CN114105817B - Method for continuously preparing adiponitrile by 1,3-butadiene hydrocyanation - Google Patents

Abstract

The invention discloses a method for continuously preparing adiponitrile by 1,3-butadiene hydrocyanation, which mainly comprises the following steps: s1: after 1,3-butadiene passes through the catalyst system, hydrocyanation occurs to generate a product containing 3-pentenenitrile; s2: enabling the product obtained in the step S1 to pass through a catalyst system, performing hydrocyanation reaction again to produce a mixed solution containing adiponitrile, and distilling under reduced pressure to respectively evaporate and recover the product and the by-product obtained from the mixed solution; s3: supplementing the liquid subjected to reduced pressure distillation in the step S2 with a catalyst, and then repeating the hydrocyanation reaction in the step S2 to continuously prepare adiponitrile; and the catalyst system comprises a mixture consisting of 1- (diphenylphosphine) -2- (ethyldiphenylphosphine) ferrocene, zero-valent nickel and monodentate phosphine ligand. The invention can obviously prolong the service life of the catalyst system and obviously reduce the using amount of the catalyst, thereby reducing the production cost of the adiponitrile, improving the production efficiency of the adiponitrile and providing a new catalyst technology for industrial application.

Description

Method for continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene

technical field

The invention relates to the field of chemical industry, in particular to a method for continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene.

Background technique

The hydrocyanation reaction is used industrially to synthesize compounds containing nitrile functionality from compounds containing unsaturation. In the hydrocyanation reaction, adiponitrile is an important chemical intermediate, especially an important intermediate for the production of nylon 66, and is obtained by the secondary hydrocyanation of 1,3-butadiene. In the first hydrocyanation, 1,3-butadiene is reacted with hydrogen cyanide in the presence of zerovalent nickel(0) stabilized with phosphorus-containing ligands to give pentenenitriles, forming linear 3-pentenenitriles and branched pentenenitrile (2-methyl-3-butenenitrile) isomerization mixture. In the second process step, branched pentenenitriles are generally isomerized to linear pentenenitriles. Finally, the hydrocyanation of 3-pentenenitrile to adiponitrile in the presence of Lewis acids and the secondary hydrocyanation of branched pentenenitrile (2-methyl-3-butenenitrile) to the undesired methylglutadiene Nitriles, for the implementation of industrial processes, the selectivity of the individual substeps is of great economic and ecological importance.

At present, there are many patents disclosing the preparation method of adiponitrile and the method of preparing corresponding catalysts, wherein a large amount of organophosphorus ligands, especially phosphites, are used to catalyze this type of hydrocyanation reaction. Monophosphite has good activity, but the positive/iso-selectivity (about 1:1) for terminally hydrocyanated compounds needs to be improved. While introducing triphenylphosphine as a ligand into nickel-catalyzed hydrocyanation reactions, the researchers investigated the use of monophosphites as ligands for nickel catalysts. It was found that the unique electronic effect of monophosphite (weak σ-electron donor, strong π-electron acceptor) accelerates the binding of olefinic substrates in the active intermediate of the nickel catalyst after its coordination, thereby accelerating the Hydrocyanation reaction rate. At the same time, phosphite is easy to prepare, and its stability to sulfides and oxides is its advantage compared with trivalent phosphine ligands. However, monophosphite is unstable in the reaction system, and it is easy to occur such as hydrolysis and alcoholysis, which will affect its use as a catalyst ligand. The bisphosphite prepared by introducing the biphenol skeleton improves the stability of the phosphite, especially the introduction of the ferrocenyl diphosphine ligand, and its unique spatial structure allows it to be used as a ligand for hydrocyanation The linear nitrile selectivity of the reaction is greatly improved (about 30:1).

Although dual phosphorus ligands can obtain high regioselectivity when the ligand is used in a small amount, due to the complex synthesis and high price, the research hopes to consume cheap single phosphorus ligands, and have similar properties to double phosphorus ligands. Effect.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene, so as to solve the problems of complicated synthesis methods and low yields of conventional conventional methods.

In order to solve the above problems, the invention provides a method for continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene, comprising the following steps:

S1: After passing 1,3-butadiene through the first catalyst system, a hydrocyanation reaction occurs to generate products including 3-pentenenitrile and by-products;

S2: pass the 3-pentenenitrile described in step S1 through the second catalyst system, and hydrocyanation reaction occurs again to produce a mixed solution containing adiponitrile, and the product and by-products obtained from the mixed solution are distilled out respectively after vacuum distillation and recycle;

The step S2 also includes the operation of adding a cocatalyst Lewis acid, and the molar ratio of the Lewis acid to zero-valent nickel is 1-5:1.

