RU2396375C1 - Electrochemical method for synthesis of organonickel sigma-complexes - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to electrochemical production, particularly to a method of obtaining organonickel sigma-complexes of general formula [NiBr(Ar)(bpy)], where Ar=2,4,6-trimethylphenyl (Mes), 2,4,6-triisopropylphenyl (Tipp), 2,6-dimethylphenyl (Xy); bpy=2,2'-bipyridyl, which can be used in catalytic oligomerisation of ethylene. The electrochemical method of obtaining organonickel sigma-complexes of formula [NiBr(Ar)(bpy)] involves electrolysis of a solution of ortho-substituted aromatic bromide (ArBr) and a nickel-containing compound in dimethylformamide in a diaphragmless cell. The solution also contains 2,2'-bipyridyl (bpy) and the nickel-containing compound used is NiBr₂. The ortho-substituted aromatic bromide is 2,4,6-trimethylphenyl bromide or 2,4,6-triisopropylphenyl bromide or 2,6-dimethylphenyl bromide in molar ratio reagents NiBr₂ : bpy : ArBr = 1 : (1-3) : (1-30).Electrolysis is carried out using a soluble nickel anode at 20°-70°C and cathode current density of 1.0-2.0 mA/cm².

EFFECT: possibility of highly efficient synthesis of organonickel sigma-complexes at constant electrochemical parametres.

2 cl, 44 ex, 2 tbl

Description

The invention relates to the field of electrochemical production, in particular, to a method for producing nickel-organic sigma complexes of the general formula [NiBr (Ar) (bpy)], where Ar = 2,4,6-trimethylphenyl (Mes), 2,4,6-triisopropylphenyl (Tipp), 2,6-dimethylphenyl (Hu); bpy = 2,2'-bipyridyl, which can be used in the process of catalytic oligomerization of ethylene, as well as in cross-coupling reactions involving organic halides and chlorophosphines.

A known method for the chemical production of the nickel-organic complex [NiBr (Mes) (bpy)] (Mes = 2,4,6-trimethylphenyl), first carried out by Siedel in 1985 [W. Siedel. Synthesis of bipyridine mesityl nickel complexes. Zeitschrift fuer Chemie 1985.25 (11). 411] according to the ligand exchange reaction from the corresponding complex [NiBr (Mes) (PPh ₃ ) ₂ ] and subsequently modified by Klein in 2001 [A.Klein. Z Anorg.Allg.Chem. 2001.627 (4). 645-650].

A known method of producing [NiBr (Mes) (bpy)] by the oxidative addition reaction of aromatic bromide (MesBr) to the complexes [Ni (COD) (bpy)] (COD = 1,5-cyclooctadiene) [D.Yakhvarov, D.Tazeev, O.Sinyashm, G. Giambastiani, C. Bianchini, AMSegarra, P. Lönnecke, E. Neu-Hawkins. Polyhedron 2006. 25. 1607-1612] is ineffective due to the low stability of nickel complexes (0).

It should be noted that all of the above chemical methods are implemented in highly flammable environments (ether, tetrahydrofuran) using highly reactive and, accordingly, unstable reagents such as Grignard reagents or nickel complexes (0).

In this regard, electrochemical methods for the production of organo-nickel complexes are of great importance.

So, there is a known method for electrochemical generation of the organo nickel sigma complex [NiBr (Tol) (bpy)] in situ for use in organophosphorus synthesis [Yu.G. Budnikova, Yu.M. Kargin, O.G. Sinyashin. Journal General Chem. 2000. 70 (4). 562-566, Yu.H. Budnikova, Yu.M. Kargin, J. Perichon, J.Y. Nedelec. J. Organomet. Chem. 1999. 575. 63-66].

The electrochemical synthesis of the nickel-organic sigma complex [NiBr (Mes) (bpy)] [D.G. Yakhvarov, Yu.G. Budnikova, O.G. Sinyashin. Electrochemistry. 2003. No. 11. 1407-1416], consisting in the electrolysis of a solution of dimethylformamide containing the complex [NiBr ₂ (bpy)], mesityl bromide and background electrolyte (NBu ₄ ) NBF ₄ .

The [NiBr (Mes) (bpy)] complex showed catalytic activity in the process of ethylene oligomerization in the presence of methylalumoxane (MAO) as an activating reagent [D. Yakhvarov, D. Tazeev, O.Sinyashin, G. Giambastiani, C. Bianchini, AMSegarrara , P. Lönnecke, E. Hey-Hawkins. // Polyhedron. 2006.25. 1607-1612].

