Diglyme

Diglyme, or bis(2-methoxyethyl) ether, is an organic compound with the chemical formula (CH₃OCH₂CH₂)₂O. It is a colorless liquid with a slight ether-like odor. It is a solvent with a high boiling point. It is the dimethyl ether of diethylene glycol. The name diglyme is a portmanteau of diglycol methyl ether. It is miscible with water as well as organic solvents.

Diglyme

Names
Preferred IUPAC name 1-Methoxy-2-(2-methoxyethoxy)ethane[1]
Other names Diglyme 2-Methoxyethyl ether Di(2-methoxyethyl) ether Diethylene glycol dimethyl ether
Identifiers
CAS Number	111-96-6 Y
3D model (JSmol)	Interactive image
Beilstein Reference	1736101
ChEBI	CHEBI:46784 Y
ChEMBL	ChEMBL1234162
ChemSpider	13839575 Y
DrugBank	DB02935 Y
ECHA InfoCard	100.003.568
EC Number	203-924-4
Gmelin Reference	26843
PubChem CID	8150
RTECS number	KN3339000
UNII	M4BH3X0MVZ Y
UN number	2252 1993
CompTox Dashboard (EPA)	DTXSID1024621
InChI InChI=1S/C6H14O3/c1-7-3-5-9-6-4-8-2/h3-6H2,1-2H3 Y Key: SBZXBUIDTXKZTM-UHFFFAOYSA-N Y InChI=1/C6H14O3/c1-7-3-5-9-6-4-8-2/h3-6H2,1-2H3 Key: SBZXBUIDTXKZTM-UHFFFAOYAG
SMILES COCCOCCOC
Properties
Chemical formula	(CH3OCH2CH2)2O
Molar mass	134.175 g·mol−1
Density	0.937 g/mL
Melting point	−64 °C (−83 °F; 209 K)
Boiling point	162 °C (324 °F; 435 K)
Solubility in water	Miscible
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H226, H360
Precautionary statements	P201, P202, P210, P233, P240, P241, P242, P243, P280, P281, P303+P361+P353, P308+P313, P370+P378, P403+P235, P405, P501
Flash point	57 °C (135 °F; 330 K)
Related compounds
Related compounds	Diethylene glycol diethyl ether, ethylene glycol dimethyl ether
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

It is prepared by a reaction of dimethyl ether and ethylene oxide over an acid catalyst.^[2]

Solvent

Structure of [Na(diglyme)₂]⁺ as found in its salt with the fluorenyl anion.^[3]

Because of its resistance to strong bases, diglyme is favored as a solvent for reactions of alkali metal reagents even at high temperatures. Rate enhancements in reactions involving organometallic reagents, such as Grignard reactions or metal hydride reductions, have been observed when using diglyme as a solvent.^[4][5]

Diglyme is also used as a solvent in hydroboration reactions with diborane.^[6][7]

It serves as a chelate for alkali metal cations, leaving anions more active.

Safety

The European Chemicals Agency lists diglyme as a substance of very high concern (SVHC) as a reproductive toxin.^[8]

At higher temperatures and in the presence of active metals diglyme is known to decompose, which can produce large amounts of gas and heat.^[9] This decomposition led to the T2 Laboratories reactor explosion in 2007.^[10]

References

1. Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 704. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.
2. Siegfried Rebsdat; Dieter Mayer. "Ethylene Glycol". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a10_101. ISBN 978-3527306732.
3. S. Neander; J. Kornich; F. Olbrich (2002). "Novel Fluorenyl Alkali Metal DIGLYME Complexes: Synthesis and Solid State Structures". J. Organomet. Chem. 656 (1–2): 89. doi:10.1016/S0022-328X(02)01563-2.
4. J. E. Ellis; A. Davison; G. W. Parshall; E. R. Wonchoba (1976). "Tris[Bis(2‐Methoxyethyl)Ether]Potassium and Tetraphenylarsonium Hexacarbonylmetallates(1–) of Niobium and Tantalum". In Fred Basolo (ed.). Inorganic Syntheses. Vol. 16. pp. 68–73. doi:10.1002/9780470132470.ch21. ISBN 978-0-470-13247-0.
5. J. E. Siggins; A. A. Larsen; J. H. Ackerman; C. D. Carabateas (1973). "3,5-Dinitrobenzaldehyde". Organic Syntheses. 53: 52. doi:10.15227/orgsyn.053.0052.
6. Michael W. Rathke; Alan A. Millard (1978). "Boranes in Functionalization of Olefins to Amines: 3-Pinanamine". Organic Syntheses. 58: 32. doi:10.15227/orgsyn.058.0032.
7. Ei-ichi Negishi; Herbert C. Brown (1983). "Perhydro-9b-Boraphenalene and Perhydro-9b-Phenalenol". Organic Syntheses. 61: 103. doi:10.15227/orgsyn.061.0103.
8. "Inclusion of Substances of Very High Concern in the Candidate List (Decision of the European Chemicals Agency)". 19 Dec 2011.
9. Pitt, Martin J. (July 12, 2010). "Chemical Safety: Dangers Of Diglyme". cen.acs.org. Archived from the original on 2012-05-11. Retrieved 2021-09-01.
10. Willey, Ronald J.; Fogler, H. Scott; Cutlip, Michael B. (March 2011). "The integration of process safety into a chemical reaction engineering course: Kinetic modeling of the T2 incident". Process Safety Progress. 30 (1): 39–44. doi:10.1002/prs.10431. hdl:2027.42/83180. S2CID 109207593.