Pyrophosphate

Diphosphates ( pyrophosphates also ( PPA; engl: PPi). ) Are salts and esters of pyrophosphoric acid H4P2O7. Diphosphates are condensates of two phosphates. They are connected by a P- O-P - bond linked anhydride ( structural formula [( O3P ) O ( PO3 ) ] 4 - ). The esters of these compounds also have a C -O -P bond and have the general structural formula R -O -[( PO2) -O-( PO 3) ] 3 - ( R: organic radical ).

Examples

Synthesis

Annealing to secondary phosphates, elimination of water diphosphate is formed:

Biochemical importance

Diphosphathaltige compounds play an important role ( cf., eg, adenosine diphosphate, obtained during the consumption of adenosine triphosphate ) for energy transfer processes in living cells. The cleavage of the diphosphate releases energy as the resulting free diphosphate by resonance and hydration on the one hand stabilized. On the other hand, is an entropic effect comes into play, since the entropy of the system has increased. This energy is often used to allow a coupled in this process, however, endothermic reaction. Frequently diphosphates are cleaved by pyrophosphatase into two phosphates to make the respective reaction irreversible. It is also discussed whether, in addition ATP also diphosphates can be used as an alternative energy donors in bacteria and plants.

Food Chemistry

Diphosphates are used in food chemistry among other suitable emulsifiers are, however, have a number of other properties and may also act as a preservative, antioxidant, cutting and baking agents, complexing agents, acidity regulators and melting salts. This artificially manufactured of emulsifiers binds water, prevents clumping powdered foods and, in conjunction with calcium to a creamy consistency. Since phosphates are suspected hyperactivity, trigger allergic reactions and osteoporosis, should always be taken when taking phosphates on the correct dosage. It has a permitted daily dose of 70 milligrams per kilogram of body weight for the total amount of recorded phosphoric acid and phosphates total set. In the EU diphosphate ( disodium, trisodium, tetrasodium, tetra potassium, dicalcium and Calciumdihydrogen diphosphate ) are approved as a food additive under the E number 450 for certain foods, each with different maximum quantity restrictions. After the additive approval regulations are the - for most approved phosphates largely uniform - individual specifications for a wide range with many different types of food. The approved maximum amounts vary from 0.5 to 50 grams per kilogram ( in creamer for ATM), or even the lack of a fixed restriction ( quantum satis - as necessary nutritional supplements and partly in chewing gum ).