The disadvantages of the above electrochemical processes is the use of an electrolyzer with separation of the anode and cathode spaces (electrolyzer with a diaphragm) due to which side oxidation processes occur in the anode chamber of the electrolyzer, leading to contamination and the difficulty of isolating the product. At the same time, the economic inefficiency of the process due to the use of expensive background electrolyte is noted.

Closest to the claimed invention is an electrochemical method for producing nickel-organic sigma complexes of the formula [NiBr _n (Ar) _m (bpy)], Ar = Mes, Tol, n = 0-1, m = 1-2 [D. G. Yakhvarov, E.G. Samieva, D.I. Tazeyev, Yu.G. Budnikova. News of the Academy of Sciences. Chemical Series, 2002.51 (5). 734-741], which consists in carrying out the process in an electrochemical cell with or without separation of the anode and cathode spaces in an inert atmosphere (nitrogen, argon) when passing through an electrolyte of 0.027; 0.0405; 0.054 A · h of electricity at a controlled potential of 1.52 V with constant stirring of the reaction mixture containing dissolved in DMF:

nickel complex [NiBr ₂ (bpy)],

background salt Et ₄ NBr or Et ₄ NBF ₄ ,

and organic halide ArBr, where Ar = Mes, Tol.

At the end of electrolysis, the solvent is distilled off, the electrolysis products are extracted from the residue with ether, then the ether is evaporated and the products are dried. The preparation of pure nickel-organic sigma complexes is carried out using additional cleaning measures from the background electrolyte, which is partially soluble in ether and is extracted together with the target product. To obtain the complexes in pure form, an additional procedure is necessary for the deposition of residues of the background electrolyte from the obtained extract, filtering the resulting suspension and subsequent recrystallization of the target complex.

The disadvantages of this electrochemical method for producing these organo nickel sigma complexes are the use of expensive background salt and the need to use the finished complex [NiBr ₂ (bpy)], which is preliminarily obtained from nickel bromide and 2,2'-bipyridyl by recrystallization from ethanol, followed by drying in vacuum. The use of the [NiBr ₂ (bpy)] complex as a nickel resource for nickel-organic sigma complexes leads to a change in the resistance (electrical conductivity) of the solution during electrolysis due to the processing of nickel (II) ions, which entails a change in the potential of the working electrode (under galvanostatic conditions ) or current drop (in potentiostatic mode). A change in the potential of the working electrode negatively affects the implementation of the whole process as a whole and is the reason for the occurrence of secondary electrochemical reactions leading to the decomposition of electrochemically generated nickel-organic sigma complexes. Moreover, the procedure for purification of the obtained complexes from background electrolyte impurities is rather laborious and requires subsequent stages of deposition, filtration, and recrystallization. These factors have a significant effect on the yield and selectivity of the electrochemical process for the production of organo nickel sigma complexes.

The objective of the invention is a new electrochemical method for producing nickel-organic sigma complexes of the general formula [NiBr (Ar) (bpy)], where Ar = 2,4,6-trimethylphenyl (Mes), 2,4,6-triisopropylphenyl (Tipp), 2, 6-dimethylphenyl (Hu); bpy = 2,2'-bipyridyl, with a large yield of the target product, which allows to simplify and reduce the cost of the process of obtaining nickel-organic sigma complexes due to available starting compounds, to avoid the occurrence of side electrochemical processes leading to contamination and the difficulty of isolating the product due to the absence of background salt and allowing to carry out the process with constant electrochemical parameters of the system (potential, current).

The technical result consists in the possibility of carrying out highly efficient synthesis of organo-nickel sigma complexes with constant electrochemical parameters due to the use of a nickel anode, which is soluble during electrosynthesis, which is a resource of Ni ^{2+ ions} . Anodically generated nickel (II) ions are capable of in situ complexing with 2,2'-bipyridyl and subsequently electrochemically reduced to nickel (0) complexes and interacting with the aromatic bromide in the reaction mixture to form the desired product.

