Monosodium citrate

Monosodium citrate, more correctly, sodium dihydrogen citrate (Latin: natrium citricum acidulatum), is an acid salt of citric acid. Disodium citrate and trisodium citrate are also known. It can be prepared by partial neutralisation of citric acid^[3] with an aqueous solution of sodium bicarbonate or carbonate. It has a slightly acidic taste.^[3]

NaHCO₃ + C₆H₈O₇ → NaC₆H₇O₇ + CO₂ + H₂O

Na₂CO₃ + 2C₆H₈O₇ → 2NaC₆H₇O₇ + CO₂ + H₂O

Monosodium citrate

Names
IUPAC name Sodium 2-(carboxymethyl)-2,4-dihydroxy-4-oxobutanoate[1]
Other names sodium dihydrogen 2-hydroxypropane-1,2,3-tricarboxylate
Identifiers
CAS Number	18996-35-5 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:53258 Y
ChemSpider	27304 N
ECHA InfoCard	100.038.834
EC Number	242-734-6
E number	E331i (antioxidants, ...)
PubChem CID	23662352
RTECS number	GE9750000
UNII	68538UP9SE Y
CompTox Dashboard (EPA)	DTXSID80872904
InChI InChI=1S/C6H8O7.Na/c7-3(8)1-6(13,5(11)12)2-4(9)10;/h13H,1-2H2,(H,7,8)(H,9,10)(H,11,12);/q;+1/p-1 N Key: HWPKGOGLCKPRLZ-UHFFFAOYSA-M N InChI=1/C6H8O7.3Na/c7-3(8)1-6(13,5(11)12)2-4(9)10;;;/h13H,1-2H2,(H,7,8)(H,9,10)(H,11,12);;;/q;3*+1/p-3 Key: HRXKRNGNAMMEHJ-DFZHHIFOAL
SMILES C(C(=O)O)C(CC(=O)O)(C(=O)[O-])O.[Na+]
Properties
Chemical formula	C6H7NaO7
Molar mass	214.105 g·mol−1
Appearance	white powder hygroscopic
Odor	odorless
Melting point	212 °C (414 °F; 485 K)
Boiling point	309.6 °C (589.3 °F; 582.8 K)
Solubility in water	soluble
Solubility	negligible in ethanol
Acidity (pKa)	3.50–3.80
Structure[2]
Crystal structure	Monoclinic
Space group	P21/a (No. 4)
Formula units (Z)	4
Hazards
Lethal dose or concentration (LD, LC):
LD50 (median dose)	5400 mg/kg (mouse, oral) >2000 mg/kg (rat, dermal)
Safety data sheet (SDS)	Carl Roth
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

It is highly soluble in water and practically insoluble in ethanol.^[3] Monosodium citrate is used as an anticoagulant in blood samples.^[4] It is used as an alkalinizing agent to prevent kidney stone disease.^[5] The crystals form as nearly perfect cubes.^[6]