1,2,3-Trichloropropane

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1,2,3-Trichloropropane
1,2,3-trichloropropane.svg
1,2,3-Trichloropropane-3D-balls.png
Identifiers
Abbreviations TCP
CAS number 96-18-4 N
ChemSpider 7013 YesY
EC number 202-486-1
KEGG C14400 YesY
ChEMBL CHEMBL346933 YesY
Properties
Molecular formula C
3
H
5
Cl
3
Molar mass 147.43 g
Appearance colorless or straw yellow transparent liquid
Density 1.387g/mL
Melting point −14 °C (7 °F; 259 K)
Boiling point 156.85 °C (314.33 °F; 430.00 K)
Solubility in water 1,750 mg/L
log P 2.27
Vapor pressure 3.1
kH 4.087 x 10-4
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

1,2,3-Trichloropropane (TCP) is a chemical compound that is commonly used as an industrial solvent. Although it is not currently labeled as a contaminant by the United States federal government, new research shows that it could have severe health effects. As of 2013, only California has significant regulation of this compound.

Production[edit]

1,2,3-Trichloropropane can be produced via the chlorination of propylene. Other reported methods for producing 1,2,3-trichloropropane include the addition of chlorine to allyl chloride, reaction of thionyl chloride with glycerol, and the reaction of phosphorus pentachloride with either 1,3- or 2,3-dichloropropanol. TCP also may be produced as a byproduct of processes primarily used to produce chemicals such as dichloropropene (a soil fumigant), propylene chlorohydrin, propylene oxide, dichlorohydrin, and glycerol.[1]

Uses[edit]

Historically, TCP has been used as a paint or varnish remover, a cleaning and degreasing agent, and in the production of pesticides. It is also used as a chemical intermediate in the process of making chemicals, such as hexafluoropropylene and polysulfides, and as an industrial solvent.[2]

Solvent

1,2,3-TCP had been used in the past primarily as a solvent for paint and varnish removal, as a cleaning and degreasing agent, and as a cleaning and maintenance solvent. No current information is available to indicate that it continues to be used for these purposes.[3]

Soil fumigants

Pre-1980s, agricultural use of chloropropane-containing soil fumigants for use as pesticides and nematicides was prevalent in the United States. Some soil fumigants, which contained a mixture of primarily 1,3-dichloropropene and 1,2-dichloropropane, and in which 1,2,3-TCP was a minor component, e.g., trade name of D-D, were marketed for the cultivation of various crops including citrus fruits, pineapples, soy beans, cotton, tomatoes,and potatoes. D-D was first marketed in 1943, but is no longer available in the United States, and has been replaced with Telone II, which was first available in 1956. Telone II reportedly contains as much as 99 percent 1,3-dichloropropane and up to 0.17 percent by weight 1,2,3-TCP (Zebarth et al., 1998). Before 1978, approximately 55 million pounds/year of 1,3-dichloropropene were produced annually in the United States, and approximately 20 million pounds/year of 1,2-dichloropropane and 1,2,3-TCP were produced as by-products in the production of 1,3-dichloropropene. Over 2 million pounds of pesticides containing 1,3-dichloropropene were used in California alone in 1978. Telone II is still used for vegetables, field crops, fruit and nut trees, grapes, nursery crops, and cotton.

Aircraft fuel tank sealers

Another documented use of 1,2,3-TCP was as a “branching” or curing agent in polysulfide polymers (Kirk Othmer Chemical Encyclopedia, 2001). Polysulfide polymers have beenused as the “standard sealant for virtually all aircraft fuel tanks and bodies” since the 1950s. Also, “one of the first large-scale applications of the liquid polysulfides was as a binder for rocket fuel,” from 1946 until 1958. Summary tables published by Kirk Othmer (2001) list the properties of a number of Morton Thiokol LP series of polysulfide polymer-based sealers, with concentrations of the branching agent (1,2,3-TCP) ranging from 0.5 to 2.0 percent. Liquid polysulfide polymers are used mainly as sealants in manufacturing applications, including applications related to double-paned windows, boat hulls and decks, printing rolls, integral aircraft fuel tanks, and aircraft bodies.