The technical result is achieved by the claimed method for the preparation of nickel-organic sigma complexes of the general formula [NiBr (Ar) (bpy)], where Ar = 2,4,6-trimethylphenyl (Mes), 2,4,6-triisopropylphenyl (Tipp), 2,6 dimethylphenyl (Hu); bpy = 2,2'-bipyridyl, wherein a dimethylformamide solution containing nickel bromide, 2,2'-bipyridyl and ortho-substituted aromatic bromide (MesBr, TippBr and XyBr) in a molar ratio of 1: (1-3) : (1-30), respectively, is subjected to electrolysis using a cathode made of platinum, nickel, iron or stainless steel and a "soluble" anode, which is a source of nickel (II) ions, at a temperature of 20-70 ° C and a cathode current density of 1.0- 2.0 mA / cm ² in the electrolyzer without separation of the anode and cathode spaces. As a soluble anode, a nickel rod is used.

The indicated intervals for changing the ratio of reagents are optimal. They are determined, firstly, by the requirements of the stoichiometry of the process, and secondly, by the need to have a working electrolyte of sufficient electrical conductivity, which is achieved by using dimethylformamide and the presence in the solution of dissociated nickel bromide, the concentration of which remains constant due to the anodic generation of nickel (II) ions.

The intervals for using the ratio of nickel bromide: bpy, corresponding to 1: (1-3), are determined by the stabilization of the homogeneous state of the electrochemically generated nickel (0) (otherwise metal nickel (nickel black) precipitates in the electrolyte solution), and the use of more than three equivalents of bpy relative to nickel leads to the formation of a coordination-saturated complex [Ni (bpy) ₃ ] that is low reactive in the oxidative addition reaction.

The temperature range at which electrolysis is carried out (20-70 ° С) is also optimal, since at lower temperatures the process of oxidative addition of ArBr to electrochemically generated nickel complexes (0) is difficult, and the use of higher temperatures reduces the stability of nickel-organic sigma complexes in solution and complicates the implementation of the method, requiring additional energy costs for heating the electrolyte and the use of special measures to prevent evaporation of the electrolyte.

The range of changes in the cathode current density is determined by the complex chemistry of the chemical and electrochemical reactions that occur during electrolysis, to achieve maximum process performance. So, for example, a decrease in current density leads to a decrease in the absolute value of the potential of the working electrode and the process stops, and with an increase in current density, the process of electrochemical decomposition of the target complexes begins.

The invention is illustrated by examples of specific performance, summarized in table 1.

Example 1

A working solution for electrolysis is prepared by dissolving in 30 ml of dimethylformamide 0.0219 g (0.1 mmol) of nickel bromide, 0.0156 g (0.1 mmol) of 2,2'-bipyridyl and 0.0185 g (0.1 mmol) of XyBr. The resulting solution is subjected to electrolysis at a cathodic current density of 1.7 mA / cm ² at a temperature of 20 ° C, supported by a thermostat. An electrolyzer is used as an electrolyzer without separation of the anode and cathode spaces using a platinum cathode with a working surface area of 30 cm ² and a nickel anode 0.5 cm in diameter coaxially located inside it, immersed in a solution of 2 cm. The voltage at the electrochemical cell is E = 9.0-11.5 C. 5.4 mA · hr of electricity are passed through the electrolyte with constant stirring of the electrolyte in an argon atmosphere. The electrolysis time (t = 7 minutes) was determined based on the Faraday constant - 26.8 A · h · mol ^-1 from the calculation of the transfer of two electrons in the electrochemical process of nickel (II) reduction to nickel (0) in terms of the amount taken in the reaction 2.2 '-bipyridyl:

t = Q (mAh) / I (mA),

where Q is the theoretically calculated amount of electricity (Q = 2 · 26.8 (A · h · mol ^-1 ) · ν (mol));

I is the strength of the current consumed in the electrolysis process.

After completion of the electrolysis, the solvent was distilled off from the reaction mixture, the electrolysis products were extracted with acetone (2 × 20 ml), and the obtained product was recrystallized from toluene. The yield of the target product is 65%.

Characteristics of complex 1 - 2,6-dimethylphenyl-nickel (II) -bromide-2,2'-bipyridyl ([NiBr (Xy) (bpy)]):

¹ H-NMR (400 MHz, THF-d ⁸ , 25 ° C): δ = 9.31 (d, 1H, bpyH ₆ , ³ JH ₆ H ₅ = 5.7 Hz); 8.16 (d, 1H, bpyH ₃ , ³ JH ₄ H ₃ = 7.9 Hz); 8.09-8.14 (m, 2H, bpyH _{3 '} , bpyH ₄ , ³ JH ₄ H ₃ = 7.9 Hz, ³ JH ₅ H ₄ = 7.3 Hz); 8.05 (m, 1H, bpyH _{4 '} ); 7.60 (dd, 1H, bpyH ₅ , ³ JH ₆ H ₅ = 5.7 Hz, ³ JH ₅ H ₄ = 7.3 Hz); 7.28 (d, 1H, bpyH _{6 '} , ³ JH _6' H _{5 '} = 5.4 Hz); 7.18 (m, 1H, bpyH _{5 '} , ³ JH _6' H _{5 '} = 5.4 Hz); 6.55 (s, 3H, HXy); 3.08 (s, 6H, o-CH ₃ ).

