Separating agent

Abstract

A mixture of chemical substances such as optical isomers, geometrical isomers and polymers having different molecular weight ranges is separated to each ingredient by use of a cellulose derivative having an aromatic ring in the chromatographic method.

Description

The invention will be illustrated below in reference to synthesis examples, examples and application examples. Each of the particular terms is defined below. $\begin{array}{c}\mathrm{volume}\⁢\⁢\mathrm{ratio}\⁢\⁢\left(k^{\text{'}}\right)=\⁢\frac{\left[\left(\mathrm{retention}\⁢\⁢\mathrm{time}\⁢\⁢\mathrm{of}\⁢\⁢\mathrm{antipode}\right)-\left(\mathrm{dead}\⁢\⁢\mathrm{time}\right)\right]}{\left(\mathrm{dead}\⁢\⁢\mathrm{time}\right)}\\ \mathrm{separation}\⁢\⁢\mathrm{factor}\⁢\⁢\left(\mathrm{\α}\right)=\⁢\frac{\left(\begin{array}{c}\mathrm{volume}\⁢\⁢\mathrm{ratio}\⁢\⁢\mathrm{of}\⁢\⁢\mathrm{antipode}\⁢\\ \mathrm{adsorbed}\⁢\⁢\mathrm{more}\⁢\⁢\mathrm{strongly}\end{array}\right)}{\left(\begin{array}{c}\mathrm{volume}\⁢\⁢\mathrm{ratio}\⁢\⁢\mathrm{of}\⁢\⁢\mathrm{antipode}\⁢\\ \mathrm{adsorbed}\⁢\⁢\mathrm{less}\⁢\⁢\mathrm{strongly}\end{array}\right)}\\ \mathrm{rate}\⁢\⁢\mathrm{of}\⁢\⁢\mathrm{separation}\⁢\⁢\left(\mathrm{Rs}\right)=\⁢\frac{\begin{array}{c}2\times (\mathrm{distance}\⁢\⁢\mathrm{between}\⁢\⁢a\⁢\⁢\mathrm{pair}\⁢\⁢\mathrm{of}\⁢\⁢\mathrm{more}\\ \mathrm{strongly}\⁢\⁢\mathrm{adsorbed}\⁢\⁢\mathrm{antipode}\⁢\⁢\mathrm{and}\⁢\⁢\mathrm{that}\\ \mathrm{of}\⁢\⁢\mathrm{less}\⁢\⁢\mathrm{strongly}\⁢\⁢\mathrm{adsorbed}\⁢\⁢\⁢\mathrm{antipode})\end{array}}{\left(\mathrm{total}\⁢\⁢\mathrm{band}\⁢\⁢\mathrm{width}\⁢\⁢\mathrm{of}\⁢\⁢\mathrm{both}\⁢\⁢\mathrm{peaks}\right)\⁢}\end{array}$

Synthesis Example 1

(Synthesis of Cellulose Benzoate)

{circle around (1)} Synthesis of low-molecular weight cellulose triacetate:

100 g of cellulose triacetate having a number-average degree of polymerization of 110 and a degree of acetylation of 2.94 was dissolved in 100 ml of acetic acid. 5.2 ml of water and 5 ml of concentrated sulfuric acid were added to the solution and the mixture was maintained at 80°C C. for 3 h to effect the reaction for obtaining a product of a lower molecular weight. After the completion of the reaction, the reaction mixture was cooled and sulfuric acid was neutralized with excess aqueous magnesium acetate solution. The solution was added to 3 l of water to precipitate cellulose triacetate of a low molecular weight. The precipitate was filtered through a G3 glass filter, dispersed in 1 l of water, further filtered and dried under vacuum. The obtained product was dissolved in methylene chloride and reprecipitated from 2-propanol. The dissolution and reprecipitation were repeated twice to purify the product, which was then dried.

From the IR and NMR spectra of the product, it was identified with cellulose triacetate. The number-average molecular weight of the product was 7900 (the degree of polymerization: 27) according to vapor pressure osmometry (Corona 117; chloroform/1% ethanol).

{circle around (2)} Synthesis of cellulose having a low molecular weight:

5.0 g of the low-molecular weight cellulose triacetate prepared as above was dissolved in 50 ml of pyridine. 4.0 ml of 100% hydrazine hydrate was added to the solution. The mixture was left to stand at room temperature for 1 h and then heated to 90°C to 100°C C. A precipitate thus formed was filtered through a glass filter and washed with pyridine. The product containing pyridine was used in the subsequent reaction.

{circle around (3)} Synthesis of low-molecular weight cellulose tribenzoate:

The low-molecular weight cellulose obtained as above was dispersed in a mixture of 50 ml of pyridine and 21 ml of triethylamine. 200 mg of 4-(dimethylamino)pyridine as catalyst was added to the dispersion. 11.6 ml of benzoyl chloride was added dropwise slowly to the mixture under stirring. The resulting mixture was left to stand at room temperature for 3 h and then kept at 120°C C. for 10 h to complete the reaction. The resulting pyridine solution was added to a large excess of methanol. A precipitate thus formed was filtered and washed with methanol. The product was dissolved in methylene chloride and reprecipitated from ethanol. This purification process was repeated three times.

From the IR and NMR spectra of the product, it was identified with cellulose tribenzoate. From the fact that no occurrence of acetylation was recognized in the NMR spectra after treating the product with acetic anhydride in pyridine, it may be concluded that the hydroxyl groups had been esterified into benzoate groups without leaving any free hydroxyl group intact.

