CN102010283A - Method for preparing anion chiral ionic liquid - Google Patents

Abstract

The invention discloses a method for preparing anion chiral ionic liquid, which comprises the following steps of: reacting chiral carboxylate with a halogenated nitrogen heterocyclic salt in an organic solvent to generate the anion chiral ionic liquid and an inorganic alkali metal halogenated salt; and removing the halogenated salt through separation to obtain the anion chiral ionic liquid, wherein the minimum ratio is selected by measuring the dissolubility of the chiral carboxylate and the halogenated salt in the organic solvent in advance to obtain ratios, so the exchange temperature is determined, and the chiral carboxylate reacts with the halogenated nitrogen heterocyclic salt in the organic solvent at the temperature. The method is used for synthesizing the anion chiral ionic liquid by using a dissolubility ratio method. Because an appropriate temperature is selected, and the halogenated salt generated in the reaction has very low dissolubility in the organic solvent, the halogenated salt can be separated and removed easily to obtain the anion chiral ionic liquid with high purity.

Description

A kind of method for preparing the negatively charged ion chiral ionic liquid

Technical field

The present invention relates to a kind of preparation method of ionic liquid, a kind of method for preparing the negatively charged ion chiral ionic liquid.

Background technology

Ionic liquid is that a class contains organic functional group melting salt, and ionic liquid can be introduced various functional groups, realizes that ion liquid functionalization satisfies specific demand.The chiral organic micromolecule grafting is obtained the chirality ionic liquid to ionic liquid, become chiral catalyst or chiral solvent.Chiral organic micromolecule grafting ionic liquid connects with covalent linkage, becomes the positively charged ion chiral ionic liquid; Connect with ionic linkage, then become the negatively charged ion chiral ionic liquid.The negatively charged ion chiral ionic liquid is the strong novel chiral catalyzer of a class applicability.

Have at present bibliographical information acid-base neutralisation method Synthetic 20 seed amino acid be anionic chiral ionic liquid Ohno (J.Am.Chem.Soc.[J], 2005,127 (8): 2398-2399.) and the Lactated synthetic Sdeeon of chiral ionic liquid 1-butyl-3-methyl-imidazoles-L-(Green Chem.[J], 1999,1:232.).During acid-base neutralisation synthesis of chiral ionic liquid, in can utilizing and the time produce water sepn and obtain purer chiral ionic liquid, but range of application has certain limitation; And Sdeeon synthetic chiral ionic liquid 1-butyl-3-methyl-imidazoles-L-lactic acid salt purity can't be understood, and does not have the chiral ionic liquid of purity preferably also just can't understand the physical parameters such as specific rotatory power of this material.

Summary of the invention

The present invention is intended to propose a kind of method for preparing the chirality ionic liquid, and a kind of method for preparing the negatively charged ion chiral ionic liquid can obtain the higher chiral ionic liquid of purity.

This method for preparing the negatively charged ion chiral ionic liquid is: by measuring chiral carboxylic acids salt and the solubleness of inorganic base metal halide salt in organic solvent and getting ratio, select minimum ratio, thereby determine temperature of reaction, under this temperature, chiral carboxylic acids salt and halo nitrogen heterocyclic salt are reacted in organic solvent, generate negatively charged ion chiral ionic liquid and halide salt, separation is removed halide salt and is obtained the negatively charged ion chiral ionic liquid again.

Method of the present invention is a kind of method of using solubleness ratioing technigue synthetic anionic chiral ionic liquid, owing to selected suitable temperature, the solubleness of halide salt in organic solvent that reaction generates is very low, thereby more easily halide salt is separated and remove, and obtain the higher negatively charged ion chiral ionic liquid of purity.

Description of drawings

Fig. 1 is NaCl and Na[RHPA] solubleness in methyl alcohol;

Fig. 2 is NaCl and Na[RHPA] ratio of solubleness in methanol solvate;

Fig. 3 is KBr and K[PAL] solubleness in acetone;

Fig. 4 is KBr and K[PAL] ratio of solubleness in acetone;

Fig. 5 is NaCl and Na[RHPA] solubleness in methyl alcohol;

Fig. 6 is NaCl and Na[RHPA] ratio of solubleness in ketone;

Fig. 7 is KCl and K[PAL] solubleness in acetone;

Fig. 8 is KCl and K[PAL] ratio of solubleness in acetone.

