http://www.ck12.org Chapter 25. Organic Chemistry
ClO(g) + O(g)→Cl(g) + O 2 (g)If these two reactions are summed together, we can see that chlorine atoms act as a catalyst for the decomposition of
ozone to oxygen gas. Since it is regenerated at the end of this pair of reactions, one single chlorine atom can catalyze
the destruction of thousands of ozone molecules. Beginning in the late 1970s, ozone depletion was recognized as a
significant phenomenon. The most dramatic decrease in ozone occurs seasonally over the continent of Antarctica.
The size and duration of the ozone hole steadily increased, with the largest hole recorded in 2006 (Figure25.17).
Fortunately, most countries have recognized the danger of CFCs and dramatically curtailed their use in recent years.
It is hoped that ozone depletion will slow, and that the ozone layer may eventually return to its earlier levels.
FIGURE 25.17
A type of alkyl halide called a chloroflu-
orocarbon (CFC) was once used nearly
exclusively as a propellant for aerosol
sprays. Since CFCs destroy the important
ozone layer in Earth’s atmosphere, their
use has been largely banned. The image
on the right shows the seasonal hole in
the ozone layer above Antarctica as of
2006.Alcohols
Analcoholis an organic compound that contains one or more hydroxyl (−OH) groups. The general formula for
alcohols is R−OH. Do not confuse alcohols with inorganic bases that contain the hydroxide ion (OH−). The –OH
group in an alcohol is covalently bonded to a carbon atom and does not ionize in solution. The steps for naming
alcohols are listed below.
- Name the parent compound by finding the longest continuous carbon atom chain that also contains the
hydroxyl group. If there is one hydroxyl group in the molecule, change the final–ein the name of the
alkane to–ol. If there is more than one hydroxyl group, use the full name of the alkane and add a suffix to
indicate the number of hydroxyl groups. For example, two hydroxyl groups is–diol, three is–triol, etc. - Number the parent carbon chain in a way that makes the sum of hydroxyl numbers as low as possible.
- Add the numerical prefix into the name before the name of the alcohol.
- Separate numbers with commas, and separate numbers from names or prefixes with hyphens. There are no
spaces in the name.
Three examples of alcohols and their IUPAC names are shown below.