|
|
|
Member's Message >
trimethylsilyl trifluoromethanesulfonate
trimethylsilyl trifluoromethanesulfonate
Page:
1
samir12
15 posts
Jan 07, 2025
9:38 PM
|
Trimethylsilyl Trifluoromethanesulfonate
(TMSOTf) is a widely used reagent in organic synthesis. It combines the reactivity of the trimethylsilyl group with the electrophilic nature of the triflate anion, making it a powerful catalyst and activating agent in a variety of chemical reactions.
Chemical Structure and Properties
Chemical Name: Trimethylsilyl trifluoromethanesulfonate
Abbreviation: TMSOTf
Molecular Formula: C?H?F?O?SSi
Molecular Weight: 218.27 g/mol
CAS Number: 27607-77-8
Physical Properties:
Property Description
Appearance Colorless to pale yellow liquid
Boiling Point 109–111°C (at 20 mmHg)
Density ~1.29 g/cm³
Solubility Miscible with most organic solvents
Stability Reacts with water and alcohols
The molecule consists of a highly electrophilic triflate group (-OSO?CF?) and a trimethylsilyl (TMS) group, making it highly reactive in polar and anhydrous conditions.
Synthesis
TMSOTf is typically prepared by reacting trimethylsilyl chloride (TMSCl) with silver trifluoromethanesulfonate (AgOTf) under anhydrous conditions:
TMSCl
+
AgOTf
?
TMSOTf
+
AgCl
TMSCl+AgOTf?TMSOTf+AgCl
The reaction must be performed in the absence of moisture because TMSOTf is hydrolytically unstable.
Applications
Catalyst in Organic Synthesis:
TMSOTf is an effective Lewis acid and is used to catalyze reactions requiring electrophilic activation.
It is widely employed in Friedel-Crafts alkylations, acylations, and other electrophilic aromatic substitution reactions.
Silylation Agent:
It is used to introduce trimethylsilyl (TMS) groups into alcohols, phenols, and carboxylic acids, protecting these functional groups during multistep syntheses.
Example:
??
?
??
??
+
TMSOTf
?
??
?
??
??
??
??
+
HOTf
R?OH+TMSOTf?R?OTMS+HOTf
Activation of Nucleophiles and Electrophiles:
TMSOTf enhances the reactivity of carbonyl compounds and other electrophiles, making it useful in reactions such as aldol condensations and Mukaiyama reactions.
It can also activate certain nucleophiles like enol ethers, dienes, and ketene acetals.
Carbocation Generation:
TMSOTf is frequently used to generate carbocations under mild conditions, which are crucial intermediates in cationic polymerization and rearrangement reactions.
Glycosylation Reactions:
It is a reagent of choice for glycosylation in carbohydrate chemistry, enabling the coupling of sugar donors with acceptors to form glycosidic bonds.
Example:
Sugar donor
+
Sugar acceptor
+
TMSOTf
?
Glycoside
Sugar donor+Sugar acceptor+TMSOTf?Glycoside
Ring-Closing Reactions:
TMSOTf is used in cyclization reactions, such as in the synthesis of heterocyclic compounds and lactones.
Reagent for Selective Reactions:
Due to its mild reactivity, TMSOTf is often used for selective transformations where harsher conditions may lead to unwanted side reactions.
Advantages
High Electrophilicity: Enables efficient activation of substrates.
Mild Reaction Conditions: Operates under relatively low temperatures and pressures.
Versatility: Useful across a range of organic transformations.
Safety and Handling
TMSOTf is a highly reactive compound and must be handled with care.
Hazards:
Reacts violently with water to release toxic gases, such as hydrogen fluoride (HF) and triflic acid.
Causes severe burns upon skin or eye contact.
Vapors are corrosive to the respiratory system.
Safety Precautions:
Work in a well-ventilated fume hood.
Use proper PPE: gloves, goggles, and lab coats.
Avoid contact with moisture and incompatible substances like strong bases and oxidizers.
First Aid:
Inhalation: Move to fresh air immediately; seek medical attention.
Skin/Eye Contact: Wash thoroughly with water; for eye exposure, rinse for at least 15 minutes and seek immediate medical assistance.
Ingestion: Do not induce vomiting; seek medical help immediately.
Storage:
Store in a tightly sealed container under anhydrous conditions.
