CN102875599B - Tridentate phosphine ligands and their applications in linear hydroformylation and similar reactions - Google Patents

Abstract

The invention discloses a class new tridentate Phosphine ligands and the application in linear hydroformylation and similar reaction thereof.Three tooth Phosphine ligands disclosed in the present invention are three tooth Phosphine ligands that current first case is applied to efficient highly selective hydroformylation reaction, are applicable to the isomerization hydroformylation reaction of efficient highly selective, hydrocarboxylation reaction, the cyanalation reaction of hydrogen, isomerization formyl reaction, hydroaminomethylation and similar reaction simultaneously.In linear hydroformylation reaction, the selectivity of the type part is apparently higher than corresponding didentate phosphine ligand; Simultaneously compared with four corresponding tooth Phosphine ligands, not only selectivity is close, and shows higher turn over number (TON); And more easily synthesize, yield is higher.1-hexene and 1-octene highly selective are converted into enanthaldehyde (synthesis for orange essence and rose compound) and n-nonyl aldehyde (food spice) by new tridentate Phosphine ligands of the present invention, significant to the industrial production based on hydroformylation reaction.

Description

Tridentate phosphine ligands and their applications in linear hydroformylation and similar reactions

technical field

The present invention relates to a series of novel tridentate phosphine ligands and their use in linear hydroformylation and similar reactions.

Background technique

The hydroformylation reaction was discovered by Professor Otto Roelen in 1938 ^[1] , and has been widely used in industry. Today, the hydroformylation reaction has become the largest homogeneous catalytic reaction in industrial production. The annual production of aldehydes and alcohols through Fe, Zn, Mn, Co, Cu, Ag, Ni, Pt, Pd, Rh, Ru and Ir metal-catalyzed hydroformylation reactions has reached 10 million tons ^{[2 ]} .

In industry, the important intermediate butyraldehyde is obtained through the linear hydroformylation reaction catalyzed by Rh with propylene as the starting material, and the annual production of the plasticizer dioctyl phthalate (DEHP) through subsequent reactions reaches 3 million t, the reaction process is shown in Figure 1. At the same time, in order to increase the molecular weight of the synthetic plasticizer to reduce the penetration of plastics and reduce the toxicity of plastics, the industry is currently using a mixture of cheap butene and isobutene as raw materials, and through Rh-catalyzed linear hydroformylation The intermediate n-valeraldehyde is obtained by the reaction, and then a plasticizer with a larger molecular weight is synthesized through subsequent reactions, and its toxicity is greatly reduced. The reaction process is shown in Figure 1. Therefore, the hydroformylation reaction is very important in industry, so the development of efficient and highly selective catalysts for the hydroformylation reaction in order to selectively obtain linear products has a pivotal role.

Although many scientific researchers have done a lot of research on the catalysts involved in the hydroformylation reaction, there are still technical problems that need to be solved urgently, such as high catalyst consumption, slow reaction speed, and poor selectivity.

The hydroformylation reaction discovered by Professor Otto Roelen used Co metal complex (HCo(CO) ₄ ) as a catalyst in the early stage, but the reaction conditions were harsh and the linear selectivity of the reaction was not good. In addition, the catalyst used in the reaction The precursor Co ₂ (CO) ₈ is highly toxic ^[3] . After the 1970s, Rh metal complexes gradually replaced Co metal complexes as the main catalysts for hydroformylation reactions. The HRh(CO)(PPh ₃ ) ₂ catalyst developed by Pruett of Union Carbide and Booth of Union Oil ^[4] has been widely used in commercialization, but in order to ensure high selectivity to obtain active catalytic species, the reaction Using 820 times the amount _of PPh ligand relative to the Rh catalyst, the ratio of linear to branched products reached 17:1. The reason why a large excess of PPh ₃ ligand is required is that the Rh-P coordination bond is easily broken, and after the PPh ₃ ligand falls from the selective active catalytic species A (HRh(CO)(PPh ₃ ) ₂ ), it will Catalytic species B and C with high activity but poor selectivity are formed, see Figure 2. When the PPh ₃ equivalent is increased, the balance of active catalytic species moves to the direction of generating selective active catalytic species A, thereby improving the selectivity of the reaction.

In order to avoid extensive use of PPh ₃ ligands and ensure high selectivity, researchers have designed and synthesized bidentate phosphine ligands, among which the most representative three types of ligands are Bisbi series ligands, Xantphos series ligands and Biphephos series ligands with large sterically hindered substituent groups ^[5] , the structure is shown in Figure 3. These three types of ligands showed good selectivity in the hydroformylation reaction, and the amount of ligands was reduced to 5 equivalents.

