Boron oxide toxicity

DOT CLASSIFICATION 4.1 Label Flammable Solid, Poison SAFETY PROFILE Poison by inhalation, ingestion, skin contact, and intraperitoneal routes. Ignites in O2 at 100°C. Forms impact-sensitive explosive mixtures with ethers (e.g., dioxane) and halocarbons (e.g., carbon tetrachloride). Incompatible with dimethyl sulfoxide. When heated to decomposition it emits toxic fumes of boron oxides. See also BORON COMPOUNDS and BORANES. 

Well-authenticated boron hydrides are listed in Table I. Characterization of these hydrides does not preclude the isolation of others (33). Properties known at present to be common to all boranes include thermal instability susceptibility to hydrolysis, to alcoholysis, and to oxidation toxicity ability to react with ammonia and with many electron-pair donor molecules [for example, (CH3)3N] and a tendency to undergo substitution of their hydrogen atoms by halogen or alkyl groups. 

Other boron-containing compounds with similar toxicity include boron oxide and or-thoboric acid (sassolite). 

Hazardous Decomp. Prods. Hydrogen bromide gas, boron oxides heated to decomp., emits toxic fumes of Br ... 

Evidence for the existence of boron hydrides appeared late in the nineteenth century. However, means of handling compounds that are toxic and, especially, pyrophoric were not available, and so serious experimention was precluded. The first study giving actual chemical formulas was reported in 1912 by the German chemist, Alfred Stock. Stock had reacted magnesium metal with boron oxide to form the refractory substance, magnesium boride,... 

It is customary to classify the various types of enamel, based on the nature of the flux used. Thus, we can distinguish lead enamels (PbO rich enamels), boron oxide enamels, alkaline enamels, alkaline-earth enamels, zinc enamels and bismuth oxide enamels [STE 85]. Lead enamels, historically the oldest, were the most commonly used for a long time. Because of the toxicity of lead, their future hinges on the evolution of legislation relating to the leaching of this element. They terrd to be replaced by enamels containing a very small qrrantity of bismuth oxide (< 5% mass) and, especially by alkaline borosilicate products. 

Except for siUca and natural abrasives containing free siUca, the abrasive materials used today are classified by NIOSH as nuisance dust materials and have relatively high permissable dust levels (55). The OSHA TWA allowable total dust level for aluminum oxide, siUcon carbide, boron carbide, ceria, and other nuisance dusts is 10 mg/m. SiUca, in contrast, is quite toxic as a respkable dust for cristobaUte [14464-46-1] and tridymite [15468-32-3] the allowable TWA level drops to 0.05 mg/m and the TWA for quartz [14808-60-7] is set at 0.1 mg/m. Any abrasive that contains free siUca in excess of 1% should be treated as a potential health hazard if it is in the form of respkable dust. Dust masks are requked for those exposed to such materials (see Industrial hygene). 

Safety considerations are paramount in any boron hydride synthesis. The energy yield from the oxidations of boron hydrides is too high for any cavalier treatment of boron hydrides. Exclusion of air is the critical consideration in diborane reactions. Decaborane(14) is less reactive, generally, in a kinetic sense, but the thermodynamic potential is comparable. In addition, all volatile boron hydrides are toxic. The procedures described in the latter two preparations are within our experience non-hazardous. These procedures should be followed in every detail improvisation is not recommended. 

The unusual amino acid (S)-2-amino-(Z)-3,5-hexadienoic acid (269), which is a component of the toxic y-glutamyl dipeptide isolated from the defensive glands of the Colorado beetle [209], has been synthesized along Scheme 17, after two initial attempts had proved unsuccessful due to the instability of 269 towards various oxidation conditions [210]. Scheme 17 relies on the hydrolysis of an ortho ester to generate the required carboxylic acid. Thus, the L-serine aldehyde equivalent 270 was treated with ( )-l-trimethylsilyl-l-propene-3-boronate to give the addition product 271. Reaction of 271 with KH gave the stereochemically pure (Z)-diene 272. Mild acid treatment of 272 followed by... 

Volatile boron compounds, especially boranes, are usually more toxic than boric acid or soluble borates (Table 29.9) (NAS 1980). However, there is little commercial production of synthetic boranes, except for sodium borohydride — one of the least toxic boranes (Sprague 1972). Boron trifluoride is a gas used as a catalyst in several industrial systems, but on exposure to moisture in air, it reacts to form a stable dihydride (Rusch etal. 1986). Eor boric oxide dusts, occupational exposures to 4.1 mg/m (range 1.2 to 8.5) are associated with eye irritation dryness of mouth, nose and throat sore throat and cough (Garabrant et al. 1984). 

This basic system was designed to deposit Si02 from the SiH4 + 02 reaction at about 400°C and atmospheric pressure. It can also deposit doped oxides by introducing PH3 for phosphorus doping or B2H6 for boron doping. In order to protect personnel from these toxic dopants, the reactor is housed in a vented enclosure. 

DOT CLASSIFICATION 8 Label Corrosive SAFETY PROFILE A very corrosive material. When heated to decomposition it emits very toxic fumes of F , B oxides. See BORON COMPOUNDS, ACETIC ACID, and FLUORIDES. 

DOT CLASSIFICATION Forbidden SAFETY PROFILE A powerful oxidant which explodes above 140°C. Explosive reaction with boron. Hypergolic reaction with dimethyl hydrazine or other strong organic bases. Forms powerfully explosive mixtures with nitrogen containing organic compounds (e.g., 2-nitroaniline). Upon decomposition it emits toxic fumes of NOx. See also NITRO COMPOUNDS. 

Flammable Liquid SAFETY PROFILE A poison by intravenous route. Moderately toxic by ingestion. An eye irritant. A flammable liquid and dangerous fire hazard when exposed to heat, flame, or oxidizers. Can react vigorously with oxidizing materials. To fight fire, use foam, CO2, dry chemical. See also ESTERS and BORON COMPOUNDS. 

SAFETY PROFILE Poison by subcutaneous route. Powerful oxidizing agent. Mixtures with boron + water are explosive. When heated to decomposition it emits toxic fumes of F. See also FLUORIDES and SILVER COMPOUNDS. 

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