Synthesis Example 2

(Synthesis of Packing for Use in the Optical Resolution)

{circle around (1)} Treatment of silica gel with silane:

10 g of silica beads (Lichrospher SI 1000: a product of Merck & Co.) was placed in a 200 ml round-bottom flask with a side arm. After vacuum-drying in an oil bath at 120°C C. for 3 h, the pressure was returned to atmospheric pressure, the temperature was lowered to room temperature and N₂ was introduced therein. 100 ml of toluene which had been preliminarily distilled was added to the dry silica beads. 3 ml of diphenyldimethoxysilane (KBM 202; a product of Shin'etsu Kagaku Co., Ltd.) was added to the mixture and they were stirred together and then reacted at 120°C C. for 1 h. After distilling off 3 to 5 ml of toluene, the reaction was carried out at 120°C C. for 2 h. The mixture was filtered under suction through a glass filter (G-4), washed with 50 ml of toluene three times and then with 50 ml of methanol three times and dried in vacuum at 40°C C. for 1 h.

About 10 g of the silica beads treated as above were placed in the 200 ml round-bottom flask with a side arm. After vacuum drying at 100°C C. for 3 h, the pressure was returned to the atmospheric pressure and the mixture was cooled to room temperature. Then, N₂ was introduced therein.

100 ml of distilled toluene was added to the dried silica beads. 1 ml of N,O-bis(trimethylsilyl)acetamide (a trimethylsilylating agent) was added thereto and the mixture was stirred to effect the reaction at 115°C C. for 3 h.

The reaction mixture was filtered through a G-4 glass filter, washed with toluene and dried under vacuum for about 4 h.

{circle around (2)} Coating

1.6 g of the cellulose benzoate obtained in Synthesis Example 1 was dissolved in 10.0 ml of methylene chloride and the solution was filtered through a G-3 glass filter.

3.5 g of the silica gel treated with silane was mixed with 7.5 ml of said cellulose benzoate solution and the solvent was distilled off under reduced pressure.

Example 1

The silica gel packing coated with cellulose benzoate obtained in Synthesis Example 2 was packed in a stainless steel column having an inner diameter of 0.46 cm and a length of 25 cm by a slurry method (solvent: methanol). Various racemic compounds were optically resolved according to high-performance liquid chromatography using this column to obtain the results shown in FIGS. 1 and 2 and Table 1.

The symbols (+ and -) in the figures and the table refer to the signs of optical rotation at 365 nm.

FIG. 1 is an optical resolution chart of trans-stilbene oxide

FIG. 2 is an optical resolution chart of a cyclobutane derivative:

TABLE 1
Optical resolution of racemic compounds
	Volume		Rate of
	ratio	Separation	separation
Racemic compounds	k'1	k'2	factor α	(Rs)
trans-stilbene oxide	0.71	1.00	1.4	2.2
	(+)	(-)
2-phenylcyclohexane	0.99	1.14	1.2	0.98
	(-)	(+)
cyclobutane derivative	0.42	0.64	1.5	0.97
	(+)	(-)
benzoin	0.53	0.58	1.1	--
	(+)	(-)
(Notes)
Column: 25 cm × 0.46 cm
Flow rate: 0.2 ml/min. solvent: ethanol.

Comparative Example 1

140 g of cellulose triacetate produced by an ordinary homogeneous acetylation process (number-average degree of polymerization as determined by vapor pressure osmometry: 110; molecular weight distribution {overscore (Mw)}/{overscore (Mn)}=2.45, free hydroxyl group content: 0.35%) was swollen in 1.4 l of acetic acid (a guaranteed reagent of Kanto Kagaku Co.). 23.2 ml of acetic anhydride, 7.0 ml of sulfuric acid and 8.4 ml of water were added thereto and the reaction was carried out at 80°C C. for 3 h. The reaction mixture was cooled with ice/water and sulfuric acid was neutralized with 86.8 g of 26% aqueous magnesium acetate solution. A solution thus obtained was added to a solvent mixture of water/2-propanol to precipitate cellulose acetate which was then filtered and dried. The obtained cellulose acetate was dissolved in acetone. An insoluble matter was filtered out under pressure. Water was added to the residue in such an amount that no precipitate would be formed. The solvent was distilled off with a rotary evaporator. A white powder thus obtained was dried under reduced pressure.

From the results of X-ray diffractometry, it was found that the resulting crystalline cellulose acetate had a crystallinity of 46% and a half width of 0.58°C. The average degree of polymerization determined based on the viscosity in a solvent mixture of methanol/methylene chloride (1:1) was 23. The free hydroxyl group content of the product was 0.8%. According to electron microscope observation, the product was in the form of porous particles having a diameter of 1 to 10μ. The resolution was effected in the same manner as in Example 1 except that the triacetylcellulose was packed by slurry process using methanol as the solvent. Trans-stilbene oxide had a resolution factor α of 1.34 and a rate of separation (Rs) of 0.91. No peak separation was observed with 2-phenylcyclohexanone and benzoin.

Synthesis Example 3

Cellulose triacetate having a number-average degree of polymerization of 110 and a degree acetylation of 2.94 was dissolved in 1 l of acetic acid. 5.2 ml of water and 5 ml of conc. sulfuric acid were added to the resulting solution and the reaction was carried out at 80°C C. for 3 h. The reaction mixture was cooled and sulfuric acid was neutralized with an excess amount of an aqueous magnesium acetate solution. The resulting solution was added to 3 l of water to precipitate cellulose triacetate having a reduced molecular weight. After filtration through a glass filter (G3), it was dispersed in 1 l of water. After filtration followed by vacuum drying, the obtained product was dissolved in methylene chloride and reprecipitation from 2-propanol. The dissolution and the reprecipitation were repeated twice to effect the purification. The product was dried. According to the IR and NMR spectra, the product was identified as cellulose triacetate. The number-average molecular weight of the product as determined by vapor pressure osmometry was 7900, which corresponded to the number-average degree of polymerization of 27. The vapor pressure osmometry was conducted with a vapor pressure osmometer Corona 117 using a solvent mixture of chloroform/1% ethanol.

