What Is Tetrahydropyran?
Tetrahydropyran is a clear, colorless liquid and a cyclic ether.
Its IUPAC name is oxane, known also as THP, oxacyclohexane, 1-oxacyclohexane, and 1,5-epoxypentane, or pentamethylene oxide.
Uses of Tetrahydropyran
1. Protecting Group
Tetrahydropyran serves as a protective group for alcohols in organic synthesis, converted to tetrahydropyranyl ether under acidic conditions by the action of 2,3-dihydropyran.
The typical procedure involves reacting alcohol with dihydropyran in the presence of p-toluenesulfonic acid in a dichloromethane solvent, with deprotection achieved through acid hydrolysis. When water is unsuitable, alcohol can be used instead.
The 2-tetrahydropyranyl group, stable against bases, nucleophiles, and reducing agents, has drawbacks such as chiral center formation at the 2-position, complicating NMR analysis, and potential diastereomer generation complicating reaction systems.
2. Solvent Applications
As a solvent, tetrahydropyran resists acidic, basic, and reducing conditions, making it suitable for reactions, extractions, and crystallizations. Its resistance under strongly basic conditions surpasses that of tetrahydrofuran, lending to its use in pharmaceutical and agrochemical productions.
Properties of Tetrahydropyran
Chemical formula: C5H10O, molecular weight: 86.13, CAS number: 142-68-7. Liquid at room temperature, melting point: -45 °C, boiling point: 88 °C, density: 0.880 g/ml at 20 °C. It exhibits a volatile, ethereal pungent odor, soluble in many organic solvents and water.
Other Information on Tetrahydropyran
1. Synthesis Methods
Produced by hydrogenating 2,3-dihydropyran with a Raney alloy catalyst or by cyclization and dehydration of 1,5-pentanediol under acidic conditions.
2. Legal and Regulatory Information
Regulated under various laws as a hazardous material and inflammable substance.
3. Handling and Storage Precautions
Use personal protective equipment in ventilated areas, avoid contact with strong oxidizers, and take care to prevent peroxide formation. Highly flammable; store in a cool, well-ventilated place away from ignition sources. In case of fire, use appropriate extinguishing methods. Wear protective clothing to prevent skin and eye exposure, and seek medical advice if irritation occurs.