In recent years, the applicant has designed and synthesized tetradentate phosphine ligands based on the research on bidentate phosphine ligands ^[6] . There are four forms of coordination between the P atom and the metal Rh in the tetradentate phosphine ligand as shown in Figure 4 . Since tetradentate phosphine ligands have multiple chelating sites, the formation of low-selectivity active catalytic species is effectively suppressed, and the hydroformylation reaction using tetradentate phosphine ligands as catalysts has achieved the best selectivity so far.

Although monodentate, bidentate, and tetradentate phosphine ligands have been widely used in hydroformylation reactions, relatively high catalyst equivalents, low reaction rates, poor selectivities, and narrow substrate ranges are still selective An urgent problem to be solved in the linear hydroformylation reaction. In view of this, the design and synthesis of efficient and highly selective phosphine ligands suitable for hydroformylation reactions is still a hot issue. At the same time, there is no literature report on any tridentate phosphine ligand.

The following references are included in the paper:

[1] Chem Abstr, 1994, 38-550;

[2] Adv.Synth.Catal.2009,351,537–540;

[3] Angew.Chem.Int.Ed.1994,33,2144;

[4] J.Org.Chem.1969,34,327;

[5] Chem.Abstr., 1988,108,7890; Acc.Chem.Res.2001,34,895; US Patent, 4769498,1988;

[6] J. Am. Chem. Soc. 2006, 128, 16058-16061.

Contents of the invention

The present invention aims at the development of novel high-efficiency and high-selectivity ligands suitable for linear hydroformylation reactions, and proposes a series of tridentate phosphine ligands, their synthesis methods and their applications in hydroformylation and similar reactions .

In order to achieve the above purpose, the tridentate phosphine ligand proposed by the present invention has the structure of general formula (I):

In general formula (I):

I, J, K, L, M, N, Q are H, R, Ar, substituted Ar, OR, OAr, COOEt, halogen, SO ₂ R, SO ₃ H, SO ₂ NHR or NR ₂ ;

X is O, _CH2 , NH or NR;

Y is R, Ar, OR, OAr, pyrrole or substituted pyrrole;

R is an alkyl group or a substituted alkyl group, and Ar is an aryl group.

In the structure represented by the general formula (I), a bridging structure can be formed between Q and L substituting atoms to form a five-membered ring or a six-membered ring.

The first type of ligands of the above-mentioned tridentate phosphine ligands have the structure of general formula (II):

In general formula (II):

a, b, c, d, I, J, K, L, M, N, Q is H, R, Ar, substituted Ar, OR, OAr, COOEt, halogen, SO ₂ R, SO ₃ H, SO ₂ NHR or NR ₂ ;

X is O, _CH2 , NH or NR;

R is an alkyl group or a substituted alkyl group, and Ar is an aryl group.

In the structure shown in the general formula (II), any two adjacent substituting atoms in a, b, c, d, I, J, K, L, M, N, Q can form a bridging structure to form a five rings or six-membered rings.

The ligands of the second type of tridentate phosphine ligands described above have the structure of the general formula (III):

In general formula (III):

a, b, c, d, E, F, G, I, J, K, L, M, N is H, R, Ar, substituted Ar, OR, OAr, COOEt, halogen, SO ₂ R, SO ₃ H , SO ₂ NHR or NR ₂ ;

X is O, _CH2 , NH or NR;

R is an alkyl group or a substituted alkyl group, and Ar is an aryl group.

In the structure shown in general formula (III), bridges can be formed between any two adjacent substituting atoms in a, b, c, d, E, F, G, I, J, K, L, M, N The chain structure forms a five-membered ring or a six-membered ring.

The third type of ligands of the above-mentioned tridentate phosphine ligands have the structure of general formula (IV):

In general formula (IV):

a, b, c, d, e, f, I, J, K, L, M, N, Q is H, R, Ar, substituted Ar, OR, OAr, COOEt, halogen, SO ₂ R, SO ₃ H , SO ₂ NHR or NR ₂ ;

X is O, _CH2 , NH or NR;

R is an alkyl group or a substituted alkyl group, and Ar is an aryl group.

In the structure shown in general formula (IV), bridges can be formed between any two adjacent substituting atoms in a, b, c, d, e, f, I, J, K, L, M, N, Q The chain structure forms a five-membered ring or a six-membered ring.

A fourth type of ligand of the above-mentioned tridentate phosphine ligands has the structure of general formula (V):

In general formula (V):

a, b, c, d, e, I, J, K, L, M, N, Q is H, R, Ar, substituted Ar, OR, OAr, COOEt, halogen, SO ₂ R, SO ₃ H, SO ₂ NHR or NR ₂ ;

X is O, _CH2 , NH or NR;

R is an alkyl group or a substituted alkyl group, and Ar is an aryl group.

