PREPARATIVE HAZARDS Poly

Plant cleaning incidents, 330 Platinum compounds, 330 Platinum group metals, 331 Poly(aminium) perchlorates, 331 Polyazacaged metal perchlorates, 332 Polycondensation reaction incidents, 332 Poly(dimercuryimmonium) compounds, 332 Poly(dimethylsilyl)chromate, 333 Polymeric peroxyacids, 333 Polymerisation incidents, 333 Polynitroalkyl compounds, 336 Polynitroaryl compounds, 337 Polynitroazopyridines, 340 Polyperoxides, 341 Polypropylene powder, 342 Precious metal derivatives, 342 Preparative hazards, 342... 

An alternative and more convenient procedure for the preparation of poly-haloalkyl fluorosulfates, which excludes handling of potentially hazardous... 

CHAPTER 12 THE PREPARATION OF POLY NITRO BENZENES Hazards Use proper ventilation and wear gloves when handling 3 5% hydrochloric acid. 3 5% Hydrochloric acid is highly fuming liquid with a choking odor. 35% Hydrochloric acid, and its vapors are highly corrosive. Handle with care. 

Diazotization in the presence of boron trifluoride enables diazonium tetrafluoroborates to be isolated from the reaction mixture and purified. Subsequent controlled decomposition produces the required fluoroaromatic. Although explosion hazards and the toxicity of the isolated salts are significant concerns with this process, known as the Balz-Schiemann process, 4,4 -di-fluorobenzophenone (BDF. 6) has been prepared by this route as a monomer for the production of the engineering plastic poly(ether ether ketone) , or PEEK , by condensation with 1,4-dihydroxybenzene in the presence of potassium carbonate. BDF 6 is superior to its chlorine analog because in aromatic systems the nucleophilic displacement of fluorine is more facile than that of chlorine, leading to a shorter polymerization time and a better quality product containing less degradation impurities. 

The European Union has taken the lead in restricting the use of some hazardous materials in the manufacture of electrical and electronic hardware. The program, referred to as Restriction of Hazardous Substances (RoHS), applies to all electrical and electronic products produced in Europe and products imported from other countries, thus has very broad application. The regulations put into force on July 1, 2006, apply to lead, cadmium, mercury, hexavalent chromium (Cr ), poly-brominated biphenyl (PBB), and polybrominated diphenyl ether (PBDE). The RoHS guideline document specifies 0.1% or 1,000 ppm as the maximum amount permitted for lead, mercury, Cr" " , PBB, and PBDE and 0.01% or 100 ppm for cadmium. The document also describes guidelines for sample preparation and analyses of the restricted materials. 

The first polymer-supported hypervalent iodine reagent, poly[(dichloroiodo)styrene], was prepared by chlorination of iodinated polystyrene in the early 1980s [8]. This method, however, involves the initial preparation of iodinated polystyrene under harsh conditions (160 h, 110 °C), requires the use of hazardous chlorine gas and affords poly[(dichloroiodo)styrene] with a relatively low loading of active chlorine. An optimized one-pot preparation of polystyrene-supported (dichloroiodo)benzene 2 (loading of -ICI2 up to 1.35 mmol g" ) from polystyrene 1, iodine and aqueous sodium hypochlorite (bleach) was reported in 2011 (Scheme 5.1) [10]. 

In spite of the well-known hazards associated with its use, and its chemical activity toward glass and many other materials, hydrogen fluoride has been used as a solvent since it was first prepared in the anhydrous state by Fr my (1856). Its boiling point, 19.5°C, is not inconveniently low, but it is easily removed from a reaction mixture by distillation during workup. HF may be handled in copper, nickel, or Monel vessels, with minimal reaction, though only Pt or Pl/Au alloy does not cause any contamination. Nowadays vessels lined with Teflon or pctfe (poly(chlorotrifluoroethene)) are used. 

With suitable precautions against the hazards associated with hydrogen and phosphines as well as phosphonium iodide, in a 2-necked, 100-ml flask 0.5 gm (0.0012 mole) of poly(2,4,6-triphenylbenzyl methacrylate) (prepared by free-radical polymerization of the monomer with AIBN in toluene [//] = 0.013 liters/gm at 20°) is suspended in 30 ml of glacial acetic acid. 

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