RU2070202C1 - Alkyl cobalt (iii)-tridentate ligand complexes as initiators of aqueous emulsion polymerization and copolymerization of vinyl and diene monomers - Google Patents

Abstract

FIELD: synthesis of polymers. SUBSTANCE: product of formula:

[RCo(3-R′-acacen)(en)]X wherein R is C₁-C₁₆ alkyl, R′ is H, C₂H₅, n-C₇H₁₅, X is J and Br, yield 44-66%. Reagent 1: acetyl acetone in mechanol. Reagent 2: aqueous ethylene diamine solution. Reagent 3: aqueous cobalt dichloride. Reagent 4: ethyl bromide. EFFECT: improved properties of initiators. 3 tbl

Description

 The invention relates to complex compounds of alkyl cobalt (III) with tridentate ligands, which can be used as initiators of emulsion polymerization of vinyl and diene monomers.

Organometallic cobalt complexes of the general formula K ₃ Co (CN) ₅ -C ₃ H ₅ and K ₃ Co (CN) ₅ -CH ₂ C ₆ H ₅ are known that are used to initiate emulsion polymerization of isoprene and butadiene (1). However, these compounds have low initiation efficiency: it takes 44 hours to achieve 82% butadiene conversion at 40 ^° C.

 Other more effective initiating systems for emulsion polymerization are known, for example, redox systems. So, it is known to use OVS isopropylbenzene hydroperoxide (GP) - an iron-trilon-rongalite complex as an initiator in the production of divinyl-styrene rubbers (2). The disadvantages of this and similar initiating systems include their multicomponent nature, which involves a significant number of operations for the preparation and dosage of ingredients for OVS. In addition, the composition of the OVS includes peroxide and hydroperoxide compounds, which are explosive and flammable during storage.

 The aim of the invention is to obtain organometallic complexes of cobalt, suitable for use as initiators of emulsion polymerization and copolymerization of vinyl and diene moments.

где R перв- или втор-алкил от C₁ до C₁₆, R' Н или алкил (C₂H₅, n-C₇H₁₅) и X Вr, J.This goal is achieved by the new structure of alkyl cobalt (III) complexes with tridentate ligands of the general formula:

where R is primary or sec-alkyl from C ₁ to C ₁₆ , R 'H or alkyl (C ₂ H ₅ , nC ₇ H ₁₅ ) and X Br, J.

 A comparative analysis with analogues allows us to conclude that the authors synthesized a series of alkyl cobalt of a new structure. Thus, the claimed technical solution meets the criterion of "novelty."

 The indicated complexes are alkyl {2 - [(2-aminoethyl) imino] -3-alkyl-pent-3-en-4-olate} (1,2-ethanediamine) cobalt (III) halides (symbolic formula [RCo (3- R'-acasen) (en)] X); special case of (R 'H) - alkyl {2 - [(2-aminoethyl) imino] pent-3-en-4-olate} (1,2-ethanediamine) cobalt (III) halides ([RCo (acacen) (en )] X) were first synthesized by the authors according to the following procedure.

Example 1 complex 2 (table. 1). The synthesis is carried out in an argon atmosphere at a temperature of 15 25 ^o C with constant stirring. 430 ml of methanol, 12.3 ml (120 mmol) of acetylacetone, 10.3 ml of a 70% aqueous solution of ethylenediamine (120 mmol), 14.1 g (60 mmol) of 6-aqueous cobalt dichloride, 19, are sequentially introduced into the reactor. 3 ml of a 50% aqueous solution of NaOH, 1 ml of a 2% solution of PdCl ₂ in a 1 M aqueous solution of KCl, 21 ml (273 mmol) of ethyl bromide. A solution of 3.2 g of NaBH ₄ (85 mmol) and 25 ml of 5% aqueous NaOH solution were added dropwise evenly over 5 hours. After gas evolution, the reaction mixture was stirred for 1 hour. Then it is filtered, the solution is evaporated to a volume of 100 ml at a residual pressure of ≈10 mm RT. Art. and a bath temperature of not higher than 40 ^° C. Then, 20 g of NaBr are added and with cooling 100 ml of water and the mixture is evaporated in the same way to a volume of 100 ml. Crystallization is carried out at 0 ^o C, the precipitate is filtered off, washed with 15 ml of ice water and dried in air. Then it is washed with dichloromethane (150 to 200 ml total) until the green color of the wash liquid disappears. Dry the product again in air. The target product is a red crystalline powder. If necessary, crystallization is carried out from methanol with the addition of sodium bromide. For identification, ion-exchange TLC on SiO _{2 is used} (silofol plates, eluent 0.1 n sodium acetate solution in methanol-water 4 1 by volume). The purity criterion is the presence of a single spot on the plate, as well as the almost complete discoloration of the complex with the addition of hydrochloric acid. The output and value of the separation factor Rf are given in table. one.

 Examples 1, 3 11. Complexes 1 and 3 9 indicated in the table. 1, obtained analogously to example 1 with the difference that the following halide alkyls are used instead of ethyl bromide: methyl iodide, n-butyl bromide, n-amyl bromide, n-octyl bromide, n-cetyl bromide, iso-propyl bromide, cyclohexyl bromide, sec-octyl bromide. Complexes 10 and 11 are prepared using, instead of acetylacetone, its 3 ethyl and 3 n heptyl derivatives, respectively.

The structure of the complexes was proved on the basis of ¹ H-NMR, IR spectra and analysis of acidolysis products. ¹ H-NMR spectra (solvent D ₂ O, 200 MHz, internal standard sodium 2,2-dimethyl-2-silapentane-5-sulfonate) of the synthesized alkyl cobalt complexes are similar to each other. The data for complex 2 (Table 1) are shown below (identified signal, δ, ppm multiplicity): CH ₃ CH ₂ Co, 0.60, t; CH ₃ -C = N, 1.70, s; CH ₃ -C = 0, 1.94, s; CH, 4.98, s, IR spectra of complexes 1 11 have characteristic absorption bands in the region of 3100 3260 cm ^-1 (wide) and 3280 3350 cm ^-1 (narrow) related to stretching vibrations of NH.

 An analysis of the acidolysis products of the synthesized complexes 1 11 carried out by gas-liquid and thin-layer chromatography confirms the above structural formula. The structure of the complexes is also confirmed by the data of elemental analysis (Table 2).

 Complexes 1 to 11 in the solid state are stable in the dark and safe during storage.

 Examples of the use of alkyl cobalt complexes as initiators of emulsion polymerization are given in table. 3.

 Given in the table. 3 data indicate that the synthesized complexes of alkyl cobalt of a new structure are effective low-temperature initiators of emulsion polymerization of diene and vinyl monomers.

Claims (1)

Complexes of alkyl cobalt (III) with tridentate ligands of the general formula

where RC ₁ C _{16 is} alkyl;
R ¹ H, C ₂ H ₅ , HC ₇ H ₁₅ ;
XJ, Br,
as initiators of water-emulsion polymerization and copolymerization of vinyl and diene monomers.

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