CN111747896B - Green mechanical synthesis method of 3,3' - (1,4-phenyl dimethylene) -bis (1-methylimidazole) metal salt - Google Patents
Green mechanical synthesis method of 3,3' - (1,4-phenyl dimethylene) -bis (1-methylimidazole) metal salt Download PDFInfo
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Abstract
The invention relates to a green mechanical synthesis method of 3,3' - (1,4-phenyl dimethylene) -bis (1-methylimidazole) metal salt. 1-methylimidazole and p-dichlorobenzyl are used as raw materials, and 3,3' - (1,4-phenyldimethylene) -bis (1-methylimidazole) chlorate (L) is synthesized by a grinding method under the condition of normal temperature and no solvent. 3,3' - (1,4-phenyl dimethylene) -bis (1-methylimidazole) chlorate (L) and metal chloride are used as raw materials, and a grinding method is utilized to prepare corresponding metal salt. The method has the advantages of convenient operation, low raw material cost, rapidness, high efficiency, no need of introducing a large amount of solvent, no need of heating in experiments, relative safety, high purity of the prepared target product and high yield.
Description
Technical Field
The invention belongs to the field of solid chemical synthesis, and particularly relates to a preparation method of precursor metal salts of an N-heterocyclic carbene ligand and an N-heterocyclic carbene metal complex, and provides a green synthesis method for rapidly preparing 3,3'- (1,4-phenyldimethylene) -bis (1-methylimidazole) chlorate (L) and 3,3' - (1,4-phenyldimethylene) -bis (1-methylimidazole) metal salt crystals at normal temperature.
Background
In organometallic chemistry, N-heterocyclic carbene ligands are one of the most important organic ligands and coordinate with most elements in the periodic table, such as Pb, pt, au, ag, ir, rh, cu, fe, co, ni, etc. The N-heterocyclic carbene molecule reacts with the metal compound to form a stable metal carbene complex. Due to its good electronic and steric properties, N-heterocyclic carbene complexes are widely used in the fields of catalysis, metallopharmaceuticals, materials science, and the like. On the basis of the above, the synthesis of N-heterocyclic carbene ligand complexes has attracted the attention of chemists. N-heterocyclic carbene metal hydrogen bond salt is also widely noticed as a precursor for synthesizing N-heterocyclic carbene complexes.
The N-heterocyclic carbene metal hydrogen bond salt is an Ionic Liquid (ILs) with thermal stability and non-flammability, and is an important precursor of a catalyst for other reactions such as cross-coupling reaction and the like. Most of the documents in recent years report little about the synthesis of precursor salts (metal hydrogen bond salts) of N-heterocyclic carbene complexes. The synthesis of the N-heterocyclic carbene complex and the N-heterocyclic carbene metal hydrogen bond salt is mostly solution synthesis, generally needs high temperature and high pressure, and also needs to be completed under the protection of nitrogen and argon, the reaction time is long, and the synthesis conditions are harsh. With the increase of environmental awareness of people after the 21 st century, a green and efficient synthesis method is particularly important in the chemical field.
Disclosure of Invention
The invention aims to provide a green synthesis method of 3,3' - (1,4-phenyl dimethylene) -bis (1-methylimidazole) chlorate and metal salt thereof. The method has the advantages of convenient operation, low cost of raw materials, rapidness, high efficiency, no need of introducing a large amount of solvents, no need of heating in experiments, relative safety, high purity of the prepared target product, high yield and the like.
The technical scheme adopted by the invention is as follows: 5363A green mechanical synthesis method of 3,3' - (1,4-phenyldimethylene) -bis (1-methylimidazole) metal salt, comprising the steps of: 3,3'- (1,4-phenyl dimethylene) -bis (1-methylimidazole) chlorate and metal chloride are used as raw materials, and grinding is carried out in a trace solvent to obtain 3,3' - (1,4-phenyl dimethylene) -bis (1-methylimidazole) metal salt.
Further, the green mechanical synthesis method, which is 3,3' - (1,4-phenyldimethylene) -bis (1-methylimidazole) chlorate, comprises the following steps: 1-methylimidazole and p-dichlorobenzyl are used as raw materials, a grinding method is utilized, a ball mill is adopted for grinding in the absence of a solvent, white solid powder is obtained, and a target product is obtained after purification.
