Sicherheitstechnik

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Occurrence, course of events, and causes of a
chemical accident and the environmental and
ecological consequences
English
Mira Arnold, Tashi Gurung, Joanna Lihs
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Phosgene
Definition of phosgene
Physical properties
History of phosgene
Effect on humans I
Effect on humans II
Protection measures
Earlier use of phosgene
Todays use of phosgene
A phosgene accident in Uerdingen

Directives
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Definition of Phosgene
Phosgene may be created when ultraviolet light
interacts with chlorinated hydrocarbons   CO
Cl2 ? COCl2
phosgene
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• Physical Properties
• Colourless gas (at 20C), smells of rotting hay
  and rotting apples.
• Soluble in organic solvents (acetone, benzene,
  toluene), oils, fats, by-products, chloropicrine
  and arsine dichloride.
• Hydrolysis takes place in cold water by quickly
  adding an alkali. Hydrogen chloride and carbon
  dioxide form.  
• Melting point -127.9C
  Boiling point 7.48C
• Solubility in water low

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Toxicity
Overview of the effect of phosgene on humans when
used as a chemical weapon
LD50 fatal dose for 50 of victims (in mg pro
kg body weight) LCt50
fatal concentration for 50 of the victims (in
mg per liter air for the time span of one minute)
LD50 LCt50 ICt50 12 3,2 1,6
ICt50 This is the concentration which renders
50 of victims incapable of action (in mg per
liter air for the time span of one minute)
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• Effect on Humans I
•  
• Reaction with water, e.g. in the lungs where it
  forms hydrochloric acid and carbon dioxide
• Blocks metabolic enzymes
• The first symptoms of poisoning tears, coughing
  and breathing problems
• Death follows some hours later due to a lung
  oedema or cardiac arrest

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History of the Discovery of Phosgene Phosgene was
discovered in 1812 by the English chemist, Sir
Humphrey Davy (1778-1829). Davy discovered it
when he exposed chloro-carbon monoxide to intense
light. This explains why the chemical is called
phosgene ( luminous green).
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• Effect on Humans II
• Mild symptoms
  
• Running eyes (relatively fast)
• Coughing
• Irritation of the upper respiratory tract
• Serious symptoms
• Breathlessness, sometimes resulting suffocation
• Lung oedemas
• Inner bleeding in the lungs
• Cardiac arrest

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• Protection Measures
• Specialised staff or military personnel
• ABC-suits and ABC-gas masks (only to be worn for
  a limited time span)
• Filters must be renewed frequently due to the
  high concentration of the poison
• Population
• practically no protection possible against
  surprise attacks
• Effective protection measures can only be carried
  out by stopping phosgene attacks.

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Early Use of Phosgene In the First World
War phosgene was one of the first chemical
weapons to be used and today it is one of the
most poisonous industrial chemicals. When
phosgene has contact with water it hydrolyses to
hydrochloric acid and becomes poisonous for the
lungs. CoCl2 H2O ? CO2 2HCl
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In addition, phosgene was used during the First
World War in grenades, mines, incendiary devices
and cylinders.
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• Todays Use of Phosgene
•  
• Phosgene is very reactive.
• It is used for producing intermediate products
  for colourings, plastics and organic syntheses
  such as pharmaceutical products or pesticides
• Phosgene can also emitted while welding if
  chlorated carbons are present

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Phosgene as a by-product in the manufacture of
polyurethane
Polyurethane is used for insulation, swimming
costumes and for tights and stockings.
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Manufacture of polycarbonates using phosgene
Polycarbonates (PC) are synthetic polymers and
belong to the group of polyesters. PC is used for
airplane windows, CDs, DVDs, electrical
components and other kinds of apparatus.
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A Phosgene Accident in Uerdingen
In December 2001 an accident occurred at the
Bayer company in the department producing
phosgene. An employee from an outside firm
suffered poisoning during this incident. No
information on the accident has been provided to
the public due to secrecy requirement stipulated
by occupational safety laws and the Trade Secrets
Act. Why does Bayer produce phosgene ?
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Use of Polycarbonates in different industrial
sectors
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Directives
Phosgene CCl2O T
Safety procedures during an accident Leave the
room immediately! During uncontrolled emission
wear a protective suit and use a gas mask that is
not dependent on circulating air. If water is
used hydrochloric acid will form.
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First Aid
After skin contact Wash immediately with water
(better with sodium carbonate). After eye
contact Rinse immediately for at least 15
minutes and keep the contaminated eye open during
this time. After inhaling Ensure fresh air, do
not give the victim anything to drink. Auxiloson
spray 10 doses every five minutes. Call a
doctor immediately. After contact with clothes
Remove contaminated clothing immediately. Soak
clothing in ammoniac solution to clean. First
Aid helpers Refer to published safety procedures.