In the structure shown by the general formula (V), a bridging structure can be formed between any two adjacent substituting atoms in a, b, c, d, e, I, J, K, L, M, N, Q Form a five-membered ring or a six-membered ring.

The fifth type of ligands of the above-mentioned tridentate phosphine ligands have the structure of general formula (VI):

In general formula (VI):

a, b, c, d, e, f, g, h, I, J, K, L, M, N, Q is H, R, Ar, substituted Ar, OR, OAr, COOEt, halogen, SO ₂ R , SO ₃ H, SO ₂ NHR or NR ₂ ;

X is O, _CH2 , NH or NR;

Z is _CH2 - _CH2 , O, _CH2 , NH or NR;

R is an alkyl group or a substituted alkyl group, and Ar is an aryl group.

In the structure shown in general formula (VI), any two adjacent substituting atoms in a, b, c, d, e, f, g, h, I, J, K, L, M, N, Q A bridging structure can be formed between them to form a five-membered ring or a six-membered ring.

A sixth type of ligand of the tridentate phosphine ligands described above has the structure of general formula (VII):

In general formula (VII):

a, b, c, d, e, I, J, K, L, M, N, Q is H, R, Ar, substituted Ar, OR, OAr, COOEt, halogen, SO ₂ R, SO ₃ H, SO ₂ NHR or NR ₂ ;

X is O, _CH2 , NH or NR;

R is an alkyl group or a substituted alkyl group, and Ar is an aryl group.

In the structure shown by the general formula (VI), a bridging structure can be formed between any two adjacent substituting atoms in a, b, c, d, e, I, J, K, L, M, N, Q Form a five-membered ring or a six-membered ring.

A seventh type of ligand of the tridentate phosphine ligands described above has the structure of general formula (VIII):

In general formula (VIII):

a, b, c, d, e, f, g, h, I, J, K, L, M, N, Q is H, R, Ar, substituted Ar, OR, OAr, COOEt, halogen, SO ₂ R , SO ₃ H, SO ₂ NHR or NR ₂ ;

X is O, _CH2 , NH or NR;

R is an alkyl group or a substituted alkyl group, and Ar is an aryl group.

In the structure shown in general formula (VIII), any two adjacent substituting elements in a, b, c, d, e, f, g, h, I, J, K, L, M, N, Q can be A bridging structure is formed to form a five-membered ring or a six-membered ring.

The chelating ring of the active catalytic species generated by the bidentate phosphine ligand in the Rh-catalyzed linear hydroformylation reaction is a nine-membered ring. The chelating ability of the nine-membered ring is obviously smaller than that of the corresponding five- and six-membered rings, therefore, at relatively high temperature, CO molecules with strong coordination ability can more easily chelate the Rh The phosphorus atoms at the metal center are replaced, see Figure 5(a), resulting in the formation of more active but less selective catalytically active species.

One of the purposes of designing the tridentate phosphine ligand in the present invention is to increase the metal chelating ability of the ligand, so that the newly generated active catalytic species has higher selectivity, thereby improving the selectivity of the linear hydroformylation reaction. The active catalytic species formed by the tridentate phosphine ligand of the present invention and metal Rh has two coordination forms, as shown in Figure 5(b). In this way, the dissociation of one phosphorus atom in the tridentate phosphine ligand can be replaced by another third phosphorus atom, so that the concentration of phosphorus in the Rh metal center is greatly increased, and thus the active catalytic species formed has a stronger chelating ability. Better selectivity will be exhibited in the hydroformylation reaction.

Compared with the existing tetradentate phosphine ligands, the selectivity of the tridentate phosphine ligands of the present invention is close to that of tetradentate phosphine ligands, but has the advantages of easy synthesis and high yield. The yield can reach 64%, but the yield of the existing disclosed tetradentate phosphine ligand is only 32%.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

The invention proposes a novel, high-efficiency and high-selectivity tridentate phosphine ligand, which can be used as a catalyst in linear hydroformylation and similar reactions. Compared with the tetradentate phosphine ligand, the selectivity of the tridentate phosphine ligand is equivalent to that of the tetradentate phosphine ligand, but the synthesis is easier and the yield is higher. The tridentate phosphine ligand of the present invention can convert 1-hexene and 1-octene into n-heptanal (for the synthesis of orange essence and rose essence) and n-nonanal (food fragrance) with high selectivity. The industrial production of hydroformylation is of great significance.