Further, the green mechanical synthesis method comprises the step of synthesizing 1-methylimidazole p-dichlorobenzyl =2:1 in a molar ratio
Further, in the green mechanical synthesis method, the metal chloride is copper chloride, cobalt chloride or zinc chloride.
Further, the green mechanosynthesis method described above, in molar ratio, 3,3' - (1,4-phenyldimethylene) -bis (1-methylimidazole) chlorate metal chloride =1:1.
Furthermore, in the green mechanical synthesis method, the trace solvent is concentrated hydrochloric acid and CH 2 Cl 2 The mixed solvent of (1).
Furthermore, the green mechanical synthesis method comprises the steps of mixing concentrated hydrochloric acid and CH according to the volume ratio 2 Cl 2 ＝1:2-3。
Further, the green mechanical synthesis method comprises a recrystallization step: placing the obtained 3,3'- (1,4-phenyl dimethylene) -bis (1-methylimidazole) metal salt in an organic solvent, standing for 3-8h at room temperature to obtain a single crystal product of 3,3' - (1,4-phenyl dimethylene) -bis (1-methylimidazole) metal salt.
Further, in the green mechanical synthesis method, the organic solvent is a mixed solvent of methanol and acetonitrile.
Furthermore, the green mechanical synthesis method comprises the step of mixing methanol to acetonitrile =1:5 in a volume ratio.
In the invention, 1-methylimidazole and p-dichlorobenzyl are used as raw materials, and are ground and synthesized by a ball mill to obtain N-heterocyclic carbene compound 3,3' - (1,4-phenyl dimethylene) -bis (1-methylimidazole) chlorate (L); n-heterocyclic carbene compound 3,3' - (1,4-phenyl dimethylene) -bis (1-methylimidazole) chlorate (L) and copper chloride, cobalt chloride and zinc chloride are used as raw materials, and solid grinding is carried out to obtain the target product imidazolium metal salt. The obtained 3,3' - (1,4-phenyl dimethylene) -bis (1-methylimidazole) metal salt has stable structure and is a precursor of the N-heterocyclic carbene metal complex catalyst.
The invention has the beneficial effects that:
1. in the invention, a ball mill is adopted for grinding to obtain 3,3' - (1,4-phenyl dimethylene) -bis (1-methylimidazole) chlorate (L), and the method has the advantages of no solvent and simple reaction process.
2. According to the invention, 3,3' - (1,4-phenyl dimethylene) -bis (1-methylimidazole) chlorate (L) and metal chloride are subjected to solid state grinding reaction to obtain the metal salt, the yield can reach 100%, the pollution is low, the method is rapid and efficient, the purity is high, and the industrial production is easy to realize.
3. According to the invention, 3,3' - (1,4-phenyl dimethylene) -bis (1-methylimidazole) metal salt is recrystallized in a low-boiling-point solvent, and the obtained single crystal product has good stability and is easy to store at normal temperature.
4. The invention adopts a grinding method to prepare 3,3' - (1,4-phenyl dimethylene) -bis (1-methylimidazole) metal salt, shortens the reaction time, uses a trace amount of solution and has high yield of the obtained product.
Drawings
FIG. 1 is a structural formula of ligand 3,3' - (1,4-phenyldimethylene) -bis (1-methylimidazole) chlorate (L) prepared by the invention.
FIG. 2 is the sequence of 3,3' - (1,4-phenyldimethylene) -bis (1-methyl) in example 2Imidazole) chlorate (L) with CuCl 2 ·2H 2 Metal salt crystal [ HL ] prepared from O] 2+ ·[CuCl 4 ] 2- The structure of the single crystal of (1).
FIG. 3 is a graph of 3,3' - (1,4-phenyldimethylene) -bis (1-methylimidazole) chloric acid (L) and CoCl in example 3 2 ·6H 2 Metal salt crystal [ HL ] prepared from O] 2+ ·[CoCl 4 ] 2- The structure of a single crystal of (1).
FIG. 4 shows example 4 combining 3,3' - (1,4-phenyldimethylene) -bis (1-methylimidazole) chlorate (L) and ZnCl 2 Prepared metal salt crystal [ HL] 2+ ·[ZnCl 4 ] 2- The structure of the single crystal of (1).
