**The Development and Application of Cellulose-Based Stationary Phases in Stereoselective Separation of Chiral Pesticides**

Jing Qiu, Shouhui Dai, Tingting Chai, Wenwen Yang, Shuming Yang and Hualin Zhao

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/56575

## **1. Introduction**

214 Cellulose – Medical, Pharmaceutical and Electronic Applications

adsorbent. Artif Cell Blood Sub. 32: 519-528.

tryptophan column. Artif Cell Blood Sub. 38:186-191.

644-650.

[50] Kong D L, Chen C Z, Lin E F, Yu Y T (1998) Clinical trials of type I and invitro studies of typeⅡ immunoadsorbents for systemic lupus erythematosus therapy. Artif Organs. 22:

[51] Yang L, Cheng Y, Yan W R, Yu Y T (2004) Extracorporeal whole blood immunoadsorption of autoimmune myasthenia gravis by cellulose tryptophan

[52] Li X H, Cheng Y, Yang L, Wang S Q, Yu Y T (2010) Extracorporeal whole blood immune-adsorption of passively transferred myasthenia gravis rabbits by cellulose-

> In the 1980s, polysaccharide-based chiral stationary phases (CSPs) were identified as versatile and useful chiral sorbents for separation of enantiomers/stereoisomers in high performance liquid chromatography (HPLC). Chiral discrimination abilities of these CSPs can be derived from the highly organized structure of the left-handed 3/2 helical chain conformations [1]. Some chiral cavities with specific configuration can be formed on the CSPs, which provide the suitable site for a particular enantiomer and make it easier to interact with CSPs by hydrogen bonding and - interactions. This leads to enantioseparation of chiral compounds by different retention and elution on CSPs between their enantiomers [2]. Okamoto et al. reported that the introduction of various kinds of substituents on the hydroxyl group of polysaccharides can improve their stereoslectivity [3].

> Cellulose is an important polysaccharide, it is also a highly crystalline polymer which occurs with various crystal structures. In the 1970s, Hesse and Hagel first synthesized microcrystalline cellulose triacetate (MCTA), and thought its chiral recognition ability might originate from secondary structures creating chiral cavities upon swelling, which can clamp stereoselectively compounds with aromatic residues [4]. In recent years, different cellulose derivatives have been synthesized, coated or covalently bonded on decorative silica gel, and broadly used as CSPs in enantiomeric separation of chiral compounds especially on pesticides and pharmaceuticals. These derivatives exhibit powerful chiral recognition ability towards a wide number of different racemic compounds. More and more commercial cellulose-based CSPs including cellulose acetate, benzoate and phenylcarbamates are being developed and applied in enantioseparation [2,3].

© 2013 Qiu et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 Qiu et al., licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Chiral compounds account for 25% of all agrochemical compounds used commercially and for 26% of the total value of the world agrochemical market [5]. The enantiomers of chiral pesticides possess similar physicochemical properties in a non-chiral environment while they show different activities in biological systems due to enantioselective interactions with enzymes, receptors, and other enantiomeric biological entities. For example, triadimenol is a systemic fungicide and has four stereisomers due to the presence of two chiral centers in its molecule. Of the four, the (1S, 2R)-isomer shows the highest fungicidal activity (up to 1000 fold more active than the other three) [6]. However, most chiral pesticides are produced and formulated as racemic mixture even though the desired biological activity may be derived from only one enantiomer. It is therefore very important to be able to separate enantiomers of chiral pesticides in order to prepare single enantiomers, develop enantiomeric analysis methods and evaluate their bioactivity and environmental fates.

The Development and Application of Cellulose-Based Stationary Phases

more frequently used for the resolution of chiral compounds than the bonded CSPs. Some of these chiral columns can be selectively used in normal-phase HPLC (NP-HPLC), like Chiralcel OD, Chiralcel OA, Chiralcel OB, Chiralcel OC, Chiralcel OF, Chiralcel OG and Chiralcel OJ etc.; some can be used in reversed-phase HPLC (RP-HPLC), like Chiralcel OD-R, Chiralcel OZ-R and Chiralcel OJ-R; and some can be used in both NP-HPLC and RP-HPLC, like Lux Cellulose-1, Lux Cellulose-2 , Lux Cellulose-3, Lux Cellulose-4, Chiralpak IB and Chiralpak IC [9,10]. Some studies have been done to evaluate comparatively the enantioselective and chromatographic properties of Chiralcel OD and Chiralpak IB using a set of 48 compounds that differ in their physical and chemical properties [11]. The uses of these CSPs in different

mobile phases mainly depend on their different preparation methods.

[9,10]

CDMPC Chiralcel OD-H; ChiralcelOD; ChiralcelOD-RH; Chiralcel OD-R; Lux Cellulose-1; Kromasil CelluCoatTM

Commercial product

CTPC ChiralcelOC Coating

CFPC Chiralcel OF Coating

 Chiralcel OX-H; Lux Cellulose-4

Chiralcel OZ-H;

CTMB Chiralcel OJ-H; ChiralcelOJ; Chiralcel OJ-RH; Lux

Cellulose-3

Chiralcel OZ-RH; Lux Cellulose-2

CMPC ChiralcelOG Coating

Coating

Coating

Coating

Coating

H3C

H3C

H3C

H3C

H3C

H3C

ed name

No. Chemical name Shorten-

1 cellulose-*tris*-(3,5 dimethylphenylcarba

mate)

2 cellulose-*tris*-

3 cellulose-*tris*-(4 fluoro-

4 cellulose-tris(4 chloro-3-

5 Cellulose-tris(3 chloro-4-

6 cellulose-*tris*-(4-

7 cellulose-*tris*-(4 methylbenzoate)

ate)

ate

ate)

phenylcarbamate

phenylcarbamate)

methylphenylcarbam

methylphenylcarbam

methylphenylcarbam

in Stereoselective Separation of Chiral Pesticides 217

Type Chemical structure of cellulose derivative

O

OCONH

O

CH3

CH3 CH3

CH3

HNOCO OCONH

O

OCONH

O

O

O

O

O

HNOCO OCONH

HNOCO OCONH

O

O OOC CH3

COO OOC

Cl Cl

HNOCO OCONH

Cl Cl

O OCONH Cl

CH3

Cl

CH3

CH3

CH3

CH3

O OCONH Cl

O OCONH CH3

O OCONH CH3

HNOCO OCONH

Cl Cl

HNOCO OCONH

This work focuses mainly on a review of the development of cellulose derivatives for CSPs which are prepared as cellulose-based chiral columns by coating and bonding on supports, and their applications in stereoselective separations of chiral pesticides.
