CS213975B1 - Bia (2-propyldiphenylsilyl) chromic acid ester and its method of preparation - Google Patents

Abstract

The invention relates to the field of chemistry, especially the chemistry of carbon metal compounds. It solves the preparation of one of the components for the production of highly active catalysts for the low-pressure polymerization of olefins, especially ethylene. The invention describes a hitherto unknown chemical compound bis (2-propyldiphenylsilyl) chromic acid ester of the general formula [(2-C3H7) (C6H5)2SiOj2 CrO2 and a method for its preparation by conversion of 2-propyldiphenyl- ; chlorosilane with silver chromate or esterification of 2-propyldiphenylsilanol with chromium oxide. The new chemical individual is identified and characterized by chemical analysis and analysis of electron, infrared and NMR spectra. Its basic physicochemical quantities are determined.

Description

The invention relates to a previously undescribed compound of bis (2-propyldiphenylsilyl) chromic acid ester of the general formula £(2-O^Hγ) (CgHgJgSK^OrOg) and a method for preparing the compound.

Chromic acid esters have gained importance in recent years as active components of industrially used catalysts for olefin polymerization, especially for the production of low-pressure polyethylene; however, purely organic chromic acid esters are not very suitable for practical use, as they are not very stable, flammable or self-igniting, and their decomposition can even be explosive. For the above reasons, organic esters are replaced by organometallic esters, e.g. variously substituted silyl or stannyl derivatives, or organometalloid esters, e.g. substituted phosphonium esters of chromic acid. Of all the esters in this group, bis(triphenylsilyl) chromic acid ester and bis(triphenylstannyl) chromic acid ester are of greatest practical importance. Similar catalytic properties can rightly be expected from the alkyldiphenylsilyl derivative, bis(8-;;propyldiphenylsilyl) chromic acid ester. This compound has not yet been described in the literature.

The subject of the invention is the compound bis(2-propyldiphenylsilyl) chromic acid ester of the structural formula

The invention also provides a method for preparing bis(2-propyldiphenylsilyl) chromic acid ester, the essence of which consists in either 2-propyldiphenylchlorosilane of the structural formula

213975 2 where X represents chlorine, is reacted with silver chromate, or 2-propyldiphenylsilanol of the same structural formula, where X represents the OH group, is reacted with chromium trioxide in an organic solvent environment.

In the preparation method according to the invention, the reaction is carried out in an environment of benzene, an aliphatic hydrocarbon _ Οθ, preferably hexane, or a chlorinated hydrocarbon θΐ “ θ4* ^{preferably carbon} tetrachloride, with which both 2-propyldiphenylsilyl components are well miscible, while the hexavalent chromium compound forms a solid phase. The actual conversion takes place under mild conditions, i.e. at room temperature and ; atmospheric pressure, by shaking the reaction mixture for several hours. The product is isolated by vacuum evaporation of the solvent. The yields exceed 90% of theory.

The synthesis of the preparation is demonstrated by the following examples.

Example 1

Preparation of bis(2-propyldiphenylsilyl)chromic acid ester from 2-propyldiphenylchlorosilane and silver chromate.

A compound is formed by the reaction expressed by the relationship

Í2 (2-σ ₃ Ηγ) (C _g H ₅ ) ₂ SiCl + Ag ₂ CrO ₄ —>/(2-0^) (CgH ₅ ) ₂ SiQ7 ₂ CrO ₂ + 2 4gCl 'A mixture of 10.9 g of 2-propyldiphenylchlorosilane, 8.3 g of silver chromate and 100 ml of benzene was shaken intensively for 24 hours without access to light. The suspension formed by the reaction was filtered to remove insoluble silver salts. After vacuum evaporation of the solvent from the filtrate, 11 g of an orange oily product (93% of theory) was obtained, which, when left to stand at a temperature of 0 to 5 °C, gave an orange crystalline mass. The same preparation was obtained in yields of 87, 'resp. 90% of theory when dichloromethane and carbon tetrachloride were used as solvents.

Example 2

Preparation of bis(2-propyldiphenylsilyl)chromic acid ester from 2-propyldiphenylsilanol and chromium trioxide.

The compound is formed by the reaction expressed by the equation (2-C-jftp (C _g H ₅ ) ₂ SiCH + CrO ₃ -^^2-0^) (CgH ₅ ) ₂ Si0j ₂ 0r0 ₂ + HgO A mixture of 7.5 g of 2-propyldiphenylsilanol, 3.9 g of chromium trioxide and 80 ml of dry n-hexane was stirred for 0.5 hour without access to light. After filtering off the unreacted chromium trioxide, 3.9 g of fresh chromium trioxide was added to the filtrate and stirring was continued for another 1 hour. After filtering off the unreacted chromium oxide, the clear filtrate was freed from the solvent by evaporation under vacuum. 7.7 g (88% of theory) of an orange oily product were obtained, which solidified into an orange crystalline mass on standing. In a yield of 88, resp. 85% of theory was obtained from the same preparation using n-pentane and carbon tetrachloride as solvents.

₃ 213975

The preparations obtained by the procedures in the previous sections can be considered identical based on identical physicochemical parameters.

Properties of chromic acid bls(2-propyldiphenylsilyl)ester and its identification.

