Diphosphite having an open 2,4-methylated outer wing structural unit

Abstract

The present invention discloses diphosphites having an open 2,4-methylated outer wing structural unit and their use in hydroformylation.

Description

Technical Field

[0001] The present invention relates to diphosphites having open 2,4-methylated outer wing structural units and their use for hydroformylation. Background Art

[0002] In many reactions, for example in hydrogenations, hydrocyanations and hydroformylations, phosphorus-containing compounds play a key role as ligands.

[0003] The reaction between olefin compounds, carbon monoxide and hydrogen in the presence of a catalyst to obtain aldehydes having more than one carbon atom is called hydroformylation or carbonylation. In these reactions, compounds of transition metals from Group VIII of the Periodic Table of the Elements are often used as catalysts. Known ligands are, for example, compounds from the group consisting of phosphines, phosphites and phosphonites, each of which contains trivalent phosphorus P. III A very good review of the state of the art with respect to the hydroformylation of olefins can be found in: R. Franke, D. Selent, A. "Applied Hydroformylation", Chem. Rev., 2012, DOI: 10.1021 / cr3001803.

[0004] In EP 0213639 A2, the following compound is shown in Example 10 on page 98:

[0005]

[0006] The compound (2) is used as a ligand for the hydroformylation of 1-butene. Summary of the Invention

[0007] The technical object of the present invention is to provide novel ligands which, compared with the ligands known from the prior art, exhibit an increased n- / is-selectivity in the hydroformylation of olefins.

[0008] This object is achieved by the compounds according to claim 1 .

[0009] Compounds of structure (I):

[0010]

[0011] Among them, R 1 、R 2 、R 3 、R 4 Selected from: -H, -(C1-C 12 )-alkyl, -O-(C1-C 12 )-alkyl.

[0012] In one embodiment, R 1 , R 3 is selected from: -H, -(C1-C 12 )-alkyl.

[0013] In one embodiment, R 1 , R 3 is -(C1-C 12 )-alkyl.

[0014] In one embodiment, R 1 , R 3 is -tBu.

[0015] In one embodiment, R 1 , R 3 are the same group.

[0016] In one embodiment, R 2 , R 4 is selected from: -H, -O-(C1-C 12 )-alkyl.

[0017] In one embodiment, R 2 , R 4 is -O-(C1-C 12 )-alkyl.

[0018] In one embodiment, R 2 , R 4 is -OMe.

[0019] In one embodiment, R 2 , R 4 are the same group.

[0020] In one embodiment, R 1 , R 2 , R 3 , R 4 are not all -CH3 simultaneously.

[0021] In one embodiment, the compound has structure (1):

[0022]

[0023] In addition to the compound itself, its use for catalyzing hydroformylation reaction is also a subject matter of the claimed invention.

[0024] Use of the above compound in a ligand-metal complex for catalyzing hydroformylation reaction.

[0025] Also claimed is a method of using the above compound as a ligand.

[0026] The method comprises the following method steps:

[0027] a) Initially charging an olefin,

[0028] b) Adding the above-mentioned compound and a metal-containing substance, wherein the metal is selected from: Rh, Ru, Co, Ir,

[0029] c) Feeding in H2 and CO,

[0030] d) Heating the reaction mixture obtained from steps a) to c), wherein the olefin is converted into an aldehyde.

[0031] In a preferred embodiment, the metal is Rh.

[0032] Here, an excess of ligand can also be used, and it is not mandatory for each ligand to be present in a coordinated manner as a ligand-metal complex, but it can be present as a free ligand in the reaction mixture.

[0033] The reaction is carried out under conventional conditions.

[0034] Preferably, the temperature is from 80 °C to 160 °C, and the pressure is from 10 to 60 bar.

[0035] Particularly preferably, the temperature is from 100 °C to 140 °C, and the pressure is from 20 to 50 bar.

[0036] In the method of the present invention, the reactants for the hydroformylation are olefins or olefin mixtures, in particular monoolefins having 2 to 24, preferably 3 to 16 and more preferably 3 to 12 carbon atoms and having terminal or internal C-C double bonds, such as 1-propene, 1-butene, 2-butene, 1- or 2-pentene, 2-methyl-1-butene, 2-methyl-2-butene, 3-methyl-1-butene, 1-, 2- or 3-hexene, the C6 olefin mixture (dipropene) obtained in the dimerization of propene, heptene, 2- or 3-methyl-1-hexene, octene, 2-methylheptene, 3-methylheptene, 5-methyl-2-heptene, 6-methyl-2-heptene, 2-ethyl-1-hexene, the C8 olefin mixture (di-n-butene, diisobutene) obtained in the dimerization of butene, nonene, 2- or 3-methyloctene, the C9 olefin mixture (tripropene) obtained in the trimerization of propene, decene, 2-ethyl-1-octene, dodecene, the C 12 olefin mixture (tetrapropene or tributene) obtained in the tetramerization of propene or the trimerization of butene, tetradecene, hexadecene, the C 16 olefin mixture (tetrabutene) obtained in the tetramerization of butene, and olefin mixtures prepared by the co-oligomerization of olefins having different numbers of carbon atoms (preferably 2 to 4).

[0037] Using the method of the present invention, the ligands of the present invention can be used to hydroformylate α-olefins, terminal-branched, internal, and internal-branched olefins. Detailed Description of the Invention

[0038] The present invention will be described in detail below with reference to the examples.

[0039] Procedure

[0040] General analysis

[0041] All preparations below were carried out using standard Schlenk techniques under a protective gas. The solvents were dried over appropriate drying agents before use.

[0042] The products were characterized by NMR spectroscopy. Chemical shifts (δ) are reported in ppm. 31 The 31P NMR signals were assigned as follows: SR 31 P = SR 1 H × (BF 31 P / BF 1 H) = SR 1 H × 0.4048.

