Oxazolidine

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Oxazolidine
Structure Oxazolidine.svg
Oxazolidine 3D Balls.png
Names
Preferred IUPAC name
1,3-Oxazolidine [1]
Other names
Oxazolidine
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.127.875 OOjs UI icon edit-ltr-progressive.svg
MeSH C064210
PubChem CID
UNII
  • InChI=1S/C3H7NO/c1-2-5-3-4-1/h4H,1-3H2 X mark.svgN
    Key: WYNCHZVNFNFDNH-UHFFFAOYSA-N X mark.svgN
  • InChI=1/C3H7NO/c1-2-5-3-4-1/h4H,1-3H2
    Key: WYNCHZVNFNFDNH-UHFFFAOYAQ
  • C1COCN1
Properties
C3H7NO
Molar mass 73.0938 g/mol
Appearancecolorless 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).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

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.

Contents

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]

Oxazolidines have even been researched and used as fuel additives. [10]

Bisoxazolidines

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

They are used as performance modifiers in polyurethane coatings and paints. [11] 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. [12] 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. [13] [14]

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

See also

Related Research Articles

<span class="mw-page-title-main">Polyurethane</span> Polymer composed of a chain of organic units joined by carbamate (urethane) links

Polyurethane refers to a class of polymers composed of organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane is produced from a wide range of starting materials. This chemical variety produces polyurethanes with different chemical structures leading to many different applications. These include rigid and flexible foams, and coatings, adhesives, electrical potting compounds, and fibers such as spandex and polyurethane laminate (PUL). Foams are the largest application accounting for 67% of all polyurethane produced in 2016.

<span class="mw-page-title-main">Carbamate</span> Chemical group (>N–C(=O)–O–)

In organic chemistry, a carbamate is a category of organic compounds with the general formula R2NC(O)OR and structure >N−C(=O)−O−, which are formally derived from carbamic acid. The term includes organic compounds, formally obtained by replacing one or more of the hydrogen atoms by other organic functional groups; as well as salts with the carbamate anion H2NCOO−.

<span class="mw-page-title-main">Oxazole</span> Chemical compound

Oxazole is the parent compound for a vast class of heterocyclic aromatic organic compounds. These are azoles with an oxygen and a nitrogen separated by one carbon. Oxazoles are aromatic compounds but less so than the thiazoles. Oxazole is a weak base; its conjugate acid has a pKa of 0.8, compared to 7 for imidazole.

In organic chemistry, a polyol is an organic compound containing multiple hydroxyl groups. The term "polyol" can have slightly different meanings depending on whether it is used in food science or polymer chemistry. Polyols containing two, three and four hydroxyl groups are diols, triols, and tetrols, respectively.

<span class="mw-page-title-main">Toluene diisocyanate</span> Chemical compound

Toluene diisocyanate (TDI) is an organic compound with the formula CH3C6H3(NCO)2. Two of the six possible isomers are commercially important: 2,4-TDI (CAS: 584-84-9) and 2,6-TDI (CAS: 91-08-7). 2,4-TDI is produced in the pure state, but TDI is often marketed as 80/20 and 65/35 mixtures of the 2,4 and 2,6 isomers respectively. It is produced on a large scale, accounting for 34.1% of the global isocyanate market in 2000, second only to MDI. Approximately 1.4 billion kilograms were produced in 2000. All isomers of TDI are colorless, although commercial samples can appear yellow.

<span class="mw-page-title-main">Carbodiimide</span> Class of organic compounds with general structure RN=C=NR

In organic chemistry, a carbodiimide is a functional group with the formula RN=C=NR. On Earth they are exclusively synthetic, but in interstellar space the parent compound HN=C=NH has been detected by its maser emissions.

<span class="mw-page-title-main">Polypropylene glycol</span> Chemical compound

Polypropylene glycol or polypropylene oxide is the polymer of propylene glycol. Chemically it is a polyether, and, more generally speaking, it's a polyalkylene glycol (PAG) H S Code 3907.2000. The term polypropylene glycol or PPG is reserved for polymer of low- to medium-range molar mass when the nature of the end-group, which is usually a hydroxyl group, still matters. The term "oxide" is used for high-molar-mass polymer when end-groups no longer affect polymer properties. Between 60 and 70% of propylene oxide is converted to polyether polyols by the process called alkoxylation.

<span class="mw-page-title-main">Polyisocyanurate</span> Type of plastic typically used for thermal insulation

Polyisocyanurate, also referred to as PIR, polyiso, or ISO, is a thermoset plastic typically produced as a foam and used as rigid thermal insulation. The starting materials are similar to those used in polyurethane (PUR) except that the proportion of methylene diphenyl diisocyanate (MDI) is higher and a polyester-derived polyol is used in the reaction instead of a polyether polyol. The resulting chemical structure is significantly different, with the isocyanate groups on the MDI trimerising to form isocyanurate groups which the polyols link together, giving a complex polymeric structure.

<span class="mw-page-title-main">Hexamethylene diisocyanate</span> Chemical compound

Hexamethylene diisocyanate (HDI) is the organic compound with the formula (CH2)6(NCO)2. It is classified as an diisocyanate. It is a colorless liquid. It has sometimes been called HMDI but this not usually done to avoid confusion with Hydrogenated MDI.