Found: C, 54.37; H 4.81; N, 7.26%.

Calculated for C ₁₈ H ₁₇ BrN ₂ Ni (M _W : 399.94 g mol ^-1 ): C, 54.06; H 4.28; N, 7.00%.

_Mp 139 ° C (decomp. 152 ° C).

Example 2

The method is carried out under the conditions of example 1, however, 0.2 mmol of 2,2'-bipyridyl and 0.2 mmol of XyBr are used and 10.7 mA · hr of electricity are passed through the electrolyte at a cathode current density of 1.7 mA / cm ² and an external voltage applied to the cell E = 9.0-11.5V. The electrolysis time is 13 minutes. Nickel is used as the cathode and the process is carried out in an inert atmosphere of nitrogen.

Yield 72%.

Example 3

The method is carried out under the conditions of example 2, but the electrolysis is carried out at a temperature of 40 ° C. The yield is 75%.

Example 4

The method is carried out under the conditions of example 2, but the electrolysis is carried out at a temperature of 70 ° C. The yield is 61%.

Example 5

The method is carried out under the conditions of Example 1, however, 0.0657 g (0.3 mmol) of nickel bromide, 0.1404 g (0.9 mmol) of 2,2'-bipyridyl and 0.1665 g (0.9 mmol) of XyBr dissolved in 30 ml of dimethylformamide are used, 48.2 mA are passed through the electrolyte · Hour of the amount of electricity at a cathode current density of 1.7 mA / cm ² (external applied voltage per cell E = 8.0-9.0V). The electrolysis time is 58 minutes. Platinum is used as the cathode and the process is carried out in a nitrogen atmosphere.

Yield 81%.

Example 6

The method is carried out under the conditions of example 5, but the electrolysis is carried out at a temperature of 50 ° C. The yield is 84%.

Example 7

The method is carried out under the conditions of example 5, but the electrolysis is carried out at a temperature of 70 ° C. The yield is 65%.

Example 8

The method is carried out under the conditions of example 1, but using 0.0468 g (0.3 mmol) of 2,2'-bipyridyl and 0.185 g (1.0 mmol) of XyBr dissolved in 30 ml of dimethylformamide, 16.1 mA · h of electricity are passed through the electrolyte at a cathode current density of 1.7 mA / cm ² in a nitrogen atmosphere. The electrolysis time is 20 minutes.

Yield 52%.

Example 9

The method is carried out under the conditions of example 8, but the electrolysis is carried out at a temperature of 50 ° C. The yield is 57%.

Example 10

The method is carried out under the conditions of example 8, but the electrolysis is carried out at a temperature of 70 ° C. The yield is 63%.

Example 11

The method is carried out under the conditions of example 1, but using 0.0312 g (0.2 mmol) of 2,2'-bipyridyl and 0.037 g (0.2 mmol) of XyBr dissolved in 30 ml of dimethylformamide and a cathode of iron. 10.7 mA · hr of electricity are passed through the electrolyte at a cathode current density of 1.0 mA / cm ² (external applied voltage per cell E = 8.0-12.0V). The electrolysis time is 21 minutes.

Yield 68%.

Example 12

The method is carried out under the conditions of example 1, but 0.0468 g (0.3 mmol) of 2,2'-bipyridyl and 0.0555 g (0.3 mmol) of XyBr dissolved in 30 ml of dimethylformamide and a stainless steel cathode are used, 16.1 mA hour of the amount of electricity, at a cathodic current density of 1.0 mA / cm ² (external applied voltage per cell E = 8.0-12.0V). The electrolysis time is 32 minutes.

Yield 72%.

Example 13

The method is carried out under the conditions of example 1, but as aromatic bromide using MesBr (external voltage E = 8.0-12.0V).

Yield 68%.