S3: Repeat the hydrocyanation reaction of step S2 to continuously prepare adiponitrile;

The first catalyst system and the second catalyst system both include 1-(diylphenylphosphine)-2-(ethyldiphenylphosphino)ferrocene, zero-valent nickel and monodentate phosphine ligands mixture.

As a preferred scheme, the structural formula of the 1-(diphenylphosphine)-2-(ethyldiphenylphosphino)ferrocene is as follows:

其中，R、R'为苯基或者甲基苯基中的一种。

Wherein, R and R' are one of phenyl or methylphenyl.

As a preferred scheme, the 1-(diphenylphosphino)-2-(ethyldiphenylphosphine) ferrocene passes through 1-(diphenylphosphino)ferrocene, vinyldiphenylphosphine, Obtained after the mixed reaction of ferric chloride and dichloromethane.

As a preferred scheme, in the catalyst system, the mol ratio of zero-valent nickel, monodentate phosphine ligand and 1-(diylphenylphosphine)-2-(ethyldiphenylphosphine) ferrocene is 1:( 1-5): (2-10).

As a preferred solution, the step S2 also includes the operation of adding a cocatalyst Lewis acid, and the molar ratio of the Lewis acid to zero-valent nickel is 1-5:1.

As a preferred solution, the step S1 also includes the operation of isomerizing by-products to prepare 3-pentenenitrile again.

As a preferred solution, the monodentate phosphine ligand is one or more of phosphine, phosphite, hypophosphite and phosphonite or a combination thereof.

As a preferred solution, the step S2 also includes the operation of recovering the zero-valent nickel catalyst and the phosphorus ligand through extraction, specifically including: after the zero-valent nickel catalyst and the phosphorus ligand are recovered by the extraction agent, continue to be put into step S3 Continuous preparation of adiponitrile.

As a preferred solution, the step S3 also includes a step of supplementing zero-valent nickel, and the supplementary amount of zero-valent nickel is 0.02% of the mass of the product adiponitrile.

The present invention has the following technical advantages: the first catalyst system and the second catalyst system provided by the present invention can effectively catalyze the continuous hydrocyanation reaction of 1,3-butadiene to prepare adiponitrile, and can significantly improve the performance of metal complex catalysts. Activity and selectivity, significantly prolonging the service life of the catalyst system, significantly reducing the usage of 1-(diphenylphosphine)-2-(ethyldiphenylphosphino)ferrocene, thereby reducing the production cost of adiponitrile, Improve the production efficiency of adiponitrile and provide new catalyst technology for its industrial application.

Detailed ways

The technical solutions of the present invention will be clearly and completely described below, and obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Example 1:

This embodiment provides a method for continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene, comprising the following steps:

S1: After passing 1,3-butadiene through the first catalyst system, a hydrocyanation reaction occurs to generate a product containing 3-pentenenitrile and by-products; the step S1 also includes isomerization of by-products again Operations for the preparation of 3-pentenenitrile;

S2: pass the 3-pentenenitrile described in step S1 through the second catalyst system, and hydrocyanation reaction occurs again to produce a mixed solution containing adiponitrile, and the product and by-products obtained from the mixed solution are distilled out respectively after vacuum distillation and recycle;

The step S2 also includes the operation of adding a cocatalyst Lewis acid, and the molar ratio of the Lewis acid to zero-valent nickel is 2.5:1.

S3: Repeat the hydrocyanation reaction of step S2 to continuously prepare adiponitrile;

The first catalyst system and the second catalyst system both include 1-(diylphenylphosphine)-2-(ethyldiphenylphosphino)ferrocene, zero-valent nickel and monodentate phosphine ligands mixture;

The monodentate phosphine ligand is one or more combinations of phosphine, phosphite, hypophosphite and phosphinate or a mixture thereof; the 1-(diylphenylphosphine)-2-(ethyl The structural formula of base diphenylphosphino) ferrocene is as follows:

其中，R、R'为苯基或者甲基苯基中的一种，Fe可以等同替换为Co、Ni、Ru、Os、Rh、Pd、Pt、Mn、Cr或V及其混合物金属。

Wherein, R and R' are one of phenyl or methyl phenyl, Fe can be equivalently replaced by Co, Ni, Ru, Os, Rh, Pd, Pt, Mn, Cr or V and their mixture metals.

The 1-(diphenylphosphine)-2-(ethyldiphenylphosphine) ferrocene passes through 1-(diphenylphosphino)ferrocene, vinyldiphenylphosphine, ferric chloride and Obtained after mixed reaction of dichloromethane.

