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Product Code: SIT8510.0

Cas No: 75-77-4

3 kg
750 g
25 g
Trimethylsilyl Blocking Agent

Used as a protecting group for reactive hydrogens in alcohols, amines, thiols, and carboxylic acids. Organosilanes are hydrogen-like, can be introduced in high yield, and can be removed under selective conditions. They are stable over a wide range of reaction conditions and can be removed in the presence of other functional groups, including other protecting groups. The tolerance of silylated alcohols to chemical transformations summary is presented in Table 1 of the Silicon-Based Blocking Agents brochure.

Alkyl Silane - Conventional Surface Bonding

Aliphatic, fluorinated aliphatic or substituted aromatic hydrocarbon substituents are the hydrophobic entities which enable silanes to induce surface hydrophobicity. The organic substitution of the silane must be non-polar. The hydrophobic effect of the organic substitution can be related to the free energy of transfer of hydrocarbon molecules from an aqueous phase to a homogeneous hydrocarbon phase. A successful hydrophobic coating must eliminate or mitigate hydrogen bonding and shield polar surfaces from interaction with water by creating a non-polar interphase. Although silane and silicone derived coatings are in general the most hydrophobic, they maintain a high degree of permeability to water vapor. This allows coatings to breathe and reduce deterioration at the coating interface associated with entrapped water. Since ions are not transported through non-polar silane and silicone coatings, they offer protection to composite structures ranging from pigmented coatings to rebar reinforced concrete. A selection guide for hydrophobic silanes can be found on pages 22-31 of the Hydrophobicity, Hydrophilicity and Silane Surface Modification brochure.

Trimethylchorosilane; Chlorotrimethylsilane; Trimethylsilyl chloride; TMCS
  • Viscosity: 0.47 cSt
  • ΔHcomb: -2,989 kJ/mol
  • ΔHform: -354 kJ/mol
  • ΔHvap: 27.6 kJ/mol
  • Dipole moment: 2.09 debye
  • Surface tension: 17.8 mN/m
  • Specific heat: 1.76 J/g/°C
  • Coefficient of thermal expansion: 1.2 x 10-3
  • Vapor pressure, 20 °: 190 mm
  • Vapor pressure, 50 °C: 591 mm
  • Critical temperature: 224.6 °C
  • Critical pressure: 31.6 atm
  • Most economical and broadly used silylation reagent
  • Enhances Claisen rearrangement
  • Enhances the deprotection of tBOC-protected amino acids
  • Enhances ethylene glycol ketalization reaction
  • Catalyzes the formation of chlorohydrin esters from diols
  • Reviewed as water scavenger in reactions of carbonyl compounds
  • Facilitates Michael additions
  • Reacts in presence of HCl acceptor
  • Will silylate strong acids with expulsion of HCl
  • High purity grade available, SIT8510.1
  • Protects hindered alcohols with Mg/DMF
  • Nafion SAC-13 has been shown to be a recyclable catalyst for the trimethylsilylation of primary, secondary, and tertiary alcohols in excellent yields and short reaction times
  • Summary of selective deprotection conditions is provided in Table 7 through Table 20 of the Silicon-Based Blocking Agents brochure
  • EINECS Number: 200-900-5

    Alternative Name: TMCS

    Specific Gravity: 0.8580

    Flashpoint: -27°C (-17°F)

    HMIS Key: 3-4-2-X

    Hydrolytic Sensitivity: 8: reacts rapidly with moisture, water, protic solvents

    Formula: C3H9ClSi


    Refractive Index: 1.3885

    Application: Review of synthetic utility.1
    Review on organosilane protecting groups.2
    Enhances Claisen rearrangement.3
    Enhances the deprotection of tBOC-protected amino acids.4
    Enhances ethylene glycol ketalization reaction.5
    Catalyzes the formation of chlorohydrin esters from diols.6
    Reviewed as water scavenger in reactions of carbonyl compounds.7
    Facilitates Michael additions.8

    Reference: 1. Handbook of Reagents for Organic Synthesis, Reagents for Silicon-Mediated Organic Synthesis, Fuchs, P. L. Ed., John Wiley and Sons, Ltd., 2011, p. 170-182.
    2. Larson, G. L. “Silicon-Based Blocking Agents” Gelest, Inc. 2014.
    3. Snider, B. B.; Hawryluk, N. A. Org. Synth. 2000, 2, 635.
    4. Chen, B. C. et al. J. Org. Chem. 1999, 64, 9294.
    5. Chan, T. H. et al. Synthesis 1983, 203.
    6. Eras, J. et al. J. Org. Chem. 2002, I, 8631.
    7. Volochnuk, D. M. et al. Synthesis 2009, 3719.
    8. Xu, L. W. et al. Chem. Commun. 2003, 2570.

    Fieser: F&F: Vol. 1, p 1232; Vol. 2, p 435; Vol.3, p 310; Vol. 4, p 32, p 537; Vol.5, p 709; Vol. 6, p 25; Vol. 7, p 66; Vol. 8, p 107; Vol. 9, p 112; Vol. 10, p 96; Vol. 11, p 125; Vol. 12, p 126; Vol. 13, p 165; Vol. 14, p 175; Vol. 15, p 89; Vol. 16, p 85; Vol. 17, p 79; Vol. 19, p 374; Vol. 20, p 348, p 380, p 404; Vol.21, p 453.

    Additional Properties: 395
    Dipole moment: 2.09 debye
    Surface tension: 17.8 mN/m
    ?Hcomb: -714 kcal/mole
    ?Hform: -84.5 kcal/mole
    31.6 atm
    ?Hvap: 6.6 kcal/mole
    Specific heat: 0.42 cal/g/°
    Coefficient of thermal expansion: 1.2 x 10-3
    Most economical and broadly used silylation reagent
    Vapor pressure, 50°: 591 mm