Description of drawings

Fig. 1 is industrially prepared the reaction principle of plasticizer DEHP by the linear hydroformylation reaction of Rh catalysis;

Figure 2 is the chemical equilibrium between active catalytic species A, B, and C, where A is a selective catalytic active species, B is a catalytic species with higher activity but poor selectivity, and C is the highest activity but the worst selectivity catalytic species;

Figure 3 is a representative structural diagram of three types of bidentate phosphine ligands, in which (a) is the structural diagram of the Bisbi series of ligands, (b) is the structural diagram of the Xantphos series of ligands, and (c) is the structural diagram of the Biphephos series of ligands;

Figure 4 is the structural diagram of the tetradentate phosphine ligand and its four chelation modes with metal Rh, in which, figure (a) is the structure diagram of the tetradentate phosphine ligand, and figure (b) is the tetradentate phosphine ligand and metal Rh Figure 5 shows the coordination modes of bidentate phosphine ligands and tridentate phosphine ligands with metal Rh, among which, figure (a) is the coordination mode of bidentate phosphine ligands with metal Rh, Fig. (b) is the coordination mode of tridentate phosphine ligand and metal Rh.

Detailed ways

The ligand with the structure of the general formula (I) proposed by the present invention is prepared by different synthesis methods according to the difference of the X group.

When X is O, the following synthetic method is used to prepare the tridentate phosphine ligand of the present invention:

When X is _CH2 , the following synthetic method is used to prepare the tridentate phosphine ligand of the present invention:

When X is NH, the following synthetic method is used to prepare the tridentate phosphine ligand of the present invention:

When X is NR, the following synthetic method is used to prepare the tridentate phosphine ligand of the present invention:

above,

I, J, K, L, M, N, Q are H, R, Ar, substituted Ar, OR, OAr, COOEt, halogen, SO ₂ R, SO ₃ H, SO ₂ NHR or NR ₂ ;

Y is R, Ar, OR, OAr, pyrrole or substituted pyrrole;

R is an alkyl group or a substituted alkyl group, and Ar is an aryl group.

In the general formula, a bridging structure can be formed between Q and L substituting atoms to form a five-membered ring or a six-membered ring.

Specific examples (L1-L153) of the tridentate phosphine ligands of the present invention are given below.

Ar in the above specific examples L37~56, L67~86, L126~145 respectively takes the following groups:

Catalysts for linear hydroformylation reactions and similar reactions can be obtained by mixing transition metal complexes with any tridentate phosphine ligands in L1-L153. Here, the similar reactions of linear hydroformylation reactions Refers to isomerization hydroformylation reaction, hydrocarboxylation reaction, hydrocyanylation reaction, isomerization formylation reaction and hydrogen aminomethylation reaction, etc. The transition metal complexes suitable for linear hydroformylation and similar reactions in the present invention can be (Rh(COD)Cl) ₂ , (Rh(COD) ₂ )X, Rh(acac)(CO) ₂ or RuH (CO) ₂ (PPh ₃ ) ₂ , where COD is 1,5-cyclooctadiene, acac is acetylacetone, and X is a counter anion, which can be BF ₄ , ClO ₄ , OTf, SbF ₆ , CF ₃ SO ₃ , B(C ₆ H ₃ (CF ₃ ) ₂ ) ₄ , Cl, Br, or I.

In order to better understand the present invention, the present invention will be further described below in conjunction with examples.

Example 1

Preparation of 2,2′,6-trimethoxybiphenyl (the preparation method of 2,2′,6-trimethoxybiphenyl can be found in literature: Chem.Eur.J.2003,9,3209-3215), synthesis The reaction formula is as follows:

Add 29.9 g of m-diphenylmethyl ether into a dry 500 ml Schlenk bottle filled with nitrogen, and then add 170 mL of anhydrous tetrahydrofuran (THF) under the protection of nitrogen to obtain a mixed solution. 136 mL of 1.6 mol/L n-hexane solution of n-butyllithium was added dropwise to obtain a reaction system. After reacting for 1 h, 69 mL of a THF solution of o-bromoanisole was added dropwise to the reaction system, wherein the mass of o-bromoanisole was 18.7 g. After stirring at room temperature for 1 h, the temperature was raised to 60° C. for 12 h. After the reaction, the reaction system was cooled to room temperature, quenched by adding 200mL of water, the organic phase was separated, the aqueous phase was extracted twice with ether, the organic phases were combined, dried with anhydrous sodium sulfate, filtered, and spin-dried, and the residue was washed with Petroleum ether and ethyl acetate as eluents were separated by silica gel column chromatography to obtain the target compound. The title compound was obtained as a powdery white solid (7.56 g, 31% yield). Rf=0.2(hexane/AcOEt=10:1); ¹ H NMR(300MHz,CDCl ₃ ):δ=3.63(s,6H;2OCH ₃ ),3.66(s,3H;OCH ₃ ),6.55-6.58(d , ³ J(H,H)=8.3Hz,2H;3,5-H),6.89-7.12(m,3H;3,5,6-H),7.17-7.24ppm(m,2H;4-H ); ¹³ C NMR (75MHz, CDCl ₃ ): δ=55.8,56.0,104.2,111.2,120.3,123.6,128.6,128.8,132.2,157.5,158.1ppm.

