Photo Racemization and Polymerization of (R)-1,1′-Bi(2-naphthol)

Abstract

(R)-1,1'-Bi(2-naphthol) ((R)-BINOL) in an acetonitrile solution lost optical activity upon irradiation with an Hg-Xe lamp. HPLC resolution of the product indicated that (R)-BINOL was racemized upon irradiation, and SEC analysis suggested that a polymeric product was formed in the course of racemization. It is proposed that polymerization of BINOL can occur before it is racemized and that a unit in a polymer derived from BINOL may lose its optical activity afterwards due to in-chain racemization and/or reduction. The polymeric products seem to consist not only of BINOL residues but also of residues derived from acetonitrile as well as those derived through reduction of BINOL.

Chirality and Excited State Proton Transfer: From Sensing to Asymmetric Synthesis

“…As a side, in addition to the formation of photoproducts in Scheme and in Scheme , Nakano and co‐workers used a combination of size‐exclusion chromatography and 1 H NMR to demonstrate that BINOL, in MeCN (non‐rigorously dried), can also undergo a polymerization reaction . The structure was not definitively established but elemental analysis and IR indicate that both BINOL and MeCN are incorporated into the chain.…”

Optical UV Dosimeters Based on Photoracemization of (R)‐(+)‐1,1′‐Bi(2‐Napthol) (BINOL) within a Chiral Nematic Liquid Crystalline Matrix

“…Work is currently ongoing to develop a photoracemizable chiral dopant that meets this latter criterion. We should note that while polymerization of the chiral dopant has been noted in previous work, [28] we assume the combination of low concentration and restricted mobility of the dopant in the host LC and lack of discernable changes in appearance of the sample suggest any polymerization had little, if any, impact on the capability of the device to act as a dosimeter.…”

“…) and its derivatives are known for their ability to photoracemize due to their photoacidity [26,27] and twisted coplanar transitions. [28] This is an interesting property, as BINOLs are usually stable towards thermal racemization due to steric restrictions, [29] although this can be overcome using an acidic or basic environment. [30] This racemization can be monitored by circular dichroism spectroscopy.…”

Ferroelectric transition of a chiral molecular crystal BINOL2DMSO

“…5) In this study, we focus on the physical properties of a chiral molecule 1,1'-bi-2-naphthol (BINOL), where two enantiomers are distinguished by the axial chirality. 6,7) By using enantiomerically-pure BINOL, the resultant crystal structure also becomes right-or lefthanded depending on the handedness of BINOL. Some organic crystals composed of BI-NOL molecules are reported by Lee and Peng.…”