Characteristics of complex 2 - 2,4,6-trimethylphenyl-nickel (II) -bromide-2,2'-bipyridyl ([NiBr (Mes) (bpy)]):

¹ H-NMR (400 MHz, Acetone-d ⁶ , 25 ° C): δ = 9.47 (dd, 1H, bpyH ₆ , ³ JH ₆ H ₅ = 5.7 Hz, ⁴ JH ₆ H ₄ = 1.2 Hz), 8.41 ( d, 1H, bpyH ₃ , ³ JH ₃ H ₄ = 7.8 Hz), 8.37 (d, 1H, bpyH _{3 '} , ³ JH _3' H _{4 '} = 8.1 Hz), 8.24 (ddd, 1H, bpyH ₄ , ³ JH ₄ H ₅ = 7.5 Hz, ³ JH ₄ H ₃ = 7.8 Hz, ⁴ JH ₄ H ₆ = 1.2 Hz), 8.21 (ddd, 1H, bpyH _{4 '} , ³ JH _4' H _{5 '} = 7.5 Hz, ³ JH _{4 '} H _3' = 8.1 Hz, ⁴ JH _{4 '} H _6' = 1.2 Hz), 7.76 (ddd, 1H, bpyH ₅ , ³ JH ₅ H ₆ = 5.7 Hz, ³ JH ₅ H ₄ = 7.5 Hz, ⁴ JH ₅ H ₃ = 1.2 Hz), 7.40 (ddd, 1H, bpyH _{5 '} , ³ JH _5' H _{6 '} = 5.7 Hz, ³ JH _5' H _{4 '} = 7.5 Hz, ⁴ JH _5' H _{3 '} = 1.2 Hz), 7.26 (dd, 1H, bpyH _{6 '} , ³ JH _6' H _{5 '} = 5.7 Hz, ³ JH _6' H _{4 '} = 1.2 Hz), 6.51 (s, 2H, mH in Mes), 3.10 (s 6H, o-CH ₃ ), 2.24 (s, 3H, p-CH ₃ ).

Found: C, 55.37; H 4.80; N 6.76%.

Calculated for C ₁₉ H ₁₉ BrN ₂ Ni (M _W : 413.98 g mol ^-1 ): C, 55.12; H 4.63; N, 6.77%.

_Mp 148 ° C (decomp. 186 ° C).

Example 14

The method is carried out under the conditions of example 5, but MesBr is used as aromatic bromide.

Yield 86%.

Example 15

The method is carried out under the conditions of example 6, but MesBr is used as aromatic bromide.

Yield 89%.

Example 16

The method is carried out under the conditions of example 7, but MesBr is used as aromatic bromide.

Yield 75%.

Example 17

The method is carried out under the conditions of example 14, but using 1.791 g (9.0 mmol) of MesBr.

Yield 92%.

Example 18

The method is carried out under the conditions of example 17, but the electrolysis is carried out at a temperature of 50 ° C. The yield is 84%.

Example 19

The method is carried out under the conditions of example 17, but the electrolysis is carried out at a temperature of 70 ° C. The yield is 82%.

Example 20

The method is carried out under the conditions of example 14, but the electrolysis is carried out for 96 minutes on a nickel cathode at a cathode current density of 1.0 mA / cm ² (E = 8.0-9.0 V). Yield 85%.

Example 21

The method is carried out under the conditions of example 20, but the electrolysis is carried out at a temperature of 70 ° C. The yield is 69%.

Example 22

The process is carried out under the conditions of Example 13 using 0.0657 g (0.3 mmol) of nickel bromide, 0.0936 g (0.6 mmol) of 2,2'-bipyridyl and 0.2388 g (1.2 mmol) of MesBr. The electrolysis is carried out for 39 minutes on an iron cathode, passing an amount of electricity of 32.2 mA · h (cathodic current density of 1.7 mA / cm ² , the external voltage on the cell is E = 8.0-12.0 V). Yield 88%.

Example 23

The process is carried out under the conditions of Example 22, using 0.0657 g (0.3 mmol) of nickel bromide, 0.0468 g (0.3 mmol) of 2,2'-bipyridyl and 0.3396 g (1.2 mmol) of TippBr as aromatic bromide. The electrolysis is carried out on a platinum cathode at a cathode current density of 1.7 mA / cm ² and an external applied voltage E = 9.0-11.5 V at a temperature of 20 ° C. Yield 80%.

