7722-76-1

Basic information

• Product Name: Ammonium dihydrogen orthophosphate
• Synonyms: azanium,dihydrogen phosphate;Ammonium dihydrogen phosphate
• CAS NO: 7722-76-1
• Molecular Formula: H₂O₄P*H₄N
• Molecular Weight: 115.025701
• EINECS: 231-764-5
• Mol File: 7722-76-1.mol
• Article Data: 4

Chemical Properties

• Melting Point: 190℃
• Boiling Point: 158 °C at 760 mmHg
• Appearance: white crystalline powder
• Density: 1.02 g/mL at 20 °C
• Water Solubility: 368 g/L (20℃)
• CAS DataBase Reference: Ammonium dihydrogen orthophosphate(CAS DataBase Reference)
• NIST Chemistry Reference: Ammonium dihydrogen orthophosphate(7722-76-1)
• EPA Substance Registry System: Ammonium dihydrogen orthophosphate(7722-76-1)

Safety Data

• Statements: 36/37/38:
• Safety Statements: S24/25:
• Hazardous Substances Data: 7722-76-1(Hazardous Substances Data)

Usage

General Description

Ammonium dihydrogen orthophosphate, also known as monobasic ammonium phosphate or MAP, is an inorganic compound with the chemical formula (NH4)H2PO4. It forms colorless, monoclinic crystals that are highly soluble in water. As an acid salt derived from phosphoric acid, it is widely used in fertilizers for its high nitrogen content. It also has applications in food processing as a pH regulator, in fire extinguishers as a flame suppressant, and in molecular biology as a buffering agent. Although its ingestion is considered generally safe, exposure to large amounts can cause eye and skin irritation, respiratory discomfort, and gastrointestinal upset. Its production mainly involves the reaction of ammonia with phosphoric acid under tightly controlled conditions.

InChI:InChI=1S/H3N.H3O4P/c;1-5(2,3)4/h1H3;(H3,1,2,3,4)

Synthetic route

phosphoric acid (86119-84-8, 7664-38-2) + urea (57-13-6) → ammonium dihydrogen phosphate (7722-76-1) + carbon dioxide (124-38-9)

Conditions	Yield
With water Kinetics;

tricalcium diphosphate → ammonium dihydrogen phosphate (7722-76-1) + phosphoric acid (86119-84-8, 7664-38-2)

Conditions	Yield
With ammonium sulfate; sulfuric acid In not given byproducts: CaSO4; in presence of 16.2-22.2% (NH4)2SO4;
With H2SO4; (NH4)2SO4 In not given byproducts: CaSO4; in presence of 16.2-22.2% (NH4)2SO4;

tricalcium diphosphate + ammonium sulfate + phosphoric acid (86119-84-8, 7664-38-2) → ammonium dihydrogen phosphate (7722-76-1)

Conditions	Yield
In not given with H3PO4 soln., at higher temp.;
In not given with H3PO4 soln., at higher temp.;

phosphorus → ammonium dihydrogen phosphate (7722-76-1)

Conditions	Yield
With ammonia; water at high temp., in sealed quarz tube in N2 flow;
With NH3; H2O at high temp., in sealed quarz tube in N2 flow;

phosphoramidic acid (14700-20-0, 2817-45-0) → ammonium dihydrogen phosphate (7722-76-1)

Conditions	Yield
With phosphoramidic acid In water boiling;
With phosphoramidic acid In water boiling;
With water In water-d2 Kinetics; hydrolysis in D2O; catalyst: acids;;

P4N6 → diammonium hydrogenphosphate + ammonium dihydrogen phosphate (7722-76-1) + ammonium dihydrogenphosphite (13446-12-3)

Conditions	Yield
With water In neat (no solvent) heating in sealed tube at 215°C, 12 h;
With H2O In neat (no solvent) heating in sealed tube at 215°C, 12 h;

P4N6 + phosphorus(V) nitride → diammonium hydrogenphosphate + ammonium dihydrogen phosphate (7722-76-1) + ammonium dihydrogenphosphite (13446-12-3)

