DIPHOSPHITES HAVING AN OPEN AND A CLOSED 2,4-METHYLATED OUTER UNIT

Abstract

Diphosphites having an open and a closed 2,4-methylated outer unit and use thereof in hydroformylation.

Claims

1. Compound of the structure (I): ##STR00009## where R.sup.1, R.sup.2 are selected from: -H, -0-(C.sub.1-C.sub.12)-alkyl.

2. Compound according to claim 1, where R.sup.1. R.sup.2 are selected from: -H, -(C.sub.1-C.sub.12)-alkyl.

3. Compound according to claim 1, where R.sup.1, R.sup.2 are -(C.sub.1-C.sub.12)-alkyl.

4. Compound according to claim 1, where R.sup.1, R.sup.2 are the same radical.

5. Compound according to claim 1, where the compound has the structure (1): ##STR00010##

6. Use of a compound according to claim 1, in a ligand-metal complex for catalysis of a hydroformylation reaction.

7. Process comprising the process steps of: a) initially charging an olefin, b) adding a compound according to claim 1 and a substance containing a metal selected from: Rh, Ru. Co, Ir, c) supplying H.sub.2 and CO, d) heating the reaction mixture from steps a) to c), with conversion of the olefin to an aldehyde.

Description

WORK PROCEDURES

[0029] General analysis

[0030] All the preparations that follow were carried out under inert gas using standard Schlenk techniques. The solvents were dried before use over suitable drying agents.

[0031] The products were characterized by NMR spectroscopy. Chemical shifts (δ) are reported in ppm. The .sup.31P NMR signals were referenced as follows: SR.sup.31P=SR.sup.1H * (BF.sup.31P/BF.sup.1H)=SR.sup.1H * 0.4048.

[0032] Synthesis

##STR00004##

[0033] Synthesis (1a)

##STR00005##

[0034] In a 500 ml Schienk flask with baffles, 10.7 g of 2,2′-bis(3,5-dimethyl)phenol (vacuum oil pump dried) were initially charged dissolved in 100 of toluene and heated to 40° C. In a glovebox, 15.5 g of chlorophosphite were weighed out into a 250 ml Schlenk flask and evacuated. The chlorophosphite was dissolved with stirring in 150 ml of toluene and 5.6 ml of Et.sub.3N were added. The chlorophosphite-Et.sub.3N-toluene solution was added slowly over 4 hours to the initially charged phenol solution at 40° C. After stirring overnight, a further 2.8 mL of Et.sub.3N were added. After 18 hours, 100 mL of degassed acetonitrile were added to the solid with stirring. The mixture was stirred overnight at room temperature, In the morning, the mixture was cooled to 0° C. and stirred at this temperature for 2 hours. The mixture was passed through a frit and then washed with a little degassed cold acetonitrile. The solid on the frit was dried and placed in the glovebox. Purity: 95%, yield 74%.

[0035] Synthesis (1b)

##STR00006##

[0036] 50 ml of toluene and 2.75 ml (0.062 mol) of phosphorus trichloride were added to a secured 250 ml Schlenk flask after flushing with argon, In the glovebox, 6 g (0.02 mol) of (1a) are weighed into a further 250 ml Schlenk flask. After evacuation, 50 mL of toluene and 4.25 mL (0.061 mol) of triethylamine are added under argon. After dissolution is complete, the solution of (la) is slowly added dropwise to the phosphorus trichloride/toluene solution. The solution was then stirred at 80° C. for 2 hours, then cooled to room temperature and stirred overnight at room temperature. For work-up the next morning, the suspension is filtered off through a G3 frit, The hydrochloride filtered off here is discarded. The resulting mother liquor is concentrated to dryness at 45° C. by means of a vacuum oil pump.

Yield: 90%, purity 94.5%.

[0037] Synthesis (1)