10.0 g of the resulting low-molecular weight cellulose triacetate was dissolved in 100 ml of pyridine. 8.0 ml of 100% hydrazine hydrate was added to the solution. The mixture was left to stand at room temperature for 1 h and then heated to 90°C to 100°C C. A precipitate thus formed was filtered through a glass filter and washed with pyridine. According to the IR spectrum, the resulting product was identified as cellulose.

Cellulose tribenzyl ether was synthesized from the resulting low-molecular weight cellulose by successive processes of Husemann et al. [Markromol. Chem., 176, 3269 (1975)]. The product was identified according to NMR and IR spectra. In the IR spectrum, no absorption due to the hydroxyl group was recognized at all. This fact suggested that the degree of substitution was about 3.

NMR (CDCl₃): δ7.1 (multiplets) 15H δ5.3∼2.8 (multiplets) 13H.

IR (KBr disc.): 1950(w), 1870(w), 1805(w), 1740(w), 1605(m), 1500(m), 740(s), 700(s) all due to the substituted benzene ring. 1050∼1100(vs) due to the glycoside bond

Synthesis Example 4

10 g of silica beads (LiChrospher SI 1000; a product of Merck & Co.) was placed in a 200 ml round-bottom flask with a side arm. After vacuum-drying in an oil bath at 120°C C. for 3 h, N₂ was introduced therein. 100 ml of toluene which had been preliminarily distilled in the presence of CaH₂ was added to the silica beads. 3 ml of diphenyldimethoxysilane (KBM 202; a product of Shin'etsu Kagaku Co., Ltd.) was added to the mixture and they were stirred together and then reacted at 120°C C. for 1 h. After distilling off 3 to 5 ml of toluene, the reaction was carried out at 120°C C. for 2 h. The mixture was filtered through a glass filter, washed with 50 ml of toluene three times and then with 50 ml of methanol three times and dried in vacuum at 40°C C. for 1 h.

About 10 g of the silica beads were placed in the 200 ml round-bottom flask with a side arm. After vacuum drying at 100°C C. for 3 h, the pressure was returned to the atmospheric pressure and the mixture was cooled to room temperature. Then, N₂ was introduced therein. 100 ml of distilled toluene was added to the dried silica beads. 1 ml of N,O-bis(trimethylsilyl)acetamide (a trimethylsilylating agent) was added thereto and the mixture was stirred to effect the reaction at 115°C C. for 3 h. The reaction mixture was filtered through a glass filter, washed with toluene and dried under vacuum for about 4 h.

Tribenzylcellulose obtained in Synthesis Example 3 was dissolved in chloroform. Methanol in an amount four times as much as chloroform was added to the solution to divide it into a soluble part and an insoluble part. 1.2 g of the soluble part was dissolved in a solvent mixture of methylene chloride and benzene (5 ml:2.5 ml). 6 ml of the resulting solution was mixed with 3.2 g of silane-treated silica gel. The solvent was distilled off under reduced pressure. The resulting silica beads were used as a packing for use in the optical resolution.

Example 2

The silica beads carrying tribenzylcellulose obtained in Synthesis Example 4 were packed in a stainless steel column having a length of 25 cm and an inner diameter of 0.46 cm by slurry process. The high-performance liquid chromatograph used was Trirotar-SR (a product of Nihon Bunko Kogyo Co., Ltd.) and the detector used was Uvidec-V. The flow rate was 0.2 ml/min and ethanol was used as the solvent. The results of resolution of various racemic compounds are shown in Table 2.

TABLE 2
Optical resolution of racemic modifications
	Volume		Rate of
	ratio	Separation	separation
Racemic compound	k'1	k'2	factor α	(Rs)
	0.75	0.99	1.32	1.50
	0.66	0.99	1.46	1.12

Synthesis Example 5

1 g of cellulose (cellulose for column chromatography; a product of Merck & Co.) was dispersed in 50 ml of dry pyridine. 8 ml of phenyl isocyanate was added to the dispersion and the mixture was kept stirred at 110°C C. After 16 h, the reaction mixture was poured into 1 l of methanol. A white solid thus formed was filtered and dried at room temperature for 2 h and then at 60°C C. for 3 h under reduced pressure. Yield: 1.45 g.

The product was substantially completely soluble in chloroform, methylene chloride and dioxane. The product was identified with cellulose trisphenylcarbamate according to the IR and NMR spectra. The degree of polymerization as determined according to GPC was 200.

Elementary analysis: C, 60.93%; H, 4.68%; N, 7.93%; calculated for (C₂₇H₂₅N₃O₈)_n: C, 62.42%; H, 4.85%; N, 8.09%.

Synthesis Example 6

102 g of silica gel (Lichrospher SI 4000; a product of Merck & Co.) was dried at 180°C C. for 2 h and then dispersed in a mixture of 600 ml of dry benzene, 6 ml of pyridine and 20 ml of 3-aminopropyltriethoxysilane to effect the reaction under reflux for 16 h. After the completion of the reaction, the reaction mixture was poured into 2 l of methanol and the modified silica gel was filtered.

0.76 g of the cellulose trisphenylcarbamate obtained in Synthesis Example 5 was dissolved in a solvent mixture of 10 ml of dioxane and 5 ml of ethanol. After removing a very small amount of an insoluble matter, 3.0 g of the modified silica gel was mixed with 5 ml of the solution and the solvent was distilled off under reduced pressure. This carrying process was repeated further twice to obtain cellulose trisphenylcarbamate-carrying silica gel.

Example 3

The carrying silica gel prepared in Synthesis Example 6 was packed in a stainless steel column having a length of 25 cm and an inner diameter of 0.46 cm by slurry process. The high-performance liquid chromatograph used was Trirotar-II (a product of Nihon Bunko Kogyo Co., Ltd.) and detector used as Uvidec-III and DIP-181 polarimeter. The solvents used were (1) hexane/2-propanol (mixing volume ratio: 90/10), (2) hexane/2-propanol (80:20), (3) hexane/2-propanol/diethylamine (80:20:0.001), (4) ethanol/water (50:50) and (5) ethanol/water (70:30). The flow rate was 0.5 ml/min and column temperature was 25°C C. in all the cases.