In the first catalyst system and the second catalyst system, the molar ratio of zero-valent nickel, monodentate phosphine ligand and 1-(diylphenylphosphine)-2-(ethyldiphenylphosphine) ferrocene It is 1:2.5:6.

The step S2 also includes the operation of recovering the zero-valent nickel catalyst and the phosphorus ligand through extraction, specifically including: after the zero-valent nickel catalyst and the phosphorus ligand are recovered by the extractant, continue to be put into the continuous preparation of adiponitrile in step S3 middle.

The step S3 also includes a step of supplementing zero-valent nickel, and the supplementary amount of zero-valent nickel is 0.02% of the mass of the product adiponitrile.

Example 1:

This embodiment provides a method for continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene, comprising the following steps:

S1: After passing 1,3-butadiene through the first catalyst system, a hydrocyanation reaction occurs to generate a product containing 3-pentenenitrile and by-products; the step S1 also includes isomerization of by-products again Operations for the preparation of 3-pentenenitrile;

S2: pass the 3-pentenenitrile described in step S1 through the second catalyst system, and hydrocyanation reaction occurs again to produce a mixed solution containing adiponitrile, and the product and by-products obtained from the mixed solution are distilled out respectively after vacuum distillation and recycle;

The step S2 also includes the operation of adding a cocatalyst Lewis acid, and the molar ratio of the Lewis acid to zero-valent nickel is 1-1.

S3: Repeat the hydrocyanation reaction of step S2 to continuously prepare adiponitrile;

The first catalyst system and the second catalyst system both include 1-(diylphenylphosphine)-2-(ethyldiphenylphosphino)ferrocene, zero-valent nickel and monodentate phosphine ligands mixture;

The monodentate phosphine ligand is one or more combinations of phosphine, phosphite, hypophosphite and phosphinate or a mixture thereof; the 1-(diylphenylphosphine)-2-(ethyl The structural formula of base diphenylphosphino) ferrocene is as follows:

其中，R、R'为苯基或者甲基苯基中的一种，Fe可以等同替换为Co、Ni、Ru、Os、Rh、Pd、Pt、Mn、Cr或V及其混合物金属。

Wherein, R and R' are one of phenyl or methyl phenyl, Fe can be equivalently replaced by Co, Ni, Ru, Os, Rh, Pd, Pt, Mn, Cr or V and their mixture metals.

The 1-(diphenylphosphine)-2-(ethyldiphenylphosphine) ferrocene passes through 1-(diphenylphosphino)ferrocene, vinyldiphenylphosphine, ferric chloride and Obtained after mixed reaction of dichloromethane.

In the first catalyst system and the second catalyst system, the molar ratio of zero-valent nickel, monodentate phosphine ligand and 1-(diylphenylphosphine)-2-(ethyldiphenylphosphine) ferrocene It is 1:1:2.

The step S2 also includes the operation of recovering the zero-valent nickel catalyst and the phosphorus ligand through extraction, specifically including: after the zero-valent nickel catalyst and the phosphorus ligand are recovered by the extractant, continue to be put into the continuous preparation of adiponitrile in step S3 middle.

The step S3 also includes a step of supplementing zero-valent nickel, and the supplementary amount of zero-valent nickel is 0.02% of the mass of the product adiponitrile.

Example 2:

This embodiment provides a method for continuously preparing adiponitrile by hydrocyanation of 1,3-butadiene, comprising the following steps:

S1: After passing 1,3-butadiene through the first catalyst system, a hydrocyanation reaction occurs to generate a product containing 3-pentenenitrile and by-products; the step S1 also includes isomerization of by-products again Operations for the preparation of 3-pentenenitrile;

S2: pass the 3-pentenenitrile described in step S1 through the second catalyst system, and hydrocyanation reaction occurs again to produce a mixed solution containing adiponitrile, and the product and by-products obtained from the mixed solution are distilled out respectively after vacuum distillation and recycle;

The step S2 also includes the operation of adding a cocatalyst Lewis acid, and the molar ratio of the Lewis acid to zero-valent nickel is 5:1.

