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Trimethylsilyldiazomethane Structural Formula V1.svg
Ball-and-stick model of the trimethylsilyldiazomethane molecule
IUPAC name
Other names
3D model (JSmol)
ECHA InfoCard 100.131.243
MeSH Trimethylsilyldiazomethane
Molar mass 114.223 g·mol−1
Appearance greenish-yellow liquid[1][2]
Boiling point 96.0[1] °C (204.8 °F; 369.1 K)
Safety data sheet External MSDS
Harmful Xn Highly Flammable F Dangerous for the Environment (Nature) N
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☑Y verify (what is ☑Y☒N ?)
Infobox references

Trimethylsilyldiazomethane is the organosilicon compound with the formula (CH3)3SiCHN2. It is classified as a diazo compound. Trimethylsilyldiazomethane is a commercially available reagent used in organic chemistry as a methylating agent and as a source of CH2 group. Its behavior is akin to the less convenient reagent diazomethane.[3]


Trimethylsilyldiazomethane may be prepared by treating (trimethylsilyl)methylmagnesium chloride with diphenyl phosphorazidate.[4]


It is a less explosive alternative to diazomethane for the methylation of carboxylic acids, it also reacts with alcohols to give methyl ethers, where diazomethane may not.[5]

It has also been employed widely in tandem with GC-MS for the analysis of various carboxylic compounds which are ubiquitous in nature; the fact that the reaction is rapid and occurs readily makes it attractive. However, it can form artifacts which complicate spectral interpretation; such artifacts are usually the trimethylsilylmethyl esters, RCO2CH2SiMe3, formed when insufficient methanol is present. Acid-catalysed methanolysis is necessary to achieve near-quantitative yields of the desired methyl esters, RCO2Me.[6]

The compound is a reagent in the Doyle-Kirmse reaction with allyl sulfides and allyl amines.


Trimethylsilyldiazomethane is deprotonated by butyllithium:

(CH3)3SiCHN2 + BuLi → (CH3)3SiCLiN2 + BuH

The lithio compound is versatile. From it can be prepared other trimethylsilyldiazoalkanes:

(CH3)3SiCLiN2 + RX → (CH3)3SiCRN2 + LiX

(CH3)3SiCLiN2 reacts with ketones and aldehydes to give, depending on the substituents, acetylenes.[7]


Trimethylsilyldiazomethane is highly toxic, it has been implicated in the death of at least two chemists, a pharmaceutical worker in Windsor, Nova Scotia, Canada and one in New Jersey.[8][9] Inhalation of diazomethane is known to cause pulmonary edema; trimethylsilyldiazomethane is suspected to behave similarly.[10]

When used as a reagent in organic synthesis to convert carboxylic acids to their methyl esters, trimethylsilyldiazomethane undergoes acid-catalysed methanolysis, forming diazomethane in situ.[6] A similar hydrolysis reaction may take place when trimethylsilyldiazomethane comes into contact with water on the surface of a human lung.[10]

Trimethylsilyldiazomethane is nonexplosive.[4]


  1. ^ a b Seyferth, Dietmar.; Dow, Alan W.; Menzel, Horst.; Flood, Thomas C. (1968). "Trimethylsilyldiazomethane and trimethylsilylcarbene". J. Am. Chem. Soc. 90 (4): 1080–1082. doi:10.1021/ja01006a055.
  2. ^ Seyferth, Dietmar; Menzel, Horst; Dow, Alan W.; Flood, Thomas C. (1972). "Trimethylsilyl-substituted diazoalkanes I. Trimethylsilyldiazomethane". J. Organomet. Chem. 44 (2): 279–290. doi:10.1016/S0022-328X(00)82916-2.
  3. ^ Shioiri, Takayuki; Aoyama, Toyohiko; Snowden, Timothy (2001). "Trimethylsilyldiazomethane". e-EROS Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rt298.pub2.CS1 maint: Uses authors parameter (link)
  4. ^ a b Takayuki Shioiri, Toyohiko Aoyama, and Shigehiro Mori (1993). "Diazo(trimethylsilyl)methane". Organic Syntheses.CS1 maint: Multiple names: authors list (link); Collective Volume, 8, p. 612
  5. ^ Armin Presser & Antje Hüfner (2004). "Diazo(trimethylsilyl)methane – A Mild and Efficient Reagent for the Methylation of Carboxylic Acids and Alcohols in Natural Products". Chemical Monthly. 135 (8). doi:10.1007/s00706-004-0188-4.
  6. ^ a b Kühnel, E.; Laffan, D. D. P.; Lloyd-Jones, G. C.; Martínez del Campo, T.; Shepperson, I. R.; Slaughter, J. L. (2007). "Mechanism of Methyl Esterification of Carboxylic Acids by Trimethylsilyldiazomethane". Angew. Chem. Int. Ed. 46 (37): 7075–7078. doi:10.1002/anie.200702131.
  7. ^ Moody, Christopher J.; Shioiri, Takayuki; Aoyama, Toyohiko (2011). "Diazo(trimethylsilyl)methyllithium". e-EROS Encyclopedia of Reagents for Organic Synthesis. pp. 1–7. doi:10.1002/047084289X.rd019.pub2.CS1 maint: Multiple names: authors list (link)
  8. ^ Family says N.S. pharmaceutical worker named chemical he used before death, The Amherst Daily News, October 20, 2008
  9. ^ N.S. probe into pharma worker's death finds vent hoods turned off in lab,, May 13th, 2009
  10. ^ a b Murphy, N. G.; Varney, S. M.; Tallon, J. M.; Thompson, J. R.; Blanc, P. D. (2009). "Fatal Occupational Exposure to Trimethylsilyl-Diazomethane". Clin. Toxicol. 47 (7): 712. doi:10.1080/15563650903076924.