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Why do some extraction techniques suggest using dangerous solvents?
| Q: |
I am a 3rd year college student majoring in neuropsychology. I was recently reading the link 'Peyote and other Psychoactive Cacti' (A.Gottlieb, 1977) in the Peyote Vault when I came across the methods of extracting mescaline from cacti. Included in the chemicals needed is Benzene (C6H6).
This worries me. Since Gottlieb's book was first published, Benzene has been found to be very carcinogenic, along with causing many other severe medical complications at the moment of exposure, including possible death. |
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| A: |
There are certainly more or less dangerous solvents that can be used. All solvents are dangerous to some degree and come into and out of favor by chemists over time. Adam Gottlieb's book was written in 1977 when the dangers of Benzene were less well known. Benzene used to be considered very useful due to its unique physical and chemical properties. However later tests showed it to be very toxic and carcinogenic, even with short term exposure. Now it is rarely used.
Chloroform and dichloromethane similarly lost favor when they were found to be carcinogenic, but their extreme utility has won them back favor for the average chemist. One must balance the utility of a solvent with its safety and toxicity. Especially when reading older references/techniques, one must be aware of possible substitutions for safety, but also recognize that a particular chosen solvent may be the best solvent for its defined purpose.
Dangerous, toxic, and/or flammable, solvents are still used. Chemists should consult a Material Safety Data Sheet (MSDS) before using a solvent for the first time, utilize proper personal protection equipment (safety glasses, gloves, labcoat, proper ventilation, etc.), avoid inhalation, avoid contact with skin, and wash hands thoroughly
after handling. Extreme care must be taken to remove any and all of a possibly dangerous solvent from a preparation that may come in contact with humans or animals. Additionally, one must be assured of the purity of solvent used, so it does not leave any contaminant residue of its own upon evaporation/removal.
See also:
Medterms.com : Benzene
References:
McMichael AJ. Carcinogenicity of benzene, toluene and xylene: epidemiological and experimental evidence. IARC Sci Publ. 1988;(85):3-18.
[ PubMed link ]
Brandt L. Leukaemia and lymphoma risks derived from solvents. Med Oncol Tumor Pharmacother. 1987;4(3-4):199-205.
[ PubMed link ] |
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Categories:
[ Chemistry ]
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