Tetrahydropyran
| Structural formula | |||||||||||||||||||
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| two different ways of presenting tetrahydropyran | |||||||||||||||||||
| General | |||||||||||||||||||
| Surname | Tetrahydropyran | ||||||||||||||||||
| other names |
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| Molecular formula | C 5 H 10 O | ||||||||||||||||||
| Brief description |
colorless, hygroscopic liquid |
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| properties | |||||||||||||||||||
| Molar mass | 86.13 g mol −1 | ||||||||||||||||||
| Physical state |
liquid |
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| density |
0.88 g cm −3 |
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| Melting point |
−49.2 ° C |
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| boiling point |
88 ° C |
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| Vapor pressure |
95.3 hPa (25 ° C) |
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| solubility |
moderate in water (80 g l −1 at 20 ° C) |
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| Refractive index |
1.421 |
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| safety instructions | |||||||||||||||||||
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| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C | |||||||||||||||||||
Tetrahydropyran is a heterocyclic , oxygen-containing , chemical compound from the group of cyclic ethers . It is a colorless, hygroscopic liquid. It is highly flammable and forms explosive peroxides in the presence of air . That is why it is usually provided with stabilizer additives.
Occurrence
The tetrahydropyran ring quite often forms the basic structure in natural products. It occurs in carbohydrates such as cane sugar , grape sugar and galactose and is called the pyranose form there . The very complex natural product maitotoxin , a strong toxin produced by marine algae, contains 28 tetrahydropyran rings in its molecular structure.
Extraction and presentation
A standard method for the synthesis of tetrahydropyran is the hydrogenation of dihydropyran with Raney nickel as a catalyst .
properties
Its vapors are three times as heavy as air. The tetrahydropyran ring does not form a planar structure in space , but mostly an armchair shape . According to Antoine, the vapor pressure function results from log 10 (P) = A− (B / (T + C)) (P in kPa, T in ° C) with A = 5.85520, B = 1131.93 and C = 205 , 83.
The compound shows an azeotrope boiling at 75 ° C. with a water content of 39.5 mol% . The miscibility with water is limited. With increasing temperature, the solubility of tetrahydropyran in water decreases and the solubility of water in tetrahydropyran increases.
Solubilities between tetrahydropyran and water temperature ° C 0 9.4 19.9 31.0 39.6 50.5 60.7 71.3 81.3 Tetrahydropyran in water in% 12.90 10.03 8.57 6.88 6.04 5.16 4.62 4.50 4.29 Water in tetrahydropyran in% 2.08 2.35 2.50 2.63 2.99 3.20 3.64 3.98 4.21
use
Tetrahydropyran is occasionally used as a solvent in Grignard reactions . It also forms the basis for many derived compounds (e.g. tetrahydropyran-2,6-dione and tetrahydropyran-2,4-diols).
As a protecting group
In organic syntheses , the 2-tetrahydropyranyl group is used as a protective group for alcohols and thiols. For this purpose, the substrate is reacted with dihydropyran to form the base-stable tetrahydropyranyl ether .
safety instructions
When tetrahydropyran comes into contact with air, peroxides and explosive vapors are formed.
See also
- Tetrahydrofuran (THF)
- Pyrans
literature
- Paul A. Clarke, Soraia Santos: Strategies for the Formation of Tetrahydropyran Rings in the Synthesis of Natural Products. In: European Journal of Organic Chemistry. 2006, p. 2045, doi: 10.1002 / ejoc.200500964 .
- Voigt, Tobias: Prins Cyclization on a Solid Phase - Combinatorial Synthesis of a Tetrahydropyran Library. Dissertation , University of Dortmund, 2006.
Web links
Individual evidence
- ↑ a b c d e f g h Entry on tetrahydropyran in the GESTIS substance database of the IFA , accessed on January 8, 2020(JavaScript required) .
- ↑ CRC Handbook of Tables for Organic Compound Identification , Third Edition, 1984, ISBN 0-8493-0303-6 .
- ↑ Hubert Koebernick: Presentation and conformational analysis of 2.4-diamino-pyranoses . 1975, OCLC 74320162 , pp. 18 ( limited preview in Google Book search).
- ↑ S. Rodríguez, H. Artigas, C. Lafuente, AM Mainar, FM Royo: Isobaric vapor – liquid equilibrium of binary mixtures of some cyclic ethers with chlorocyclohexane at 40.0 and 101.3 kPa , in: Thermochim. Acta , 2000 , 362 , pp. 153-160 ( doi: 10.1016 / S0040-6031 (00) 00580-3 ).
- ↑ J. Gmehling, J. Menke, J. Krafczyk, K. Fischer: Azeotropic Data , VCH, Weinheim 1994, ISBN 3-527-28671-3 , p. 936.
- ^ A b R. M. Stephenson: Mutual Solubilities: Water-Ketones, Water-Ethers, and Water-Gasoline-Alcohols in J. Chem. Eng. Data 37 (1992) 80-95, doi: 10.1021 / je00005a024 .