The results of the resolution of various racemic compounds are shown in Tables 3-1 to 3-4 and those of the separation of achiral compounds are shown in Table 4.

Measurement of molecular weight

The molecular weight was determined by GPC method using a calibration curve of standard polystyrene. The GPC column used was Shodex A 80M and the solvent was tetrahydrofuran.

TABLE 3
Optical resolution with cellulose
trisphenylcarbamate
		k'1 (optical
		rotatory
Racemic compound	Eluenta	power)b	α	RS
	1	1.92	1.46	1.27
	1	3.64	1.20	--
	1	0.65	1.88	1.06
	1	2.39	1.23	0.77
	1	1.32	1.13	0.58
	1	1.42	1.47	1.38
	1	6.38	1.19	0.97
	1	5.92	1.95	3.36
	1	0.58(+)	1.53	2.00
	1	1.02	1.39	1.73
	1	2.06(-)	1.68	2.56
	1	3.67(-)	1.52	3.50
Cr(acac)3	1	2.00(-)	1.48	1.14
Co(acac)3	1	2.24(+)	1.31	0.75
	1	0.50(+)	3.09	2.26
	2	1.07(+)	1.08	0.53
	3	6.38(-)	1.24	1.07
	4	4.27(-)	1.22	0.86
	4	5.35(+)	1.12	--
	4	11.3(+)	1.36	1.74
	4	6.70(+)	1.17	0.85
	5	0.49(-)	1.13	--
	5	1.85(+)	1.31	1.58
	5	1.30(+)	1.21	0.9
	5	0.85(+)	1.27	0.68
aeluent 1: hexanes/2-propanol (90/10)
eluent 2: hexanes/2-propanol (80/20)
eluent 3: hexanes/2-propanol/diethylamine (80:20:0.001)
eluent 4: ethanol/water(50:50)
eluent 5: ethanol/water(70:30)
bwavelength: 365 am

TABLE 4

Separation of achiral compounds
with cellulose trisphenylcarbamatea
           Retention time
Compound   (min)

           6.30

           6.80

           6.90

           7.60

           8.33

           8.65

           8.95

           10.05

           15.25

           16.30

CH3COOC2H5 8.85
CH3COCH3   9.75
Et3N       6.75
Et3NH      7.70

aeluent: hexane/2-propanol (80:20)

Synthesis Example 7

Cellulose triacetate having a number-average degree of polymerization of 110 and a degree of acetylation of 2.49 was dissolved in 1 l of acetic acid. 5.2 ml of water and 5 ml of conc. sulfuric acid were added to the resulting solution and the reaction was carried out at 80°C C. for 3 h. The reaction liquid was cooled and sulfuric acid was neutralized with an excess amount of an aqueous magnesium acetate solution. The resulting solution was added to 3 l of water to precipitate cellulose triacetate having a reduced molecular weight. After filtration through a glass filter (G 3), it was dispersed in 1 l of water. After filtration followed by vacuum drying, the obtained product was dissolved in methylene chloride and then reprecipitated from 2-propanol. The dissolution and the reprecipitation were repeated twice to effect the purification. The product was dried. According to the IR and NMR spectra, the product was identified with cellulose triacetate. The number-average molecular weight of the product as determined by vapor pressure osmometry was 7900 which corresponded to the number-average degree of polymerization of 27. The vapor pressure osmometry was conducted with a vapor pressure osmometer Corona 117 using a solvent mixture of chloroform/1% ethanol.

10.0 g of the resulting low-molecular weight cellulose triacetate was dissolved in 100 ml of pyridine. 8.0 ml of 100% hydrazine hydrate was added to the solution. The mixture was left to stand at room temperature for 1 h and then heated to 90°C to 100°C C. A precipitate thus formed was filtered through a glass filter and washed with pyridine. According to the IR spectrum, the obtained product was identified with cellulose.

100 ml of dry pyridine was added to a mixture of 5 g of the resulting low molecular weight cellulose and a small amount of pyridine to obtain a dispersion. 100 ml of benzene was added to the dispersion to remove water. After distillation through a rectifier tube, the remaining suspension of the low molecular weight cellulose in pyridine was heated to 60°C to 70°C C. 16.3 ml of phenyl isocyanate was added dropwise to the suspension under stirring. The mixture was kept at 100°C to 105°C C. for 3 h 35 min. Pyridine and phenyl isocyanate were distilled off under reduced pressure and the reaction mixture was dissolved in methylene chloride. A by-product insoluble in methylene chloride was filtered out through a glass filter (G 3) and a soluble matter was fractionated with 2-propanol. The 2-propanol-insoluble product was obtained in an amount of 5.67 g as a light yellow solid. According to the IR and NMR spectra, the product was identified as cellulose trisphenylcarbamate.

IR spectrum: 3500 cm^-1(ν_NH), 3300^-1cm(ν_NH), 1700 cm^-1(ν_c=0), 1530 cm^-1(ν_NH),

NMR spectrum: 18 H Broad singlet centered at δ7 7 H multiplets δ6.0∼3∅

Synthesis Example 8

Silica gel (Lichrospher SI 1000, a product of Merck & Co.) was dried by heating to 120°C to 150°C C. in dry nitrogen stream for 2 to 10 h. 20 g of the dried silica gel was suspended in 100 ml of anhydrous benzene. 6 g of 3-aminopropyltrimethoxysilane was added thereto and the mixture was heated under reflux in dry nitrogen stream. While removing formed methanol from the reaction system, the reaction was carried out for 5 to 10 h. After the completion of the reaction, the reaction mixture was cooled to room temperature and filtered through a glass filter. The resulting modified silica gel was washed with anhydrous benzene and dried at 40°C C. in vacuum.

