Eschenmoser's salt

Eschenmoser's salt

Names
Preferred IUPAC name N,N-Dimethylmethaniminium iodide
Identifiers
CAS Number	33797-51-2 (Iodide) Y 30354-18-8 (Chloride) N
3D model (JSmol)	Interactive image Interactive image
ChemSpider	2006292 Y
ECHA InfoCard	100.046.968
PubChem CID	2724133
UNII	5C42I004S1 Y
CompTox Dashboard (EPA)	DTXSID10369115
InChI InChI=1S/C3H8N.HI/c1-4(2)3;/h1H2,2-3H3;1H/q+1;/p-1 Y Key: VVDUZZGYBOWDSQ-UHFFFAOYSA-M Y InChI=1/C3H8N.HI/c1-4(2)3;/h1H2,2-3H3;1H/q+1;/p-1 Key: VVDUZZGYBOWDSQ-REWHXWOFAW
SMILES C[N+](C)=C.[I-] [I-].[N+](=C)(C)C
Properties
Chemical formula	C3H8NI
Molar mass	185.01 g/mol
Appearance	colorless hygroscopic crystals
Melting point	116 °C (241 °F; 389 K)
Solubility in water	decomposes
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H319, H335
Precautionary statements	P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P403+P233, P405, P501
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

In organic chemistry, Eschenmoser's salt (named for Albert Eschenmoser) is the ionic, organic compound [(CH₃)₂NCH₂]I. It is the iodide salt of the dimethylaminomethylene cation [(CH₃)₂NCH₂]⁺.

The dimethylaminomethylene cation is a strong dimethylaminomethylating agent, used to prepare derivatives of the type RCH₂N(CH₃)₂. Enolates, silyl enol ethers, and even more acidic ketones undergo efficient dimethylaminomethylation. Once prepared, such tertiary amines can be further methylated and then subjected to base-induced elimination to afford methylidenated ketones. The salt was first prepared by the group of Albert Eschenmoser after whom the reagent is named.

Structure and bonding

Dimethylaminomethylene cation is described as a resonance hybrid of the carbocation and an iminium cation:

${\ce {(CH3)2N-CH2+ <=> (CH3)2N+=CH2}}$

The C₃N atoms are coplanar. The cation is isoelectronic with isobutene.

Preparation

Pyrolysis of iodomethyltrimethylammonium iodide affords the desired salt:

${\ce {[(CH3)3N-CH2I]I -> [(CH3)2NCH2]I + CH3I}}$

An alternative route starts with bis(dimethylamino)methane:

${\ce {[(CH3)2N]2CH2 + (CH3)3SiI -> [(CH3)2NCH2]I + (CH3)3SiN(CH3)2}}$

Related salts

Other salts of the dimethylaminomethylene cation:

• Dimethyl(methylidene)ammonium trifluoroacetate.
• Dimethyl(methylidene)ammonium chloride (Böhme's salt, after Horst Böhme)

See also

• Vilsmeier reagent, [(CH₃)₂NCHCl]Cl.