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Chemical defense
Chemical defense The Last Word
42
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n the early days of my industrial research career, I studied novel corrosion inhibitors for use in cooling towers. For many years, chromate was the gold standard (a mixed metal metaphor) for corrosion inhibition in many types of metal systems. Chromate is inexpensive, forgiving of errors in dosage, and very effective at controlling corrosion in aqueous systems. However, hexavalent chromium is a known carcinogen. In open, recirculating cooling towers, water cools as it cascades down a tower that is open to the surrounding atmosphere. Some of the water evaporates and some forms a mist that leaves the system. People in the vicinity are exposed to the chromate, and the yellow color boldly announces its menacing presence. Molybdenum is located right under chromium in the periodic table, and molybdate is not nearly as toxic as is chromate. So, I was asked to explore whether molybdate would work as a non-toxic corrosion inhibitor. I suspected that the effectiveness of chromate as a corrosion inhibitor was related to its greater toxicity. The research showed that molybdate was a corrosion inhibitor but not as effective as chromate. If you think about extremely reactive chemicals, most of them are hazardous. Consider the properties of fluorine gas, nitric and sulfuric acids, sodium metal, phosgene, sodium hydroxide, trinitrotoluene, and vinyl chloride. A reactive material that comes in contact with a living system is just reacting with a different substrate. Put another way, learning about the hazards of a given chemical is understanding a particular type of reaction that is undesirable. So there is a positive benefit to learn about the hazards of specific chemicals. A chemistry colleague of mine from the University of Wisconsin had a eureka moment when she was told that sociologists usually study the problems in society with a hope to make a difference in people’s lives.1 She realized that this was analogous to her teaching a lengthy list of ‘‘negative’’ topics in her chemistry courses because our appreciation of chemistry’s complexity evolves through study of real-world applications. Medical students spend a significant percentage of their years in school studying how to help people when things go wrong within their bodies. It is the deviation from what we anticipate that teaches us the potential for creative action. Good team athletes spend as much time learning defense as they spend learning offense; they learn what to do to prevent certain things
ß Division of Chemical Health and Safety of the American Chemical Society Elsevier Inc. All rights reserved.
from happening (i.e., prevent the opponent from scoring). A skilled synthetic chemist controls the interaction between molecules and attempts to thwart undesired side reactions by use of blocking groups or different solvents or higher/ lower temperatures. A chemical or mechanical engineer strives to make alloys or polymers that are impervious to corrosion or degradation. A medicinal chemist designs a new medicine that cures disease without the unfortunate side effects of existing drugs. A chemical safety professional collaborates with colleagues to achieve a goal while preventing adverse reactions that can cause injury or property damage. There is a sports adage that says ‘‘the best offense is a good defense.’’ In American football, the defense prevents the other team from scoring but also tries to get the ball under favorable conditions that make it easier for the offense to score. Sometimes the defense itself scores a touchdown, making the task of the offense easier. In our chemical reaction analogy, we increase the probability of achieving the desired reaction if we can take precautions to prevent undesirable reactions from happening. If we wear safety glasses or goggles whenever we work in the laboratory, we significantly decrease the odds that our work will be stopped or delayed because of an incident that damages our eyes. If an exothermic reaction is started at a low temperature to control heat release, a different, perhaps more interesting, reaction may be observed. I am not suggesting that we wander through our labs cheering on those colleagues who work safely, although positive reinforcement is a more subtle way of encouraging appropriate action. Safety is a major component of successful chemical research and education. Preventing injury or damage to the surrounding environment removes obstacles to accomplishment. As we teach young chemists how to carry out a research project or a chemical analysis, it is equally as important that we teach them what they should not do and what precautions must be taken. Let’s help our colleagues and students reach the desired goals in their experiments and avoid unwanted results. Be careful out there and practice good chemical defense.
REFERENCE 1. Middlecamp, C. H. J. Chem. Educ. 2007, 84, 31.