6 g of the silica gel treated with the aminopropylsilane was dried at 80°C C. under reduced pressure for 2 h and then dispersed in 50 ml of dry methylene chloride. 2 ml of triethylamine and 1 ml of phenyl isocyanate were added to the dispersion and mixed well. The mixture was left to stand for one day and then heated to 40°C C. for 1 h. The solvent was removed by decantation and the residue was washed with methylene chloride, ethanol and acetone and dried.

0.9 g of cellulose trisphenylcarbamate obtained in Synthesis Example 7 was dissolved in 4.5 ml of methylene chloride. The resulting solution was mixed with 3.5 g of the modified silica gel. The solvent was distilled off under reduced pressure to obtain a cellulose trisphenylcarbamate-carrying silica gel.

Example 4

The silica gel carrying cellulose trisphenylcarbamate obtained in Synthesis Example 8 was packed in a stainless steel column having a length of 25 cm and an inner diameter of 0.46 cm by slurry method. The high-performance liquid chromatograph used was Trirotar-SR (a product of Nihon Bunko Kogyo Co., Ltd.) and the detector used was Uvidec-V. The flow rate was 0.2 ml/min and hexane/2-propanol (9:1) was used as the solvent. The results of resolution of various racemic compounds are shown in Table 5.

TABLE 5
Optical resolution of racemic compounds
	Volume	Resolution	Rate of
	ratio	factor	separation
Racemic compound	k'1	k'2	α	Rs
	1.13	1.39	1.23	1.89
	2.18	2.60	1.19	1.30
	4.50	5.60	1.24	0.90
	2.33	2.70	1.16	0.5
	11.9	13.3	1.12	--

Synthesis Example 9

10 g of silica beads (Lichrospher SI 1000; a product of Merck & Co.) was placed in a 200 ml round-bottom flask with a side arm. After vacuum-drying in an oil bath at 120°C C. for 3 h, N₂ was introduced therein. 100 ml of toluene which had been preliminarily distilled in the presence of CaH₂ was added to the silica beads. 3 ml of diphenyldimethoxysilane (KBM 202; a product of Shin'etsu Kagaku Co., Ltd.) was added to the mixture and they were stirred together and then reacted at 120°C C. for 1 h. After distilling off 3 to 5 ml of toluene, the reaction was carried out at 120°C C. for 2 h. The mixture was filtered through a glass filter, washed with 50 ml of toluene three times and then with 50 ml of methanol three times and dried in vacuum at 40°C C. for 1 h.

About 10 g of the silica beads were placed in the 200 ml round-bottom flask with a side arm. After vacuum drying at 100°C C. for 3 h, the pressure was returned to the atmospheric pressure and the mixture was cooled to room temperature. Then, N₂ was introduced therein. 100 ml of distilled toluene was added to the dried silica beads. 1 ml of N,O-bis(trimethylsilyl)acetamide (a trimethylsilylating agent) was added thereto and the mixture was stirred to effect the reaction at 115°C C. for 3 h. The reaction mixture was filtered through a glass filter, washed with toluene and dried under vacuum for about 4 h.

Synthesis Example 10

Cellulose triacetate (a product of Daicel Ltd.) having a number-average degree of polymerization of 110 and a degree of substitution of 2.97 was dissolved in 1 l of acetic acid (a product of Kanto Kagaku Co.). 5.2 ml of water and 5 ml of conc. sulfuric acid were added to the resulting solution and the reaction was carried out at 80°C C. for 3 h. The reaction mixture was cooled and sulfuric acid was neutralized with an excess amount of an aqueous magnesium acetate solution. The resulting solution was added to 3 l of water to precipitate cellulose triacetate having a reduced molecular weight. After filtration through a glass filter (G3), it was dispersed in 1 l of water. After filtration followed by vacuum drying, the obtained product was dissolved in methylene chloride and reprecipitated from 2-propanol. The dissolution and the reprecipitation were repeated twice to effect the purification. The product was dried. According to the IR and NMR spectra, the product was identified with cellulose triacetate. The number-average molecular weight of the product as determined by vapor pressure osmometry was 7900, which corresponded to the number-average degree of polymerization of 27. The vapor pressure osmometry was conducted with a vapor pressure osmometer Corona 117 using a solvent mixture of chloroform/1% ethanol.

60 g of the obtained cellulose triacetate was dispersed in 200 ml of 2-propanol. 60 ml of 100% hydrazine hydrate (a product of Nakai Kagaku Co.) was added dropwise slowly to the dispersion under gentle stirring. The suspension was maintained at 60°C C. for 3 h and the resulting cellulose was filtered through a glass filter, washed with acetone repeatedly and vacuumdried at 60°C C. In the IR spectrum of the product, no absorption band due to the carbonyl group at around 1720 cm^-1 was observed and the IR spectrum coincided with that of cellulose.

Synthesis Example 11

70 ml of dehydrated pyridine, 7.7 ml of dehydrated triethylamine and 50 mg of 4-dimethylaminopyridine were added to 1.5 g of the cellulose obtained in Synthesis Example 10. 12.2 g of thiophene-2-carbonyl chloride was added to the mixture under stirring. The mixture was stirred at 100°C C. for 5 h to carry out the reaction. After cooling, the product was added to 400 ml of ethanol under stirring to form precipitates, which were filtered through a glass filter and then washed thoroughly with ethanol. After vacuum drying, the product was dissolved in 30 ml of methylene chloride. An insoluble matter was removed and the product was reprecipitated from 400 ml of ethanol. The precipitate was filtered and washed with ethanol. After removing the liquid, the product was dried.

Thus, 3.9 g of cellulose thiophene-2-carboxylate was obtained.