Example 2

The preparation of 2,2′,6-trimethoxybiphenyl, the synthesis reaction formula is as follows:

Add 182mg of 2,6-dimethoxyphenylboronic acid to a dry Schlenk tube, then add 2.2mg of Pd(OAc) ₂ , 14.3mg of Xphos, 318.5mg of anhydrous K ₃ PO ₄ . After replacing the Schlenk tube with a nitrogen atmosphere, 0.5 mmol of o-bromoanisole and 3 ml of anhydrous THF were added to obtain a reaction system, and the reaction system was reacted at 60° C. for 24 h. After the reaction was finished, add 3ml of water to quench, extract 3 times with dichloromethane, combine the obtained organic phases with anhydrous sodium sulfate, dry and spin dry, use petroleum ether and ethyl acetate as eluents and go through silica gel column chromatography The product obtained was a white solid with a yield of 82%. Rf=0.2(hexane/AcOEt=10:1); ¹ H NMR(300MHz,CDCl ₃ ):δ=3.63(s,6H;2OCH ₃ ),3.66(s,3H;OCH ₃ ),6.55-6.58(d , ³ J(H,H)=8.3Hz,2H;3,5-H),6.89-7.12(m,3H;3,5,6-H),7.17-7.24ppm(m,2H;4-H ); ¹³ C NMR(75MHz CDCl ₃ ):δ=55.8,56.0,104.2,111.2,120.3,123.6,128.6,128.8,132.2,157.5,158.1ppm.

Example 3

The preparation of 2,2′,6-trihydroxybiphenyl, the synthesis reaction formula is as follows:

2.44 g of 2,2',6-trimethoxybiphenyl was added to a dry 250 mL Schlenk bottle, and after replacing the Schlenk bottle with a nitrogen atmosphere, 100 mL of anhydrous dichloromethane was added to obtain a mixed solution. Add 4.4 mL of boron tribromide dropwise to the mixed solution at -78 °C to obtain a reaction system. The reaction system was raised to room temperature and reacted for 5 h. After the reaction was finished, the reaction system was cooled to 0°C, quenched by adding 50ml of water dropwise, the organic phase was separated and collected, the aqueous phase was extracted three times with ethyl acetate, each extraction was performed with 25mL ethyl acetate, the organic phases were combined and washed with anhydrous After drying over sodium sulfate, it was filtered and spin-dried, and the residue was separated by silica gel column chromatography with petroleum ether and ethyl acetate as eluents to obtain a powdery white solid (2.00 g, 99% yield). Rf=0.5(AcOEt/hexane=1:1); ¹ H NMR(300MHz,DMSO):δ=6.34-6.37(d, ³ J(H,H)=7.8Hz,1H;2-OH),6.74- 7.09(m,7H),8.81-8.84ppm(d, ³ J(H,H)=10.8Hz,2H;2',6-OH), ¹³ C NMR(75MHz,DMSO):δ=106.4,113.4, 115.3, 118.3, 122.5, 127.6, 127.8, 132.5, 155.2, 156.1ppm.

Example 4

The preparation of dipyrrole phosphorus chloride (the preparation method of 2,2′,6-trimethoxybiphenyl can be found in the literature: Organometallics, 2002, 21, 3873-3883), the synthesis reaction formula is as follows:

Add 8.7mL phosphorus trichloride and 200mL anhydrous THF to a dry 500mL Schlenk bottle successively under nitrogen protection to obtain a THF solution of phosphorus trichloride. After cooling the THF solution of phosphorus trichloride to 0°C, the Add a mixture of mL pyrrole and 100mL (excess) anhydrous triethylamine in 50mL anhydrous THF dropwise to a THF solution of phosphorus trichloride to obtain a reaction system, and a white precipitate of NEt ₃ .HCl precipitates out immediately. The reaction system was stirred and reacted at room temperature for 12 h. After the reaction, the resulting suspension was diluted with 100 mL of anhydrous THF, and filtered to remove NEt ₃ .HCl. After the filtrate was spin-dried, the target product was collected by vacuum distillation (boiling point: 88° C., 2.7 mmHg). The obtained product was a colorless transparent liquid with a yield of 41%. ¹ H NMR(300MHz,CDCl ₃ ):δ=6.35(m,4H),7.04-7.05ppm(m,4H); ¹³ C NMR(75MHz,CDCl ₃ ):δ=113.9,122.7ppm.

