CS216331B1 - Chromic acid bis (cyclohexyldiphenylsilyl) ester and its preparation - Google Patents

Abstract

The invention relates to the field of chemistry, especially the chemistry of organometallic compounds. It concerns the preparation of components for the production of highly active catalysts for the low-pressure polymerization of -olefins, especially ethylene. The invention relates to a hitherto unknown chemical compound bis(cyclohexyldiphenylsilyl)ester of chromic acid of the general formula and to a method and conditions for its preparation by conversion of cyclohexyldiphenylchlorosilane and silver chromate or; esterification of cyclohexyldiphenylsilane with chromium oxide. The new chemical individual is identified and characterized by chemical analysis, analysis of electron and infrared spectra and 13c and 29^^ NMR spectra and melting point. The compounds can further be used as oxidizers of organic and organometallic compounds in nonpolar organic solvents.

Description

The invention relates to a previously undescribed compound bis(cyclohexyldiphenylsily)chromic acid ester of the formula [Wii»' ^{0 and} to ^{a process} for the preparation of this compound.

Chromic acid esters have gained importance in recent years as active components of industrially used catalysts for the polymerization of olefins, especially for the production of low-pressure polyethylene. However, purely organic chromic acid esters are not very suitable for practical use, because 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(triphenylsilyDester of chromic acid and bis(triphenyl3tannyDester of chromic acid are of greatest practical importance. Similar catalytic properties can rightly be expected from the alkyldiphenylsilyl derivative, bis(cyclohexyldiphenylsilyDester of chromic acid. This compound has not yet been described in the literature. ¹

The subject of the invention is the compound bis(cyclohexyl diphenylsily) chromic acid ester of the structural formula

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Whose

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The invention also relates to a method for preparing bis(cyclohexyldiphenylsilyster of chromic acid), the essence of which consists in preparing cyclohexyldiphenylchlorosilane of the structural formula

where X = Cl, is reacted with silver chromate, or cyclohexyldiphenylsilanol of the same structural formula, where X = OH, is reacted with chromium trioxide in an organic solvent environment.

In the preparation process according to the invention, the reaction is carried out in an organic medium. Benzene or chlorinated hydrocarbons - C1-4, especially carbon tetrachloride, are most suitable, with which both cyclohexyldiphenylsilyl compounds are well miscible, while the hexavalent chromium compounds form a solid phase.

The reaction itself takes place by shaking the mixture for several hours under mild reaction conditions, at room temperature and atmospheric pressure. The product is isolated by vacuum evaporation of the solvent and further extraction and crystallization with a saturated aliphatic hydrocarbon - ζθ, preferably n-hexene. The yields exceed 75% of theory. .

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

Example 1

Preparation of bis(cyclohexyldiphenylsilyl)chromic acid ester from cyclohexyldiphenylchlorosilane and silver chromate

The compound is formed by the reaction (CgH^XCgHj^SiCl + AgCrO ₄

A mixture of 10 g of cyclohexyldiphenylchlorosilane, 6.62 g of silver chromate and 80 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 and the benzene was evaporated from the filtrate under vacuum until the residue had an oily consistency. 40 ml of hexane was added and the solvent removal was continued. The procedure with the addition of another 40 ml of hexane was repeated 1x until spontaneous precipitation of the crystalline product occurred, which was sharply suctioned off on a frit after cooling the residue, covered with a small amount of cooled pentane and dried by air filtration. 8.2 g of orange-red crystalline product was obtained, which represents 7.6.3% of theory.

The compound was prepared in 77.5% yield using dichloromethane as solvent.

Example 2

Preparation of bis(cyclohexyldiphenylsilyl) chromic acid ester from cyclohexyldiphenylsilanol and chromium oxide The compound is formed by

A mixture of 12 g cyclohexyldiphenylsilanol, 6.4 g chromium trioxide, 5 g anhydrous magnesium perchlorate and 150 ml carbon tetrachloride was shaken intensively without access to light for 1.5 hours. After standing in a refrigerator for one day at a temperature of 0 °C, the solution was filtered off from the solid phase and evaporated under vacuum to remove most of the solvent. After adding 50 ml of hexane, the solvent was evaporated under vacuum until the crystalline product spontaneously separated. The product was sharply suctioned off on a frit, covered with cooled pentane and dried by air filtration. 10.5 g of orange-red crystalline product (76.1% of theory) was obtained.

The compound can be prepared in a yield of 75% of theory using benzene as solvent.

The preparations obtained by the procedures described in the previous paragraphs were recrystallized from a mixture of carbon tetrachloride and hexane. The recrystallized products can be considered identical based on the identical physicochemical parameters.

Properties of b).s(cyclohexyldiphenylsilyl)chromic acid ester and its identification

Product appearance and stability:

The prepared chromic acid ester forms orange-red crystals, stable in the dark and at temperatures below 0 °C. It decomposes in the light and turns brown on prolonged standing at room temperature. The compound is easily reduced by 1 weak reducing agents, such as alcohols or olefins. The melting point is 90 - 94 °C.