The product was dissolved in methylene chloride and the solution was applied on a sodium chloride tablet and dried. The infrared absorption spectrum of the product had the following characteristic absorption bands:

3100 cm^-1: stretching vibration of aroamtic C--H,

1720 cm^-1: stretching vibration of C═O of carboxylic acid ester

1360, 1420, 1520 cm^-1: stretching vibration of thiophene ring,

1260 cm^-1: stretching vibration of C--O of ester,

1060 to 1160 cm^-1: stretching vibration of C--O--C of cellulose, and

860 cm^-1: out-of-plane deformation vibration of disubstituted thiophene.

Substantially no absorption at around 3450 cm^-1 due to OH of cellulose was observed. This fact suggested that the product substantially comprised a trisubstituted compound. In the proton NMR spectrum determined in CDCl₃, the characteristic absorptions were as follows:

6.8 to 7.8 ppm: proton of thiophene ring,

2.8 to 5.4 ppm: protons of the cellulose ring and methylene in position 6.

The ratio of the thiophene ring proton to the cellulose proton was about 9:7, which coincided with that of the trisubstituted compound.

According to elementary analysis of the product, the sulfur content thereof was 19.40% which suggested that the product substantially comprised a trisubstituted compound.

Example 5

1.2 g of cellulose tris(thiophene-2-carboxylate) obtained in Synthesis Example 11 was dissolved in 7.5 ml of dichloromethane. The solution was filtered. The silica gel particles obtained in Synthesis Example 9 were impregnated with 7.5 ml of the resulting solution. The solvent was distilled off under reduced pressure to obtain powdery, supported material.

Application Example 1

The silica beads carrying cellulose tris(thiophene-2-carboxylate) obtained in Example 5 were packed in a stainless steel column having a length of 25 cm and an inner diameter of 0.46 cm by slurry process. The high-performance liquid chromatograph used was Trirostar-RS (a product of Nihon Bunko Kogyo Co., Ltd.) and the polarimeter detector was DIP-181 (a product of Nihon Bunko Kogyo Co., Ltd.). The results of the resolution of trans-stilbene oxide are shown in Table 6.

In the determination effected by using the polarimeter as the detector of the high-performance chromatograph, the terms were defined as follows: $I^{\text{'}}=\frac{\left(\begin{array}{c}\mathrm{time}\⁢\⁢\mathrm{required}\⁢\⁢\mathrm{for}\⁢\⁢\mathrm{attaining}\⁢\⁢\mathrm{the}\⁢\⁢\mathrm{top}\\ \mathrm{of}\⁢\⁢\mathrm{the}\⁢\⁢\mathrm{peak}\⁢\⁢\mathrm{of}\⁢\⁢\mathrm{antipode}\⁢\⁢\mathrm{with}\⁢\⁢\mathrm{the}\⁢\\ \mathrm{polarimeter}\⁢\⁢\mathrm{detector}\end{array}\right)-\left(\mathrm{dead}\⁢\⁢\mathrm{time}\right)}{\left(\mathrm{dead}\⁢\⁢\mathrm{time}\right)}$ $\mathrm{\β}=\frac{\left(I^{\text{'}}\⁢\⁢\mathrm{of}\⁢\⁢\mathrm{antipode}\⁢\⁢\mathrm{adsorbed}\⁢\⁢\mathrm{more}\⁢\⁢\mathrm{strongly}\right)}{\left(I^{\text{'}}\⁢\⁢\mathrm{of}\⁢\⁢\mathrm{antipode}\⁢\⁢\mathrm{adsorbed}\⁢\⁢\mathrm{less}\⁢\⁢\mathrm{strongly}\right)}$

	TABLE 6
					Flow rate
	Racemic compound	I1'	I2'	β	ml/min
		1.88	2.28	1.21	1.0
	Solvent: hexane/2-propanol (9:1)

Synthesis Example 12

(Synthesis of Cellulose Tris-3-Chlorobenzoate)

3.0 g of cellulose obtained in Synthesis Example 10 and 0.05 g of 4-dimethylaminopyridine (a product of Aldrich Chemical Company) were suspended in a liquid mixture of 50 ml of pyridine and 15 ml of triethylamine. 25 g of m-chlorobenzoyl chloride (a product of Aldrich Chemical Company) was added to the suspension and the mixture was kept at 100°C C. for 6 h. The reaction mixture was added to ethanol and the resulting precipitate was filtered, washed with ethanol repeatedly and vacuum-dried to obtain 9.1 g of a product. In the IR spectrum of the product, an absorption due to the ester bond (1740 cm^-1 and 1250 cm^-1) were remarkable but no absorption due to the O--H stretching vibration was recognized. This fact suggested that the product was a trisubstituted compound.

Synthesis Example 13

(Synthesis of Cellulose Tris-3,5-Dichlorobenzoate)

49.4 g of thionyl chloride and 0.21 g of pyridine were added to 20 g of 3,5-dichlorobenzoic acid and the mixture was refluxed for 20 hours. Excessive thionyl chloride was removed by distillation. Dry hexane was added to the residue and an insoluble matter was filtered out of the resulting solution and hexane was removed under reduced pressure. The remaining solution was crystallized. 3,5-Dichlorobenzoyl chloride was obtained quantitatively.

1.0 g of the cellulose obtained in Synthesis Example 10 was reacted with 11.6 g of 3,5-dichlorobenzoyl chloride in a mixture of 25 ml of pyridine, 4.3 ml of triethylamine and 50 mg of 4-dimethylaminopyridine at 100°C C. for 5 h. The reaction mixture was added to ethanol and the precipitated cellulose tris-3,5-dichlorobenzoate was filtered, washed with ethanol and vacuum-dried. In the IR spectrum of the product, an absorption characteristic to the ester group was recognized but no absorption at around 3500 cm^-1 due to free hydroxy group was recognized. It was thus concluded that the product was a trisubstituted compound.

