4/4/2012 - What Makes Old Paper Yellow?

I apologize for once again another prolonged absence, for I have started physiotherapy and the pain has risen significantly, and writing a blog post was the least of my concerns.  I don't currently have my organometallic text book on me at this moment, so I thought I would diverge from the organometallic history for a moment to talk about paper.
If you have ever studied upon an old piece of paper, you would have noticed that the paper is no longer white but appears yellow.  If you were me, you would have had risen two questions, one, whether the paper was made in this tone, or two, whether some chemical reaction had been performed on the paper to make it this colour.  So I decided to look at what actually happens to the paper and have found that what makes it yellow is the formation of the molecules called Chromophores.  This process is done through the oxidation of cellulose over time creating many different products, but of most importance the aldehydic chromophores responsible for the yellowing.
Finding this information receives it's importance when researchers want to look into restoring old papers through a reduction process removing these chromophores.

Source: Science Magazine