RU2355672C1 - Method of catalytic transformation of cyclic hydrocarbons into acyclic (linear) hydrocarbons under action of lanthanides complexes - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention refers to the methods of linear hydrocarbons obtaining, specifically to the method of n-alkanes obtaining. The essence of the method lies in cycloalkanes hydrogenolyse in presence of the catalysts - complexes of lanthanides chlorides crystallohydrates with aluminium alkoxyde LnCl₃·3H₂O·3(EtO)₂AlOH in combination with i-Bu₂AlH in dioxane medium at atmospheric pressure and 80°C during 6 hrs.

EFFECT: increasing of the target product yield.

1 cl, 1 tbl, 6 ex

Description

The present invention relates to methods for producing hydrocarbons of a linear structure, specifically to a method for producing alkanes of the general formula

CH ₃ - (CH ₂ ) _n —CH ₃

where n = 4, 5, 6.

Saturated hydrocarbons are widely used in motor and jet fuels, as raw materials for the chemical and petrochemical industries, as solvents, extractants, eluents, in the production of plastics, rubbers, synthetic fibers, detergents, as well as in the food industry, electrical and radio engineering.

The known method (X.M. Minachev, M.A. Markov, V.I. Bogomolov. Transformations of cyclohexane and N. alkanes on oxides of rare-earth elements. - Petrochemistry, 1961, v.2, No. 2, p.144-149) the conversion of cyclohexane in the dehydrogenation reaction in the presence of catalysts of lanthanide oxides on activated carbon: Nd ₂ O ₃ -C, But ₂ O ₃ -C, Yt ₂ O ₃ -C. The reactions are carried out in a flow-through installation, at atmospheric pressure and a temperature of 500-560 ° C, for 6 hours. The yield of liquid catalysis is 85-91% (isohexanes content is 2.5%, based on catalysis).

The disadvantages of this method include high energy consumption (high temperature and duration of the process), the need to use special equipment (flow installation), low yield of n-alkanes, as well as preliminary multi-stage synthesis of the catalyst (pre-treatment of activated carbon in an aggressive environment - HNO ₃ , salt impregnation REE, drying at 110 ° C, etc.).

The closest way to obtain cyclic acyclic hydrocarbons, selected as a prototype, is the method (M.E. Vol'pin, ISAkhrem, SV Reznichenko and Grushin VV Activation of CC bonds in alkanes and cycloalkanes by Ziegler-type systems. J.Of Organometallic Chemistry , 1987, 334, p.109-116.) The production of n-alkanes by hydrogenolysis of the corresponding cycloalkanes (cyclohexane, cyclopentane, methylcyclopentane, cyclodecane) under the action of rhenium carbonyl and carbonyl hydride complexes: Re ₂ (СО) ₁₀ , Re ₃ H ₃ (СО) ₁₂ , Re ₄ H ₄ (СО) ₁₂ in combination with organoaluminum compounds (Et ₃ Al, i-Bu ₂ AlH) at a molar ratio of RH: AlR ₃ : R e _n L _m equal to 100: 6: 1, an initial hydrogen pressure of 50 atm and a reaction temperature of 150-180 ° C, in an autoclave, for 3-15 hours. The maximum conversion during hydrogenolysis of cyclohexane (22%) is achieved using Re ₂ ( CO) ₁₀ + i-Bu ₂ AlH.

The disadvantages of this method include high energy consumption (high temperature, pressure and duration of the process), the need to use special equipment (autoclave), as well as the high cost of the rhenium complex Re ₂ (CO) ₁₀ , and the need to obtain complexes

Re ₃ H ₃ (СО) ₁₂ , Re ₄ H ₄ (СО) ₁₂ (long (up to 110 h), energy-consuming, multi-stage and labor-intensive synthesis).

The task of the invention is to simplify the method of producing n-alkanes.

The essence of the method is the hydrogenolysis of cycloalkanes under the action of i-Bu ₂ AlH in the presence of catalysts LnCl ₃ · 3H ₂ O · 3 (EtO) ₂ AlOH, with a molar ratio of reagents 60: 90: 1. The reaction is carried out at 80 ° C, atmospheric pressure, for 6 hours. Dioxane was used as a solvent. The reaction proceeds according to the scheme.

Ln = Ce, Nd, Eu, Tb; n = 4,5,6.

Significant differences of the proposed method

1. In the proposed method, the catalyst used is formed from commercial and readily available: LnCl ₃ · 6Н ₂ О with Al (OEt) ₃ in siti complex LnCl ₃ · 3Н ₂ О · 3 (EtO) ₂ AlOH. The hydrogenolysis reaction occurs at atmospheric pressure, 80 ° C, in a solvent of dioxane, with a higher yield (38-78%) of the target product. In the known methods use more expensive compounds: Re ₂ (CO) ₁₀ , Re ₃ H ₃ (CO) ₁₂ , Re ₄ H ₄ (CO) ₁₂ (inaccessible) or Nd ₂ O ₃ -C, But ₂ O ₃ -C, Yt ₂ About ₃ -C (not manufactured by the industry) and requiring preliminary special multi-stage synthesis.