1871-5532/$32.00 doi:10.1016/j.jchas.2007.11.013
42
I
n the early days of my industrial research career, I studied novel corrosion inhibitors for use in cooling towers. For many years, chromate was the gold standard (a mixed metal metaphor) for corrosion inhibition in many types of metal systems. Chromate is inexpensive, forgiving of errors in dosage, and very effective at controlling corrosion in aqueous systems. However, hexavalent chromium is a known carcinogen. In open, recirculating cooling towers, water cools as it cascades down a tower that is open to the surrounding atmosphere. Some of the water evaporates and some forms a mist that leaves the system. People in the vicinity are exposed to the chromate, and the yellow color boldly announces its menacing presence. Molybdenum is located right under chromium in the periodic table, and molybdate is not nearly as toxic as is chromate. So, I was asked to explore whether molybdate would work as a non-toxic corrosion inhibitor. I suspected that the effectiveness of chromate as a corrosion inhibitor was related to its greater toxicity. The research showed that molybdate was a corrosion inhibitor but not as effective as chromate. If you think about extremely reactive chemicals, most of them are hazardous. Consider the properties of fluorine gas, nitric and sulfuric acids, sodium metal, phosgene, sodium hydroxide, trinitrotoluene, and vinyl chloride. A reactive material that comes in contact with a living system is just reacting with a different substrate. Put another way, learning about the hazards of a given chemical is understanding a particular type of reaction that is undesirable. So there is a positive benefit to learn about the hazards of specific chemicals. A chemistry colleague of mine from the University of Wisconsin had a eureka moment when she was told that sociologists usually study the problems in society with a hope to make a difference in people’s lives.1 She realized that this was analogous to her teaching a lengthy list of ‘‘negative’’ topics in her chemistry courses because our appreciation of chemistry’s complexity evolves through study of real-world applications. Medical students spend a significant percentage of their years in school studying how to help people when things go wrong within their bodies. It is the deviation from what we anticipate that teaches us the potential for creative action. Good team athletes spend as much time learning defense as they spend learning offense; they learn what to do to prevent certain things
ß Division of Chemical Health and Safety of the American Chemical Society Elsevier Inc. All rights reserved.
from happening (i.e., prevent the opponent from scoring). A skilled synthetic chemist controls the interaction between molecules and attempts to thwart undesired side reactions by use of blocking groups or different solvents or higher/ lower temperatures. A chemical or mechanical engineer strives to make alloys or polymers that are impervious to corrosion or degradation. A medicinal chemist designs a new medicine that cures disease without the unfortunate side effects of existing drugs. A chemical safety professional collaborates with colleagues to achieve a goal while preventing adverse reactions that can cause injury or property damage. There is a sports adage that says ‘‘the best offense is a good defense.’’ In American football, the defense prevents the other team from scoring but also tries to get the ball under favorable conditions that make it easier for the offense to score. Sometimes the defense itself scores a touchdown, making the task of the offense easier. In our chemical reaction analogy, we increase the probability of achieving the desired reaction if we can take precautions to prevent undesirable reactions from happening. If we wear safety glasses or goggles whenever we work in the laboratory, we significantly decrease the odds that our work will be stopped or delayed because of an incident that damages our eyes. If an exothermic reaction is started at a low temperature to control heat release, a different, perhaps more interesting, reaction may be observed. I am not suggesting that we wander through our labs cheering on those colleagues who work safely, although positive reinforcement is a more subtle way of encouraging appropriate action. Safety is a major component of successful chemical research and education. Preventing injury or damage to the surrounding environment removes obstacles to accomplishment. As we teach young chemists how to carry out a research project or a chemical analysis, it is equally as important that we teach them what they should not do and what precautions must be taken. Let’s help our colleagues and students reach the desired goals in their experiments and avoid unwanted results. Be careful out there and practice good chemical defense.
REFERENCE 1. Middlecamp, C. H. J. Chem. Educ. 2007, 84, 31.
1871-5532/$32.00 doi:10.1016/j.jchas.2007.11.013