S3: Repeat the hydrocyanation reaction of step S2 to continuously prepare adiponitrile;

The first catalyst system and the second catalyst system both include 1-(diylphenylphosphine)-2-(ethyldiphenylphosphino)ferrocene, zero-valent nickel and monodentate phosphine ligands mixture;

The monodentate phosphine ligand is one or more combinations of phosphine, phosphite, hypophosphite and phosphinate or a mixture thereof; the 1-(diylphenylphosphine)-2-(ethyl The structural formula of base diphenylphosphino) ferrocene is as follows:

其中，R、R'为苯基或者甲基苯基中的一种，Fe可以等同替换为Co、Ni、Ru、Os、Rh、Pd、Pt、Mn、Cr或V及其混合物金属。

Wherein, R and R' are one of phenyl or methyl phenyl, Fe can be equivalently replaced by Co, Ni, Ru, Os, Rh, Pd, Pt, Mn, Cr or V and their mixture metals.

The 1-(diphenylphosphine)-2-(ethyldiphenylphosphine) ferrocene passes through 1-(diphenylphosphino)ferrocene, vinyldiphenylphosphine, ferric chloride and Obtained after mixed reaction of dichloromethane.

In the first catalyst system and the second catalyst system, the molar ratio of zero-valent nickel, monodentate phosphine ligand and 1-(diylphenylphosphine)-2-(ethyldiphenylphosphine) ferrocene It is 1:5:10.

The step S2 also includes the operation of recovering the zero-valent nickel catalyst and the phosphorus ligand through extraction, specifically including: after the zero-valent nickel catalyst and the phosphorus ligand are recovered by the extractant, continue to be put into the continuous preparation of adiponitrile in step S3 middle.

The step S3 also includes a step of supplementing zero-valent nickel, and the supplementary amount of zero-valent nickel is 0.02% of the mass of the product adiponitrile.

Example 4:

The raw material, raw material quality and reaction conditions and productive rate that add during specific operation are provided in embodiment 4, specifically as follows:

Preparation of catalyst 1-(diphenylphosphine)-2-(ethyldiphenylphosphine) ferrocene:

(1) Synthesis of 1-(diphenylphosphino)ferrocene, synthesis of vinyldiphenylphosphine

Under the protection of argon, ferrocene (1mol, 186g) and n-butyl lithium n-BuLi (700mL, 1.1mol, 1.6M n-hexane solution) injection. In an inert gas atmosphere, inject N,N,N',N'-tetramethylethylenediamine (TMEDA) (1mL, 6.7mmol) with a 20ml disposable syringe and stir for 2 hours, then drop it into the system at -20°C Add diphenylphosphine chloride (1mol, 180g), then react at -20°C for 3 hours, add water to the system to quench, then separate the layers, dry the organic layer with anhydrous magnesium sulfate, filter, and distill off the solvent under reduced pressure Finally, a yellow solid was obtained, which was recrystallized from methanol under the protection of argon to obtain 317 g of 1-(diphenylphosphino)ferrocene, with a yield of 96%;

Under the protection of argon, add diphenylphosphine chloride (1mol, 220g) and 0.5L tetrahydrofuran to the dry reactor, and then add 2M tetrahydrofuran solution (1.1mol, 0.55L) of vinylmagnesium chloride dropwise to the system at 0°C , after the dropwise addition, react at room temperature for 10 hours, add water to the system to quench, then separate the layers, the organic layer is dried with anhydrous magnesium sulfate, filtered, and the solvent is removed by distillation under reduced pressure to obtain a white solid, dichloromethane and Methanol recrystallization obtained 201 g of vinyl diphenylphosphine with a yield of 95%.

(2) Synthesis of 1-(diphenylphosphine)-2-(ethyldiphenylphosphino)ferrocene

Under argon protection, 1-(diphenylphosphino)ferrocene (0.5mol, 165g), vinyldiphenylphosphine (0.5mol, 106g), iron trichloride ( 0.05mol, 8.1g) and 1L dichloromethane, then reacted at 25°C for 12 hours, added water to the system to quench, then separated the layers, dried the organic layer with anhydrous magnesium sulfate, filtered, and distilled off the solvent under reduced pressure to obtain The yellow solid was recrystallized from a mixed solution of dichloromethane and methanol to obtain 249 g of (I), with a yield of 92%.

S1: Hydrocyanation of 1,3-butadiene:

Under the protection of nitrogen in the fume hood, 5 g of nano-sized nickel (0) powder, 80 g of 1-(diphenylphosphine)-2-(ethyldiphenylphosphine) ferrocene, and 250 g of phosphorous acid were successively added to a 2000 mL autoclave. Trimethylphenyl ester, after mixing for about 1 hour, add 400g of dehydrated butadiene, heat the mixture to 70-90°C, and set the reaction pressure to 15bar. After 60 minutes, continuously measure and pump 200 g of freshly distilled hydrogen cyanide at 0° C., and then maintain a constant temperature of 100° C. for 60 minutes to complete the reaction. Then cool and the pressure drops to 1 bar. After sampling, no cyanide was found in the Volhard cyanide determination, and the hydrogen cyanide had been completely converted.

