Glaser's "Chemistry is in the News"
To Accompany Wade Organic Chemistry 4/e.
Chapter 26. Polymers.
by Alan Bruzel (@about.com, 2000)
|Useful links when reading the article:
US Environmental Protection Agency
The European Union's (EU) Solvent Emissions Directive
Freon is currently the second largest (in volume) smuggled import from Mexico into the United States. It is second only to marihuana. This unfortunate smuggling activity proceeds despite the knowledge of the hazards that freon poses to the environment. Freon, before being banned due to its harmful effects on the stratospheric ozone layer, was used as a propellant in hairsprays (aerosols). (Find out how hairspray is made through the Mad Scientist Network. Just type in “Hairspray” and go to the “RE: Hairspray” option.) Freon, or dichlorodiflouromethane, (Chemfinder) was initially thought to be a most favorable industrial compound because of its relative non-toxicity, its unreactive behavior and its ability as an excellent and efficient coolant. Unfortunately, two major environmental problems arose as a result of the excessive use of this compound over the past 40 years. The first problem is the depletion of the ozone layer as mentioned before. The second is the resultant global warming due to the increase of gases in the upper atmosphere which have the capabilities to absorb large amounts of infra-red waves, thus trapping the heat within our stratosphere that would otherwise escape back into outer atmosphere. Read about freon and regulatory information regarding air and radiation at the USEPA website.
According to John Christie of La Trobe University in Victoria, Australia there are essentially two types of freon substitutes that are used in today’s products (such as aerosols) hydrogenated flourocarbons and hydrocarbons.
Hydrogenated flourocarbons are non-toxic and do not exist for lengthy periods of time in our environment. Even if these compounds make it to the stratosphere where a reaction with the ozone layer would normally take place, their fragments are not efficient in reacting with and breaking down ozone molecules. A drawback to using hydrogenated flourocarbons is the resulting decay products of hydrogen flouride and flouracetic acid both of which can be harmful to the environment.
such as propane and butane could be ideal substitutes due to their non-toxicity.
Though their decay products are toxic, they already naturally exist in our
environment so they are not of major concern. Unfortunately, hydrocarbons
as a general rule are not favorable refrigerants and are rather flammable. If
you have questions regarding aerosols, freon, or other science-related queries
for more information.
don’t current aerosol hairsprays create a fine mist, as in the past?
Should aerosol sprays be banned for reasons of environmental safety and if so,
is this an economically reasonable proposition? (see EPA and chloroflourocarbon
Question 3: (RQD) How do you synthesis polyurethane?
Answer: see link (same as link above).
Discuss how CFCs destroy the ozone layer through writing a chemical
reaction and determining the molecules produced. Also identify the catalyst in
the reaction to better understand why CFCs are so dangerous to the ozone layer.
In referring to the answer you found to question #4 define the greenhouse
effect and how the lifetime of freon aids in its enhancement.