Hexachloroethane, odor

Hexachloroethane [67-72-17, perchloroethane, CCl CCl, is a white crystalline soHd with a camphorlike odor. Hexachloroethane is nonflammable and has a number of minor industrial uses which are limited because of its toxic nature. Crystalline hexachloroethane is a minor product in many industrial chlorination processes of saturated and unsaturated hydrocarbons. 

Hexachloroethane has a camphorlike odor, readily sublimes, and, when heated to decomposition, emits phosgene. Sublimation of hexachloroethane may contribute to exposure control problems. Sedimented hexachloroethane dust may accumulate on fluorescent mbe illuminators and other warm surfaces and act as an exposure reservoir, adding to exposure levels. ... 

Research suggests that the odor of a particular molecule is determined more by its shape than by the presence of a particular functional group. For example, hexachloroethane (CI3CCCI3) and cyclooctane have no obvious structural similarities, but they both have a camphor-like odor, a fact attributed to their similar spherical shape. Each molecule binds to spherically shaped olfactory receptors present on the nerve endings in the nasal passage, resulting in similar odors (Figure 5.13). 

Hexachloroethane (perchloroelhane [CAS 67-72-1]) Hot fumes irritating to eyes, skin, and mucous membranes. Based on animal studies, causes CNS depression and kidney and liver injury at high doses. Limited evidence of carcinogenicity in test animals (IARC 3). 1 ppm, A3 NIOSH CA 300 ppm White solid with a camphor-llke odor. Vapor pressure is 0.22 mm Hg at20 C (68 F). Notcombushble. Thermal-breakdown products include phosgene, chlorine gas, and hydrogen chloride. 

The physical integrity of a pyrotechnic formulation may, exceptionally, be threatened by evaporation. This can occur when a rather volatile compound is a necessary component because of unique properties that make it difficult or impossible to replace it with a more stable ingredient. Two such compounds have been described earlier One is metaldehyde of a sublimation point of about 112 C and found only in novelty items such as repeatedly ignitible matches, hence of little concern in commercial practice the other is the HC smoke ingredient hexachloroethane. Its vapor pressure, as eviden d by the odor at room temperature, is sufficient to cause concern. In practice, however, with tightly compressed and sealed mixtures in substantial units, the volatility of HC seems to cause no trouble. 

You can verify quickly that compounds with molecules of roughly similar shape have similar odors if you compare nitrobenzene and acetophenone with ben-zaldehyde or d-camphor and hexachloroethane with cyclooctane. Each group of substances has the same basic odor type (primary), but the individual molecules differ in the quality of the odor. Some of the odors are sharp, some pungent, others sweet, and so on. The second group of substances all have a camphoraceous odor, and the molecules of these substances all have approximately the same shape. 

The reaction products formed in plasma metal etchers are a complex mixture of chlorinated and fluorinated compounds. The maintenance of metal etchers often involves short duration operations that generate strong odors. Hexachloroethane was found to be the major cause of odor in one type of aluminum etcher.h l In another, cyanogen chloride was the main problem exposure levels were 11 times the 0.3 ppm TLV .[20] In still other types of etchers, hydrogen chloride is associated with the odor (maximum exposure measured was 68 ppm odor threshold for HCl is less than 5 ppm). The paper by Mueller and Kunesh is a good source of additional information on the subject.I l... 

The first daughter plasma product of CCI4, hexachloroethane, is colorless solid with a camphorlike odor that sublimes at 189°C. It has also been identified as a human carcinogen. C2Clg acts primarily as a central nervous system depressant, resulting in narcosis in high concentrations. 

Olfactory impressions are of course very individual and depend on the experience of the worker. An odor can be characteristic of a whole class of substances in one case, and in other cases only of a certain limited group of substances (the smokey odor of medium alcohols). Sometimes two completely different compounds possess an almost identical odor (for example, the camphorlike odor of hexachloroethane), and very often the odor changes even in a homologous series (lower, medium, and higher aliphatic alcohols or acids). 

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