Sodium methanethiolate

For sodium 2-mercaptoethanesulfonate, see Mesna.

Sodium methanethiolate or sodium thiomethoxide is an organosulfur compound with the formula CH₃SNa. It is the sodium salt of the conjugate base of methanethiol. This compound is commercially available as a white solid that is soluble in polar organic solvents. Sodium methanethiolate is a reagent in organic synthesis^[1] and a byproduct of some industrial processes. Hydrolysis of sodium methanethiolate, e.g. in humid air, produces methanethiol, which has a low odor threshold and a noxious "rotten egg" smell.

Sodium methanethiolate

Names
Preferred IUPAC name Sodium methanethiolate
Other names sodium thiomethoxide, sodium methyl mercaptide, sodium thiomethylate, methanethiol sodium salt, methyl mercaptan sodium salt, MeSNa
Identifiers
CAS Number	5188-07-8 Y
3D model (JSmol)	Interactive image
ChemSpider	71198 Y
ECHA InfoCard	100.023.609
EC Number	225-969-9
PubChem CID	4378561
UNII	LB29JWW8H7 N
CompTox Dashboard (EPA)	DTXSID7027592
InChI InChI=1S/CH4S.Na/c1-2;/h2H,1H3;/q;+1/p-1 Y Key: RMBAVIFYHOYIFM-UHFFFAOYSA-M Y InChI=1/CH4S.Na/c1-2;/h2H,1H3;/q;+1/p-1
SMILES [Na+].[S-]C
Properties
Chemical formula	CH3NaS
Molar mass	70.08 g·mol−1
Appearance	white[1]
Density	1.43 g/cm3[2]
Melting point	88–90 °C (190–194 °F; 361–363 K)
Solubility in water	soluble[1]
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

Preparation

Sodium methanethiolate can be produced by treating a solution of methanethiol in an etherial solvent with sodium hydride:

CH₃SH + NaH → CH₃SNa + H₂

It is also prepared and used in situ (i.e., without isolation) by treatment of a solution of methanethiol with strong base such as sodium hydroxide.^[3][4]

Reactions

Sodium methanethiolate is a source of methanethiolate, a powerful nucleophile. It is used to cleave methoxy-aryl ethers:^[1]

NaSCH₃ + Ar−O−CH₃ → Ar−ONa + CH₃SCH₃ (Ar = aryl)

It converts alkyl halides to methyl thioethers:^[5]

NaSCH₃ + RX → RSCH₃ + NaX (X = halogen, R = alkyl)

Oxidation of sodium methanethiolate gives dimethyldisulfide:

2 NaSCH₃ + I₂ → CH₃SSCH₃ + 2 NaI