DNBPG phase

The DNBPG phase has a number of features which are typical for almost all of the brush-type CSPs. It has two amide groups which are rigid (planar) therefore the whole chiral moiety will prefer a limited (i.e. not an unlimited) number of conformations which is important for chiral recognition. The amide... 

Bakerbond Chiral DNBPG (ionic or covalent).4 r-BuOH, 2-PrOH, Butyl methyl ether, hexane, CHC13, and phases below. Chiral mixts of alcohols, acids, amines, variety of enantiomeric compds... 

The brush-type of CSP was introduced by Pirkle who was one of the pioneers of modern enantioselective liquid chromatography [55]. The most frequently used 7i-acceptor phases are derived from the amino acids phenylglycine (DNBPG) (Fig. 6.8) or leucine (DNBLeu) covalently or ionically bonded to 3-aminopropyl silica gel [56, 57]. These CSPs are commercially available for analytical or preparative separation of enantiomers. Further CSPs based on amino acid or amine chiral selectors such as valine, phenylalanine, tyrosine [58] and l,2-tr s-diaminocyclohexane (DACH-DNB phase) [59] and 1,2-traus-diphenylethylene diamine (ULMO phase) [60] were also developed (Fig. 6.8). These CSPs have been applied for the preparative separation of the enantiomers of a few racemic compounds, but the number of reported preparative applications has remained very limited over the last 10 years. 

Section 7.5 outlined how silica can be derivatized with almost any functional group the resulting monomer structures are known as brushes . The first broadly used and still very important CSP is the brush-type dinitrobenzoylphenylglycine (DNBPG), the first one shown in Table 22.1. According to its inventor, William H. Pirkle, it is often called Pirkle-phase , although a more correct name is Pirkle T because it is not the only one of his phases that is on the market. 

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