FIG. 5 shows [ HL] 2+ ·[CuCl 4 ] 2- PXRD ray diffraction of the milled powder was compared to that of the recrystallized powder.
FIG. 6 shows [ HL] 2+ ·[CoCl 4 ] 2- PXRD ray diffraction of the milled powder was compared to that of the recrystallized powder.
FIG. 7 shows [ HL] 2+ ·[ZnCl 4 ] 2- PXRD ray diffraction of the milled powder was compared to that of the recrystallized powder.
Detailed Description
In order that the invention may be better understood, the invention will now be further described by way of example.
Example 1
5363A green synthesis method of 3,3' - (1,4-phenyldimethylene) -bis (1-methylimidazole) chlorate comprises the following steps:
at normal temperature, 1-methylimidazole (1.59mL, 0.02mol) and p-dichlorobenzyl (1.75g, 0.01mol) are placed in a 100mL grinding bowl, 5 steel balls with the diameter of 9mm and 5 steel balls with the diameter of 6mm are added, the mixture is placed in a planetary ball mill and ground for 4 hours at the rotating speed of 450r/min, then the obtained reactant is dissolved in 10mL methanol, filtered, the methanol is removed under reduced pressure, and CH is used for removing the methanol 2 Cl 2 Washing to give a white solid, i.e., 3,3' - (1,4-phenyldimethylene) -bis (1-methylimidazole) chlorate as L in 68.5% yield, m.p.:279 ℃. The structural formula of L is shown in figure 1.
Example 2
5363A green synthesis method of 3,3' - (1,4-phenyl dimethylene) -bis (1-methylimidazole) metal copper salt comprises the following steps:
mixing L (0.0337g, 0.10mmol) and CuCl 2 ·2H 2 O (0.0171g, 0.10mmol) was placed in a mortar, and 30. Mu.L of concentrated hydrochloric acid and 60-90. Mu.L of CH were added 2 Cl 2 Grinding for about 5min until the blue powder in the mortar becomes yellow powder and is dry powder, stopping grinding to obtain 3,3' - (1,4-phenyl dimethylene) -bis (1-methylimidazole) metal copper salt, and marking as [ HL] 2+ ·[CuCl 4 ] 2- Yield 100%, m.p.:202 ℃.
And (3) recrystallization: will grind the [ HL] 2+ ·[CuCl 4 ] 2- Transferring the powder to a 50mL conical flask, adding 1mL methanol and 5mL acetonitrile, standing for 2-5h to obtain yellow transparent flaky crystal [ HL] 2+ ·[CuCl 4 ] 2- The product was recrystallized in 76% yield.
Obtaining a three-dimensional structure of the crystal, [ HL ] by single crystal X-ray diffraction] 2+ ·[CuCl 4 ] 2- The single crystal structure of (a) is shown in fig. 2.
[HL] 2+ ·[CuCl 4 ] 2- The PXRD ray diffraction patterns of the ground product and the recrystallized product of (1) are shown in FIG. 5, and as can be seen from FIG. 5, [ HL] 2+ ·[CuCl 4 ] 2- The milled and recrystallized products of (a) were powder diffraction-compared, indicating that the two are identical.
Example 3
5363A green synthesis method of 3,3' - (1,4-phenyl dimethylene) -bis (1-methylimidazole) metal cobalt salt comprises the following steps:
l (0.0337g, 0.10mmol) and CoCl were mixed 2 ·2H 2 O (0.0238g, 0.10mmol) was placed in a mortar, and 30. Mu.L of concentrated hydrochloric acid and 60-90. Mu.L of CH were added 2 Cl 2 Grinding for about 5min until the purple powder turns into blue powder and is dry powder, stopping grinding to obtain 3,3' - (1,4-phenyl dimethylene) -bis (1-methylimidazole) metal cobalt salt, and marking as [ HL ] of grinding] 2+ ·[CoCl 4 ] 2- Yield 100%, m.p.:256 ℃.
And (3) recrystallization: will grind the [ HL] 2+ ·[CoCl 4 ] 2- Transferring the powder to a 50mL conical flask, adding 1mL methanol and 5mL acetonitrile, standing for 5-8h to obtain blue transparent block crystal [ HL [] 2+ ·[CoCl 4 ] 2- The product was recrystallized in 68% yield.