Characteristics of complex 3 - 2,4,6-triisopropylphenyl-nickel (II) -bromide-2,2'-bipyridyl ([NiBr (Tipp) (bpy)]):

¹ H-NMR (400 MHz, Acetone-d ⁶ , 25 ° C): δ = 9.50 (d, 1H, bpyH ₆ , ³ JH ₆ H ₅ = 3.6 Hz); 8.37 (d, 1H, bpyH ₃ , ³ JH ₄ H ₃ = 5.1 Hz); 8.33 (d, 1H, bpyH _{3 '} , ³ JH _4' H _{3 '} = 5.1 Hz); 8.21 (dd, 1H, bpyH ₄ , ³ JH ₄ H ₃ = 5.1 Hz, ³ JH ₅ H ₄ = 4.8 Hz); 8.15 (dd, 1H, bpyH _{4 '} , ³ JH _4' H _{3 '} = 5.1 Hz, ³ JH _5' H _{4 '} = 4.8 Hz); 7.72 (dd, 1H, bpyH ₅ , ³ JH ₆ H ₅ = 3.6 Hz, ³ JH ₅ H ₄ = 4.8 Hz); 7.33 (dd, 1H, bpyH _{5 '} , ³ JH _6' H _{5 '} = 3.6 Hz, ³ JH _5' H _{4 '} = 4.8 Hz); 7.20 (d, 1H, bpyH _{6 '} , ³ JH _6' H _{5 '} = 3.6 Hz); 5.71 (sp, 2H, CH (o-iPr), ³ JH _(CH) H _(CH3) = 4.5 Hz); 2.88 (sp, 1H, CH (p-iPr), ³ JH _(CH) H _(CH3) = 4.5 Hz); 1.35 (d, 6H, CH3 (o-iPr), ³ JH _(CH) H _(CH3) = 4.5 Hz); 1.23 (d, 6H, CH3 (o-iPr), ³ JH _(CH) H _(CH3) = 4.5 Hz); 1.12 (d, 6H, CH3 (p-iPr), ³ JH _(CH) H _(CH3) = 4.5 Hz).

Found: C, 60.12; H 6.51; N, 5.26%.

Calculated for C ₂₅ H ₃₁ BrN ₂ Ni (M _W : 498.13 g mol ^-1 ): C, 60.28; H 6.27; N 5.62%

_Mp 219 ° C (decomp.).

Example 24

The method is carried out under the conditions of example 23, but the electrolysis is carried out at a temperature of 40 ° C. The yield is 82%.

Example 25

The method is carried out under the conditions of example 23, but the electrolysis is carried out at a temperature of 60 ° C. The yield is 81%.

Example 26

The method is carried out under the conditions of example 14, using TippBr as the aromatic bromide (cathodic current density 1.7 mA / cm ² , E = 8.5-9.5 V). Yield 78%.

Example 27

The method is carried out under the conditions of example 26, but the electrolysis is carried out at a temperature of 40 ° C. The yield is 82%.

Example 28

The method is carried out under the conditions of example 26, but the electrolysis is carried out at a temperature of 60 ° C. The yield is 81%.

Example 29

The method is carried out under the conditions of example 26, but the electrolysis is carried out on a nickel cathode for 48 minutes (cathodic current density of 2.0 mA / cm ² , E = 8.0-10.5 V). The yield is 76%.

Example 30

The method is carried out under the conditions of example 29, but the electrolysis is carried out at a temperature of 60 ° C. The yield is 80%.

Example 31

The method is carried out under the conditions of example 26, but using 1.2735 g (4.5 mmol) of TippBr (cathodic current density of 1.7 mA / cm ² , E = 7.0-8.5 V). The yield is 72%.

Example 32

The method is carried out under the conditions of example 31, but the electrolysis is carried out at a temperature of 40 ° C. The yield is 79%.

Example 33

The method is carried out under the conditions of example 31, but the electrolysis is carried out at a temperature of 60 ° C. The yield is 81%.

Example 34

The method is carried out under the conditions of example 31, but using 2.547 g (9.0 mmol) of TippBr and an iron cathode (cathodic current density of 1.7 mA / cm ² , E = 5.5-9.5 V). The yield is 68%.

Example 35

The method is carried out under the conditions of example 34, but the electrolysis is carried out at a temperature of 40 ° C. The yield is 79%.

Example 36

Example 36 is carried out under the conditions of example 34, but the electrolysis is carried out at a temperature of 60 ° C. The yield is 81%.

Example 37

The method is carried out under the conditions of example 34, but the electrolysis is carried out at a temperature of 80 ° C. The yield is 56%.

