View source for 1,1'-bi-2-naphthol

{{Chembox new
|   Name = 1,1&#39;-Bi-2-naphthol  
|   ImageFileL1 = R-BINOL-2D-skeletal.png  
|   ImageSizeL1 = 100px  
|   ImageNameL1 = R-BINOL  
|   ImageFileR1 = S-BINOL-2D-skeletal.png  
|   ImageSizeR1 = 100px  
|   ImageNameR1 = S-BINOL
|   ImageFile2 = BINOL 3D.png  
|   ImageSize2 = 150px
|   IUPACName = 1,1'-Binaphthalene-2,2'-diol  
|   OtherNames = 1,1'-Bi-2-naphthol<br />1,1-Binaphthol<br />BINOL
| Section1 = {{Chembox Identifiers
|   CASNos = Racemic: [602-09-5]<br />(R)-(+): [18531-94-7]<br />(S)-(-): [18531-99-2]  
|   SMILES =<small>Oc1c(c2c(O)ccc3c2cccc3)c(cccc4)c4cc1</small>  
  }}
| Section2 = {{Chembox Properties
|   Formula = C<sub>20</sub>H<sub>14</sub>O<sub>2</sub>  
|   MolarMass = 286.32 g/mol  
|   Density =   
|   MeltingPt = 205-211 °C 
  }}
}}

'''1,1'-Bi-2-naphthol''' (BINOL) is an [[organic compound]] that is often used as a ligand for transition-metal catalysed [[asymmetric synthesis]]. BINOL has [[axial chirality]] and the two enantiomers can be readily separated and are stable toward racemisation.  The [[specific rotation]] of the two enatiomers is +/- 35.5° (c=1 in [[THF]]). BINOL is a precursor for another [[chiral ligand]] called [[BINAP]].<ref name="binap">[http://www.rhodia-phosphines.com/docs/Rhodia.pdf "Binap: An industrial approach to manufacture"]</ref>

==Preparation==
The [[organic synthesis]] of BINOL is not a challenge as such but the preparation of the individual [[enantiomer]]s is.

(''S'')-BINOL can be prepared directly from an asymmetric [[oxidative coupling]] of [[2-naphthol]] with [[copper(II) chloride]]. The [[chiral ligand]] in this reaction is (+)-[[amphetamine]].

[[Image:CuCl2 naphthol coupling.png|400px|''Coupling of beta-naphthol using CuCl2'']]

Racemic BINOL can also be produced using [[iron(III) chloride]] as an oxidant. The mechanism involves complexation of iron(III) into the [[hydroxyl]], followed by a radical coupling reaction of the naphthol rings initiated by iron(III) oxidizing into iron(II).

[[Optically active]] BINOL can also be obtained from [[racemic]] BINOL by optical resolution. In one method, the [[alkaloid]] N-benzylcinchonidinium chloride form a crystalline [[inclusion compound]].  The inclusion compound of the ''S''-enantiomer is soluble in [[acetonitrile]] but that of the ''R''-enantiomer is not.<ref name="orgsyn">[http://www.orgsyn.org/orgsyn/prep.asp?prep=v76p0001 "RESOLUTION OF  1,1'-BI-2-NAPHTHOL"], Dongwei Cai, David L. Hughes, Thomas R. Verhoeven, and Paul J. Reider, in [[Organic Syntheses]] Coll. Vol. 10, p.93; Vol. 76, p.1</ref>

In another method BINOL is reacted with the [[acid chloride]] pentanoyl chloride to obtain the di-[[ester compound]]. The enzyme [[cholesterol]] [[esterase]] is then added in the form of [[bovine]] [[pancreas]] acetone powder which is able to [[Hydrolysis|hydrolyse]] the (''S'')-di-ester but not the (''R'')-di-ester.<ref name="orgsyn" /> The (''R'')-dipentanoate is hydrolysed in a second step with [[sodium methoxide]].<ref name="orgsyn2">[http://www.orgsyn.org/orgsyn/prep.asp?prep=cv9p0077 "(S)-(−)- AND (R)-(+)-1,1'-BI-2-NAPHTHOL"], Romas J. Kazlauskas in [[Organic Syntheses]], Coll. Vol. 9, p.77; Vol. 70, p.60</ref>

Third method employs [[HPLC]] with chiral stationary phases. A very efficient phase is described here<ref>
{{cite journal
| last = Landek
| first = G.
| coauthors = Vinković M., Kontrec D. and Vinković V.
| year = 2006
|date=2006
| title = Influence of mobile phase and temperature on separation of 1,1 '-binaphthyl-2,2 '-diol enantiomers with brush type chiral stationary phases derived from L-leucine
| journal = Chromatographia
| volume = 64
| pages = 469-473
}}
</ref>.

==References==
{{reflist|2}}

==External links==
* [http://www.chemexper.com/chemicals/supplier/cas/18531-94-7.html Datasheet]

[[Category:phenols|Bi-2-naphthol, 1,1'-]]

[[pt:1,1'-Bi-2-naftol]]

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