Dihydropyran

• 3,4-dihydro -2H-pyran (IUPAC - Name )
• 2,3-dihydro- 4H-pyran
• 2,3-dihydro- γ -pyran
• Δ2 - dihydropyran
• Dihydropyran
• DHP

Yellowish, flammable foul-smelling fluid

Liquid

0.93 g · cm -3

-70 ° C

89 ° C

• Poorly in water (20 g · l-1 at 20 ° C)
• Soluble in ethanol

1,440

Risk

> 4000 mg · kg -1 ( LD50, rat, oral)

Template: Infobox chemical / molecular formula search available

3,4-dihydro -2H-pyran ( or short- dihydropyran ) is a heterocyclic, oxygen-containing chemical compound is selected from the group of the cyclic enol ether.

Production and representation

Dihydropyran can be obtained by dehydration of tetrahydrofurfuryl alcohol over alumina at 300-400 ° C.

Properties

Physical Properties

Chemically, it is an enol ether, that is, the ether oxygen is attached directly to a carbon- carbon double bond. Enol ethers M- effect of oxygen are due to the electron-rich unsaturated compounds which can easily with electrophiles, such as protons (H ) react.

Chemical Properties

In organic synthesis the 2- tetrahydropyranyl group is used as a protecting group for alcohols and thiols. The reaction of an alcohol with dihydropyran leads to the formation of a base-stable tetrahydropyranyl or a cyclic acetal, whereby the alcohol is protected from a variety of undesirable side reactions. The alcohol can then be easily released by acid hydrolysis again. As a byproduct 5 - hydroxypentanal.

Safety characteristics

The compound forms flammable vapor - air mixtures. The flash point is -9 ° C. The explosion range is between 1.1 vol% as the lower explosive limit ( LEL) and 13.8 vol% as the upper explosive limit ( UEL). The ignition temperature is 240 ° C. The substance falls within the temperature class T3.

Use

Dihydropyran is an intermediate for the production of pesticides and pharmaceuticals. It also serves the formation of a protective group for various functional groups ( eg, alcohol, sulfhydryl, amines, and amides ) in organic synthesis.

Safety

Dihydropyran is highly flammable, volatile and forms with air when exposed to light explosive peroxides.