Embodiment

Present method is by measuring positively charged ion and the solubleness of the corresponding salt of negatively charged ion in certain organic solvent of forming the negatively charged ion chiral ionic liquid, obtain two kinds of solubility of substances ratios then, and draw solubleness ratio curve, find out solubleness ratio temperature hour as the only temperature of carrying out ion-exchange this solvent from curve, use the exchange of chiral carboxylic acids salt and halo nitrogen heterocyclic reactant salt to produce negatively charged ion chiral ionic liquid and halide salt, remove halide salt by separation, obtain the negatively charged ion chiral ionic liquid.

Chirality organic carboxylate in present method is meant:

R represents the natural number of phenyl, n=1-3 in the formula, and Z represents amino and hydroxyl, and M represents sodium Metal 99.5 or potassium.

Halo nitrogen heterocyclic ionic liquid refers to a kind of material in following two kinds of structures:

R represents benzyl or CH in the formula ₃(CH ₂) _n, (n=3,4); X represents chlorine or bromine.

If the solubleness of used halide salt in used solvent is S _MX, the solubleness of used halo nitrogen heterocyclic salt in this solvent is S _RCOOM, both ratio is S ^*, i.e. S ^*=S _MX/ S _RCOOMRecord S through experiment ^*Value and the purity of product negatively charged ion chiral ionic liquid, and can set up degree of purity of production and S ^*Relational expression is as follows:

$(w\%)=\frac{1}{1+\mathrm{\αg}{\left(\frac{S_{\left[\mathrm{MX}\right]}}{S_{\left[\mathrm{RCOOM}\right]}}\right)}^2}=\frac{1}{1+\mathrm{\α}\×{\left(S^{*}\right)}^2}$

W% represents the mass percent of chiral ionic liquid in the product, and α is a constant, and is relevant with molecular weight.

As shown from the above formula, the purity of chiral ionic liquid is followed constant alpha and S in the product ^*Relevant, in suitable temperature and solvent, seek minimum S ^*, can make the higher negatively charged ion chiral ionic liquid of purity.Work as S ^*Less than 0.05 o'clock, the synthetic product purity can reach more than 98%.Therefore, select S ^*Solvent less than 0.05 and temperature with halo nitrogen heterocyclic ionic liquid and chiral carboxylic acids salt in organic solvent by ion-exchange synthetic anionic chiral ionic liquid, can obtain satisfied result.

This by measuring inorganic salt and the solubleness of organic salt in organic solvent, ratio and the ratio of solubleness and the relation of product purity by two kinds of solubleness, calculate synthesis of chiral anionic ion purity liquid, can when the chirality negatively charged ion is synthetic, in the selection of raw material and reaction parameter, use.

Embodiment 1

Preparation 1-benzyl-3-Methylimidazole-(-)-2-hydroxyl-4-benzenebutanoic acid salt

(1) raw material

(a) chirality organic carboxylate: selection (-)-2-hydroxyl-4-phenylbutyrate sodium (Na[RHPA]) (R=phenyl, n=2, Z=hydroxyl, M=sodium)

(b) halo nitrogen heterocyclic ionic liquid: selective chlorination-1-benzyl-3-Methylimidazole (R=benzyl, X=chlorine)

(2) preparation process

(a) parameter is selected: measure sodium-chlor and (the R)-2-hydroxyl-solubleness of 4-phenylbutyrate sodium in ethanol, draw solubility curve such as Fig. 1 of 15-65 ℃, obtain relation such as Fig. 2 of solubleness ratio and temperature, therefrom select S ^*=0.040, corresponding temperature of reaction is 65 ℃, therefore reacts under this temperature, and the theoretical purity that calculated by formula (I) this moment is 98.9%.

(b) operating process: in the 50ml there-necked flask, add ethanol 20ml, chlorination-1-benzyl-3-Methylimidazole 2.08g (0.01mol), (R)-2-hydroxyl-4-phenylbutyrate sodium 2.02g (0.01mol), stir 8h down at 65 ℃, filter out sodium-chlor, evaporate to dryness ethanol, process centrifugation device is with the small amount of solid Impurity removal in the liquid, obtain 1-benzyl-3-Methylimidazole-(-)-2-hydroxyl-4-benzenebutanoic acid salt, recording purity through chromatography of ions is 98.4%.

Embodiment 2

Preparation butyl-pyridinium-L-phenylalanine salt

(1) raw material

(a) chirality organic carboxylate: selection L-phenylalanine potassium (K[PAL]) (R=phenyl, n=1, Z=amino, M=potassium)

(b) halo nitrogen heterocyclic ionic liquid: select bromination butyl-pyridinium ([BP] Br) (R=butyl, X=bromine)

(2) preparation process

(a) parameter is selected: measure Potassium Bromide and the solubleness of L-phenylalanine potassium in acetone, draw solubility curve such as Fig. 3 of 5-50 ℃, obtain relation such as Fig. 4 of solubleness ratio and temperature, therefrom select S ^*=0.055, corresponding temperature of reaction is 5 ℃, therefore reacts under this temperature, and the theoretical purity that calculated by formula (I) this moment is 99.3%.

