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238902 Sigma-Aldrich

2-(Trimethylsilyl)ethoxymethyl chloride

technical grade

Synonym: (2-Chloromethoxyethyl)trimethylsilane, Chloromethyl 2-trimethylsilylethyl ether, SEM-Cl, SEM-chloride

  • CAS Number 76513-69-4

  • Linear Formula (CH3)3SiCH2CH2OCH2Cl

  • Molecular Weight 166.72

  •  Beilstein/REAXYS Number 3587289

  •  EC Number 278-483-4

  •  MDL number MFCD00009919

  •  PubChem Substance ID 24854351



Related Categories Chemical Synthesis, Protecting and Derivatizing Reagents, Protection and Derivatization, Silicon-Based, Synthetic Reagents More...
grade   technical grade
contains   10 ppm diisopropylethylamine as stabilizer
refractive index   n20/D 1.435 (lit.)
bp   170-172 °C(lit.)
  57-59 °C/8 mmHg(lit.)
density   0.942 g/mL at 25 °C (lit.)
storage temp.   2-8°C


General description

Learn More at the Professor and Product Portal of Professor Bruce Lipshutz.


1, 5, 25, 100 g in glass bottle


Phenol protecting group in the synthesis of laterifluorones.

Used to prepare a SEM-ether which was, in turn, removed with BBr3 and cyclized to a benzo-oxapane.

Features and Benefits

Convenient hydroxyl-protecting reagent. SEM-ethers are stable over a wide pH range, and can be selectively cleaved with fluoride ion under mild aprotic conditions.

Safety & Documentation

Safety Information

Signal word 
Hazard statements 
Precautionary statements 
UN 2920 3(8) / PGII
WGK Germany 
Flash Point(F) 
114.8 °F
Flash Point(C) 
46 °C

Frequently Asked Questions

Which document(s) contains shelf-life or expiration date information for a given product?
If available for a given product, the recommended re-test date or the expiration date can be found on the Certificate of Analysis.
How do I get lot-specific information or a Certificate of Analysis?
The lot specific COA document can be found by entering the lot number above under the "Documents" section.
Why is Product 238902 2-(Trimethylsilyl)ethoxymethyl chloride, such a popular hydroxyl protecting agent?
2-(Trimethylsilyl)ethoxymethyl chloride is widely used in the protection of alcohols because the SEM ethers are easily prepared. They are stable to a number of synthetic transformations, and they are easily removed.
What are the advantaged of using Product 238902,2-(Trimethylsilyl)ethoxymethyl chloride, in carbohydrate chemistry?
In carbohydrate chemistry, the SEM group has shown distinct advantages over other groups such as the 2-methoxyethoxymethyl (MEM) group, because the SEM group is removed under milder acidic conditions.
Are SEM protected carboxylic acids like Product 238902 stable enough for chromatography?
SEM protected carboxylic acids are stable enough for chromatography but are readily deprotected without affecting either acid of base-sensitive functionalities.
How is the SEM group, Product 238902, 2-(Trimethylsilyl)ethoxymethyl chloride,used in the protection of nitrogen atoms in heterocyclic compounds?
In SEM protected indole, the aminal oxygen is used to direct lithiation to the 2-position. A similar approach has been used for pyrroles and imidazoles.
How do I find price and availability?
There are several ways to find pricing and availability for our products.Once you log onto our website, you will find the price and availability displayed on the product detail page.You can contact any of our Customer Sales and Service offices to receive a quote. USA customers: 1-800-325-3010 orview local office numbers.
What is the Department of Transportation shipping information for this product?
Transportation information can be found in Section 14 of the product's (M)SDS.To access the shipping information for this material, use the link on the product detail page for the product.
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Protocols & Articles


Activating Reagents and Protecting Groups

The use of activating agents and protecting groups in organic synthesis is necessary to prevent unwanted side reactions from occurring when using other common reagents such as oxidizing or reducing a...
Chemfiles Volume 1 Article 3
Keywords: Organic synthesis

Lipshutz Group – Products available at Aldrich from the Lipshutz Laboratory

From our library of Articles, Sigma-Aldrich presents Lipshutz Group – Products available at Aldrich from the Lipshutz Laboratory
Keywords: Addition reactions, Catalysis, Cross couplings, Environmental, Green chemistry, Ligands, Metathesis, Nucleophilic aromatic substitution, Olefin metathesis, Organic synthesis, Solvents, Substitutions

Peer-Reviewed Papers


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