Diammonium hydrogenphosphate is also called DAP. It is a white powder that is insoluble in alcohol, acetone and liquid ammonia but soluble in water. The substance has the chemical formula (NH₄)₂HPO₄. In addition, its IUPAC name is diammonium hydrogen phosphate. Meanwhile, its EINECS registry number is 231-987-8 and the CAS number is 7783-28-0. Additionally, its classification code is Pharmaceutic aid.

Properties: Diammonium hydrogenphosphate should be sealed and stored in cool and dry place. It should be protected from oxides and air. It is soluble in water and aqueous solution is alkaline. In addition, it can react with ammonia water to generate triammonium phosphate. It should be prohibitted to store and transport with toxic substance.

Preparation: Diammonium hydrogenphosphate can be produced when ammonia reacts with phosphoric acid. Solid diammonium phosphate shows a dissociation pressure of ammonia as given by the following expression and equation:

(NH₄)₂HPO₄(s) → NH₃(g) + NH₄H₂PO₄(s)   log PmmHg = -3063 / T + 175 log T + 3.3

Diammonium hydrogenphosphate commonly can be prepared by neutralization reaction that thermal phosphoric acid or extraction of phosphoric acid phosphoric acid reacts with liquid ammonia in industrial production. The former product is high purity and the latter will cost more lower.

H₃PO₄ + 2 NH₃ → (NH₄)₂HPO₄

You can also use wetphosphoricacid as the raw material. This reaction will need two steps of defluorination, there steps of ammoniation and pyrolyzation of triammonium phosphate:

H₃PO₄ + 2 NH₃ → ( NH₄)₂HPO₄
(NH₄)₂HPO₄ + NH₄OH → (NH₄)₃PO₄ + H₂O
(NH₄)₃HPO₄.3H₂O [70°C] → (NH₄)₂HPO₄ + NH₃ + 3 H₂O

Uses: Diammonium hydrogenphosphate is used as a fertilizer. When used as plant food, it temporarily increases the soil pH. In addition, it also can be used as a fire retardant and yeast nutrient in winemaking and brewing mead. Meanwhile, it is also used for seed corrosion inhibitors, mixing agent, medium reagents. What's more, Diammonium hydrogenphosphate can also be used as waterproof agent in paper and fabric, waterproof paint additive, etc.

When using Diammonium hydrogenphosphate, you should be very careful, because it is irritant and harmful. This chemical is harmful by inhalation and if swallowed and is irritating to respiratory system and skin. In case of contact with eyes, you can rinse immediately with plenty of water and seek medical advice. Whenever you will contact it, please wear suitable protective clothing.

Descriptors computed from structure of Diammonium hydrogenphosphate:
(1)Canonical SMILES: [NH4+].[NH4+].OP(=O)([O-])[O-]
(2)InChI: InChI=1S/2H3N.H3O4P/c;;1-5(2,3)4/h2*1H3;(H3,1,2,3,4)
(3)InChIKey: MNNHAPBLZZVQHP-UHFFFAOYSA-N