Synthesis Example 14

(Synthesis of Cellulose Tris-4-Chlorobenzoate)

2.43 g of the cellulose obtained in Synthesis Example 10 was reacted with 15.75 g of 4-chlorobenzoyl chloride in a mixture of 50 ml of pyridine, 20 ml of triethylamine and 200 mg of 4-dimethylaminophridine under stirring at 110°C C. for 8 h. The product was added to 500 ml of methanol and the resulting precipitate was filtered, washed with water and then methanol and dissolved in benzene. The resulting solution was added to ethanol to purify the product by reprecipitation. The product was filtered and vacuum-dried. In the I.R. spectrum of the product, an absorption characteristic to the ester linkage was recognized but no absorption due to free hydroxyl group at around 3500 cm^-1 was recognized. It was thus considered that the product was a trisubstituted compound.

Example 6

1.2 g of cellulose tris(3-chlorobenzoate) obtained in Synthesis Example 12 was dissolved in 7.5 ml of dichloromethane. The silica beads obtained in Synthesis Example 9 were impregnated with 7.5 ml of the resulting solution. The solvent was removed under reduced pressure to obtain a powdery, supported material.

EXAMPLE 7

1.2 g of cellulose tris(3,5-dichlorobenzoate) obtained in Synthesis Example 13 was dissolved in 7.5 ml of dichloromethane. 3.2 g of silica beads obtained in Synthesis Example 9 were impregnated with 7.5 ml of the resulting solution. The solvent was removed under reduced pressure to obtain a powdery, supported material.

Example 8

Cellulose tris(4-chlorobenzoate) obtained in Synthesis Example 14 was supported on silica beads in the same manner as in Example 7 to obtain a powdery material.

Application Example 2

The silica beads carrying cellulose tris(3-chlorobenzoate) obtained in Example 6 were packed in a stainless steel column having a length of 25 cm and an inner diameter of 0.46 cm by a slurry process. The high-performance liquid chromatograph used was Trirotar-SR (a product of Nihon Bunko Kogyo Co., Ltd.) and the detector was UVIDEC-V. Various racemic compounds were resolved to obtain the results shown in Table 7.

TABLE 7
		Resolu-	Rate of	Flow
	Volume	tion	separa-	rate
Racemic	ratio	factor	tion	(ml/
compound	k1'	k2'	(α)	(Rs)	min)
	1.48	1.96	1.33	1.24	0.5
	5.97	7.50	1.26	1.05	0.5
	4.8	5.14	1.07	--	0.5
	10.9	12.0	1.10	--	0.5
Solvent: hexane/2-propanol (9:1)

Application Example 3

The silica beads carrying cellulose tris(3,5-dichlorobenzoate) obtained in Example 7 were packed in a stainless steel column having a length of 25 cm and an inner diameter of 0.46 cm by a slurry process. The high-performance liquid chromatograph used was Trirotar-SR (a product of Nihon Bunko Kogyo Co., Ltd.) and the detector was Uvidec-V. Various racemic compounds were resolved to obtain the results shown in Table 8.

TABLE 8
		Resolu-	Rate of	Flow
	Volume	tion	separa-	rate
Racemic	ratio	factor	tion	(ml/
compound	k1'	k2'	(α)	(Rs)	min)
	1.91	2.31	1.21	1.22	0.5
	5.36	7.16	1.33	1.71	0.5
	2.84	3.96	1.39	1.33	0.5
	5.99	7.37	1.23	1.54	0.5
Solvent: hexane/2-propanol (9:1)

Application Example 4

The silica beads carrying cellulose tris(4-chlorobenzoate) obtained in Example 8 were packed in a stainless steel column having a length of 25 cm and an inner diameter of 0.46 cm by a slurry process. The high-performance liquid chromatograph used was Trirotar-SR (a product of Nihon Bunko Kogyo Co., Ltd.) and the detector was Uvidec-V. Various racemic compounds were resolved to obtain the results shown in Table 9.

TABLE 9
		Resolu-	Rate of	Flow
	Volume	tion	separa-	rate
Racemic	ratio	factor	tion	(ml/
compound	k1'	k2'	(α)	(Rs)	min)
	1.69	2.11	1.25	0.6	0.5
	1.61	2.03	1.27	0.6	0.5
Solvent: hexane/2-propanol (9:1)

Synthesis Example 15

70 ml of dry pyridine, 7.7 ml of dry triethylamine and 50 mg of 4-dimethylaminopyridine were added to 1.5 g of the cellulose obtained in Synthesis Example 10. 12.9 g of phenylacetyl chloride was added to the mixture under stirring and the reaction was carried out at 100°C C. for 5 h. After cooling, the product was added to 400 ml of ethanol under stirring to form a precipitate, which was filtered through a glass filter and washed thoroughly with ethanol. After drying in vacuum, the product was dissolved in 30 ml of methylene chloride to remove an insoluble matter and reprecipitated with 400 ml of ethanol. The precipitate was filtered and washed with ethanol. After dehydration followed by drying, 4.3 g of cellulose phenylacetate was obtained.

The product was dissolved in methylene chloride and the solution was applied on a plate of common salt and dried. The I.R. absorption spectrum of the product had the following characteristic absorption bands:

3050 cm^-1: C--H stretching vibration of the aromatic ring

1750 cm^-1: C═O stretching vibration of the carboxylic ester group

1610 cm^-1, 1500 cm^-1, 1460 cm^-1: skeletal vibration due to the C--C stretching of the benzene ring carbon atoms

1250 cm^-1: C--O stretching vibration of the ester group

1030∼1160 cm^-1: C--O--C stretching vibration of cellulose

690∼900 cm^-1: out-of-plane deformation vibration of the benzene ring

Substantially no absorption due to OH of the cellulose at around 3450 cm^-1 was recognized. The product was substantially a trisubstituted compound. Its proton NMR spectrum in CDCl₃ had the following characteristic resonances:

6.0 to 7.8 ppm: proton of the benzene ring

3 to 4 ppm: methylene proton of the phenylacetyl acid group

3 to 5.4 ppm: protons of the cellulose ring and methylene on position 6.