Product properties and stability: The prepared chromic acid ester is an orange solid stable in the dark and at temperatures below 0 °C.

Melting point: 53 to 58 °C (after recrystallization from carbon tetrachloride)

Refractive index (subcooled melt) : 1.6220 (20 °C)

Specific gravity (supercooled melt): 1155 kgm” ³ (20 °C)

Table I

Elemental analysis results for ¢30^34 ⁸ ½° ¹ ^

Element content, % C H You Cr calculated 63.58 6.05 9.91 9.17 found 63.90 6.12 9.87 8.77

Electron spectrum.

In agreement with the theory, three absorption bands were found in the region from 700 to 240 nm in the spectrum of bis(2-propyldiphenylsilyl) chromic acid ester (hexane solution), their characteristics are given in Table II.

Table II

Characteristics of the bands of the electronic spectrum of fe-Cýí?) (CgH ₅ ) ₂ SIC^CrO ₂

_in (cm ^-1 ) Λ (nm) £(lmol“^cm”· ¹ ·) note —“ ¹ ? 1st belt 29,200 343 4,9.10 ³ 2nd belt 35,400 311 6,6.10 ³ fold 3rd belt 38,200 262 8.5.10 ³ the belt has a soft

structure

The positions of the bands and their intensities correspond to the results found for known triphenyl trialkyl- and alkyldiphenylsilyl-esters of chromic acid.

Infrared spectrum.

In the infrared spectrum of the ester, absorption bands were found in the region of 400 to 4000 cm^, the wavenumbers and assignments of which are given in Table III.

In the infrared spectrum, bands belonging to vibrations of phenyl groups, 2-propyl groups, vibrations of Si-0 bonds and vibrations of CrO^ groups were identified. Their assignment resulted from vibrational analysis and comparison with the spectra of (2-C ₃ H _? ) (C ₆ H ₅ ) ₂ SiCl, (2-0 ₃ Η _γ ) (CgHj^SiOH, f(CgH ₅ ) ₃ SioJ ₂ CrO ₄ .and other organometallic esters of chromic acid.

213975 4

Table III

Infrared spectrum of bis(2-propyldiphenylsilyl) chromic acid ester

abs. waist (cm ^- · ¹ ·) assigned abs. waist (cm ^- · ¹ ·) assignment 469 m X-senz 1476 m V(C-C)Ph 503 vs. X-senz 1580 8 V(O-C)Ph 591 m V(Si-O-Cr) 1761 vw 617 658 w o(XCCC) 1810 w > comb. and harm. B X-senz 1875 w Í(C-H) 696 VS breathing circle 1949 w 705 vs. I(C-H)Ph 2866 vs. 736 868 with v(Si-C) V(Si-O) 2894 with In (C-H)Pr vs. 2926 sh 380 vs v(Si-0) 2950 vs 966 vs ý(Cr-0) 2995 m 981 UK y(Cr-O) 3008 i s 990 sh ring def. /?(C-H)Ph 3020 m V(C-H)Ph 1027 m 3048 ⁸ 1066 m ^(C-H)Ph 3067 VS 1117 vs. X-senz Ph 3082 m 1155 w /S(C-H)Ph Ph Z - phenyl 1182 m (C-H)Ph Pr - 2--propyl Λ-senz - passport sensitive on 1233 W <5 (ch ₃ ) substitution 1258 w (C-H)Ph 1299 w /3 (O-H)Ph Band intensities 1324 w In (C-C)Ph vw - w - very weak weak 1362 w é (ch ₃ ) m - s - medium strong 1379 m 8 (ch ₃ ) vs sh - very strong fold 1420 vs. in (C-C)Ph 1455 i_ in 8 (ch ₃ )

¹³ (£hJmr and ² ΜΜ»μη spectrum ^C^HjNMR spectrum of the compound was measured at a frequency of 19.788 MHz. For the measurement of the form with tetramethylsilane as the internal at a frequency of 25.047 MHz, ^SJ^HjNMR spectrum was used '2% solution of the substance in deuteriumchlorostandard.

/é ( ¹³ C)

TMS á( ²⁹ Si)

TMS

Measurements were performed at 25 °C. Chemical shift values are expressed in ppm (positive values indicate a shift to a lower field).

¹³ C$M NMR spectrum

6(C _X ) = 133.1 é(C ₄ ) = 130.3 <S(C ₂ ) = 134.8 a(0 ₅ ) = 14.3 £(0 ₃ ) =. 127.9 6(σθ) . 17.1

²⁹ si1M NMR spectrum <5(Si) =. 10.2

Claims (3)

SUBJECT OF THE INVENTION A chromic acid bis (2-propyldiphenylsilyl) ester of the structural formula 2. A process for the preparation of the compound of claim 1, wherein 2-propyldiphenylchlorosilane of the structure wherein X is chlorine is reacted with silver bromide, or 2-propyldiphenylsilanol of the same structure wherein X is OH is reacted with chromium trioxide in an organic solvent environment. Method according to claim 2, characterized in that benzene or an aliphatic hydrocarbon C 8 -C 8, preferably hexane, or a chlorinated hydrocarbon O 4 -C 6, preferably carbon tetrachloride, is used as the medium.