Stibines chemical oxidation

Compared to the analogous trisubstituted phosphines, the trisubstituted arsines are oxidized at slightly higher potentials (50-100mV) as expected from the decrease in electron-donating ability in the series N, P, As. However, the analogous stibines are oxidized at almost the same potentials as the arsines but dilferences in the rates of the follow-up reactions may be the cause of this apparent coincidence in irreversible potentials. Trimesitylarsine and trimesitylstibine are oxidized in diffusion-controlled, chemically reversible one-electron processesand the reversible potentials for these oxidations show (cf Table 14) that the stibine is 60 m V more difficult to oxidize than the arsine. 

Stibonic and Stibinic Acids. The stibonic acids, RSbO(OH)2, and stibinic acids, R2SbO(OH), are quite different in stmcture from their phosphoms and arsenic analogues. The stibonic and stibinic acids are polymeric compounds of unknown stmcture and are very weak acids. lUPAC classifies them as oxide hydroxides rather than as acids. Thus CgH3SbO(OH)2 is named phenyl antimony dihydroxide oxide [535-46-6], the Chemical Abstracts n.2ixn.e is dihydroxyphenylstibine oxide [535-46-6], CgH OgSb. 

TABLE 14. Half-wave potentials ( 1 2) chemically irreversible oxidation at Pt electrodes of trisubstituted arsines, stibines and bismuthines in MeCN°... 

STERICOL (1300-71-6) see xylenols. STIBINE (7803-52-3) SbHj Flammable, highly poisonous, and thermally unstable gas (Fire Rating 4). Reacts with moisture, forming explosive hydrogen. Elevated temperatures above 390°F/198°C can cause fire and explosion. Reacts violently or explosively with strong oxidizers, nitric acid (especially concentrated HNOj), halogenated hydrocarbons, ammonia, ozone. Forms heat-sensitive explosive mixtures with ammonia. Only if flow can be stopped on small fires, use dry chemical powder (such as Purple-K-Powder), foam, or COj extinguishers. If flow cannot be stopped, evacuate and let fire bum itself out. 

Among antimony compounds are antimony hydride (stibine, a gas) which is the most deadly, followed by antimony sulfide (stibinite), which is used in modern times in camouflage paints (because it reflects IR), and the antimony oxide/lead oxide and carbonate mixture Naples yellow, was used as a pigment and paint as well as a flame retardant in plastics (PVC) for their use in car components, in televisions and so on, because it quenches the fire by reacting chemically with burning materials, although it was also accused of causing cot deaths (see Chapter 10). 

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