Example 38

The method is carried out under the conditions of example 22, but using TippBr and a stainless steel cathode (cathodic current density of 1.7 mA / cm ² , E = 9.0-12.0 V). The yield is 84%.

The study of the catalytic activity of Nickel-organic complexes

Example 39

A portion of complex 1 (12 μmol) is evacuated (1.6 10 ^-3 mm Hg) in an autoclave with a volume of 500 ml for 3 hours. After that, 100 ml of toluene solution containing (3600 μmol) of MAO is added to the autoclave. After stirring the reaction mixture at room temperature for several seconds, an ethylene pressure of 5 atm was created in the autoclave and the reaction mixture was left under stirring under pressure for 15 minutes. After that, the autoclave is cooled to -10 ° C, the pressure of ethylene is released and 2 ml of a 5% solution of HCl in methanol are added to the reaction mixture. Analysis of the obtained oligomerization products in the reaction mixture is carried out by gas chromatography.

Example 40

The process is carried out under the conditions of example 39, but they take 1.2 μmol of complex 1.

Example 41

The process is carried out under the conditions of example 39, but take complex 2.

Example 42

The process is carried out under the conditions of example 40, but take complex 2.

Example 43

The process is carried out under the conditions of example 39, but take complex 3.

Example 44

The process is carried out under the conditions of example 40, but take complex 3.

The results of studies of the catalytic activity of nickel-organic complexes 1-3 are shown in Table 2. The ethylene conversion is calculated based on the mass of ethylene that has reacted (by the increase in mass of the autoclave during the catalytic process and based on gas chromatography of the reaction mixture with an internal standard), and the Schulz constant -Flory (α) is determined based on the average molar ratio of C6, C8 and C10 fractions of the obtained olefins. As the results show, the conversion of ethylene using complex 1 (example 39) is 9.72 g (the ratio of oligomers in the mixture C4 is 5.17 g; C6 is 2.60 g; C8 is 1.16 g; C10 is 0.49 g; C12 is 0.20 g, α = 0.335 ), which exceeds the conversion of ethylene when using complex 2 (example 41) - 6.93 g (the ratio of oligomers in the mixture C4 is 3.49 g; C6 is 1.87 g; C8 is 0.89 g; C10 is 0.40 g; C12 is 0.17 g; α = 0.357 ) and complex 3 (example 43) - 2.69 g (the ratio of oligomers in the mixture C4 is 1.02 g; C6 is 0.70 g; C8 is 0.43 g; C10 is 0.25 g; C12 is 0.14 g; α = 0.460). A change in the complex / MAO ratio (examples 40, 42 and 44) reduces the conversion of ethylene in the catalytic process, but experiments also show a higher catalytic activity of complex 1 (0.75 g of ethylene conversion; C4 - 0.39 g; C6 - 0.20 g; C8 - 0.09 g ; C10 - 0.04 g; C12 - 0.02 g, α = 0.342) relative to complexes 2 (0.56 g of ethylene conversion; C4 - 0.26 g; C6 - 0.15 g; C8 - 0.08 g; C10 - 0.04 g; C12 - 0.02 g, α = 0.390) and 3 (0.44 g of ethylene conversion; C4 - 0.16 g; C6 - 0.12 g; C8 - 0.08 g; C10 - 0.05 g; C12 - 0.03 g, α = 0.491).

The proposed new electrochemical method for producing nickel-organic sigma complexes of the general formula [NiBr (Ar) (bpy)], where Ar = 2,4,6-trimethylphenyl (Mes), 2,4,6-triisopropylphenyl (Tipp), 2,6- dimethylphenyl (Hu); bpy = 2,2'-bipyridyl, allows:

to simplify and reduce the cost of their production process due to the available starting compounds: directly from nickel bromide, 2,2'-bipyridyl and aromatic bromides, with a good yield (up to 92%),

avoid side electrochemical processes leading to contamination and the difficulty of isolating the product,

to carry out the process with constant electrochemical parameters of the system (potential, current).

