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Trimethylsilyldiazomethane

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Trimethylsilyldiazomethane
Ball-and-stick model of the trimethylsilyldiazomethane molecule
Names
IUPAC name
(Diazomethyl)trimethylsilane
Other names
Trimethylsilyldiazomethane
Diazo(trimethylsilyl)methane
Identifiers
3D model (JSmol)
1902903
ChemSpider
ECHA InfoCard 100.131.243 Edit this at Wikidata
EC Number
  • 605-915-4
MeSH Trimethylsilyldiazomethane
UNII
  • InChI=1S/C4H10N2Si/c1-7(2,3)4-6-5/h4H,1-3H3 checkY
    Key: ONDSBJMLAHVLMI-UHFFFAOYSA-N checkY
  • InChI=1/C4H10N2Si/c1-7(2,3)4-6-5/h4H,1-3H3
    Key: ONDSBJMLAHVLMI-UHFFFAOYAN
  • C[Si](C)(C)[CH-][N+]#N
  • [N-]=[N+]=C[Si](C)(C)C
Properties
C4H10N2Si
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)
Hazards
GHS labelling:[3]
GHS02: FlammableGHS06: ToxicGHS08: Health hazardGHS09: Environmental hazard
Danger
H330, H350, H370
P201, P202, P210, P233, P240, P241, P242, P243, P260, P261, P264, P270, P271, P273, P280, P281, P284, P302+P352, P303+P361+P353, P304+P340, P307+P311, P308+P313, P310, P311, P314, P320, P332+P313, P362, P370+P378, P391, P403+P233, P403+P235, P405, P501
Safety data sheet (SDS) External MSDS[dead link]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Trimethylsilyldiazomethane is the organosilicon compound with the formula (CH3)3SiCHN2. It is classified as a diazo compound. Trimethylsilyldiazomethane, which is a commercially available, reagent used in organic chemistry as a methylating agent of carboxylic acids. Its behavior is akin to the reagent diazomethane, but the trimethylsilyl (TMS) analog is nonexplosive.[4]

Preparation

Trimethylsilyldiazomethane can be prepared by treating (trimethylsilyl)methylmagnesium chloride with diphenyl phosphorazidate.[5] An isotopically labelled variant, with 13C at the diazomethyl carbon, is also known.[6]

Reactions

Trimethylsilyldiazomethane convert carboxylic acids to their methyl esters. It had been proposed that TMS reagent converts to diazomethane itself by a pathway involving the solvent and acidic substrate, giving the active methylating agent.[7] More recent studies instead support that the TMS reagent itself is the active methylating agent.[8] Regardless of the mechanistic details, the overall result is methylation of the substrate with Methoxytrimethylsilane (CH3OTMS) and nitrogen gas as byproducts:

RCO2H + TMSCHN2 + CH3OH → RCO2CH3 + CH3OTMS + N2

It also reacts with alcohols to give methyl ethers, where diazomethane may not.[9]

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.[10]

Applications

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.[7]

Safety

Trimethylsilyldiazomethane is highly toxic. It has been implicated in the death of at least two chemists, a pharmaceutical worker in Windsor, Nova Scotia and one in New Jersey.[11][12][13] Inhalation of diazomethane is known to cause pulmonary edema; trimethylsilyldiazomethane is suspected to behave similarly.[14]

It is possible that upon contact with water on the surface of the lung, trimethylsilyldiazomethane converts to diazomethane.[14]

Trimethylsilyldiazomethane is nonexplosive.[5]

References

  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. ^ "Trimethylsilyldiazomethane". pubchem.ncbi.nlm.nih.gov.
  4. ^ Shioiri, Takayuki; Aoyama, Toyohiko; Snowden, Timothy (2001). "Trimethylsilyldiazomethane". e-EROS Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rt298.pub2. ISBN 0471936235.
  5. ^ a b Takayuki Shioiri; Toyohiko Aoyama; Shigehiro Mori (1990). "Trimethylsilyldiazomethane". Organic Syntheses. 68: 1. doi:10.15227/orgsyn.068.0001.
  6. ^ Nottingham, Chris; Lloyd-Jones, Guy C. (2018). "Trimethylsilyldiazo[13C]methane: A Versatile 13C-Labelling Reagent". Organic Syntheses. 95: 374–402. doi:10.15227/orgsyn.095.0374. hdl:20.500.11820/c801073c-6b4b-4a85-be68-2c4313b6e53d.
  7. ^ 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. PMID 17691089.
  8. ^ Kühnel, Erik; Laffan, David D. P.; Lloyd-Jones, Guy C.; Martínez del Campo, Teresa; Shepperson, Ian R.; Slaughter, Jennifer L. (2007). "Mechanism of Methyl Esterification of Carboxylic Acids by Trimethylsilyldiazomethane". Angew. Chem. Int. Ed. Engl. 46 (37): 7075–7078. doi:10.1002/anie.200702131. PMID 17691089.
  9. ^ 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. S2CID 93420685.
  10. ^ 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. ISBN 978-0471936237.
  11. ^ "Guilty plea in N.S. drug lab death".
  12. ^ "N.S. probe into pharma worker's death finds vent hoods turned off in lab | SaltWire". www.saltwire.com. Retrieved 2022-05-03.
  13. ^ "OSHA accident report regarding a trimethylsilyldiazomethane fatality". osha.gov/. Retrieved 10 April 2020.
  14. ^ 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. S2CID 218859698.
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