2.2.2-Cryptand

The correct title of this article is [2.2.2]Cryptand. The omission of any brackets is due to technical restrictions.

[2.2.2]Cryptand is the organic compound with the formula N(CH₂CH₂OCH₂CH₂OCH₂CH₂)₃N. This bicyclic molecule is the most studied member of the cryptand family of chelating agents.^[2] It is a white solid. Many analogous compounds are known. Their high affinity for alkali metal cations illustrates the advantages of "preorganization", a concept within the area of supramolecular chemistry.

[2.2.2]Cryptand

Skeletal formula of 2.2.2-cryptand
Names
Preferred IUPAC name 4,7,13,16,21,24-Hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane
Other names Cryptating agent 222[1]
Identifiers
CAS Number	23978-09-8 Y
3D model (JSmol)	Interactive image
Abbreviations	Crypt-222
Beilstein Reference	620282
ChemSpider	65637 Y
ECHA InfoCard	100.041.770
EC Number	245-962-4
MeSH	Cryptating+agent+222
PubChem CID	72801
RTECS number	MP4750000
UNII	18V22YHN6G Y
CompTox Dashboard (EPA)	DTXSID00178697
InChI InChI=1S/C18H36N2O6/c1-7-21-13-14-24-10-4-20-5-11-25-17-15-22-8-2-19(1)3-9-23-16-18-26-12-6-20/h1-18H2 Y Key: AUFVJZSDSXXFOI-UHFFFAOYSA-N Y InChI=1/C18H36N2O6/c1-7-21-13-14-24-10-4-20-5-11-25-17-15-22-8-2-19(1)3-9-23-16-18-26-12-6-20/h1-18H2 Key: AUFVJZSDSXXFOI-UHFFFAOYAX
SMILES C1COCCN2CCOCCOCCN(CCO1)CCOCCOCC2
Properties
Chemical formula	C 18N 2H 36O 6
Molar mass	376.4882 g mol−1
Melting point	68 to 71 °C (154 to 160 °F; 341 to 344 K)
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H319, H335
Precautionary statements	P261, P305+P351+P338
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

For the design and synthesis of [2.2.2]cryptand,^[3] Jean-Marie Lehn shared the Nobel Prize in Chemistry. The compound was originally prepared starting with the diacylation of the diamine-diether:^[4]

[CH₂OCH₂CH₂NH₂]₂ + [CH₂OCH₂COCl]₂ → [CH₂OCH₂CH₂NHC(O)CH₂]₂ + 2 HCl

The resulting macrocyclic diamide is reduced by lithium aluminium hydride. The resulting macrocyclic diamine tetraether reacts with a second equivalent of [CH₂OCH₂COCl]₂ to produce the macrobicyclic diamide. This di(tertiary)amide is reduced to the diamine by diborane.

[2.2.2]Cryptand binds K⁺ as an octadentate N₂O₆ ligand. The resulting cation K([2.2.2]cryptand)⁺ is lipophilic.

Structure of [2.2.2]cryptand encapsulating a potassium cation (purple) as determined by X-ray crystallography^[5]