It was shown in 1912 by Willstatter et al. that chlorophyll is a mixture of chlorophyll-a and chlorophyll-b. These compounds are identical to each other except for an aldehyde group in chlorophyll-b that replaces a methyl group in chlorophyll-a. Because of this the two compounds can be separated by shaking a light petroleum solution of chlorophyll with aqueous methanol, with chlorophyll-b moving to the methanol layer whilst chlorophyll-a remains in the petroleum.
Chlorophyll has an intense green colour due to strong absorbance in the red and blue regions of the visible spectrum:
The most important role of chlorophyll is in photosynthesis. For further information visit