Oxazoline
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| Names | |
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IUPAC name
2-oxazoline
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Systematic IUPAC name
4,5-dihydrooxazole
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| Other names
Δ2-oxazoline
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| Identifiers | |
504-77-8 (2-oxazoline)  95879-85-9 (3-oxazoline) 6569-13-7 (4-oxazoline)
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| 3D model (Jmol) | Interactive image |
| ChemSpider |
61465 
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| ECHA InfoCard | 100.007.274 |
| PubChem | 68157 |
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| Properties | |
| C3H5NO | |
| Molar mass | 71.08 g·mol−1 |
| Density | 1.075 |
| Boiling point | 98 °C (208 °F; 371 K) |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 (what is ?) |
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| Infobox references | |
Oxazoline is a five-membered heterocyclic chemical compound containing one atom each of oxygen and nitrogen. It was first characterised in 1889 and was named in-line with the Hantzsch–Widman nomenclature. It is part of a family of heterocyclic compounds, where it exists between oxazole and oxazolidine in terms of saturation. Oxazoline itself has no current applications however compounds containing the ring, which are referred to as oxazolines or oxazolyls, have a wide variety of uses; particularly as ligands in asymmetric catalysis, as protecting groups for carboxylic acids and, increasingly, as monomers for the production of polymers.
The synthesis of 2-oxazoline rings is well established and has been the topic of several literature reviews (most notably in 1949, 1971, and 1994). In general the synthesis proceeds via the cyclisation of a 2-amino alcohol (typically obtained by the reduction of amino acids) with a suitable functional group; the mechanism of which is subject to Baldwin's rules. Many methods exist for doing this however the current literature is dominated by 4 main processes:
Owing to its simplicity and general reliability SOCl2 is one of the most commonly used reagents for the synthesis of oxazoline rings, however it is often necessary to maintain anhydrous conditions, as oxazolines can be ring-opened by chloride if the imine becomes protonated. The reaction is typically performed at room temperature and is a rare example of a carbonyl oxygen acting as a nucleophile and is similar to the Robinson–Gabriel synthesis. If milder regents are required then SOCl2 may be replaced with oxalyl chloride.
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