Chlorophyll chemical transformations

Several chemical transformations in the chlorin series were discovered during the course of Woodward s total synthesis of chlorophyll a.3a d An important reaction in the final steps of this total synthesis is the removal of an a-oxo acid ester residue from the 17-position of the chlorin 22, which proceeds very smoothly in the presence of base by a retro-aidol-type fragmentation to yield the chlorin isopurpurin methyl ester (23) which is also available by degradation of chlorophyll a, so that at this point of the synthesis synthetically derived material could be compared with an authentic sample prepared from natural chlorophyll a. 

Before we discuss how chlorophylls can transform light into chemical energy, let s review some of the basic properties of light. Light is an oscillating electromagnetic field (fig. 

The photosynthetic process involves photochemical reactions followed by sequential dark chemical transformations (Fig. 3). The photochemical processes occur in two photoactive sites, photosystem I and photosystem II (PS-I and PS-II, respectively), where chlorophyll a and chlorophyll b act as light-active compounds [6, 8]. Photoinduced excitation of photosystem I results in an electron transfer (ET) process to ferredoxin, acting as primary electron acceptor. This ET process converts light energy to chemical potential stored in the reduced ferredoxin and oxidized chlorophyll. Photoexcitation of PS-II results in a similar ET process where plastoquinone acts as electron acceptor. The reduced photoproduct generated in PS-II transfers the electron across a chain of acceptors to the oxidized chlorophyll of PS-I and, consequently, the light harnessing component of PS-I is recycled. Reduced ferredoxin formed in PS-I induces a series of ET processes,... 

Chemical transformations of chlorophyll and its use for producing ecologically pure dyes of new type 04UK197. 

The electron is then transferred through the membrane via chlorophyll, a quinone, and iron-sulfur clusters to a ferridoxin on the inside of the chloroplast. The electron is then used to generate NADPH, an organic proton and electron carrier, which carries out many chemical transformations inside the chloroplast. 

As we now understand this phenomenon, absorption of a photon leads to an electronically excited state, characterized by high energy and a strongly perturbed electronic structure. The result often is an in-depth—but selective—chemical transformation. As everyone can easily appreciate, photochemistry has a key role in nature (e.g., chlorophyll photosynthesis, vision) and in a variety of applications. Photography and other methods of reproducing an image, the fast hardening of varnishes and of dental cement, and many other applications are based on photochemical reactions. 

Because of their basic role in nature, chlorophylls have been the subject of many investigations. For a better understanding of photosynthesis it is necessary that chlorophylls and their derivatives be determined qualitatively and quantitatively. Investigations into their chemical structure, genesis, transformations, and functions in plants supply valuable information for plant physiological studies (92). 

Chlorophyll Green pigment that can absorb light rays during photosynthesis. It captures the energy from the sun and transforms it into chemical bond energy. Chlorophylls are found in the chloroplasts of plants and algae and in some bacteria. 

Harris, P.G., Carter, J.F., Head, R.N., Harris, R.P., Eglinton, G., and Maxwell, J.R. (1995) Identification of chlorophyll transformation products in zooplankton faecal pellets and marine sediment extracts by liquid chromatography/mass spectrometry atmospheric pressure chemical ionization. Rapid Cornmun. Mass Spectrom. 9, 1177-1183. 

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