diglyme
{{chembox
|Watchedfields = changed
|verifiedrevid = 443685984
|ImageFile = Diglyme.png
|ImageAlt = Skeletal formula of diglyme
|ImageFile1 = Diglyme 3D spacefill.png
|ImageAlt1 = Space-filling model of the diglyme molecule
|PIN = 1-Methoxy-2-(2-methoxyethoxy)ethane{{cite book | title = Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 (Blue Book) | publisher = The Royal Society of Chemistry | date = 2014 | location = Cambridge | page = 704 | doi = 10.1039/9781849733069-FP001 | isbn = 978-0-85404-182-4}}
|OtherNames = Diglyme
2-Methoxyethyl ether
Di(2-methoxyethyl) ether
Diethylene glycol dimethyl ether
|Section1={{Chembox Identifiers
| CASNo = 111-96-6
| CASNo_Ref = {{cascite|correct|CAS}}
| Beilstein = 1736101
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 46784
| ChEMBL = 1234162
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 13839575
| EINECS = 203-924-4
| DrugBank_Ref = {{drugbankcite|correct|drugbank}}
| DrugBank = DB02935
| Gmelin = 26843
| PubChem = 8150
| RTECS = KN3339000
| UNNumber = 2252 1993
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = M4BH3X0MVZ
| SMILES = COCCOCCOC
|InChI = 1/C6H14O3/c1-7-3-5-9-6-4-8-2/h3-6H2,1-2H3
|InChIKey = SBZXBUIDTXKZTM-UHFFFAOYAG
|StdInChI_Ref = {{stdinchicite|correct|chemspider}}
|StdInChI = 1S/C6H14O3/c1-7-3-5-9-6-4-8-2/h3-6H2,1-2H3
|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
|StdInChIKey = SBZXBUIDTXKZTM-UHFFFAOYSA-N
}}
|Section2={{Chembox Properties
|Formula = {{chem2|(CH3OCH2CH2)2O}}
|C=6|H=14|O=3
|Density = 0.937 g/mL
|MeltingPtC = -64
|BoilingPtC = 162
|Solubility = Miscible
}}
|Section7={{Chembox Hazards
|FlashPtC = 57
| GHSPictograms = {{GHS02}}{{GHS08}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|226|360}}
| PPhrases = {{P-phrases|201|202|210|233|240|241|242|243|280|281|303+361+353|308+313|370+378|403+235|405|501}}
}}
|Section9={{Chembox Related
|OtherCompounds = Diethylene glycol diethyl ether, ethylene glycol dimethyl ether}}
}}
Diglyme, or bis(2-methoxyethyl) ether, is an organic compound with the chemical formula {{chem2|(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.
It is prepared by a reaction of dimethyl ether and ethylene oxide over an acid catalyst.{{Ullmann | author1 = Siegfried Rebsdat | author2 = Dieter Mayer | title = Ethylene Glycol | doi = 10.1002/14356007.a10_101}}
Solvent
File:(Na(diglyme)2)cation-3D-balls.png anion.{{cite journal|title=Novel Fluorenyl Alkali Metal DIGLYME Complexes: Synthesis and Solid State Structures|author=S. Neander |author2=J. Kornich |author3=F. Olbrich |journal=J. Organomet. Chem.|year=2002|volume=656|issue=1–2|page=89|doi=10.1016/S0022-328X(02)01563-2}}]]
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.{{cite book |author=J. E. Ellis |author2=A. Davison |author3=G. W. Parshall |author4=E. R. Wonchoba |chapter=Tris[Bis(2‐Methoxyethyl)Ether]Potassium and Tetraphenylarsonium Hexacarbonylmetallates(1–) of Niobium and Tantalum |editor=Fred Basolo |title=Inorganic Syntheses |volume=16 |pages=68–73 |year=1976|doi=10.1002/9780470132470.ch21 |isbn=978-0-470-13247-0}}{{cite journal |doi=10.15227/orgsyn.053.0052|title=3,5-Dinitrobenzaldehyde|journal=Organic Syntheses|year=1973|volume=53|page=52|author=J. E. Siggins |author2=A. A. Larsen |author3=J. H. Ackerman |author4=C. D. Carabateas}}
Diglyme is also used as a solvent in hydroboration reactions with diborane.{{cite journal |doi=10.15227/orgsyn.058.0032|title=Boranes in Functionalization of Olefins to Amines: 3-Pinanamine|journal=Organic Syntheses|year=1978|volume=58|page=32|author=Michael W. Rathke |author2=Alan A. Millard}}{{cite journal |doi=10.15227/orgsyn.061.0103|title=Perhydro-9b-Boraphenalene and Perhydro-9b-Phenalenol|journal=Organic Syntheses|year=1983|volume=61|page=103|author=Ei-ichi Negishi |author2=Herbert C. Brown}}
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.{{Cite web|url=https://www.echa.europa.eu/documents/10162/ee023359-daa8-43a2-8c82-242f0a7588f7|title=Inclusion of Substances of Very High Concern in the Candidate List (Decision of the European Chemicals Agency)|date=19 Dec 2011}}
At higher temperatures and in the presence of active metals diglyme is known to decompose, which can produce large amounts of gas and heat.{{Cite web|last=Pitt|first=Martin J.|date=July 12, 2010|title=Chemical Safety: Dangers Of Diglyme|url=https://cen.acs.org/articles/88/i28/Chemical-Safety-Dangers-Diglyme.html|url-status=live|access-date=2021-09-01|website=cen.acs.org|archive-url=https://web.archive.org/web/20120511210410/http://cen.acs.org/articles/88/i28/Chemical-Safety-Dangers-Diglyme.html |archive-date=2012-05-11 }} This decomposition led to the T2 Laboratories reactor explosion in 2007.{{Cite journal|last1=Willey|first1=Ronald J.|last2=Fogler|first2=H. Scott|last3=Cutlip|first3=Michael B.|date=March 2011|title=The integration of process safety into a chemical reaction engineering course: Kinetic modeling of the T2 incident|url=https://onlinelibrary.wiley.com/doi/10.1002/prs.10431|journal=Process Safety Progress|language=en|volume=30|issue=1|pages=39–44|doi=10.1002/prs.10431|hdl=2027.42/83180|s2cid=109207593|hdl-access=free}}