TABLE 3.14 The "Dirty Dozen"

1. Organic azides

Explosion hazards, especially with ground glass joints

2. Perchlorate salts of organic,

Explosion hazards organometallic, and inorganic complexes

3. Diethyl ether

Fires (see also entry 10 below)

4. Lithium aluminum hydride

Fires on quenching

5. Sodium, potassium

Fires on quenching

6. Potassium metal

Fires on quenching

7. Sodium-benzophenone ketyl still pots

Fires on quenching

8. Palladium on carbon

Fires on removal from the inert atmosphere, especially if wet with organic solvent or when contacting combustible materials such as filter paper

9. Heat

Exothermic reactions causing violent spills on scale-up due to inadequate provision for heat removal

10. Ethers with a-hydrogen atom

Dangerous peroxide concentration during distillation; explosion hazards, especially with ground glass joints

11. Carbon monoxide

Toxicity and role in forming nickel tetracarbonyl from steel gas lines and autoclaves

12. Organic peroxides

Sensitivity to shock, sparks, and other forms of accidental detonation; sensitivity to heat, friction, impact, and light, as well as to strong oxidizing and reducing agents

vacuum systems. Injury due to flying glass is not the only hazard in vacuum work. Additional dangers can result from possible toxicity of the chemicals contained in the vacuum system, as well as from fire following breakage of a flask (e.g., of a solvent stored over sodium or potassium).

Because vacuum lines typically require cold traps (generally liquid nitrogen) between the pumps and the vacuum line, precautions regarding the use of cryogens should be observed also. Health hazards associated with vacuum gauges have recently been reviewed (Peacock, 1993). The hazards include the toxicity of mercury used in manometers and McLeod gauges, overpressure and underpressure situations arising with thermal conductivity gauges, electric shock with hot cathode ionization systems, and the radioactivity of the thorium dioxide used in some cathodes.

3.E.5 Ultraviolet, Visible, and Near-Infrared Radiation

Ultraviolet, visible, and near-infrared radiation from lamps and lasers in the laboratory can produce a number of hazards. Medium-pressure Hanovia 450 Hg lamps are commonly used for ultraviolet irradiation in photochemical experiments. Powerful arc lamps can cause eye damage and blindness within seconds. Some compounds, for example, chlorine dioxide, are explosively photosensitive.

When incorrectly used, the ultraviolet, visible, or near-infrared light from lasers poses a hazard to the eyes of the operators and other people present in the room and is also a potential fire hazard. Depending on the type of laser, the associated hazards can include mutagenic, carcinogenic, or otherwise toxic laser dyes

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