3,4-dihydro-2 H -pyran-2-carboxaldehyde
| Structural formula | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
||||||||||||||||
| General | ||||||||||||||||
| Surname | 3,4-dihydro-2 H -pyran-2-carboxaldehyde | |||||||||||||||
| other names |
|
|||||||||||||||
| Molecular formula | C 8 H 8 O 2 | |||||||||||||||
| Brief description |
clear, colorless, pungent smelling liquid |
|||||||||||||||
| External identifiers / databases | ||||||||||||||||
|
||||||||||||||||
| properties | ||||||||||||||||
| Molar mass | 112.13 g mol −1 | |||||||||||||||
| Physical state |
liquid |
|||||||||||||||
| density |
1.08 g cm −3 at 25 ° C |
|||||||||||||||
| boiling point | ||||||||||||||||
| solubility |
water-soluble, miscible with diethyl ether , acetone , tetrahydrofuran , 1,4-dioxane and dichloromethane , slightly soluble in benzene |
|||||||||||||||
| Refractive index |
1.466 (20 ° C) |
|||||||||||||||
| safety instructions | ||||||||||||||||
|
||||||||||||||||
| Toxicological data | ||||||||||||||||
| 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 | ||||||||||||||||
3,4-dihydro-2 H -pyran-2-carboxaldehyde , often referred to as acrolein dimer is formed during the thermal dimerization of acrolein to obtain 2-propenal in a Diels-Alder reaction at the same time as a diene and dienophile functions. At high temperatures (> 400 ° C) the dimer is split back into acrolein.
Manufacturing
Acrolein 1 reacts under pressure and elevated temperature in the presence of polymerization inhibitors, such as. B. Hydroquinone , with itself in a [4 + 2] cycloaddition to the cyclic dimer (2-formyl-3,4-dihydro-2 H -pyran) 2 .
The dimerization of acrolein can also be achieved by microwave irradiation with a yield of 91% of theory. be brought about within 5 minutes.
Reaction mechanism
The mechanism is illustrated here using the product 2-formyl-3,4-dihydro-2 H -pyran 2 . Acrolein reacts with itself under pressure and elevated temperature via a six-membered transition state to product 2. In theory, 1 can react to the structurally isomeric product 3-formyl-3,4-dihydro-2 H -pyran, but only 2 is formed .
The lower activation energy of the reaction to 2 is due to the larger contribution to the mixture of the highest occupied molecular orbital HOMO of acrolein as a diene component with the lowest unoccupied molecular orbital LUMO of acrolein as a dienophile in this orientation.
properties
Acrolein dimer is a clear and colorless liquid with an unpleasantly pungent smell that is miscible with water and polar organic solvents, but not miscible with non-polar solvents such as benzene . Acrolein dimer tends to polymerize spontaneously with the formation of a polyacetal that can be thermally cleaved back into the dimer. The addition of a radical scavenger such. B. Hydroquinone suppresses the autoxidation , but not the spontaneous polymerization. Acrolein can be polymerized cationically with boron trifluoride diethyl etherate , anionically with phenylmagnesium bromide and radically by γ radiation .
Applications
2-Formyl-3,4-dihydro-2 H -pyran is the starting compound for 1,2,6-hexanetriol , which is used as a polyol in many applications instead of the less stable and more viscous glycerine .
The dimer can serve as a stable storage form for acrolein. The biocidally active acrolein produced by thermal cleavage was used as a fumigant for plant pests such. B. Nematode contaminated soils considered.
The patent literature describes the preparation of racemic DL - glutamic acid from acrolein dimer via the reaction sequence ozonation , oxidative cleavage of the ozonation product, reaction with ammonia to form ammonium pyrrolidone carboxylate, its hydrolysis and subsequent work-up. The complex synthesis and modest yield (33.5% of theory) of pure, but racemic glutamic acid make this synthesis uninteresting.
When fully hydrogenated on an activated nickel contact, 2-formyl-3,4-dihydro-2 H -pyran provides the heterocyclic alcohol 2-hydroxymethyl-tetrahydropyran in virtually quantitative yield, which is used as a solvent and starting compound for esters with plasticizer properties.
