Urea phosphate

Urea phosphate is a 1:1 combination of urea and phosphoric acid that is used as a fertilizer. It has an NPK formula of 17-44-0,^[1] and is soluble in water, producing a strongly acidic solution.

Urea phosphate

Names
IUPAC name phosphoric acid;urea
Identifiers
CAS Number	4401-74-5 4861-19-2
3D model (JSmol)	Interactive image
ChemSpider	19748
ECHA InfoCard	100.023.149
EC Number	225-464-3
PubChem CID	20994
UNII	TJR09610O7
CompTox Dashboard (EPA)	DTXSID3063627
InChI InChI=1S/CH4N2O.H3O4P/c2-1(3)4;1-5(2,3)4/h(H4,2,3,4);(H3,1,2,3,4) Key: DZHMRSPXDUUJER-UHFFFAOYSA-N
SMILES C(=O)(N)N.OP(=O)(O)O
Properties
Chemical formula	CH7N2O5P
Molar mass	158.050 g·mol−1
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H314
Precautionary statements	P260, P264, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P363, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Urea phosphate is available in fertilizer vendor bags that carry a UP signet on the packaging. It is sometimes added to blends which contain calcium nitrate, magnesium nitrate and potassium nitrate to produce water-soluble formulas such as 15-5-15 and 13-2-20. The acidity of urea phosphate allows Ca, Mg and P to co-exist in solution. Under less acidic conditions, there would be precipitation of Ca–Mg phosphates. Urea phosphate is often used in drip irrigation to clean pipe systems.^[2][3]

The phosphoric acid and urea molecules in the urea phosphate crystal structure form a complex hydrogen-bonding network,^[4] with the hydrogen atoms bonding more strongly to urea molecules.^[5] It freely dissociates when dissolved in water.

Urea phosphate is produced as a non-ionic adduct of urea and phosphoric acid,^[6] with the typical 17-44-0 grade of fertilizer produced using wet process phosphoric acid at concentrations that vary from 54%^[1] to 90%:^[7]

H₃PO₄(aq) + (NH₂)₂CO(s) → (NH₂)₂CO · H₃PO₄(s)