Example 5

The preparation of tridentate phosphine ligand L1, the synthetic reaction formula is as follows:

In a dry 250mL Schlenk bottle, 8.7g of dipyrrole phosphorus chloride and 50mL of anhydrous THF were respectively added under the protection of nitrogen. At room temperature, add 15mL (excessive) anhydrous triethylamine and 100mL 2,2′,6-trihydroxybiphenyl THF solution dropwise in sequence to obtain a reaction system, and a white precipitate of NEt ₃ .HCl precipitates immediately, 2,2 The mass of 2,2',6-trihydroxybiphenyl in THF solution of ',6-trihydroxybiphenyl is 2.02g. The reaction system was stirred at room temperature for 6 h. After the reaction, the white precipitate of NEt ₃ .HCl was removed by filtration. After the obtained filtrate was spin-dried, the resulting mixture was first passed through a thin and long basic alumina chromatography column for rapid crude purification. After the eluent containing the target product was spin-dried, the residue was recrystallized in methanol to obtain a white flaky solid (4.26 g), with a yield of 64%. Rf=0.4(hexane/AcOEt=20:1); ¹ H NMR(300MHz, CDCl ₃ ):δ=6.21-6.23(d, ³ J(H,H)=5.1Hz,12H),6.66-6.69(m ,14H),6.83-6.85(d, ³ J(H,H)=8.4Hz,1H),7.14-7.19(m,3H),7.29-7.34ppm(m,1H); ¹³ C NMR(75MHz,CDCl ₃ ):δ=112.5,112.7,115.5,119.6,121.5,121.7,124.8,130.1,130.3,132.6ppm; ³¹ P NMR:δ=107.8ppm.

Example 6

Hydroformylation of Simple Terminal Alkenes

In a 5mL glass bottle with a magnet, add 0.2mL of toluene solution in which 0.8umol of the tridentate phosphine ligand L1 prepared in Example 5 is dissolved, and 0.2mL of the Rh metal complex Rh(acac)(CO )2 in toluene, stirred at room temperature for 5 min. Then add 2 mmol of terminal olefins and 0.1 mL of n-decane (as an internal standard), then add toluene to make the total volume of the reaction solution 1 mL, and transfer the glass bottle to an autoclave. The air in the autoclave was replaced with _N2 three times, followed by 5 bar each of CO and _H2 gas. The autoclave was heated to 80° C. with an oil bath, and after 2 h of reaction, the autoclave was placed in an ice-water bath to cool. Carefully release the gas in the autoclave in the fume hood, and immediately analyze the reaction mixture by gas chromatography (GC) to obtain the n:i value, which is the linear product and branched chain product formed after the hydroformylation reaction The ratio of the amount of substance.

Example 7

Hydroformylation of simple internal alkenes:

In a 5mL glass bottle with a magnet, add 0.2mL of toluene solution in which 0.8umol of the tridentate phosphine ligand L1 prepared in Example 5 is dissolved, and 0.2mL of the Rh metal complex Rh(acac)(CO )2 in toluene, stirred at room temperature for 5 min. Then add 2 mmol of internal olefins and 0.1 mL of n-decane (as an internal standard), then add toluene to make the total volume of the reaction solution 1 mL, and transfer the glass bottle to a high-pressure reactor. The air in the autoclave was replaced three times with N ₂ , and then filled with CO and H ₂ gases at 5 bar each. The autoclave was heated to 100° C. with an oil bath, and after 1 hour of reaction, the autoclave was placed in an ice-water bath to cool. Release the gas in the autoclave completely in the fume hood, and immediately analyze the reaction mixture by gas chromatography (GC) to obtain the n:i value, which is the ratio of the linear product and the branched chain product generated after the hydroformylation reaction The ratio of the amount of matter.

Example 8

Hydroformylation of styrene:

In a 5mL glass bottle with a magnet, add 0.1mL of toluene solution in which 2umol of the tridentate phosphine ligand L1 prepared in Example 5 is dissolved, and 0.1mL of the Rh metal complex Rh(acac)(CO) is dissolved in 0.1mL The toluene solution was stirred at room temperature for 5 min. Then add 1mmol styrene and 0.1mL n-decane (as an internal standard), then add toluene to make the total volume of the reaction solution 1mL, and transfer the glass bottle to a high-pressure reactor. The air in the autoclave was replaced three times with N ₂ , and then filled with CO and H ₂ gases at 5 bar each. The autoclave was heated to 80° C. with an oil bath, and after 1 h of reaction, the autoclave was placed in an ice-water bath to cool. Release the gas in the autoclave completely in the fume hood, and immediately analyze the reaction mixture by gas chromatography (GC) to obtain the n:i value, which is the ratio of the linear product and the branched chain product generated after the hydroformylation reaction The ratio of the amount of matter.