Conditions	Yield
With water hydrolysis;
With H2O hydrolysis;

phosphorus(V) nitride → diammonium hydrogenphosphate + ammonium dihydrogen phosphate (7722-76-1)

Conditions	Yield
With water In neat (no solvent) heating in sealed tube at 215°C, 12 h;
With H2O In neat (no solvent) heating in sealed tube at 215°C, 12 h;

anhydrous calcium hydrogen phosphate + ammonium bicarbonate (1066-33-7) → ammonium dihydrogen phosphate (7722-76-1)

Conditions	Yield
In not given at higher temp.;
In not given at higher temp.;

ammonium dihydrogenphosphite (13446-12-3) → ammonium dihydrogen phosphate (7722-76-1)

Conditions	Yield
With water byproducts: H2; heated under pressure;
With H2O byproducts: H2; heated under pressure;

diammonium hydrogenphosphate → ammonium dihydrogen phosphate (7722-76-1)

Conditions	Yield
warming at 100°C in dry air flow, 2h;
In neat (no solvent) heated in platinum boat to 155°C;
warming at 100°C in dry air flow, 2h;
In neat (no solvent) heated in platinum boat to 155°C;

diammonium hydrogenphosphate → ammonium dihydrogen phosphate (7722-76-1) + ammonia (7664-41-7)

diammonium hydrogenphosphate + phosphoric acid (86119-84-8, 7664-38-2) → ammonium dihydrogen phosphate (7722-76-1)

Conditions	Yield
In not given added equiv. amt. H3PO4 to (NH4)2HPO4 soln.;
In not given added equiv. amt. H3PO4 to (NH4)2HPO4 soln.;

phosphoric acid (86119-84-8, 7664-38-2) + ammonia (7664-41-7) → ammonium dihydrogen phosphate (7722-76-1) + Mg(2+)*2NH4(1+)*4H(1+)*2P2O7(4-)*2H2O = Mg(NH4)2H4(P2O7)2*2H2O + diammonium-dihydrogenodiphosphate + (Fe,Al)(NH4)P2O7

Conditions	Yield
In not given neutralization of H3PO4 (made by wet process from natural Karatau phosphorite) with NH3, evapn., dehydration (230 - 250.degree, 3.0 - 3.5 h); mixt. not sepd.; X-ray diffraction;

phosphoric acid (86119-84-8, 7664-38-2) + ammonia (7664-41-7) → diammonium hydrogenphosphate + ammonium dihydrogen phosphate (7722-76-1)

Conditions	Yield
In water Kinetics; injection of a micro-drop of H3PO4 (concn. 50-88.5%) into a flowing mixt. of He and NH3 or leading a dose of NH3 in a He flow over H3PO4 (concn. 50-88.5%), 203-353K;

phosphoric acid (86119-84-8, 7664-38-2) + ammonia (7664-41-7) → ammonium dihydrogen phosphate (7722-76-1)

Conditions	Yield
75% H3PO4 soln.;
In ammonia added NH3 soln. to H3PO4 (to acidic reaction of litmus and no more ppt. with BaCl2);
In not given neutralised of H3PO4 soln. with NH3 by methyl orange indicator; purifn. by repeated recrystn., dried over P2O5 in vac.;

calcium hydrogen phosphate (7789-77-7) + ammonium bisulfate (7803-63-6) → ammonium dihydrogen phosphate (7722-76-1)

Conditions	Yield
CaHPO4 was treated with equivalent amount of NH4HSO4;;
CaHPO4 was treated with equivalent amount of NH4HSO4;;

hydrogen (1333-74-0) + nitrogen(II) oxide (10102-43-9) → ammonium dihydrogen phosphate (7722-76-1) + hydroxylamine phosphate + nitrous oxide (227934-46-5) + nitrogen (7727-37-9)

Conditions	Yield
With palladium on activated charcoal In further solvent(s) Kinetics; 40 °C, P(H2) = 50 kPa, P(NO) = 10 kPa;

calcium dihydrogen phosphate + ammonium sulfate → ammonium dihydrogen phosphate (7722-76-1)

Conditions	Yield
Ca(H2PO4)2 was treated with equivalent amount of (NH4)2SO4;;
Ca(H2PO4)2 was treated with equivalent amount of (NH4)2SO4;;

