Tuesday, November 11, 2014

Green Chemistry

My history teacher emailed me with this article about "Green Chemistry", and I thought it was pretty cool so I decided to explore it a little more.

Heres the link to the article: http://www.nytimes.com/2014/11/10/opinion/making-chemistry-green.html?_r=0

The article is about two chemicals, triclosan and triclocarban, which are commonly used in soaps, cosmetics, and other consumer products.




                  triclosan                                    triclocarban


Triclosan and triclocarban are part of a chemical group called organohalogens, and because of their strong carbon-halogen bonds, they are not biodegradable. Perhaps the most famous organohalogen is DDT (see my post about 5 chemicals that changed history). Since triclosan and triclocarban are not biodegradable, they remain in the human body when consumed, building up and getting passed to babies, which show altered hormone levels, lower birth rate, and reduced head circumference.

The article basically elaborates on these harmful effects and says that people should take more action to convince the FDA to make more regulations. This article just goes to show how immense the application of chemistry is; I was not aware of this particular problem until I had read this article.




Now for more on green chemistry:

The American Chemical Society has twelve fundamental principles of green chemistry:
http://www.acs.org/content/acs/en/greenchemistry/what-is-green-chemistry/principles/12-principles-of-green-chemistry.html

In summary, green chemistry wants to maximize chemical efficiency while minimizing environmental impact, or waste. One of the cool twelve fundamental principles I wanted to elaborate on is "catalytic reagents are superior to stoichiometric reagents." The example they provided for this was ketone to a secondary alcohol. In the case where they use sodium borohydride to reduce ketone, it has a 81 percent efficiency, but when it is reduced with a palladium on charcoal catalyst it has a 100 percent efficiency. In such ways, catalytic reagents are superior and produce less waste, thus becoming the "greener" option.

An interesting example of "green chemistry" is the process of metathesis, which won the Noble Prize in Chemistry in 2005. Metathesis reactions occur when cations and anions switch partners.
Learn more: http://www.science.uwaterloo.ca/~cchieh/cact/c120/metathes.html

Thanks for reading!