Orthophosphoric acid, diesters

Phosphate Esters. Mono and diesters of orthophosphoric acid ... 

The phosphoric mono- and diesters of the sugars are strongly acidic substances isolated often as crystalline barium, calcium, lead, sodium, cyclo-hexylammonium, or alkaloid salts. They are usually stronger acids than free orthophosphoric acid (Table II), a fact which has been rationalized according to modern theory (152). 

In the biosphere, triesters of orthophosphoric acid are unknown, however, this does not exclude the possibility that this binding may be present in certain macromolecules. The diesters of orthophosphoric acid which exist in the biosphere are often mixed esters. Acid or alkaline hydrolysis slowly transforms them into monoesters. Most of the complex lipides are diesters and vitamin also falls into this category. The mono-phosphoric esters of alcohols form a very important biochemical group. The two free acid groups are more strongly acidic than when they were... 

Most of the complex lipides are diesters of orthophosphoric acid. Those not belonging to this category will be described with those that do. The fact that the complex lipides described here are extremely widely distributed in the biosphere, confers upon them the status of fundamental cellular constituents. 

The different varieties of orthophosphoric monoesters and diesters which are present in all living species are exceedingly numerous. Biologically important monoesters include the mononucleotides such as, for example, adenylic acid (adenosine monophosphate, AMP), inosinic acid, vitamin Bg and many phosphorylated proteins, for example, milk caseins. Biologically important diesters include the phospholipids (e.g. lecithin and phosphatidyl inositol), plasmalogens, sphingomyelins, cyclic nucleotide monophosphates (e.g. cyclic AMP), some teichoic acids, vitamin Bj2 and of course the immensely important nucleic acids (polynucleotides) (Chapters 10 and 11). The great stability of diesters is an essential feature of the chemistry of polynucleotides. 

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