Condition screening and application of tridentate phosphine ligand of the present invention in linear hydroformylation reaction

Table 1 will illustrate the reactivity and selectivity of the tridentate phosphine ligand L1 synthesized in the present invention in the linear hydroformylation reaction. The reactivity and selectivity of bidentate and tetradentate phosphine ligands are also compared with tridentate phosphine ligands in this invention. To this end, 1-octene and 1-hexene were selected as substrates, and the tridentate phosphine ligand L1, the bidentate phosphine ligand, and the tetradentate phosphine ligand were used for linear hydroformylation reactions, and hydroformylation The reaction conditions are: S/C=10,000, Rh concentration [Rh]=0.2mmol/L, the molar ratio of ligand and Rh(acac)(CO) ₂ is 3:1 (the tridentate phosphine ligand is 4:1) , with toluene as the solvent and n-decane as the internal standard, reacted for 1h, and obtained the n:i value by gas chromatography (GC), and repeated the detection twice to get the average value, the results are shown in Table 1; Styrene was selected as the substrate, The tridentate phosphine ligand L1, the bidentate phosphine ligand, and the tetradentate phosphine ligand were used in the hydroformylation reaction, and the hydroformylation reaction conditions were: S/C=1000, Rh concentration [Rh]=1mmol/ L, the molar ratio of ligand and Rh(acac)(CO) ₂ is 2:1, with toluene as solvent and n-decane as internal standard, react for 30 minutes, and get the n:i value by gas chromatography (GC), The average value was obtained by repeating the detection three times, and the results are shown in Table 1. The data in Table 1 are the best n:i values obtained by the three phosphine ligands under their respective optimal conditions. It can be seen from the results in the table that the selectivity of the tridentate phosphine ligand L1 in the linear hydroformylation reaction is significantly better than that of the bidentate phosphine ligand, and is close to that of the tetradentate phosphine ligand.

Table 1 Comparison of the selectivities of bidentate, tridentate and tetradentate phosphine ligands in linear hydroformylation reactions

In order to further compare the reactivity and selectivity of the above three phosphine ligands, 2-octene, 1-hexene and styrene substrates were selected to test the selectivity and reactivity of the tridentate phosphine ligand L1 under different reaction conditions , the reaction conditions used are: S/C=10,000, Rh concentration [Rh]=0.2mmol/L, the molar ratio of tridentate phosphine ligand L1 to Rh(acac)(CO) ₂ is 4:1, bidentate The molar ratio of phosphine ligand L2 to Rh(acac)(CO) ₂ is 3:1, the molar ratio of tetradentate phosphine ligand L3 to Rh(acac)(CO) ₂ is 3:1, using toluene as solvent, and n-decane was used as internal standard, and the n:i value was obtained by gas chromatography (GC), and the average value was obtained by repeating the detection twice. The results are shown in Table 2, and the reaction formula is as follows:

It can also be seen from the data in Table 2 that the selectivity of the tridentate phosphine ligand L1 in the hydroformylation reaction is obviously better than that of the bidentate phosphine ligand, and at the same time is close to that of the tetradentate phosphine ligand. The TON value in Table 2 is the number of molecules converted by one molecule of catalyst into the substrate.

Table 2 Hydroformylation results of 1-hexene and 2-octene

Table 3. Hydroformylation reaction results of styrene

The data listed in table 3 is styrene in the hydroformylation reaction, tridentate phosphine ligand and metal catalyst Rh (acac) ( _CO ) Reactivity and selectivity under different ratios, reaction condition is: S/ C=1000, Rh concentration [Rh]=1mmol/L, with toluene as the solvent and n-decane as the internal standard, the n:i value was obtained by gas chromatography (GC), and the average value was obtained by repeating the detection three times. The results are shown in the table 3. The TOF value in Table 3 is the number of molecules of the substrate converted by one molecule of catalyst per unit time, and the reaction formula is as follows:

The main factors affecting the hydroformylation reaction are: the ratio of ligand to metal catalyst, reaction temperature, pressure of CO and _H2 gas, reaction time and others, such as the amount of catalyst to substrate and reaction solvent. In the following, 1-octene is used as the substrate to study the tridentate phosphine ligand L1 on the linear _hydrogen Reactivity and selectivity in formylation. Table 4-Table 7 show the reactivity and selectivity of 1-octene using tridentate phosphine ligand L1 under different reaction conditions in the linear hydroformylation reaction.

