Ortho-phosphoric acid and phosphoric acid are both organic compounds with the chemical formula H3PO4. However, there are differences between the two in terms of their molecular structure and properties.
Ortho-phosphoric acid (also known as o-phosphoric acid) is a symmetrical molecule with three identical acid groups attached to the central phosphorus atom. This molecule is highly reactive and can form complexes with metal ions and other organic compounds.
Phosphoric acid, on the other hand, is a mixture of ortho-phosphoric acid and its various derivatives, such as pyrophosphoric acid (H4P2O7), and higher molecular weight polyphosphoric acids. These derivatives have different properties and reactivity compared to ortho-phosphoric acid, depending on the number and arrangement of the phosphorus atoms in the molecule.
In summary, ortho-phosphoric acid is a specific molecule with a distinct molecular structure, while phosphoric acid is a more general term that encompasses a range of different compounds with different properties.
The esterification of starch
Ortho-phosphoric acid can be used as a catalyst in the esterification of starch, where it can help to increase the rate of reaction between starch and other reagents, such as vinyl acetate or other alcohols, to form esterified starch products. The presence of ortho-phosphoric acid can increase the reactivity of the starch molecules, making it easier for the esterification reaction to occur. Additionally, ortho-phosphoric acid can also act as a cross-linking agent in the modified starch production, helping to form a three-dimensional network of chemically bonded starch molecules that can improve the properties and performance of the modified starch in various applications.