Organolead Compounds
I. Background
a. Lead: A brief history [1]
i. Organolead refers to lead attached to at least one carbon ii. Lead was used in past, first showed up around 3000 bc iii. Has received bad reputation due to toxicity, especially tetraethyllead. iv. Lead poisoning due to paint first discovered-1904
b. General Properties: Physical and Chemical [1], [2], [3]
i. Blueish grey, soft ii. Occurs naturally iii. General synthesis ways: from metal as Grignard reagents or from other reactions. [3]
[3]
Catalytic properties[3]
Stabilization properties[3] iv. Tarnishes on exposure to air
v. organoLead poisonous
1. High levels needed
2. No obvious symptoms vi. Generally not soluble in water vii. Stored in bone and tissue in the body viii. Not corrosive when using acid ix. Will corrode many things
c. Uses: Past and Present [1], [2], [3]
Lead and organolead compounds have had far reaching uses since they were first discovered in 3000 BC. Lead has been found in decorative sculptures and weapons from past civilizations. It is still used today for bullets. Before lead was known to have toxic properties, it was most often identified and known for it’s use as a base for paints. Lead has been identified in things such as roofing and pipes. Today, lead is most commonly used as radiation shielding for x-ray machines. It is also used for electrodes in electrolysis. It is also found as a component in the lead-acid batteries used in automobiles.
Organolead compounds such as tetraethyllead were once used as antiknock agents, added to gasoline. This practice ceased once the toxic and derogatory effects on humans and the environment were discovered. While organolead compounds suffer from bad publicity due to their toxic nature, there are some po...
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...to move away from that and come up with new methods.
Look at Pb(thd)2 as replacement for tetraethyllead. Found that with ozone, could be used for PbO2 thin film growth with low H and C impurities.
V. The Future of Organolead Compounds
a. As an antimicrobial agent [10]
i. Due to antibiotic resistance, new compounds needed ii. iii. Looked at fungicide studies, bacterial studies, and TB similar disease. iv. Concluded that antibacterial properties might be enhanced and definitely possess antimicrobial properties.
v. Lead complex in antimyco were effective at killing tb microorganism
b. As a sensitizer in photovoltaic cells [11], [12]
Photovoltaic cells used for light to energy conversion looking to overcome low absorption coefficients and narrow absorption bands.
Effectively sensitized titanium oxide. Including spectral responsivity
Capacble of high photovoltages
This last process is significant not only because it brought dioxin the current notoriety but it also is a chemical process used to make products that were used and are still been used in many applications. These applications include pesticide, herbicide, defoliating agent such as Agent Orange, cleaning agent and electrical insulation. Consequently, human exposure to dioxin is not a recent phenomenon and the dangers of dioxin are not unknown. Only in recent years, especially after the Vietnam War, has the media concentrated on the dangers and impact of dioxin.
Question: In considering the monetary estimates of childhood lead poisoning prevention, list and note the relative importance of the categories of costs and benefits that need to be considered is projecting a cost/benefit ratio. Use a standard housing remediation approach for those expenses. Where does the balance lay? What are the options and barriers to moving it forward?General Effects of Childhood Lead Poisoning When lead in inhaled it, the lead could be deposited in the bones where some essential body function occurs e.g. blood formations, calcium absorption. Lead is also transported in blood stream and deposited in muscle and nerves and blood vessels. The deposition of lead in these organs systems eventually results in the malfunctioning of these organs. These malfunctions could include decrease in bone and muscle growth/co-ordination, damage to the nervous system and other organs of the body. (KidsHealth, 1995-2010) The above mentioned effects could also impair breakdown and use of nutrients by the body, decreased hearing ability. In addition, it affects child growth, in the sense that it has been shown that children with higher blood lead levels may on average be shorter than their genetic potential by 1cm.Effect of Lead on cognition and Behavior of Children: Lead poisoning have been identified as one of the factors responsible for cognitive deficits and mental illness among children. There has been shown a correlation between Blood Lead Level and cognitive functioning in children and infant (Bruce P. Lanphear, 2005). Bruce P et al in a study of Low-level environmental lead exposure and children's intellectual function, showed an inverse relationship between blood lead concentrations and IQ score...
Lead toxicity has been an area of unending research in recent years. There have been positive and negative correlation’s relating its toxic effects to both child developmental deficiencies and adult regression problems. This review will focus on the problems associated with the children. It will discuss various routes of entry of lead into the child’s system, both prenatally and postnatally, the mechanisms employed by lead to cause the dysfunction’s, and some of the neurological deficits believed to be caused by the lead exposure.
Rudel , R. A., Camann, D. E., Spengler, J. D., Korn, L. R., & Brody, J. G. (2003). Phthalates, Alkylphenols, Pesticides, Polybrominated Diphenyl Ethers, and Other Endocrine-Disrupting Compounds in Indoor Air and Dust. Environmental Science and Technology, 37(20), 4543-4553. Retrieved from http://pubs.acs.org/doi/abs/10.1021/es0264596
There are differences in the primary routes of exposure, Babies and children can swallow lead through breast feeding. They can be exposed to lead in the womb if their mothers have lead in their bodies. In children ingestion is the major route of exposure. Lead paint is the major source. In older houses as the lead paint deteriorates, peels, chips or is...
U.S. Chemical Safety and Hazard Investigation Board. (March 20, 2007). Final Investigation Report. Retrieved July 26, 2010, from U.S. Chemical and Safety Board: http://www.csb.gov/assets/document/CSBFinalReportBP.pdf
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