The proposed method has the following advantages:

1. The method does not require a long and multi-stage preliminary preparation of the catalyst LnCl ₃ · 3H ₂ O · 3 (EtO) ₂ AlOH, in contrast to the complexes Re ₂ (СО) ₁₀ ,

Re ₃ H ₃ (CO) ₁₂ , Re ₄ H ₄ (CO) ₁₂ or Nd ₂ O ₃ -C, But ₂ O ₃ -C, Yt ₂ O ₃ -C (labor-intensive, lengthy synthesis in an aggressive environment).

2. The method allows to reduce the yield (38-78%) of the target product by reducing the interaction temperature.

3. The method allows to significantly reduce the temperature (from 560 to 80 ° C), the synthesis time (from 15 hours to 6 hours), does not require special equipment (autoclave), and thereby significantly simplifies the synthesis and reduce the cost of the target product.

The method is illustrated by the following examples:

EXAMPLE 1. 12.5 ml of dioxane, 0.08 mmol of crystalline hydrate LnCl ₃ · 6H ₂ O and 0.24 mmol of Al (OEt) ₃ are placed in a 50 ml glass thermostatic reactor mounted on a magnetic stirrer. After the complete disappearance (dissolution) of LnCl ₃ · 6H ₂ O and the formation of a homogeneous solution (1-2 h) at 20 ° C, 4.8 mmol of cycloalkane and 7.2 mmol of i-Bu ₂ AlH are added, heated for 6 h at 80 ° C with stirring . Cooled to 10 ° C, the reaction mass is hydrolyzed with a 10% aqueous HCl solution (15 ml), extracted three times with ether (3 × 20 ml), the combined extracts are dried over anhydrous Na ₂ SO ₄ , the solvent is distilled off, and the residue is fractionated in vacuo. The yield of n-alkanes is 67-78%.

Other examples confirming the method are given in the table.

Example Cycloalkane Catalyst T, ° С Time, hours Exit % Target product one Cyclohexane C ₆ H ₁₂ TbCl ₃ · 3H ₂ O · 3 (EtO) ₂ AlOH 80 6 67 N-hexane 2 Cyclohexane C ₆ H ₁₂ EuCl ₃ · 3H ₂ O · 3 (EtO) ₂ AlOH 80 6 52 N-hexane 3 Cyclohexane C ₆ H ₁₂ NdCl ₃ · 3H ₂ O · 3 (EtO) ₂ AlOH 80 6 40 N-hexane four Cyclohexane C ₆ H ₁₂ CeCl ₃ · 3H ₂ O · 3 (EtO) ₂ AlOH 80 6 38 N-hexane 5 Cycloheptane C ₇ H ₁₂ TbCl ₃ · 3H ₂ O · 3 (EtO) ₂ AlOH 80 6 72 N-heptane 6 Cyclooctane C ₈ N ₁₂ TbCl ₃ · 3H ₂ O · 3 (EtO) ₂ AlOH 80 b 78 N-octane All experiments were carried out in dioxane at a molar ratio of cycloalkane: i-Bu ₂ AlH: Ln equal to 60: 90: 1.

The resulting compounds have the following physicochemical characteristics:

N-hexane. n _D ²⁰ = 1.3752. ¹ H NMR spectrum, δ, ppm: 0.96 t (6H, 2CH ₃ ), 1.35 br. s (8H,

4CH ₂ ). ¹³ C NMR spectrum, δ, ppm: 14.03 t (C ¹ , C ⁶ ), 23.04 t (C ² , C ⁵ ), 32.13 t (C ³ , C ⁴ ).

N-heptane. n _D ²⁰ = 1.3879. ¹ H NMR spectrum, δ, ppm: 1.02 t (6H, 2CH ₃ ), 1.42 br. s (10H, 5CH ₂ ). ¹³ C NMR spectrum, δ, ppm: 14.09 k (C ¹ , C ⁷ ), 23.18 t (C ² , C ⁶ ), 29.43 t (C ⁴ ), 32.29 t (C ³ , C ⁵ ).

N-octane. n _D ²⁰ = 1.3976. ¹ H NMR spectrum, δ, ppm: 0.92 t (6H, 2CH ₃ ), 1.45 br. s (12H, 6CH ₂ ). ¹³ C NMR spectrum, δ, ppm: 14.19 k (C ¹ , C ⁸ ), 22.90 t (C ² , C ⁷ ), 29.45 t (C ⁴ C ⁵ ), 32.30 t (C ³ , C ⁶ ) .

Claims (1)

The method of catalytic conversion of cyclic hydrocarbons to acyclic (linear) of the General formula
CH ₃ - (CH ₂ ) _n —CH ₃ ,
where n = 4, 5, 6,
by hydrogenolysis of cycloalkanes under the action of i-Bu ₂ AlH in the presence of catalysts, characterized in that the catalysts are the complexes of lanthanides LnCl ₃ · 3H ₂ O · 3 (EtO) ₂ AlOH (Ln = Ce, Nd, Eu, Tb), at a molar ratio of cycloalkane: i-Bu ₂ AlH: Ln equal to 60: 90: 1, at atmospheric pressure, 80 ° C, for 6 hours, in a solvent of dioxane.