Table I

Elemental analysis results for ³ 36 ^H 42 ³ⁱ 2 ^3rO 4

Element content (%) C H You Cr calculated 66.84 6.54 8.68 8.04 found 66.98 6.62 8.65 8.01

Electron spectrum

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

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

Table II

Characteristics of the bands of the electron spectrum [CC ₆ H _n ) (CgH ₅ ) ₂ SÍQj>CrO ₂

Wavenumber V(cm ^-1 ) Wavelength (ACnm) Molar absorption coefficient £(1 mol“ ¹ cm“ ¹ ) note 1st belt 29,500 339 4,3.10 ³ 2nd belt 35,400 311 5.5.10 ³ fold 3rd belt 38,300 261 7,1.10 ³ the belt of my fine structure

Infrared spectrum '

In the infrared spectrum of the ester, absorption bands were found in the region 400 - 4,000 cm" ¹ , their wavenumbers and assignments are given in Table III.

In the infrared spectrum, bands belonging to the vibrations of the present phenyl groups, cyclohexyl groups, vibrations of Si-0 bonds and vibrations of the CrO^ group were clearly identified. Their assignment resulted from vibrational analysis and comparison with the spectra of (CgH ₁₁ )(CgHj) ₂ SiC| ^6^1^^6^5^2 ³¹⁰¹¹ » D ^C 6 ^H 5^3 ^S10 J2 ^CrO 2 ^and other organometallic esters of chromic acid.

Table III

Infrared spectrum of chromic acid bi(cyclohexyldiphenylsilyl)ester

abs . belt (cm ^-1 ) assignment abs. oase (cm •b assignment I 469 m X-senz Ph 1 476 m ý(C-C)Ph 503 vs. X-senz Ph 1 580 m ý(C-C)Ph 532 m <f(C-C)Cy 1 762 vw * ! 595 m ý(Si-O-Cr) 1 812 VW with comb. and 618 ra oOÍCCG) 1 876 vw harrn. ^(C-H) 695 vs. breathing circularly 1 950 vw hu Ph 705 vs. j{(C-H)Ph 2 846 vs. 723 m |J(Si-C) 2 895 sh > ý(C-H)Cy 732 with jf(C-H)Ph 2 920 VS 776 m ^(C-H)Ph 2 997 w 811 with ^(C-H)Ph 3 010 sh 841 sh Z( _CH2 )Cy 3 021 m ^(C-H)Ph 867 VS V(SÍ-O) 3 047 with 882 vs. Ý(Sl-O) 3 067 with 968 in 9(Cr-0) 3 086 w 981 vs. ý(Cr-O) 992 sh def. ring Ph 1 026 w 4(C-H)Ph 1 066 w MC-H)Ph 1 116 vs. X-senz Ph 1 166 w /J(C-H)Ph 1 183 ra /j(C-H)Ph 1 256 w <f(CH ₂ )Cy 1 295 vw 4(C-H)Ph 1 318 vw 9(C-C)Fh 1 420 vs. ý(C-C)Ph 1 437 with r( _CH2 )Cy

Ph - phenyl Band intensities Cy - cyclohexyl vw - very weak s - s X-senz - belt sensitive to w - weak vs - very strong substitution m - medium sh - fold

¹³ C {·*·η| NMR and ^Sif^NMR spectrum ¹³ C {''ή} NMR spectrum of the compound was measured at a frequency of 25.047 MHz, ² 9sí(~h\ NMR spectrum at a frequency of 19.788 MHz. A 25% solution of the substance in deuteriochloroform with tetramethylsilane as an internal standard was used for the measurement / Zí^C),^ = O ; Z( ² ^Si) _ipM e; = 0 /. The measurements were carried out at a temperature of 25 °C. The chemical shift values are expressed in ppm (positive values indicate a shift to a lower field).

spectrum

<T(C ₁ ) = 133.3 /(C ₂ ) = 134.8

Z(C ₃ ) = 127.9 <f(C ₄ ) = 130.2 <f(C ₅ ) = 26.4 Z (Cg) ='27.8 or 26.9 <f(C ₇ ) = 27.8 or 26.9 Z(Cg) - 26.6

NMR spectrum

Z(S1) = 7.7

Claims (3)

SUBJECT OF THE INVENTION 1) Chromic acid bis (cyclohexyldiphenylsilyl) ester of structural formula 2. A process for the preparation of chromic acid bis (cyclohexyldiphenylsilyl) ester according to claim 1, characterized in that cyclohexyldiphenylchlorosilane of the structural formula wherein X 71 is reacted with chromium silver or cyclohexyldiphenyldilanol of the same structural formula wherein X = OH is reacted with oxide chromium in the environment of organic solvents. 3) The method according to claim 2, characterized in that as the medium used, benzene or a chlorinated hydrocarbon - C, preferably carbon tetrachloride, at which recrystallization or isolation of the product replaces saturated aliphatic hydrocarbon - C _g, preferably hexane.