| 词条 | 2-Ethyl-2-oxazoline |
| 释义 |
| ImageFile = 2-Ethyl-2-oxazoline structure01.svg | ImageSize = 150px | ImageAlt = | IUPACName = 2-Ethyl-4,5-dihydro-1,3-oxazole | OtherNames = 2-Ethyloxazoline | Section1 = {{Chembox Identifiers | CASNo = 10431-98-8 | PubChem = 66412 | SMILES = CCC1=NCCO1 | ChemSpiderID = 59786 | StdInChI = 1S/C5H9NO/c1-2-5-6-3-4-7-5/h2-4H2,1H3 | StdInChIKey = NYEZZYQZRQDLEH-UHFFFAOYSA-N | Section2 = {{Chembox Properties | C=5|H=9|N=1|O=1 | Appearance = | Density = 0.982 g/mL[1] | MeltingPtC = −62 | MeltingPt_ref = [1] | BoilingPtC = 128.4 | BoilingPt_ref = [1] | Solubility = | Section3 = {{Chembox Hazards | MainHazards = | FlashPt = | AutoignitionPt = }}2-Ethyl-2-oxazoline (EtOx) is an oxazoline which is used particularly as a monomer for the cationic ring-opening polymerization to poly(2-alkyloxazoline)s.[2] This type of polymers are under investigation as readily water-soluble and biocompatible materials for biomedical applications.[3] ProductionFrom propionic acid and derivativesCarboxylic acids, carboxylic esters, carboxylic amides and nitriles can react with 2-amino alcohols at 200 °C upon dehydration to the corresponding N-(2-hydroxy)carbamide, which react further at 260–280 °C upon dehydration to the 2-alkyl-2-oxazoline. For example N-(2-hydroxyethyl)propionamide is first formed from propionic acid and ethanolamine in 74% yield which can be dehydrated to give 2-ethyl-2-oxazoline in about 75% yield.[4] Less drastic reaction conditions require the dehydration of the N-(2-hydroxyethyl)propionamide in vacuo in the presence of iron(III)chloride, which delivers the product in 90% yield.[5] An even higher yield of 96.2% is obtained by heating with zinc acetate.[6] An economic one-pot reaction is heating the salt of propionic acid with ethanolamine at 200 °C in vacuo in the presence of zinc chloride yielding 82% 2-ethyl-2-oxazoline.[6] From the water-containing distillate pure 2-ethyl-2-oxazoline can be isolated by extraction with diethylbenzene and subsequent distillation[6] or by distillation only after addition of diethyl phosphite or dimethyldichlorosilane. The product can be dried to a residual water content of 10 ppm.[7] In another one-pot reaction propionic acid is converted first with 2-aminoethanol to 2-hydroxyethylamide, than reacted with boric acid at 130 °C yielding a boric acid ester which is finally thermolyzed at 280 °C in 92% yield to 2-ethyl-2-oxazoline.[8] From propionic acid and thionyl chloride can be obtained propanoyl chloride, which reacts with ethanolamine in the presence of an acid scavenger (for example pyridine) to N-propionyl-2-aminoethanol. With further thionyl chloride this reacts further to 2-chloroethylamide. With the chloride ion as a better leaving group, this intermediate is cyclized by simple heating to the oxazoline. Water must be excluded du to the tendency of oxazolines towards ring-opening by chloride ions during protonation of the imine nitrogen.[9] The direct reaction of propanoyl chloride with 2-chloroethylamine hydrochloride in the presence of triethylamine avoids the formation of water. From propanalPropanal reacts with 2-aminoethanol in t-butanol to 2-ethyl-2-oxazoline in the presence of the iodinating reagent 1,3-diiodo-5,5-dimethylhydantoin (DIH) and potassium carbonate.[10]Properties2-Ethyl-2-oxazoline is a readily water-soluble, colorless liquid which is also soluble in a variety of organic solvents and possesses an amine-like smell.[11] Aqueous solutions react alkaline. The compound is stable in alkaline but hydrolyses under acid action. ApplicationsIn anhydrous form, 2-ethyl-2-oxazoline is mostly used as a monomer.[2] The cationic ring-opening polymerization of 2-ethyl-2-oxazoline[12] can be initiated by alkylation with e.g. methyl tosylate or triflates (in particular methyl triflate) and leads to the water-soluble poly(2-ethyl-2-oxazoline) which is a propionyl-substituted linear polyethylenimine and can also be seen as a pseudo-polypeptide.[13] The polymerization of 2-ethyl-2-oxazoline can also be carried out as living cationic polymerization.[14] Copolymers with other 2-alkyl-2-oxazolines[15] and other monomers[16] allow the preparation of random copolymers and block copolymers. The copolymers obtained can be used as biocompatible drug carriers,[17] in coatings and adhesives, and in many other applications.