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Sodium methylsulfinylmethylide (also called NaDMSO or dimsyl sodium) is the sodium salt of the conjugate base of
dimethyl sulfoxide
Dimethyl sulfoxide (DMSO) is an organosulfur compound with the formula ( CH3)2. This colorless liquid is the sulfoxide most widely used commercially. It is an important polar aprotic solvent that dissolves both polar and nonpolar compounds a ...
. This unusual salt has some uses in organic chemistry as a base and nucleophile
In chemistry, a nucleophile is a chemical species that forms bonds by donating an electron pair. All molecules and ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they are ...
.
Since the first publication in 1965 by Corey
Corey is a masculine given name and a surname. It is a masculine version of name Cora, which has Greek origins and is the maiden name of the goddess Persephone. The name also can have origins from the Gaelic word ''coire'', which means "in a caul ...
''et al.'', a number of additional uses for this reagent have been identified.
Preparation
Sodium methylsulfinylmethylide is prepared by heating sodium hydride or sodium amide in DMSO :CH3SOCH3 + NaH → CH3SOCH2−Na+ + H2 :CH3SOCH3 + NaNH2 → CH3SOCH2−Na+ + NH3Reactions
As a Base
The pKa of DMSO is 35, which leads NaDMSO to be a powerful Brønsted base. NaDMSO is used in the generation of phosphorus andsulfur
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...
ylide An ylide or ylid () is a neutral dipolar molecule containing a formally negatively charged atom (usually a carbanion) directly attached to a heteroatom with a formal positive charge (usually nitrogen, phosphorus or sulfur), and in which both atoms h ...
s. NaDMSO in DMSO is especially convenient in the generation of dimethyloxosulfonium methylide and dimethylsulfonium methylide.
Reaction with esters
NaDMSO condenses with esters (1) to form β-ketosulfoxides (2), which can be useful intermediates. Reduction of β-ketosulfoxides withaluminium amalgam Aluminium can form an amalgam in solution with mercury. Aluminium amalgam may be prepared by either grinding aluminium pellets or wire in mercury, or by allowing aluminium wire to react with a solution of mercury(II) chloride in water.
This amalga ...
gives methyl
In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula . In formulas, the group is often abbreviated as Me. This hydrocarbon group occurs in many ...
ketone
In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bo ...
s (3). Reaction with alkyl halides followed by elimination gives α,β-unsaturated ketones (4). β-ketosulfoxides can also be used in the Pummerer rearrangement to introduce nucleophile
In chemistry, a nucleophile is a chemical species that forms bonds by donating an electron pair. All molecules and ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they are ...
s alpha to a carbonyl (5).
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References
External links
* * {{cite web , url = http://stenutz.eu/sop/sop401.html , title = Preparation of dimsyl sodium , date=June 2009 Reagents for organic chemistry Organosodium compounds