Example 9

1.2 g of the product obtained in Synthesis Example 15 was dissolved in 7.5 ml of dichloromethane. The silica gel beads obtained in Synthesis Example 9 were impregnated with 7.5 ml of the resulting solution. The solvent was distilled off under reduced pressure to obtain a powdery, supported material.

Application Example 5

The silica beads carrying cellulose trisphenylacetate obtained in Example 9 were packed in a stainless steel column having a length of 25 cm and an inner diameter of 0.46 cm by a slurry process. The high-performance liquid chromatograph used was Trirotar-RS (a product of Nihon Bunko Koguo Co., Ltd.) and the detector was Uvidec-V.

Tr/öger's base was resolved to obtain the results shown in Table 10.

TABLE 10
Optical resolution of various racemic compounds
	Volume		Flow
	ratio	Resolution	rate
Racemic compound	k'1	k'2	factor α	ml/min
	1.46	1.59	1.09	0.5
Solvent: hexane/2-propanol (9:1)

Claims

1. A separating agent which comprises a cellulose derivative selected from the group consisting of cellulose tribenzoate and cellulose tribenzoate ring-substituted with alkyl, alkenyl, alkynyl, nitro, halogen, amino, alkyl-substituted amino, cyano, hydroxyl, alkoxy, acyl, thiol, sulfonyl, carboxyl or alkoxy carbonyl, said cellulose derivative being supported on a porous carrier having a particle size of from 1 micron to 10 millimeters and a pore size of from 10 Angstrom units to 100 microns.

2. A separating agent as claimed in claim 1 in which said cellulose derivative is cellulose tribenzoate.

3. A separating agent as claimed in claim 1, wherein the amount of said cellulose derivative supported on said carrier is from 1-100 wt.% based on the weight of the carrier.

4. A separating agent as claimed in claim 1, wherein the ratio of pore size to particle size of said carrier is not larger than 0.1:1.

5. A separating agent as claimed in claim 1, wherein said carrier is an inorganic substance selected from the group consisting of silica, alumina, magnesia, titanium oxide, glass, silicate and kaolin.

6. A separating agent as claimed in claim 1, wherein said carrier is an organic substance selected from the group consisting of polystyrene, polyacrylamide and polyacrylate.

7. A separating agent as claimed in claim 1 in which said cellulose derivative is coated on said carrier and has been prepared by mixing said carrier with a solution of said cellulose derivative in a solvent therefor, and then removing said solvent.

8. A separating agent as claimed in claim 1, in which said carrier is an inorganic substance.

9. A separating agent as claimed in claim 8, in which said inorganic substance is silica gel.

10. A chromatographic isomer separating agent comprising a derivative of cellulose selected from the group consisting of cellulose tribenzoate and cellulose tribenzoate ring-substituted with alkyl, alkenyl, alkynyl, nitro, halogen, amino, alkyl-substituted amino, cyano, hydroxyl, alkoxy, acyl, thiol, sulfonyl, carboxyl or alkoxy carbonyl having a number average degree of polymerization in the range of 5-5000 supported on a solid carrier having a particle size of from 1 micron to 10 millimeters.

11. A chromagraphic isomer separating agent as claimed in claim 10 in which said cellulose derivative is cellulose tribenzoate.

12. A chromagraphic isomer separating agent as claimed in claim 10 in which said cellulose derivative is cellulose tris(3-chlorobenzoate).

13. A chromagraphic isomer separating agent as claimed in claim 10 in which said cellulose derivative is cellulose tris(3,5-dichlorobenzoate).

14. A chromagraphic isomer separating agent as claimed in claim 10 in which said cellulose derivative is cellulose tris(4-chlorobenzoate).

15. A chromatographic isomer separating agent as claimed in claim 10, wherein said cellulose derivative is immobilized on solid carrier particles, wherein said carrier particles are from 1 μm-10 mm in diameter and the amount of said cellulose derivative supported is from 1-100 wt.% based on the weight of the carrier particles.

16. A chromatographic isomer separating agent as claimed in claim 15 wherein said carrier particles are porous and have pore diameters of from 10 Å-100 μm.

17. A chromatographic isomer separating agent as claimed in claim 16, wherein said carrier particles have an approximate pore size to particle size ratio of no greater than 0.1:1.

18. A chromatographic isomer separating agent as claimed in claim 15, wherein said carrier is an inorganic substance selected from among silica, alumina, magnesia, titanium oxide, glass, silicate and kaolin.

19. A chromatographic isomer separating agent as claimed in claim 15, wherein said carrier is silica gel.

20. A chromatographic isomer separating agent as claimed in claim 15, wherein said carrier is an organic substance selected from the group consisting of polystyrene, polyacrylamide and polyacrylate.

21. In a chromatographic column used in the chiral separation of a chemical substance from a mixture containing the same, the improvement comprising said column containing a porous carrier having a pore size of 50 to 50,000 Å and supported thereon a cellulose derivative separating agent consisting of cellulose having a ring-substituted or unsubstituted phenyl group attached thereto through a urethane group, the separating agent being in a dissolved state during the supporting thereof on the carrier.

22. The column of claim 21, wherein said carrier has a particle size of about 1 μm to about 10 mm.

23. The column of claim 21, wherein said separating agent is cellulose trisphenylcarbamate.

24. The column of claim 21, wherein said phenyl group is ring-substituted with a group selected from among an alkyl group and a halogen group.

25. The column of claim 24, wherein said phenyl group is ring-substituted with an alkyl group.

26. The column of claim 24, wherein said phenyl group is ring-substituted with a halogen group.

27. The column of claim 26, wherein said halogen group is chloro.

28. The column of claim 21, wherein said porous carrier is silica.