Chemical intermediates

By the early 1980s, approximately 95 percent of chloropropanes were being used as chemical intermediates. Chemical intermediates are industrial chemicals that are used as the starting point to produce other chemicals. 1,2,3-TCP is currently used as an intermediate in the production of polysulfone liquid polymers, the synthesis of hexafluoropropylene, and as a cross-linking agent in the synthesis of polysulfides. Polysulfone liquid polymers are used in the following industries: aerospace, automotive,consumer goods, electrical and electronic, health care, and in industrial equipment, such as compressor and pump valve components. Hexafluoropropylene is a fluorointermediate that is a key building block required to produce Teflon fluoropolymers; it has applications in the agrochemical, electronics, dyes/pigments, pharmaceutical, and specialty polymermarkets. Polysulfides are used as catalyst sulfidation agents and in the formulation of lubricant additives created for use in high-pressure environments or applications.

Manufacturers

1,2,3-TCP is manufactured as a stand-alone product in the United States. It also is produced in significant quantities as an unwanted by-product of the production of other chlorinated compounds such as epichlorohydrin, and is used internally by manufacturers as an intermediate in the production of other chemicals such as polysulfone and epoxy resins.[4]

Effects of exposure[edit]

Humans can be exposed to TCP by inhaling its fumes or through skin contact and ingestion. TCP is recognized in California as a human carcinogen, and extensive animal studies have shown that it causes cancer. Short term exposure to TCP can cause throat and eye irritation and can affect muscle coordination and concentration. Long term exposure can affect body weight and kidney function.[2]

Regulation[edit]

Existing regulation[edit]

The California Department of Public Health (CDPH) established a non-enforceable Notification Level of 5 ng/L (parts per trillion)[5] and the Office of Environmental Health Hazard Assessment[6] established a Public Health Goal (PHG) of 0.7 ng/L. CDPH is working to establish legally enforceable Maximum Contaminant Level (MCL) which is set as close to the PHG as is technically and economically feasible. The state of Alaska has promulgated standards establishing cleanup levels for 1,2,3-trichloropropane contamination in soils and groundwater.[7] The state of California considers 1,2,3-trichloropropane to be an unregulated contaminant that should be monitored. The state of Colorado has also promulgated a groundwater standard although there is no drinking water standard. Although there is not much regulation on this substance, it has proved that TCP is a carcinogen in laboratory mice, and most likely a human carcinogen as well. On a federal scale, there is no MCL for this contaminant. The Permissible Exposure Limit (PEL) in occupational setting for air is 50 ppm or 300 mg/m3. The concentration in air at which TCP becomes an Immediate Danger to Life and Health (IDLH) is at 100 ppm. These regulations were reviewed in 2009.

Proposed United States federal regulation[edit]

In a new drinking water project that was proposed by the United States Environmental Protection Agency (EPA), TCP is one of sixteen chemicals that are being considered for regulation. These sixteen chemicals are all suspected human carcinogens.[8]

TCP as an emerging contaminant[edit]

TCP does not contaminate soil. Instead, it leaks down into groundwater and settles at the bottom of the reservoir because TCP is more dense than water. This makes TCP in its pure form a DNAPL (Dense Nonaqueous Phase Liquid) and it is, therefore, harder to remove it from groundwater.[2] There is no evidence that TCP can naturally decompose, but it might in favorable conditions. Groundwater remediation of TCP can occur through in situ chemical oxidation, permeable reactive barriers, and other remediation techniques.[9] Several TCP remediation strategies have been studied and/or applied with varying degrees of success. These include extraction with granular activated carbon, in situ chemical oxidation, and in situ chemical reduction.[10] Recent studies suggest that reduction with zerovalent metals, particularly zerovalent zinc, may be particularly effective in TCP remediation.[11][12][13] Bioremediation may also be a promising clean-up technique.[14][15]

References[edit]

