4-Cyano-4'-pentylbiphenyl is a commonly used nematic

liquid crystal Liquid crystal (LC) is a state of matter whose properties are between those of conventional liquids and those of solid crystals. For example, a liquid crystal can flow like a liquid, but its molecules may be oriented in a common direction as i ...

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 The University of Hull is a public research university in Kingston upon Hull, a city in the East Riding of Yorkshire, England. It was founded in 1927 as University College Hull. The main university campus is located in Hull and is home to the Hu ...

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 The Ministry of Defence (MOD or MoD) is a ministerial department of the Government of the United Kingdom. It is responsible for implementing the defence policy set by the government and serves as the headquarters of the British Armed Forces. ...

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 Aluminium chloride, also known as aluminium trichloride, is an inorganic compound with the formula . It forms a hexahydrate with the formula , containing six water molecules of hydration. Both the anhydrous form and the hexahydrate are col ...

and C₄H₉COCl is added to the sample, followed by the addition of

potassium hydroxide Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which utili ...

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 Copper(I) cyanide (cuprous cyanide) is an inorganic compound with the formula CuCN. This off-white solid occurs in two polymorphs; impure samples can be green due to the presence of Cu(II) impurities. The compound is useful as a catalyst, in ele ...

and DMF results in the removal of the bromine and its replacement with CN, yielding 5CB. :

References

External links

Space Filling Model of 5CB
* {{DEFAULTSORT:Cyano-4'-Pentylbiphenyl, 4- Liquid crystals Liquid crystal displays Nitriles Pentyl compounds

Production

References

Further reading

External links