In the catalytic dehydrogenation of acrolein dimer on metal oxides, such as. B. nickel (II) oxide and temperatures above 200 ° C is formed with ring contraction of cyclopentanone at 70% conversion in 80% yield.
The synthesis of the pheromone brevicomin proceeds, starting from 2-formyl-3,4-dihydro-2 H -pyran, in a one-pot reaction in 69% overall yield to the target product as a 4: 1 mixture of the endo / exo isomers.
The literature mentions the use of acrolein dimer for textile finishing, paper treatment, the production of rubber chemicals, active pharmaceutical ingredients, plasticizers and synthetic resins.
Individual evidence
- ↑ a b Datasheet: Acrolein Dimer, stabilized , from Cameo Chemicals , accessed on September 11, 2014.
- ↑ a b c d data sheet 3,4-Dihydro-2H-pyran-2-carboxaldehyde 97% from Sigma-Aldrich , accessed on September 11, 2014 ( PDF ).
- ↑ a b c d e f Potnis, VS, Shohara, K., Schulz, RC and Kern, W .: Studies on the polymerization of 2-formyl-Δ5-dihydropyran . In: Makromol. Chem. Band 63 , 1963, pp. 77-88 , doi : 10.1002 / macp.1963.020630106 ( PDF ).
- ↑ a b fluorochem: data sheet 3,4-Dihydro-2H-pyran-2-carbaldehyde , accessed on December 27, 2019.
- ↑ a b N.N .: Acrolein Dimerization ( Memento of the original from September 4, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ a b Patent US5866614 : Methods for fumigating soil using acrolein. Published February 2, 1999 , Applicant: BetzDearborn Inc., Inventor: EJ Bockowski, DP Davis.
- ↑ Alder K., Rüden E .: On the knowledge of the polymerization processes, X. Communication: About the dimeric acrolein . In: Ber. dtsch. Chem. Ges. A / B . tape 74 , 1941, pp. 920-926 , doi : 10.1002 / cber.19410740610 .
- ↑ Patent US3159651 : Acrolein dimer production. Published December 1, 1964 , Applicant: Shell Oil Co., Inventor: GF Johnson, LC Teague.
- ↑ Patent US6187963 : Processes for the manufacture of acrolein derivatives. Published February 13, 2001 , Applicant: Union Carbide Chemicals & Plastics Technology Corp., Inventor: WG Etzkorn, RA Galley, TE Snead, JL Brockwell, MA Young, JM Maher, BK Warren.
- ↑ H.-P. Hsieh, S.-T. Chen, K.-T. Wang: Microwave Induced Synthesis of 3,4-Dihydro-2H-pyran-2-carboxaldehyde: A Versatile Linker for Solid Phase Combinatorial Library . In: J. Chinese Chem. Soc. tape 44 , 1997, pp. 597-600 , doi : 10.1002 / jccs.199700092 .
- ↑ Patent US2897209 : Synthesis of glutamic acid. Published July 28, 1959 , Applicant: International Minerals & Chemical Corp., Inventor: R. Kodras.
- ↑ Patent US3187012 : Process for preparing 2-hydroxymethyl-tetrahydrpyran. Published June 1, 1965 , Applicant: The Quaker Oats Co., Inventor: AP Dunlop, DG Maaly.
- ↑ Patent US3812190 : Conversion of acrolein dimer to cyclopentanone. Published May 21, 1974 , Applicant: Monsanto Co., Inventor: JP Petrovich, DA Tyssee.
- ↑ Patent US4609743 : Method for brevicomin synthesis and use in beetle control. Published September 2, 1986 , Applicant: University of Pittsburgh, Inventor: T. Cohen, M. Bhupathy.
- ↑ T. Cohen, M. Bhupathy: A one-flask, high-yield, stereoselective synthesis of racemic endo-brevicomin . In: Tetrahedron Lett. tape 34 , 1983, pp. 4163-4164 , doi : 10.1016 / S0040-4039 (00) 88288-X .
- ↑ entry to exo Brevicomin in the ChemSpider database of the Royal Society of Chemistry , accessed on 2014-09-11.
- ↑ Lawrence Fishbein: Chemical Mutagens Environmental Effects on Biological Systems . Elsevier Science, 2012, ISBN 0-323-15325-9 , pp. 378 .