  1. ^ Agency for Toxic Substances and Disease Registry (1992). Toxicological Profile for 1,2,3-Trichloropropane (Report). U.S. CDC. http://www.atsdr.cdc.gov/toxprofiles/tp.asp?id=912&tid=186.
  2. ^ a b c Cooke, Mary (2009). Emerging Contaminant--1,2,3-Trichloropropane (TCP) (Report). United States EPA. http://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P1000SKK.txt.
  3. ^ National Toxicity Program, 2005
  4. ^ CH2M Hill (2005). Interim Guidance for Investigating Potential 1,2,3-Trichloropropane Sources in San Gabriel Valley Area 3 (Report). U.S. EPA. http://yosemite.epa.gov/r9/sfund/r9sfdocw.nsf/3dc283e6c5d6056f88257426007417a2/a554456e6ae6250a8825771c007c9c60/$FILE/REVISED_123-TCP%20Interim%20Guidance.pdf.
  5. ^ http://www.cdph.ca.gov/certlic/drinkingwater/Pages/123tcp.aspx
  6. ^ Sedman, Richard (2009). Public Health Goals for Chemicals in Drinking Water: 1,2,3-Trichloropropane (Report). California EPA. http://oehha.ca.gov/water/phg/123tcp082009.html.
  7. ^ http://www.dec.state.ak.us/commish/regulations/pdfs/18%20AAC%2075.pdf
  8. ^ Basic Questions and Answers for the Drinking Water Strategy Contaminant Groups Effort (Report). US EPA. 2011. http://water.epa.gov/lawsregs/rulesregs/sdwa/dwstrategy/upload/FactSheet_DrinkingWaterStrategy_VOCs.pdf.
  9. ^ Stepek, Jan (2009). Groundwater Information Sheet: 1,2,3-Trichloropropane (TCP) (Report). California State Water Resources Control Board. http://www.swrcb.ca.gov/water_issues/programs/gama/docs/coc_tcp123.pdf.
  10. ^ Tratnyek, P. G.; Sarathy, V.; Fortuna, J. H. (2008). "Fate and remediation of 1,2,3-trichloropropane". 6th International Conference on Remediation of Chlorinated and Recalcitrant Compounds: Monterey, CA. Paper C-047. 
  11. ^ Sarathy, Vaishnavi; Salter, Alexandra J.; Nurmi, James T.; o’Brien Johnson, Graham; Johnson, Richard L.; Tratnyek, Paul G. (2010). "Degradation of 1,2,3-Trichloropropane (TCP): Hydrolysis, Elimination, and Reduction by Iron and Zinc". Environmental Science & Technology 44 (2): 787. doi:10.1021/es902595j. 
  12. ^ Bylaska, Eric J.; Glaesemann, Kurt R.; Felmy, Andrew R.; Vasiliu, Monica; Dixon, David A.; Tratnyek, Paul G. (2010). "Free Energies for Degradation Reactions of 1,2,3-Trichloropropane from ab Initio Electronic Structure Theory". The Journal of Physical Chemistry A 114 (46): 12269–82. doi:10.1021/jp105726u. PMID 21038905. 
  13. ^ Salter-Blanc, Alexandra J.; Tratnyek, Paul G. (2011). "Effects of Solution Chemistry on the Dechlorination of 1,2,3-Trichloropropane by Zero-Valent Zinc". Environmental Science & Technology 45 (9): 4073–4079. doi:10.1021/es104081p. 
  14. ^ Pavlova, Martina; Klvana, Martin; Prokop, Zbynek; Chaloupkova, Radka; Banas, Pavel; Otyepka, Michal; Wade, Rebecca C; Tsuda, Masataka; Nagata, Yuji; Damborsky, J (2009). "Redesigning dehalogenase access tunnels as a strategy for degrading an anthropogenic substrate". Nature Chemical Biology 5 (10): 727–33. doi:10.1038/nchembio.205. PMID 19701186. 
  15. ^ Yan, J.; Rash, B. A.; Rainey, F. A.; Moe, W. M. (2009). "Isolation of novel bacteria within the Chloroflexi capable of reductive dechlorination of 1,2,3-trichloropropane". Environmental Microbiology 11 (4): 833–43. doi:10.1111/j.1462-2920.2008.01804.x. PMID 19396942. 

External links[edit]