Obtaining the three-dimensional structure of the crystal by single crystal X-ray diffraction, [ HL)] 2+ ·[CoCl 4 ] 2- The single crystal structure of (a) is shown in fig. 3.
[HL] 2+ ·[CoCl 4 ] 2- The PXRD ray diffraction patterns of the ground product and the recrystallized product of (A) are shown in FIG. 6, and can be seen from FIG. 6, [ HL ]] 2+ ·[CoCl 4 ] 2- The milled and recrystallized products of (a) were powder diffraction-compared, indicating that the two are identical.
Example 4
5363A green synthesis method of 3,3' - (1,4-phenyl dimethylene) -bis (1-methyl imidazole) metal zinc salt comprises the following steps:
mixing L (0.0337g, 0.10mmol) and ZnCl 2 (0.0136g, 0.10mmol) was placed in a mortar, and 30. Mu.L of concentrated hydrochloric acid and 60-90. Mu.L of CH were added 2 Cl 2 Grinding for about 5min until the transparent powder in the mortar becomes white powder and is dry powder, stopping grinding to obtain 3,3' - (1,4-phenyl dimethylene) -bis (1-methylimidazole) zinc metal salt, and marking as [ HL] 2+ ·[ZnCl 4 ] 2- Yield 100%, m.p.:269 ℃.
And (3) recrystallization: will grind the [ HL] 2+ ·[ZnCl 4 ] 2- Transferring the powder into a 50mL conical flask, adding 1mL methanol and 5mL acetonitrile, standing for 5-8h to obtain colorless transparent block crystal [ HL] 2+ ·[ZnCl 4 ] 2- The product was recrystallized in 66% yield.
Subjecting the product to single crystal X-ray diffraction to obtain crystal with three-dimensional structure [ HL ]] 2+ ·[ZnCl 4 ] 2- The single crystal structure of (a) is shown in fig. 4.
[HL] 2+ ·[ZnCl 4 ] 2- The PXRD ray diffraction patterns of the ground product and the recrystallized product of (1) are as followsFIG. 7 shows that [ HL ] is shown in FIG. 7] 2+ ·[ZnCl 4 ] 2- The milled and recrystallized products of (a) were powder diffraction-compared, indicating that the two are identical.
Claims (7)
- 5363 a green mechanical synthesis method of 1.3,3 ″ (1,4-phenyldimethylene) -bis (1-methylimidazole) metal salt, characterized in that it comprises the following steps:1) Using 1-methylimidazole and p-dichlorobenzyl as raw materials, grinding by a grinding method in a solvent-free manner by using a ball mill to obtain white solid powder, and purifying to obtain 3,3 ″ (1,4-phenyldimethylene) -bis (1-methylimidazole) chlorate;2) Using 3,3 ″ (1,4-phenyldimethylene) -bis (1-methylimidazole) chlorate and metal chloride as raw materials, and grinding the raw materials in a mortar in a trace solvent to obtain 3,3 ″ (1,4-phenyldimethylene) -bis (1-methylimidazole) metal salt; the metal chloride is copper chloride, cobalt chloride or zinc chloride; the trace solvent is concentrated hydrochloric acid and CH 2 Cl 2 The mixed solvent of (1).
- 2. The green mechanosynthesis method as defined in claim 1 wherein 1-methylimidazole to p-dichlorobenzyl =2:1 in a molar ratio.
- 3. The green mechanosynthesis method as defined in claim 1 wherein, in molar ratio, 3,3 ″ (1,4-phenyldimethylene) -bis (1-methylimidazole) chlorate, metal chloride =1:1.
- 4. A green mechanical synthesis method according to claim 1, characterized in that, according to the volume ratio, concentrated hydrochloric acid: CH 2 Cl 2 =1:2-3。
- 5. A green mechanical synthesis method according to claim 1, characterized by comprising a recrystallization step: the resulting 3,3 ″ (1,4-phenyldimethylene) -bis (1-methylimidazole) metal salt was placed in an organic solvent, and 3 to 8h was left to stand at room temperature to obtain 3,3 ″ (1,4-phenyldimethylene) -bis (1-methylimidazole) metal salt single crystal product.
- 6. The green mechanical synthesis method according to claim 5, wherein the organic solvent is a mixed solvent of methanol and acetonitrile.
- 7. The green mechanosynthesis method of claim 6 wherein methanol to acetonitrile =1:5 by volume ratio.
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