<span class="mw-page-title-main">Isoxazolidine</span> Chemical compound

Isoxazolidine is the organic compound with the formula (CH2)3(NH)O. It is the parent of a family of compounds called Isoxazolidines, which are saturated C3NO heterocyclic rings where the nitrogen and oxygen occupy adjacent positions (1 and 2). They are the saturated analogues of Isoxazoles, and they are isomeric with oxazolidines, where the N and O are separated by one carbon.

<span class="mw-page-title-main">Oxazoline</span> Chemical compound

Oxazoline is a five-membered heterocyclic organic compound with the formula C3H5NO. It is the parent of a family of compounds called oxazolines, which contain non-hydrogenic substituents on carbon and/or nitrogen. Oxazolines are the unsaturated analogues of oxazolidines, and they are isomeric with isoxazolines, where the N and O are directly bonded. Two isomers of oxazoline are known, depending on the location of the double bond.

In polymer chemistry, the term prepolymer or pre-polymer, refers to a monomer or system of monomers that have been reacted to an intermediate-molecular mass state. This material is capable of further polymerization by reactive groups to a fully cured, high-molecular-mass state. As such, mixtures of reactive polymers with un-reacted monomers may also be referred to as pre-polymers. The term "pre-polymer" and "polymer precursor" may be interchanged.

Moisture-cure polyurethanes -- or polyurethane prepolymer -- are isocyanate-terminated prepolymers that are formulated to cure with ambient water. Cured PURs are segmented copolymer polyurethane-ureas exhibiting microphase-separated morphologies. One phase is derived from a typically flexible polyol that is generally referred to as the “soft phase”. Likewise the corresponding “hard phase” is born from the di- or polyisocyanates that through water reaction produce a highly crosslinked material with softening temperature well above room temperature.

<span class="mw-page-title-main">Tetramethylxylylene diisocyanate</span> Chemical compound

Tetramethylxylylene diisocyanate (TMXDI) is an organic compound with the formula C6H4(CMe2NCO)2 (Me = CH3). Introduced in the 1980s by American Cyanamid, the molecule features two isocyanate groups. TMXDI is generally classified as an aliphatic isocyanate, which are generally more UV stable than their aromatic counterparts.

Hydrogenated MDI (H12MDI or 4,4′-diisocyanato dicyclohexylmethane) is an organic compound in the class known as isocyanates. More specifically, it is an aliphatic diisocyanate. It is a water white liquid at room temperature and is manufactured in relatively small quantities. It is also known as 4,4'-methylenedi(cyclohexyl isocyanate) or methylene bis(4-cyclohexylisocyanate) and has the formula CH2[(C6H10)NCO]2.

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Blocked isocyanates are organic compounds that have their isocyanate functionality chemically blocked to control reactivity. They are the product of an isocyanate moiety and a suitable blocking agent. It may also be a polyurethane prepolymer that is NCO terminated but this functionality has also been chemically reacted with a blocking agent. They are usually used in polyurethane applications but not always. They are extensively used in industrial applications such as coatings, sealants and adhesives.

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1,6-Hexanediol diglycidyl ether is an organic chemical in the glycidyl ether family. It is an aliphatic compound that is a colorless liquid. It has two epoxide (oxirane) groups per molecule. Its main use is in modifying epoxy resins especially viscosity reduction whilst flexibilizing. It is REACH registered.

<span class="mw-page-title-main">Poly(propylene glycol) diglycidyl ether</span> Chemical compound

Poly(propylene glycol) diglycidyl ether (PPGDGE) is an organic chemical in the glycidyl ether family. There are a number of variations depending on the starting molecular weight of the polypropylene glycol. They have the formula (C3H6O)n.C6H10O3 and the IUPAC name is Poly[oxy(methyl-1,2-ethanediyl)],a-(2-oxiranylmethyl)-w-(2-oxiranylmethoxy)- A key use is as a modifier for epoxy resins as a reactive diluent and flexibilizer. It is REACH registered.

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. 1 2 3 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. ↑ Oviedo-Roa, R.; Ramírez-Pérez, J. F.; Servín-Nájera, A. G.; Mena-Cervantes, V. Y.; Martínez-Magadán, J. M.; Cerón-Camacho, R.; Cisneros-Dévora, R.; Soto-Castruita, E.; Zamudio-Rivera, L. S. (2022-05-01). "Quantum molecular modeling of oxazolidines as detergent-dispersant additives for gasoline: A valuable technological adviser". Fuel. 315: 122715. doi:10.1016/j.fuel.2021.122715. ISSN   0016-2361.
  11. ↑ Howarth G.A "Synthesis of a legislation compliant corrosion protection coating system based on urethane, oxazolidine and waterborne epoxy technology" Master of Science Thesis April 1997 Imperial College London
  12. ↑ Emission control Archived 2003-01-06 at the Wayback Machine chembytes e-zine 2001.
  13. ↑ "2-[2-(propan-2-yl)-1,3-oxazolidin-3-yl]ethanol - Registration Dossier - ECHA". echa.europa.eu. Retrieved 2018-11-14.
  14. ↑ 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.
  15. ↑ 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.

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