionic group other than halogen, have been prepared by the reaction of dihalo- or halostibines with lithium, sodium, or ammonium alkoxides (118,119), amides (120), azides (121), carboxylates (122), dithiocarbamates (123), mercaptides (124,125), or phenoxides (118). Dihalo- and halostibines can also be converted to compounds in which an antimony is linked to a main group (126) or transition metal (127). 

Vinyl and phenyl mfluoromethyl groups are reactive in the presence of aluminum chloride [10] Replacement of fluorine by chlorine often occurs Polyfluori-nated trifluoromethylbenzenes form reactive a,a-difluorobenzyl cations in antimony pentafluoride [11] 1 Phenylperfluoropropene cyclizes in aluminum chloride to afford 1,1,3-trichloro 2 fluoroindene [10] (equation 10) The reaction IS hypothesized to proceed via an allylic carbocation, whose fluoride atoms undergo halogen exchange... 

The role of Lewis acids in the formation of oxazoles from diazocarbonyl compounds and nitriles has primarily been studied independently by two groups. Doyle et al. first reported the use of aluminium(III) chloride as a catalyst for the decomposition of diazoketones.<78TL2247> In a more detailed study, a range of Lewis acids was screened for catalytic activity, using diazoacetophenone la and acetonitrile as the test reaction.<80JOC3657> Of the catalysts employed, boron trifluoride etherate was found to be the catalyst of choice, due to the low yield of the 1-halogenated side-product 17 (X = Cl or F) compared to 2-methyI-5-phenyloxazole 18. Unfortunately, it was found that in the case of boron trifluoride etherate, the nitrile had to be used in a ten-fold excess, however the use of antimony(V) fluoride allowed the use of the nitrile in only a three fold excess (Table 1). 

Many metal sulfides when mixed intimately with metal halogenates form heat-, impact- or friction-sensitive explosive mixtures [1], That with antimony trisulfide can be initiated by a spark [2] and with silver sulfide a violent reaction occurs on heating [3], For the preparation of oxygen mixture , antimony trisulfide was used in error instead of manganese dioxide, and dining grinding, the mixture of sulfide and chlorate exploded very violently [4],... 

The most commonly used and widely marketed GC detector based on chemiluminescence is the FPD [82], This detector differs from other gas-phase chemiluminescence techniques described below in that it detects chemiluminescence occurring in a flame, rather than cold chemiluminescence. The high temperatures of the flame promote chemical reactions that form key reaction intermediates and may provide additional thermal excitation of the emitting species. Flame emissions may be used to selectively detect compounds containing sulfur, nitrogen, phosphorus, boron, antimony, and arsenic, and even halogens under special reaction conditions [83, 84], but commercial detectors normally are configured only for sulfur and phosphorus detection [85-87], In the FPD, the GC column extends... 

More recently, based on the results of an extensive series of small scale degradation studies, two additional mechanisms for the volatilization of antimony from antimony oxide/organohalogen flame retardant systems have been proposed (23,24). Of these two proposed mechanisms, [4] and [5], [4] does not involve HX formation at all and [5] suggests an important role for the direct interaction of the polymer substrate with the metal oxide prior to its reaction with the halogen compound. 

This renders the halogen unavailable for reaction with the antimony compound, and therefore neither the halogen nor the antimony are transported into the flame zone during combustion. 

Oki and his co-workers (177) also found that these halogenated compounds (107) exhibited enormous differences in reactivity when they were treated with Lewis acids. The sc form undergoes a Friedel-Crafts type cyclization in the presence of titanium tetrachloride, which is a weak Lewis acid, whereas the ap form survives these conditions. The latter reacts in the presence of the stronger Lewis acid antimony pentachloride. This difference is apparently caused by a chloro group in proximity to the site where a cationic center develops during the reaction (Scheme 12). 

Sb reacts with chlorine or bromine forming antimony chloride or bromide with iodine, the reaction occurs in boiling benzene or halogenated organic solvent to form antimony truodide, Sbls. 

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