[0043] Synthesis (1):

[0044]

[0045] In a glove box, 9 g (0.01 mol) of the diorganophosphite dichlorophosphite was weighed into a clamped 250 mL Schlenk flask, which was then evacuated and dissolved in 75 mL of dried toluene. In a second clamped 250 mL Schlenk flask, 2.5 g (0.02 mol) of 2,4-dimethylphenol and 3 mL (0.022 mol) of degassed triethylamine were dissolved in 50 mL of toluene. The chlorophosphite was slowly and continuously added to the phenol-triethylamine solution over 1.5 hours at room temperature. The reaction mixture was stirred overnight at room temperature. The reaction mixture was heated to 80 °C. After 18 hours, the reaction mixture was filtered through a fritted glass filter, and the filtrate was concentrated at 40 °C under oil pump vacuum. Subsequently, the solid was dried under oil pump vacuum for 18 hours. Then the solid was triturated and stirred in 50 mL of dried ACN. The precipitated white solid was then removed by filtration through a fritted glass filter. Purity 96%, yield 48%.

[0046] Synthesis (2) (Comparative Ligand)

[0047]

[0048] In a glove box, 9 g (0.01 mol) of a diorganophosphite dichlorophosphite was weighed into a fixed 250 mL Schlenk flask, then evacuated and dissolved in 75 mL of dry toluene. In a second fixed 250 mL Schlenk flask, 2.2 g (2.1 mL, 0.02 mol) of 2-methylphenol was weighed and subsequently dried under an oil pump vacuum at room temperature for 12 hours. 50 mL of dry toluene and 3 mL = 2.2 g (0.022 mol) of degassed triethylamine were added with stirring and dissolved. The dichlorophosphite was added to the phenol-triethylamine solution at room temperature over 1.5 hours. The reaction mixture was stirred at room temperature for 2 hours and then heated to 80 °C. The reaction mixture was stirred at this temperature for 15 hours, and subsequently 3 × 1.5 mL (0.011 mol) of triethylamine was metered in and stirring was continued for 15 hours. Ammonium chloride was removed through a glass frit, washed subsequently with 1 × 10 mL of dry toluene and concentrated to dryness. The solid was dried at room temperature for 15 hours and stirred with 40 mL of degassed acetonitrile. The precipitated white solid was removed through a glass frit, the Schlenk flask was rinsed subsequently with 2 × 10 mL of ACN, and after drying, it was introduced into the glove box. Yield: 90%, purity: 95%.

[0049] Catalytic experiment

[0050] Hydroformylation was carried out in a 16 ml autoclave equipped with a pressure maintaining device, a gas flow meter and a jet stirrer from HEL Group, Hertfordshire, UK. The n-octene used as the substrate (a mixture of octene isomers from Oxeno GmbH: 1-octene: 3%; cis + trans-2-octene: 49%; cis + trans-3-octene: 29%; cis + trans-4-octene: 16%; structural isomer octene: 3%) was heated to reflux over sodium for several hours and distilled under argon.

[0051] For the experiments, the reaction solution was pre-prepared under an argon atmosphere. For this purpose, 0.0021 g of Rh(acac)(CO)2 and the corresponding amount of the phosphite compound were weighed in and diluted with 8.0 ml of toluene. The mass of toluene introduced in each case was determined for GC analysis. Then 1.80 g of 1-octene (16 mmol) was added. The pre-prepared solution was then charged into the autoclave, which was flushed three times with argon and three times with synthesis gas (Linde; H2(99.999%):CO(99.997%) = 1:1). The autoclave was then heated to the desired temperature under a total pressure of 10 bar with stirring (900 rpm). When the reaction temperature was reached, the synthesis gas pressure was increased to 20 bar and the reaction was carried out for 4 hours at a constant pressure. After the reaction time had ended, the autoclave was cooled to room temperature, depressurized with stirring and flushed with argon. In each case, 0.5 ml of the reaction mixture was taken out after the reaction, diluted with 4 ml of pentane and analyzed by gas chromatography: HP 5890 Series II plus, PONA, 50 m × 0.2 mm × 0.5 μm. The residual olefins and aldehydes were quantitatively determined relative to the solvent toluene as the internal standard.

[0052] Results of catalytic experiment

[0053] Reaction conditions:

[0054] [Rh]: 120 ppm, L:Rh = 1:2, p: 20 bar, T: 120 °C; t: 4 h

[0055] Table 1: Hydroformylation of 1-octene

[0056] Ligand Normal / isomeric selectivity, in % <![CDATA[1 ＊ > 72 2 56

[0057] ＊ Compound of the invention

[0058] Definition of "selectivity":

[0059] In the hydroformylation, there is a normal / iso selectivity, which is the ratio of linear aldehyde (= normal) to branched aldehyde (= iso). Here, the selectivity with respect to the normal aldehyde means that this amount of linear product is formed. The remaining percentage then corresponds to the branched isomers. Thus, in the case of a regioselectivity of 50%, normal and iso aldehydes are formed in equal proportions.

[0060] Compared with the comparative ligand (2), an increase in normal / iso selectivity was achieved using the compound (1) of the invention.

[0061] The experiments carried out have proven that the object set has been achieved by means of the compounds of the invention.

Claims

1. A compound having structure (1): （1）。 2. Use of the compound according to claim 1 in a ligand-metal complex for catalyzing a hydroformylation reaction.

3. A method comprising the following method steps: a) Initially charging an olefin, b) Adding the compound according to claim 1 and a metal-containing substance, the metal being selected from: Rh, Ru, Co, Ir, c) Feeding in H2 and CO, d) Heating the reaction mixture obtained from steps a) to c), wherein the olefin is converted into an aldehyde.

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