Oxazolidine

Oxazolidine is a five-membered heterocycle ringwith the formula (CH2)3(NH)O.The O atom and NH groups are not mutually bonded, in contrast to isoxazolidine.[2][3] Oxazolidines (emphasis on plural) are derivatives of the parent oxazolidine owing to the presence of substituents on carbon and/or nitrogen. Oxazolines are unsaturated analogues of oxazolidines.

Oxazolidine
Names
Preferred IUPAC name
1,3-Oxazolidine[1]
Other names
Oxazolidine
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.127.875
MeSH C064210
UNII
  • InChI=1S/C3H7NO/c1-2-5-3-4-1/h4H,1-3H2 ☒N
    Key: WYNCHZVNFNFDNH-UHFFFAOYSA-N ☒N
  • InChI=1/C3H7NO/c1-2-5-3-4-1/h4H,1-3H2
    Key: WYNCHZVNFNFDNH-UHFFFAOYAQ
  • C1COCN1
Properties
C3H7NO
Molar mass 73.0938 g/mol
Appearance colorless liquid
Density 1.063 g/mL
Melting point 90 °C (194 °F; 363 K)
Boiling point 200 °C (392 °F; 473 K) 20 torr
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)
Infobox references

Synthesis and reactions

First synthesized in the 1800s,[4] oxazolidines are traditionally prepared by condensation of 2-aminoalcohols with aldehydes and ketones. The ready availability of chiral amino alcohols by reduction of amino acids enables the synthesis of chiral oxazolidines.[5]

Oxazolidines are prone to hydrolysis, the reverse of their syntheses. Perhaps for this reason, their basicity is rarely discussed.[6]

Uses and occurrence

Several oxazolidine derivatives occur naturally, Some occur as post translational modifications of proteins.[7] Others are components of alkaloids, a few of which are highly active against some tumors. Examples include terazomine, quinocarcin, and tetrahydroisoquinoline.[5]

Oxazolidines are used as moisture scavengers in polyurethane and other systems.[8][9]

Bisoxazolidines

Bisoxazolidines contain two oxazolidine rings. They are the saturated analogues of bisoxazolines.

They are used as performance modifiers in polyurethane coatings and paints. The rings hydrolyze in the presence of moisture to give amine and hydroxyl groups, which can then react with diisocyanates, polyisocyanates and polyurethane prepolymers to form a coating. The amine groups will form urea linkages and the hydroxyl group will form urethane links.[10] The use of a bisoxazolidine in a polyurethane system can prevent the unwanted reaction between isocyanate and moisture resulting in coating defects, as a result of carbon dioxide release. This moisture-triggered curing route is preferential to moisture cure. As the ring opening reaction is catalyzed by acids, usually organic acids or anhydrides of carboxylic acids are added in a small amount.

The choice of linker between the two oxazolidine rings has a large impact on the performance when used to cure isocyanates. A rigid linker group increases a polyurethanes toughness. A flexible linker group imparts flexibility and increases elongation of a coating. These differences are the reason why bisoxazolidines are used to enhance the performance of polyurethane systems. Usually the rings are linked by esters, urethanes, carbonate or have the two rings fused together. A key intermediate in manufacturing bisoxazolidines is 2-[2-(propan-2-yl)-1,3-oxazolidin-3-yl]ethanol. The hydroxy group on the molecule allows for further reaction with hexamethylene diisocyanate for example.[11][12]

Depending on the linker, bisoxazolines can function as chelating ligands.[5]

See also

References
  1. International Union of Pure and Applied Chemistry (2014). Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013. The Royal Society of Chemistry. p. 142. doi:10.1039/9781849733069. ISBN 978-0-85404-182-4.
  2. "SID 3881507 -- PubChem Substance Summary". The PubChem Project. United States National Center for Biotechnology Information. Retrieved 13 December 2005.
  3. Cordero, Franca M.; Giomi, Donatella; Lascialfari, Luisa (2013). Five-Membered Ring Systems. Progress in Heterocyclic Chemistry. Vol. 25. pp. 291–317. doi:10.1016/B978-0-08-099406-2.00012-1. ISBN 978-0-08-099406-2.
  4. Bergmann, Ernst D. (1953). "The Oxazolidines". Chemical Reviews. 53 (2): 309–352. doi:10.1021/cr60165a005.
  5. Wolf, Christian; Xu, Hanhui (2011). "Asymmetric catalysis with chiral oxazolidine ligands". Chemical Communications. 47 (12): 3339–3350. doi:10.1039/c0cc04629a. PMID 21246142.
  6. Bergmann, Ernst D. (1953-10-01). "The Oxazolidines". Chemical Reviews. 53 (2): 309–352. doi:10.1021/cr60165a005. ISSN 0009-2665.
  7. Roy, Ranabir Sinha; Gehring, Amy M.; Milne, Jill C.; Belshaw, Peter J.; Walsh, Christopher T.; Roy, Ranabir Sinha; Gehring, Amy M.; Milne, Jill C.; Belshaw, Peter J.; Walsh, Christopher T. (1999). "Thiazole and oxazole peptides: Biosynthesis and molecular machinery". Natural Product Reports. 16 (2): 249–263. doi:10.1039/a806930a. PMID 10331285.
  8. Florio, John J.; Miller, Daniel J. (2004-05-26). Handbook Of Coating Additives. CRC Press. ISBN 978-0-8247-5626-0.
  9. Howarth, Graham A. "High Solids Polyurethane Coatings Using Oxazolidine Reactive Diluents" (PDF). Archived from the original (PDF) on 16 August 2018.
  10. Emission control Archived 2003-01-06 at the Wayback Machine chembytes e-zine 2001.
  11. "2-[2-(propan-2-yl)-1,3-oxazolidin-3-yl]ethanol - Registration Dossier - ECHA". echa.europa.eu. Retrieved 2018-11-14.
  12. Howarth, GA (July 2003). "Polyurethanes, polyurethane dispersions and polyureas: Past, present and future". Surface Coatings International Part B: Coatings Transactions. 86 (2): 111–118. doi:10.1007/bf02699621. ISSN 1476-4865. S2CID 93574741.
  13. Franz Müller; Peter Ackermann; Paul Margot (2012). "Fungicides, Agricultural, 2. Individual Fungicides". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.o12_o06. ISBN 978-3-527-30673-2.

Further reading
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