MSMA

Description

Sodium methylarsonate · CAS 2163-80-6 · CH4AsNaO3. UNII 600QCW45IV. Melting Point: 235 to 241 °F (NTP, 1992); Melting Point: 130-140 °C; Solubility: In water, 5.8X10+5 mg/l @ 20 °C..

Identification

CAS Registry Number	2163-80-6
PubChem CID	23664719
Molecular formula	CH4AsNaO3
IUPAC name	sodium hydroxy(methyl)arsinate
UNII (FDA)	600QCW45IV

Computed Descriptors

Molecular Weight	161.952
Hydrogen Bond Donor Count	1
Hydrogen Bond Acceptor Count	3
Rotatable Bond Count	0
Exact Mass	161.927408
Monoisotopic Mass	161.927408
Topological Polar Surface Area	60.4
Heavy Atom Count	6
Formal Charge	0
Complexity	71.2

Physical & Chemical Properties

Melting Point	235 to 241 °F (NTP, 1992)
Melting Point	130-140 °C
Solubility	In water, 5.8X10+5 mg/l @ 20 °C.
Vapor Pressure	0.00000008 [mmHg]
Vapor Pressure	1X10-5 Pa @ 25 °C (7.8X10-8 mm Hg)
LogP	log Kow= -3.10
Dissociation Constants	pKa1= 4.1; pKa2 = 9.02

Physical description & handling notes

• Methanearsonic acid, [sodium salt] appears as odorless colorless solid. Solution may be red or green. Solid may float or sink in water; solid and solution mix with water. (USCG, 1999)
• White solid; [Hawley] Colorless odorless solid; [CAMEO]
• White solid
• None
• Decomposes (NTP, 1992)
• Mp: 113-116 °C /Sodium methanearsonate sesquihydrate/

GHS Hazard Classification

Reported hazard statements	H301 (90.7%), H331 (90.7%), H400 (90.7%), H410 (90.7%)

Documented Uses

• Used as post-emergence herbicide for turf, cotton, and non-cropland; [HSDB]
• Post-emergence herbicide for grassy weeds.
• Information on 5 consumer products that contain Monosodium acid methanearsonate in the following categories is provided:
• MSMA is produced by the reaction of diarsenic trioxide with methyl chloride and aq sodium hydroxide or by the methylation of sodium arsenite by dimethyl sulfate
• MSMA ... formed from DSMA at pH 6-7.
• Methyl chloride + arsenic trioxide + sulfuric acid + sodium hydroxide (reaction/neutralization)

Synonyms

2163-80-6; Monosodium methanearsonate; Daconate; SODIUM METHANEARSONATE; Gepiron; Mesamate; Monoban; Drexar; Monate; Phyban; Bueno; Super Arsonate; Sodium hydrogen methylarsonate; Ansar 6.6; Herb-All; Herban M

Frequently Asked Questions

What are the CAS number and molecular formula of Sodium methylarsonate?

CAS 2163-80-6; molecular formula CH4AsNaO3; molecular weight — g/mol.

What other names is Sodium methylarsonate known by?

2163-80-6, Monosodium methanearsonate, Daconate, SODIUM METHANEARSONATE, Gepiron, Mesamate.

Is Sodium methylarsonate classified as hazardous?

Hazard statements reported: H301, H331, H400, H410.

What are the key physical properties of Sodium methylarsonate?

Melting Point: 235 to 241 °F (NTP, 1992); Melting Point: 130-140 °C; Solubility: In water, 5.8X10+5 mg/l @ 20 °C.; Vapor Pressure: 0.00000008 [mmHg].

Facts on this page are taken from PubChem (US National Library of Medicine) and Wikidata. Grade-specific data — assay, moisture, particle size, packaging, shelf life — is issued per batch on the COA and is not published here.