The selection of the ratio of ligand and metal reagent has a great impact on reaction results such as selectivity and conversion rate. Table 4 lists that 1-octene is selected as the template reaction substrate, and the ligand and Rh (acac) (CO ) The reaction data obtained by changing the molar ratio of ₂ from 1:1 to 8:1, obtained under the adopted reaction conditions: with 1-octene as the substrate, the metal complex used is Rh(acac)(CO ) ₂ , S/C=10,000, with toluene as solvent and n-decane as internal standard; reaction temperature 80°C, reaction time 1h, pressure of CO and H ₂ gases both 10bar; The n:i value was obtained by chromatographic (GC) detection, and the average value was obtained by repeating the detection twice. The results are shown in Table 4, and the reaction formula is as follows:

Table 4 Effect of the ratio of ligand to metal catalyst on the hydroformylation of 1-octene

In the linear hydroformylation reaction, the reaction temperature has a great influence on the selectivity, conversion and TON value of the reaction. Using 1-octene as the substrate, the reaction data obtained at different reaction temperatures are shown in Table 5. The reaction conditions in table 5 are as follows: adopt metal catalyst Rh (acac) ( _CO ) complex compound and tridentate phosphine ligand L1, S/C=10,000, Rh concentration [Rh]=0.2mmol/L, compound Body L1 and metal catalyst Rh(acac)(CO) _The molar ratio is shown in Table 5, with toluene as solvent, with n-decane as internal standard, reaction time 1h, CO and H _The pressure of gas is 10bar; Finally, the n:i value was obtained by gas chromatography (GC), and the average value was obtained by repeating the detection twice. The results are shown in Table 5, and the reaction formula is as follows:

Table 5. Effect of reaction temperature on 1-octene hydroformylation reaction

For the hydroformylation reaction, CO and H ₂ gas pressures affect the reaction rate, selectivity, TON value, etc. Using 1-octene as the substrate, the reaction data obtained under different CO and _H2 gas pressures are shown in Table 6. The reaction conditions in Table 6 are as follows: using Rh(acac)(CO) ₂ complex and tridentate phosphine ligand L1, S/C=10,000, Rh concentration [Rh]=0.2mmol/L, ligand L1 and metal The molar ratio of the catalyst Rh(acac)(CO) ₂ and the pressure of CO and H ₂ are shown in Table 6. With toluene as the solvent and n-decane as the internal standard, the reaction time was 1 h and the reaction temperature was 80°C; The n:i value was obtained by chromatographic (GC) detection, and the average value was obtained by repeating the detection twice. The results are shown in Table 6, and the reaction formula is as follows:

Table 6. Effect of CO and H gas pressure on ₁ -octene hydroformylation reaction

In the hydroformylation reaction, the reaction time affects the conversion rate and yield of the reaction. Using 1-octene as the substrate, the reaction data obtained under different reaction times are shown in Table 7. The reaction conditions of table 7 are as follows: adopt Rh (acac) (CO) ₂ complexes and tridentate phosphine ligand L1, S/C=10,000, Rh concentration [Rh]=0.2mmol/L, ligand L1 and The molar ratio of the metal catalyst Rh(acac)(CO) ₂ is shown in Table 7. Toluene is used as solvent, n-decane is used as internal standard, the reaction temperature is 80°C, and the pressure of CO and _H2 gas is 5bar; after the reaction, The n:i value was obtained by gas chromatography (GC), and the average value was obtained by repeating the detection twice. The results are shown in Table 7, and the reaction formula is as follows:

Table 7 Effect of reaction time on linear hydroformylation of 1-octene

Claims (7)

1. The tridentate phosphine ligand is characterized in that its structure is: 2. The preparation method of tridentate phosphine ligand, is characterized in that, comprises the steps: Step 1, in the presence of palladium catalyst and bidentate phosphine ligand Xphos: Perform a coupling reaction to obtain a compound Step 2, will Reaction with BBr ₃ in dichloromethane gives the compound Step 3, in THF, add triethylamine Et ₃ N, The reaction gives the tridentate phosphine ligand Wherein, I, J, K, L, M, N, Q are all H; X is O; Y is pyrrole. 3. The tridentate phosphine ligand as claimed in claim 1 is mixed with a transition metal complex and prepared as a catalyst in a hydroformylation reaction. 4. A catalyst for hydroformylation, characterized in that: The catalyst is prepared by the mixed reaction of the tridentate phosphine ligand and the transition metal complex described in claim 1. 5. the described catalyst for hydroformylation reaction of claim 4 is characterized in that: The metal atoms in the transition metal complex are Fe, Zn, Mn, Co, Cu, Ag, Ni, Pt, Pd, Rh, Ru or Ir. 6. the catalyst for hydroformylation reaction as claimed in claim 5, is characterized in that: The transition metal complex is (Rh(COD)Cl) ₂ , (Rh(COD) ₂ )X, Rh(acac)(CO) ₂ or RuH(CO) ₂ (PPh ₃ ) ₂ , where X as the counter anion. 7. the catalyst for hydroformylation reaction as claimed in claim 6, is characterized in that: The X is BF ₄ , ClO ₄ , OTf, SbF ₆ , CF ₃ SO ₃ , B(C ₆ H ₃ (CF ₃ ) ₂ ) ₄ , Cl, Br or I.