This article may be too technical for most readers to understand.(January 2019) |
| Names | |
|---|---|
| IUPAC name (1R,5S)-7,8-Dioxabicyclo[3.2.1]octan-2-one | |
| Other names Cyrene | |
| Identifiers | |
3D model (JSmol) | |
| ChemSpider | |
| ECHA InfoCard | 100.234.612 |
| EC Number |
|
PubChem CID | |
CompTox Dashboard (EPA) | |
| |
| |
| Properties | |
| C6H8O3 | |
| Molar mass | 128.127 g·mol−1 |
| Appearance | clear to yellowish liquid |
| Density | 1.2473 g/cm3 (25 °C) [1] |
| Boiling point | 226 °C (439 °F; 499 K) [2] |
| miscible | |
| Vapor pressure | 12.98 Pa (25 °C) [1] 14.4 Pa (25 °C) [2] |
Refractive index (nD) | 1.4732 (20 °C) [2] |
| Hazards [3] | |
| GHS labelling: | |
| | |
| Warning | |
| H319 | |
| P305+P351+P338, P313 | |
| Flash point | 108 °C (226 °F; 381 K) |
| 296 °C (565 °F; 569 K) | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
Dihydrolevoglucosenone (Cyrene) is a bicyclic, chiral, seven-membered heterocyclic cycloalkanone which is a waste derived and fully biodegradable aprotic dipolar solvent. [4] [5] [6] It is an environmentally friendly alternative to dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP). [7]
Dihydrolevoglucosenone can be prepared through the hydrogenation of unsaturated ketone levoglucosenone (LGO) with heterogenous palladium catalysts under mild conditions. [8] [9] LGO is a chemical building block obtained by acid-catalyzed pyrolysis [10] of lignocellulosic biomass such as sawdust.
Dihydrolevoglucosenone is a clear colorless, to light-yellow liquid with a mild, smoky ketone-like odor. [11] It is miscible with water and many organic solvents. [11] Dihydrolevoglucosenone has a boiling point of 226 °C at 101.325 kPa (vs 202 °C for NMP), and a vapor pressure of 12.98 Pa near room temperature (25 °C). [1] It has a comparatively high dynamic viscosity of 14.5 cP (for comparison DMF: 0.92 cP at 20 °C, NMP: 1.67 cP at 25 °C). [12]
The compound is stable at temperatures up to 195 °C and weak acids and bases.[ citation needed ] Dihydrolevoglucosenone can react with inorganic bases via an aldol condensation mechanism.[ citation needed ] Dihydrolevoglucosenone is readily biodegradable (99% within 14 days) and reacts to oxidants such as aqueous 30% hydrogen peroxide solution even at room temperature.[ citation needed ]
Dihydrolevoglucosenone can be used as a renewable building block to produce valuable chemicals such as drugs, flavours and fragrances and specialty polymers. [8]
As dihydrolevoglucosenone is produced as a single enantiomer, it can be used for chiral pool synthesis. For instance, oxidation with peroxy acids such as peroxyacetic acid produces optically pure 5-hydroxymethyldihydrofuranone, [13] from which zalcitabine, formerly a HIV drug, is available. [14]
]
In a two-step hydrogenation process with a metal catalyst – first at 60 °C then at 180 °C – 1,6-hexanediol is mainly obtained via several intermediates. [15] 1,6-hexanediol can be used as a starting material for the production of polyesters, polyurethanes and diamine 1,6-diaminohexane.
At elevated temperature and in the presence of a palladium catalyst, hydrogenolysis of dihydrolevoglucosenone via levoglucosanol selectively yields tetrahydrofuran-2,5-dimethanol (THF-dimethanol), [8] which is a biodegradable solvent and a bio-based precursor to 1,6-hexanediol (and 1,6-diaminohexane). [16]
The search for alternative "green" solvents made from biomass or low-cost renewable raw materials, which are accessible through high-efficiency processes, in high yields, and meet the performance of conventional solvents, [17] has triggered intensive research activities in industry and academia worldwide.
Dihydrolevoglucosenone is considered a "green" replacement for DMF. [5] Several standard reactions of organic chemistry, e.g. Menshutkin reaction, [5] Sonogashira coupling, [18] Suzuki-Miyaura coupling [19] and the production of ureas [20] have been carried out in dihydrolevoglucosenone.
Circa Group produces dihydrolevoglucosenone from cellulose under the Cyrene brand and has built a 50-tonne demonstration plant with partners in Tasmania. The company estimates that dihydroglucosenone performs better than NMP in 45% and comparably to NMP in 20% of trials to date. Circa received authorization in 2018 from the European Chemicals Agency (ECHA) to produce or import up to 100 tonnes per year of dihydroglucosenone to the EU. [21]