4-Cyano-4'-pentylbiphenyl

4-Cyano-4'-pentylbiphenyl

Skeletal formula of 4-cyano-4'-pentylbiphenyl
Space-filling model of the 4-cyano-4'-pentylbiphenyl molecule
Names
Preferred IUPAC name 4′-Pentyl[1,1′-biphenyl]-4-carbonitrile
Other names 4'-Amyl-4-biphenylcarbonitrile, 4'-Pentyl-4-biphenylcarbonitrile, 4-Amyl-4'-cyanobiphenyl
Identifiers
CAS Number	40817-08-1 ☒N
3D model (JSmol)	Interactive image
ChemSpider	83347 ☒N
ECHA InfoCard
EC Number	255-093-2
E number
PubChem CID	92319
UNII	2R6RYG3ZGM checkY
CompTox Dashboard (EPA)	{{#property:P3117}}
InChI InChI=1S/C18H19N/c1-2-3-4-5-15-6-10-17(11-7-15)18-12-8-16(14-19)9-13-18/h6-13H,2-5H2,1H3 ☒N Key: HHPCNRKYVYWYAU-UHFFFAOYSA-N ☒N InChI=1/C18H19N/c1-2-3-4-5-15-6-10-17(11-7-15)18-12-8-16(14-19)9-13-18/h6-13H,2-5H2,1H3 Key: HHPCNRKYVYWYAU-UHFFFAOYAV
SMILES N#Cc1ccc(cc1)c2ccc(cc2)CCCCC
Properties
Chemical formula	C18H19N
Molar mass	249.357 g·mol−1
Appearance	Colorless if isotropic or cloudy white if nematic
Density	1.022 g/cm3
Melting point	22.5 °C (72.5 °F; 295.6 K)
Refractive index (nD)	n// = 1.71, n⟂ = 1.53
Viscosity	28 mPa·s
Hazards
GHS labelling:
Pictograms	GHS07: Exclamation mark
Signal word	Warning
Hazard statements	H302, H312, H315, H319, H332, H335
Precautionary statements	P261, P264, P270, P271, P280, P301+P312, P302+P352, P304+P312, P304+P340, P305+P351+P338, P312, P321, P322, P330, P332+P313, P337+P313, P362, P363, P403+P233, P405, P501
NFPA 704 (fire diamond)	2 1 0
Safety data sheet (SDS)	[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). ☒N verify (what is checkY☒N ?) Infobox references

4-Cyano-4'-pentylbiphenyl is a commonly used nematic liquid crystal with the chemical formula C₁₈H₁₉N. It frequently goes by the common name 5CB. 5CB was first synthesized by George William Gray, Ken Harrison, and J.A. Nash at the University of Hull in 1972 and at the time it was the first member of the cyanobiphenyls. The liquid crystal was discovered after Gray's group received a grant from the UK Ministry of Defence to find a liquid crystal that had liquid crystal phases near room temperature with the specific intention of using them in liquid crystal displays. The molecule is about 20 Å long. The liquid crystal 5CB undergoes a phase transition from a crystalline state to a nematic state at 22.5 °C and it goes from a nematic to an isotropic state at 35.0 °C.

Production

5CB is produced by modifying biphenyl in a linear manner. First Br₂ is added to the biphenyl to introduce a bromine atom to the end of the moiety. Next aluminium chloride and C₄H₉COCl is added to the sample, followed by the addition of potassium hydroxide and NH₂NH₂. By this point the molecule will have a bromine atom on one end of the rigid core and C₅H₁₁ on the other end. Finally, introduction of copper(I) cyanide and DMF results in the removal of the bromine and its replacement with CN, yielding 5CB.

File:Synthesis of 5CB..svg

External links

• Space Filling Model of 5CB