2NH4(1+)*H(1+)*P2O6NH2(3-)=(NH4)2HP2O6NH2 → diammonium hydrogenphosphate + ammonium dihydrogen phosphate (7722-76-1)

Conditions	Yield
With H2O In water decompn. by heating (at ambient temp. very slow);

ammonium cyclotriphosphate + water (7732-18-5) → ammonium dihydrogen phosphate (7722-76-1)

Conditions	Yield
In neat (no solvent) heating (glass ampoule, H2O pressure 24 GPa, 200 and 252+/-0.2°C); thin layer chromy., X-ray diffraction;

ammonium cyclotriphosphate + ammonia (7664-41-7) + water (7732-18-5) → ammonium dihydrogen phosphate (7722-76-1) + diammonium-dihydrogenodiphosphate

Conditions	Yield
In neat (no solvent) heating (glass ampoule, H2O pressure 24 GPa, NH3 pressure 906 GPa, 220 or 286°C); thin layer chromy., X-ray diffraction;

urea phosphate (4861-19-2) → ammonium dihydrogen phosphate (7722-76-1) + ammonium metaphosphate + carbon dioxide (124-38-9) + ammonia (7664-41-7) + urea (57-13-6)

Conditions	Yield
at 140°C;

hexaaminocyclotriphosphazene (13597-92-7) → ammonium sulfate + ammonium dihydrogen phosphate (7722-76-1)

Conditions	Yield
With H2SO4 In not given react. with H2SO4; formation of a mixture of NH4H2PO4 and (NH4)2SO4 and white vapors of volatile N compounds;;

Upstream product

• 86119-84-8 phosphoric acid 
• 7664-41-7 ammonia 
• 57-13-6 urea 
• 1336-21-6 ammonium hydroxide 
• 7732-18-5 water 
• 7647-19-0 phosphorus pentafluoride 
• 13597-92-7 hexaaminocyclotriphosphazene 
• 4861-19-2 urea phosphate 
• 1333-74-0 hydrogen 
• 10102-43-9 nitrogen(II) oxide 
• 7789-77-7 calcium hydrogen phosphate 

Downstream Products

• 86119-84-8 phosphoric acid 
• 7664-41-7 ammonia 
• 18649-05-3 cesium dihydrogen phosphate 
• 7789-77-7 calcium hydrogen phosphate 
• 7732-18-5 water 
• 10192-29-7 ammonium chlorate 
• 13762-75-9 lithium metaphosphate 

Relevant articles and documents

Solid-Phase Interaction of Fluorapatite with Ammonium Hydrogen Difluoride

A solid-phase interaction of fluorapatite with ammonium difluoride was studied in the temperature range 25-900°C. At room temperature, calcium fluoride and ammonium dihydrogen phosphate or isostructural ammonium florophosphate were formed as the result of grinding a mixture of theinitial components. Above 200°C, the reaction was accompanied by the formation of a volatile phosphor compound. At the final stage of th e process (above 500°C), glassy ammonium hydrogen ultrafluorophosphate of nonstoichiometric composition was formed, which again yielded fluorapatite upon reaction with calcium fluoride.

FORMATION OF INSOLUBLE COMPOUNDS IN AMMONIUM POLYPHOSPHATE MADE FROM WET-PROCESS PHOSPHORIC ACID.

A study was made of the influence of pH on formation of insoluble compounds in solid APP (Ammonium Polyphosphate). Orthophosphoric acid made by the wet process (WOPA) from Karatau phosphorites of the composition (mass %): P//2O//5//t//o//t equals 23. 1, R//2O//3 equals 2. 9, Fe//2O//3 equals 0. 96, F equals 0. 79, SO//3 equals 2. 5, MgO equals 1. 8 was used in the experiments. It is shown that the production of APP by evaporation and dehydration of ammonium phosphate slurries of various pH values is accompanied by retrogradation of the available and water-soluble form of P//2O//5, which intensifies with increase of pH. This investigation led to the development of a process for production of solid APP from unevaporated orthophosphoric acid obtained from Karatau phosphorites, with insignificant retrogradation of available P//2O//5.