Table 1 Examples of electrochemical synthesis of sigma complexes 1-3 Example No. Complex / Method NiBr ₂ , mmol 2,2'-bpy, mmol ArBr, mmol Q, mAh Current density, mA / cm ² Time min T, ° С Exit, % one 1 / Pt 0.1 0.1 0.1 5.4 1.7 7 twenty 65 2 1 / Ni 0.1 0.2 0.2 10.7 1.7 13 twenty 72 3 1 / Ni 0.1 0.2 0.2 10.7 1.7 13 40 75 four 1 / Ni 0.1 0.2 0.2 10.7 1.7 13 70 61 5 1 / Pt 0.3 0.9 0.9 48.2 1.7 58 twenty 81 6 1 / Pt 0.3 0.9 0.9 48.2 1.7 58 fifty 84 7 1 / Pt 0.3 0.9 0.9 48.2 1.7 58 70 65 8 1 / Pt 0.1 0.3 1.0 16.1 1.7 twenty twenty 52 9 1 / Pt 0.1 0.3 1.0 16.1 1.7 twenty fifty 57 10 1 / Pt 0.1 0.3 1.0 16.1 1.7 twenty 70 63 eleven 1 / Fe 0.1 0.2 0.2 10.7 1.0 21 twenty 68 12 1 / stainless steel 0.1 0.3 0.3 16.1 1.0 32 twenty 72 13 2 / Pt 0.1 0.1 0.1 5.4 1.7 7 twenty 68 fourteen 2 / Pt 0.3 0.9 0.9 48.2 1.7 58 twenty 86 fifteen 2 / Pt 0.3 0.9 0.9 48.2 1.7 58 fifty 89 16 2 / Pt 0.3 0.9 0.9 48.2 1.7 58 70 75 17 2 / Pt 0.3 0.9 9.0 48.2 1.7 58 twenty 92 eighteen 2 / Pt 0.3 0.9 9.0 48.2 1.7 58 fifty 84 19 2 / Pt 0.3 0.9 9.0 48.2 1.7 58 70 82 twenty 2 / Ni 0.3 0.9 0.9 48.2 1.0 96 twenty 85 21 2 / Ni 0.3 0.9 0.9 48.2 1.0 96 70 69 22 2 / Fe 0.3 0.6 1.2 32.2 1.7 39 twenty 88 23 3 / Pt 0.3 0.6 0.6 32.2 1.7 39 twenty 80 24 3 / Pt 0.3 0.6 0.6 32.2 1.7 39 40 82 25 3 / Pt 0.3 0.6 0.6 32.2 1.7 39 60 81 26 3 / Pt 0.3 0.9 0.9 48.2 1.7 58 twenty 78 27 3 / Pt 0.3 0.9 0.9 48.2 1.7 58 40 82 28 3 / Pt 0.3 0.9 0.9 48.2 1.7 58 60 81 29th 3 / Ni 0.3 0.9 0.9 48.2 2.0 48 twenty 76 thirty 3 / Ni 0.3 0.9 0.9 48.2 2.0 48 60 80 31 3 / Pt 0.3 0.9 4.5 48.2 1.7 58 twenty 72 32 3 / Pt 0.3 0.9 4.5 48.2 1.7 58 40 79 33 3 / Pt 0.3 0.9 4.5 48.2 1.7 58 60 81 34 3 / Fe 0.3 0.9 9.0 48.2 1.7 58 twenty 68 35 3 / Fe 0.3 0.9 9.0 48.2 1.7 58 40 79 36 3 / Fe 0.3 0.9 9.0 48.2 1.7 58 60 81 37 3 / Fe 0.3 0.9 9.0 48.2 1.7 58 80 56 38 3 / stainless steel 0.3 0.6 1.2 32.2 1.7 39 twenty 84

Claims (2)

1. The electrochemical method for producing nickel-organic sigma complexes of the formula [NiBr (Ar) (bpy)], comprising electrolysis of a solution of ortho-substituted aromatic bromide (ArBr) and a nickel-containing compound in dimethylformamide in a diaphragmless electrolyzer, characterized in that:
the solution additionally contains 2,2'-bipyridyl (bpy),
as a nickel-containing compound, NiBr _{2 is used} ,
the ortho-substituted aromatic bromide is 2,4,6-trimethyl phenyl bromide, or 2,4,6-triisopropyl phenyl bromide, or 2,6-dimethyl phenyl bromide,
when the molar ratio of reagents NiBr ₂ : bpy: ArBr = 1: (1-3) :( 1-30),
wherein electrolysis is carried out using soluble nickel
the anode at a temperature of 20-70 ° C and a cathode current density of 1.0-2.0 mA / cm ² . 2. The electrochemical method according to claim 1, characterized in that the diaphragmless electrolyzer is equipped with a cathode of platinum, or nickel, or iron, or stainless steel.