[18] The elimination of the propionyl group from poly (2-ethyl-2-oxazoline) yields linear polyethyleneimine.[19][20] References1. ^1 2 {{cite web | url = http://www.sigmaaldrich.com/catalog/product/aldrich/137456?lang=en | title = 2-Ethyl-2-oxazoline | publisher = Sigma-Aldrich}} {{DEFAULTSORT:Ethyl-2-oxazoline, 2-}}2. ^1 {{citation|author1=T. Kagiya|author2=S. Narisawa|author3=T. Maeda|author4=K. Fukui|periodical=J. Polym. Chem., Polym. Lett.|title=Ring-opening polymerization of 2-substituted 2-oxazolines|volume=4|issue=7|pages=441–445 |doi=10.1002/pol.1966.110040701}} 3. ^{{citation|author=R. Hoogenboom|periodical=Angew. Chem. Int. Ed.|title=Poly(2-oxazoline)s: A polymer class with numerous potential applications|volume=48|issue=43|pages=7978–7994 |doi=10.1002/anie.200901607}} 4. ^{{citation|author=H. Wenker|periodical=J. Am. Chem. Soc.|title=The synthesis of Δ2-oxazolines and Δ2-thiazolines from N-acyl-2-aminoethanols|volume=57|issue=6|pages=1079–1080 |doi=10.1021/ja01309a034}} 5. ^{{Cite patent|country = US|number =4203900 |Code= |title=Process for preparing 2-oxazolines |V-Datum =1980-5-20 |A-Datum =1977-1-3 |Erfinder =M.E. Kaiser | Anmelder =The Dow Chemical Co. | DB =Google}} 6. ^1 2 {{Cite patent|country = US|number =4354029 |Code= |title=Preparation of 2-substituted 2-oxazolines with organic zinc salt catalysts |V-Datum =1982-10-12 |A-Datum =1981-11-30 |Erfinder =M.E. Kaiser, D.L. Larson | Anmelder =The Dow Chemical Co. | DB =Google}} 7. ^{{Cite patent|country = US|number =4281137 |Code= |title=Purification of 2-oxazolines |V-Datum =1981-7-28 |A-Datum =1980-2-20 |Erfinder =J.W. Sanner, P.W. Owen | Anmelder =The Dow Chemical Co. | DB =Google}} 8. ^{{citation|author1=B. Ilkgul|author2=D. Gunes|author3=O. Sirkecioglu|author4=N. 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Bull.|title=Ring-opening polymerization of 2-ethyl-2-oxazoline|volume=18|issue=3|pages=189–194 |doi=10.1007/BF00255109}} 13. ^{{citation|author1=H. Schlaad|author2=R. Hoogenboom|periodical=Macromol. Chem. Rapid Commun.|title=Poly(2-oxazoline)s and Related Pseudo-Polypeptides|volume=33|issue=19|pages=1599 |doi=10.1002/marc.201200571}} 14. ^{{citation|author1=C. Guerrero-Sanchez|author2=R. Hoogenboom|author3=U.S. Schubert|periodical=Chem. Commun.|title=Fast and “green” living cationic ring opening polymerization of 2-ethyl-2-oxazoline in ionic liquids under microwave irradiation|volume=36|pages=3797–3799 |doi=10.1039/B608364A}} 15. ^{{citation|author1=M. Glassner|author2=K. Lava|author3=V.R. de la Rosa|author4=R. Hoogenboom|periodical=Polym. Chem.|title=Tuning the LCST of poly(2-cyclopropyl-2-oxazoline) via gradient copolymerization with 2-ethyl-2-oxazoline|volume=52|issue=21|pages=3118–3122 |doi=10.1002/pola.27364}} 16. ^{{citation|author1=S. Motokucho|author2=M. Furukawa|author3=M. Kawashima|author4=K. Kojio|author5=K. Yoshinaga|periodical=Polym. J.|title=Physical properties of poly(tetrahydrofuran)-block-poly(2-ethyl-2-oxazoline) triblock copolymer|volume=45|pages=1115–1119 |doi=10.1038/pj.2013.39}} 17. ^{{citation|author=V.R. de la Rosa|periodical=J. Mater. Sci. Mater. Med.|title=Poly(2-oxazoline)s as materials for biomedical applications|volume=25|issue=5|pages=1–15 |doi=10.1007/s10856-013-5034-y}} 18. ^{{cite web|title=Etox, 2-Ethyl-2-Oxazoline, Product Information Sheet|trans-title=|periodical=|publisher=Polymer Chemistry Innovations, Inc.|url=https://www.polychemistry.com/etox/|deadurl=|format=|accessdate=2016-07-19|archiveurl=|archivedate=|last=|date=|year=|month=|day=|language=|pages=|quote=}} 19. ^{{Cite patent|country = US|number =20100197888 |Code=A1 |title=Method for manufacturing linear polyethyleneimine (PEI) for transfection purpose and linear PEI obtained with such method |V-Datum =2010-8-5 |A-Datum =2008-7-31 |Erfinder =A. Adib, F. Stock, P. Erbacher | Anmelder =Polyplus Transfection | DB =Google}} 20. ^{{citation|author1=H.M.L. Lambermont-Thijs|author2=F.S. van der Woerdt|author3=A. Baumgaertel|author4=L. Bonami|author5=F.E. Du Prez|author6=U.S. Schubert|author7=R. Hoogenboom|periodical=Macromolecules|title=Linear Poly(ethylene imine)s by Acidic Hydrolysis of Poly(2-oxazoline)s: Kinetic Screening, Thermal Properties, and Temperature-Induced Solubility Transitions|volume=43|issue=2|pages=927–933 |doi=10.1021/ma9020455}} 2 : Imines|Oxazolines |
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