Acetylated Cellulose Powder

Applications. Acetylated cellulose powder is in principle suitable for separation of all lipophilic substances. Separation alone is not enough however the separated substances must be detectable. This fact has been responsible for the relatively modest extent of application of Ac-cellulose layers. They may be recommended for coloured substances and for those which are detectable in UV light. Some examples of use are separation of polynuclear aromatic compounds [31, 309, 357, 599, 600, 755], anthraquinone dyes [768], antioxidants [596], cutin acids [98], sweetening materials [595], rhodanine derivatives of acetoacetic acid and acetone in urine [574] and ketocarboxylic acids [575]. 

On the other hand, Salo [80] has separated numerous p-hydroxybenzoates (C1--C12) on mixed layers of polyamide powder (Firm 153) and acetylated cellulose powder (Firm 83) (90 + 10), using Shell Sol A-acetic acid (83 + 17) as solvent. 

Salo and co-workers have separated artificial sweeteners on mixed layers of acetylated cellulose and polyamide [82]. A good separation of dulcin (hi / 66), saccharin (47) and cyclamate (28) was possible using the solvent Shell Sol A-n-propanol-acetic acid-formic acid (75 + 10 + 12 + 3). Rhodamine B (Rgt. No. 220) or dichlorofluorescein (Rgt. No. 63) were used for detection. The layers were prepared from 9 g acetylated cellulose powder (MN 300 Ac, Firm 83) and 6 g polyamide powder for TLC (Firm 153). These were mechanically mixed into a homogeneous suspension with 60 ml methanol and then spread the layers were dried for 10 min at 70° C. A 10 cm run took about 25 min at chamber saturation. 

To obtain individual sialic acids in pure, or almost pure, form, the sialic acid mixture obtained from the procedures just described are subjected to partition chromatography on cellulose powder, using, as the solvent,74107 1 2 1 (v/v/v) 1 -butanol-l-propanol-water. The (less hydrophilic) tri- and di-O-acetylated sialic acids are eluted first, followed by mono-O-acetylated sialic acids, NeuoAc, and Neu5Gc, ac-... 

Powdered carboxymethyl cellulose and acetyl cellulose showed... 

A 0.5 M standard solution of silyiated xanthine (22 mL, 11 mmol), l-0-acetyl-2,3,5-tri-(9-benzoyl-/5-D-ri-bofuranose (5.04 g, 10 mmol) in anhyd 1,2-dichloroethane (80 raL) were refluxed for 1 h with a standard solution of TMSOTf (17.5 raL, 12 mmol). After dilution with CH Clj and the usual workup, the crude product (6.18 g) showed on TI.C besides the main product (Rj- = 0.38) a number of minor faster moving spots. After saponification with methanolic NHj (200 mL) for 3 d at 24°C and standard workup, concentration of the aqueous phase afforded in 6 crops 0,95 g of pure xanthosine. The mother liquor was evaporated with cellulose powder (2 g) and chromatographed (Avicel, 40 g, MeOH). After a forerun of 250 mL, the next fractions (350 raL) eluted a further 0,43 g of xanthosine. Combined yield of xanthosine 1.38 g (49%). 

The overall method on which most of the preparation of immunoadsorbent is based is that of Gurvich et al. (Fig. 4). The initial preparation of cellulose powder can be carried out by refluxing cotton wool with ethanol and acetyl chloride. However, a more convenient alternative is to use commercially available microgranular cellulose (Whatman Ltd., Springfield MUl, Maidstone, Kent). Five grams of cellulose are suspended in 20 ml of 90% ethanol containing 0.5 g of sodium acetate and 1.4 g of nitrobenzyloxymethyl pyridinium chloride (British Drug House, Poole, Dorset, U.K.). Sodium acetate is dissolved first in 2 ml of water, and the... 

The formation of the A-oxide was avoided when trifluoroperacetic acid was reacted with the trifluoroacetate of acetyltropenol (67a, b). Recently it has been shown that hydrogen peroxide in formic acid gave a still better yield of epoxides without detectable A-oxides (67b). Acetylscopine (LXV) has been isolated as the picrate, (m.p. 212°) (67a), identical with the sample obtained from scopine (XLa) (75) hydrochloride by acetyl chloride (67a). The conversion of acetylscopine into ( ) scopolamine (LXV->XLb) has been realized (67b). Hydrolysis with A NaOH in acetone led to scopine (XLa), the hydrochloride of which was acylated, in turn, with acetyltropoyl chloride in nitrobenzene to acetylscopolamine besides a number of by-products. Separation was achieved using cellulose powder chromatography in butanol-A HCl. Acid hydrolysis of this ester with 2A HCl led to ( ) scopolamine hydrochloride (XLb) (67b) identical with the natural... 

It has become apparent that, in addition to the known disadvantages of loosely spread layers, the solvents quoted [71, 82] cannot necessarily be used without difficulty. The possibilities of separating numerous dyes, using TLC, have been subsequently investigated. Along with siUca gel G and alumina G and H (Firm 88), 1 1 mixtures of both, MN-cellulose powder, acetylated MN-cellulose powder (Ac) (Firm 83) and polyamide powder (Firm 153) have proved useful in thin-layer chromatographic separation. 

Native and microcrystalline cellulose precoated plates are used in the life sciences for the separation of polar compounds (e.g. carbohydrates, carboxylic acids, amino acids, nucleic acid derivatives, phosphates, etc) [85]. These layers are unsuitable for the separation of compounds of low water solubility unless first modified, for example, by acetylation. Several chemically bonded layers have been described for the separation of enantiomers (section 10.5.3). Polyamide and polymeric ion-exchange resins are available in a low performance grade only for the preparation of laboratory-made layers [82]. Polyamide layers are useful for the reversed-phase separation and qualitative analysis of phenols, amino acid derivatives, heterocyclic nitrogen compounds, and carboxylic and sulfonic acids. Ion-exchange layers prepared from poly(ethyleneimine), functionalized poly(styrene-divinylbenzene) and diethylaminoethyl cellulose resins and powders and are used primarily for the separation of inorganic ions and biopolymers. 

Poly(lactic acid) (PLA commercial grade 4042D Mw 390,000 Da) used in this research was obtained from NatureWorks LLC. Cellulose acetate (CA white powder Mw = 30,000 Da acetyl content = 39.7 wt% degree of acetyl substitution 2.4) was purchased from Sigma-Aldrich (Switzerland). Polyethylene glycol (PEG Mw 1,500 Da) was supplied from Scharlau Chemie S.A. Gentamicin sulfate (GS) was purchased from T.P. Drug Laboratories (1969) Co., Ltd. The solvents used in this work were dichloromethane (DCM) and N,N-dimethylformamide (DMF) from Lab scan (Asia) (Thailand). 

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