(b) operating process: in the 50ml there-necked flask, add ethanol 20ml, bromination butyl-pyridinium 2.08g (0.01mol), L-phenylalanine potassium 2.02g (0.01mol), stir 8h down at 5 ℃, filter out Potassium Bromide, evaporate to dryness ethanol, process centrifugation device is with the small amount of solid Impurity removal in the liquid, obtain butyl-pyridinium-L-phenylalanine salt, recording purity through chromatography of ions is 96.6%.

Embodiment 3

Preparation benzyl-pyridine-(-)-2-hydroxyl-4-benzenebutanoic acid salt

(1) raw material

(a) chirality organic carboxylate: selection (-)-2-hydroxyl-4-phenylbutyrate sodium (Na[RHPA]) (R=phenyl, n=2, Z=hydroxyl, M=sodium)

(b) halo nitrogen heterocyclic ionic liquid: selective chlorination benzyl-pyridine ([BnP] Cl) (R=butyl, X=chlorine)

(2) preparation process

(a) parameter is selected: measure sodium-chlor and (-)-2-hydroxyl-solubleness of 4-phenylbutyrate sodium in methyl alcohol, draw solubility curve such as Fig. 5 of 5-60 ℃, obtain relation such as Fig. 6 of solubleness ratio and temperature, therefrom select S ^*=0.400, corresponding temperature of reaction is 5 ℃, therefore reacts under this temperature, and the theoretical purity that calculated by formula (I) this moment is 46.9%.

(b) operating process: in the 50ml there-necked flask, add methyl alcohol 20ml, zephiran chloride pyridine 2.06g (0.01mol), (-)-2-hydroxyl-4-phenylbutyrate sodium 2.02g (0.01mol), stir 8h down at 5 ℃, filter out sodium-chlor, evaporate to dryness methyl alcohol, process centrifugation device is with the small amount of solid Impurity removal in the liquid, obtain benzyl-pyridine-(-)-2-hydroxyl-4-benzenebutanoic acid salt, recording purity through chromatography of ions is 44.6%.

Embodiment 4

Preparation 1-butyl-3-Methylimidazole-L-phenylalanine salt

(1) raw material

(a) chirality organic carboxylate: selection L-phenylalanine potassium (K[PAL]) (R=phenyl, n=1, Z=amino, M=potassium)

(b) halo nitrogen heterocyclic ionic liquid: selective chlorination-1-butyl-3-Methylimidazole (R=butyl, X=chlorine)

(2) preparation process

(a) parameter is selected: measure Repone K and the solubleness of L-phenylalanine potassium in acetone, draw solubility curve such as Fig. 7 of 5-50 ℃, obtain relation such as Fig. 8 of solubleness ratio and temperature, therefrom select S ^*=0.00015, corresponding temperature of reaction is 50 ℃, therefore reacts under this temperature, and the theoretical purity that calculated by formula (I) this moment is 99.9%.

(b) operating process: in the 50ml there-necked flask, add acetone 20ml, chlorination-1-butyl-3-Methylimidazole 1.75g (0.01mol), L-phenylalanine potassium 2.04g (0.01mol), stir 8h down at 50 ℃, filter out Repone K, evaporate to dryness acetone, process centrifugation device is with the small amount of solid Impurity removal in the liquid, obtain 1-butyl-3-Methylimidazole-L-phenylalanine salt, recording purity through chromatography of ions is 97.6%.

Claims (2)

1. method for preparing the negatively charged ion chiral ionic liquid, chiral carboxylic acids salt and halo nitrogen heterocyclic salt are reacted in organic solvent, generate negatively charged ion chiral ionic liquid and inorganic base metal halide salt, separation is removed halide salt and is obtained the negatively charged ion chiral ionic liquid again, it is characterized in that in advance by measuring chiral carboxylic acids salt and the solubleness of halide salt in organic solvent and getting ratio, select minimum ratio, thereby determine temperature of reaction, under this temperature, chiral carboxylic acids salt and halo nitrogen heterocyclic salt are reacted in organic solvent.

2. a kind of method for preparing the negatively charged ion chiral ionic liquid as claimed in claim 1, it is characterized in that the temperature of reaction of selecting be described halide salt in this solvent solubleness and the ratio of the solubleness of described halo nitrogen heterocyclic salt in this solvent less than 0.05.

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