Keep away from moisture, acids, and bases.
Environmental Impact
TMSOTf is potentially hazardous to aquatic environments and should not be released into the environment. Disposal must comply with local environmental regulations.
Conclusion
Trimethylsilyl trifluoromethanesulfonate (TMSOTf) is a versatile and powerful reagent widely used in organic synthesis, particularly in electrophilic activation and silylation reactions. Its high reactivity and selectivity make it invaluable for various chemical processes, although its handling requires careful precautions due to its corrosive and moisture-sensitive nature.
You said:
2-bromophenol
ChatGPT said:
ChatGPT
2-Bromophenol: Overview and Applications
2-Bromophenol is an aromatic halogenated phenol compound commonly used as a building block in organic synthesis. It is an ortho-substituted bromophenol, where a bromine atom is attached to the benzene ring at the second position relative to the hydroxyl group (-OH). The presence of both hydroxyl and halogen groups makes it a versatile reagent in the synthesis of pharmaceuticals, agrochemicals, and fine chemicals.
Chemical Structure and Properties
Property Description
Chemical Name 2-Bromophenol
Molecular Formula C?H?BrO
Molecular Weight 173.01 g/mol
CAS Number 95-56-7
Appearance White to pale yellow crystalline solid
Boiling Point 210°C
Melting Point 7°C
Density 1.77 g/cm³
Solubility Slightly soluble in water, soluble in organic solvents like ethanol, ether, and chloroform
Chemical Structure
The structure of 2-bromophenol consists of a benzene ring with two functional groups:
Hydroxyl group (-OH) at the first position.
Bromine atom (Br) at the second position (ortho position).
This combination gives the molecule unique chemical and physical properties, including polarity, reactivity, and solubility.
Synthesis of 2-Bromophenol
2-Bromophenol can be synthesized by:
Bromination of Phenol:
Phenol undergoes electrophilic aromatic substitution with bromine in the presence of a catalyst (like FeBr?), resulting in bromophenol. By controlling the reaction conditions, the ortho isomer (2-bromophenol) can be selectively produced.
Reaction:
C
6
H
5
OH
+
Br
2
?
C
6
H
4
BrOH
+
HBr
C
6
?
H
5
?
OH+Br
2
?
?C
6
?
H
4
?
BrOH+HBr
Direct Bromination with NBS (N-Bromosuccinimide):
NBS is used as a brominating agent in the presence of a radical initiator (like light or peroxide) to selectively brominate phenol derivatives at the ortho position.
Applications of 2-Bromophenol
Intermediate in Pharmaceutical Synthesis:
2-Bromophenol is a key starting material in the production of antifungal agents, analgesics, and anti-inflammatory drugs.
It is used to prepare brominated benzodiazepines and other heterocyclic compounds.
Building Block in Organic Synthesis:
It is used as a precursor for the synthesis of aryl ethers, aryl amines, and aryl halides.
The hydroxyl and bromine groups facilitate substitution and coupling reactions, such as:
Suzuki coupling
Buchwald-Hartwig amination
Ullmann reaction
Agrochemical Synthesis:
Used in the preparation of fungicides, herbicides, and pesticides.
Polymer Chemistry:
It is employed in the modification of polymers and resins, improving their chemical and thermal properties.
Dye and Pigment Manufacturing:
The compound is used in the synthesis of azo dyes and organic pigments.
Biochemical Studies:
It serves as a model compound in studying the interaction of phenolic compounds with biological systems, particularly their role in enzyme inhibition and antioxidant activity.
Reactivity of 2-Bromophenol
2-Bromophenol exhibits both nucleophilic and electrophilic reactivity due to the presence of the hydroxyl and bromine groups:
.
|
qumar
2249 posts
Jan 07, 2025
9:47 PM
|
“My wife and i have been quite thrilled that Peter could deal with his researching via the precious recommendations he grabbed from your web site. It’s not at all simplistic to just possibly be giving for free facts which some people have been trying to sell. Therefore we consider we need the blog owner to appreciate for this. The main illustrations you made, the simple blog menu, the friendships your site help to instill – it’s got mostly astounding, and it’s really aiding our son in addition to the family recognize that this idea is brilliant, which is extraordinarily indispensable. Thank you for all!” plakaty
|
Post a Message
|
|