##STR00007##

[0038] In a glovebox, 7.89 g (0.011 mol) of diorganophosphite dichlorophosphite (1b) were weighed out into a secured 250 ml Schlenk flask, then evacuated and dissolved in 80 mL of dried toluene. 2.64 ml (2.69 g =0.022 mol) of 2,4-dimethylphenol were filled into a second secured 250 ml Schlenk flask by means of an argon-flushed syringe. Then, with stirring, 60 ml of dried toluene and 6.6 ml =4.8 g (0.047 mol) of degassed triethylamine were added and dissolved with stirring. To the phenol-triethylamine solution was then added the previously prepared chlorophosphite solution in one go. The reaction mixture was then immediately heated to 80° C. and vigorously stirred overnight at this reaction temperature. For the workup, the resulting amine hydrochloride was removed by frit at room temperature. To improve the ability of the amine hydrochloride to be filtered off, the stirrer was switched off beforehand and the reaction mixture allowed to stand for 1.5 hours. The resulting filtrate was concentrated to dryness and further dried at room temperature for 18 hours by means of a vacuum oil pump, The residue was then stirred with 100 ml of degassed acetonitrile, which did not dissolve, after which the solvent was again removed. 100 ml of degassed n-heptane were added to the resulting solid. In this case, the majority of the solid dissolved in the heptane. The cloudy solution was passed through a frit. The clear filtrate was concentrated to dryness. Purity 76.6%. In order to achieve higher purity. TLC with various eluents were carried out. The best eluent proved to be the mixture n-heptanelethyl acetate 96:4. The product was dissolved in 15 ml of n-heptane and the liquid loaded onto an automated column system. For this purpose, a 120 g silica gel column was used. With the aid of the Rf values ascertained, a gradient was determined by automation. Purity 95%, yield: 30%,

[0039] Synthesis () (comparative ligand)

##STR00008##

[0040] In a glovebox, 9 g (0.01 mol) of diorganophosphite dichlorophosphite were weighed into a secured 250 mL Schlenk flask, then evacuated and dissolved in 75 mL of dried toluene. In a second secured 250 mL Schlenk flask, 2.2 g (2.1 mL 0,02 mol) of 2-methylphenol were weighed out and dried at room temperature for 12 hours by means of an oil vacuum pump. 50 mL of dried toluene and 3 mL=2.2 g (0.022 mol) of degassed triethylamine were added with stirring and dissolved. The dichlorophosphite was added at room temperature to the phenol-triethylamine solution 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 then 3 times 1.5 mL (0.011 mol) of triethylamine were metered in and left to stir for a further 15 hours. The ammonium hydrochloride was removed by frit, washed with 1 x 10 mL of dried 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 by frit, the Schlenk flask was post-rinsed with 2 times 10 mL of ACN and after drying introduced into a glove box. Yield 90%, purity: 95%.

[0041] Catalysis experiments The hydroformylation was carried out in a 16 ml autoclave from HEL Group, Hertfordshire, United Kingdom, equipped with a pressure-retaining valve, gas flowmeter and sparging stirrer. The n-octene used as substrate (Oxeno GmbH, mixture of octene isomers of 1-octene: 3%; cis+rans-2-octene: 49%; cis+trans-3-octene: 29%; cis+trans-4-octene: 16%; structurally isomeric octenes: 3%) was heated under reflux for several hours over sodium and distilled under argon.

[0042] The reaction solutions for the experiments were prepared beforehand under an argon atmosphere. For this, 0.0021 g of Rh(acac)(CO).sub.2 and the corresponding amount of phosphite compound were weighed out and filled with 8.0 ml of toluene. The mass of toluene introduced in each case was determined for the GC analysis. 1.80 g of n-octene (16 mmol) was then added. The prepared solutions were then introduced into the autoclave, which was flushed three times with argon and three times with syngas (Linde; H.sub.2 (99.999%): CO (99.997%) =1:1). The autoclave was then heated to the desired temperature at an overall pressure of 10 bar with stirring (900 rpm). On reaching the reaction temperature, the syngas pressure was increased to 20 bar and the reaction carried out at constant pressure for 4 h. At the end of the reaction time, the autoclave was cooled to room, temperature, depressurized while stirring and flushed with argon. 0.5 ml of each reaction mixture was removed at the end of the reaction, diluted with 4 ml of pentane and analysed by gas chromatography: HP 5890 Series II plus, PONA, 50 m x 0.2 mm x 0.5 μm. Residual olefin and aldehyde were quantitatively determined against the solvent toluene as internal standard.

[0043] Results of the catalysis experiments

[0044] Reaction conditions:

[0045] [Rh]: 120 ppm, L:Rh=1:2, p: 20 bar, T: 120° C.; t: 4 h

TABLE-US-00001 TABLE 1 Hydroformylation of n-octenes Ligand n/iso selectivity in % 1* 77 2 56 *inventive compound

[0046] Definition of selectivity:

[0047] In the hydroformylation there is n/iso selectivity, which is the ratio of linear aldehyde (=n) to branched aldehyde (=iso). The selectivity here in respect of the n-aldehyde signifies that this amount of linear product was formed. The remaining percentages then correspond to the branched isomer. Thus, at a regioselectivity of 50%, n-aldehyde and iso-aldehyde are formed in equal proportions.

[0048] The compound of the invention (1) achieved an increase in n/iso selectivity compared with the comparative ligand (2).

[0049] The experiments carried out demonstrate that the stated object is achieved by the compound of the invention.