Physically Coated Cellulose and Amylose Derivatives

This type of chiral stationary phase, developed by Okamoto and commercialized by Daicel Chemical Industries, can be considered to be the most universally applicable type of chiral stationary phase for both analytical and preparative chromatographic applications. Many different column types are available on the market. However, experience suggests that, with four different types of phases, a wide range of racemates, belonging to a broad variety of product classes, can be separated. The most interesting phases in our view are:

1. Cellulose derivatives:

(a) Chiralcel OD (3,5 dimethylphenyl carbamate derivative)

(b) Chiralcel OJ (p^ra-methylbenzoyl derivative)

2. Amylose derivatives:

(a) Chiralpak AD (3,5 dimethylphenyl carbamate derivative)

(b) Chiralpak AS [(S)-a-methylbenzyl carbamate derivative)]

The analytical phases are coated on a 10 |im wide pore silica. However, some types of phases are also available on a 5 |im silica matrix. Furthermore, two phases, which are specifically designed for rever-sed-phase applications, have been brought on to the market. An overview of the different types of commercially available coated phases is given in Table 1.

Table 1 Commercially available silica-coated phases for enantioseparation

Cellulose esters

Type ofabsorbent

Chiralcel OJ

p-Methylbenzoyl

Chiralcel OJ-R

For reversed-phase application

Chiralcel OB

Benzoyl

Chiralcel OB-H

Coated on a 5 ^m silica matrix

Chiralcel OA

Acetyl

Chiralcel OK

Cinnamoyl

Chiralcel CA-1

Acetyl

Cellulose carbamates

Chiralcel OD

3,5-Dimethylphenyl

Chiralcel OD-H

Coated on a 5 ^m silica matrix

Chiralcel OD-R

For reversed-phase applications

Chiralcel OD-RH

For reversed-phase applications

Chiralcel OC

Phenyl

Chiralcel OG

p-Methylphenyl

Chiralcel OF

p-Chlorophyenyl

Amylose carbamates

Chiralpak AD

3,5 Dimethylphenyl

Chiralpak AS

(S)a-Methylbenzyl

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