Through gas chromatography analysis with internal standard (benzonitrile), calculate based on hydrogen cyanide, 3-pentenenitrile and 2-methyl-3-butenenitrile yield 85%, 3-pentenenitrile: 2 - Methyl-3-butenenitrile ratio = 30:1.

S2: Preparation of adiponitrile:

Get 0.003mol zero-valent nickel catalyst, catalyst mixing system makes the concentration of zero-valent nickel Ni(0) be 300mg/L, zero-valent nickel Ni(0)/monodontate phosphorus ligand/1-(diylphenylphosphine)-2 The molar ratio of -(ethyldiphenylphosphino)ferrocene is 1:2:4. Under the protection of nitrogen, dissolve the Lewis acid in a certain amount of 3-pentenenitrile (the molar ratio of 3-pentenenitrile to zero-valent nickel catalyst is 160:1), and add it to the reaction bottle with mechanical stirring and condensing reflux tube Medium; wherein, the molar ratio of Lewis acid to zero-valent nickel catalyst is 2:1, the ligand containing monodentate phosphorus is trimethyl phosphite, the stirring is started, and the temperature is raised to 70-90°C, and then the liquid hydrogen cyanide The acid is blown into the reaction bottle at a certain flow rate; after the hydrocyanic acid is fed, the reaction solution is kept at normal pressure for 4.5 hours. After the heat preservation is over, the unreacted hydrocyanic acid, 3-pentenenitrile, product adiponitrile and other by-products are distilled and recovered by vacuum distillation, and the zero-valent nickel catalyst and phosphorus ligand are extracted and recovered with an extractant .

The product adiponitrile was analyzed by gas chromatography, calculated based on hydrocyanic acid, and the reaction reached a conversion rate of 96% and a selectivity of 92%.

S3: Continuous preparation of adiponitrile

Continuously repeat the secondary hydrocyanation reaction according to the above S2 operation steps. After 120 hours of continuous operation, the zero-valent nickel catalyst and phosphorus ligand were extracted and recovered with an extractant, and 0.001 mol of zero-valent nickel was added, and then the same reaction was carried out in the above-mentioned single-pot simulation cycle test method to obtain the product.

The product adiponitrile was analyzed by gas chromatography, calculated based on hydrocyanic acid, and the reaction reached a conversion rate of 98.5% and a selectivity of 92%.

Also prove further by above-mentioned embodiment, the production efficiency of the adiponitrile prepared by the present invention is high, and preparation method is simple, and the yield of the adiponitrile obtained by continuous preparation method is compared with the adiponitrile yield that initial reaction obtains also greatly improve.

The above description shows and describes several preferred embodiments of the invention, but as mentioned above, it should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations , modification and environment, and can be modified within the scope of the inventive concept described herein, through the above description or through technology or knowledge in the relevant field. However, changes and changes made by those skilled in the art do not depart from the spirit and scope of the present invention, and should all be within the protection scope of the appended claims of the present invention.

Although the present disclosure is disclosed as above, the protection scope of the present disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications will all fall within the protection scope of the present invention.

Claims (1)

1. A method for continuously preparing adiponitrile by 1,3-butadiene hydrocyanation, comprising the steps of:

s1:1,3-hydrocyanation of butadiene:

under the protection of nitrogen in a ventilation kitchen, sequentially adding 5g of nanoscale zero-valent nickel powder, 80g of 1- (diphenylphosphino) -2- (ethyldiphenylphosphino) ferrocene and 250g of trimethylphenyl phosphite into a 2000mL high-pressure autoclave, reacting and mixing for 1 hour, adding 400g of dehydrated butadiene, heating the mixture to 70-90 ℃, and setting the reaction pressure to be 15bar; continuously pumping 200g of hydrocyanic acid with the temperature of 0 ℃ which is newly distilled in a metering way for 60 minutes, keeping the temperature of 100 ℃ for 60 minutes to ensure that the reaction is complete, and then cooling the mixture, and reducing the pressure to 1bar; after this sampling, no cyanide was found in the Volhard cyanide assay and hydrogen cyanide had been completely converted;

by gas chromatographic analysis with an internal benzonitrile standard, calculated on the basis of hydrogen cyanide, yields of 85% for 3-pentenenitrile and 2-methyl-3-butenenitrile, 3-pentenenitrile: 2-methyl-3-butenenitrile ratio =30:1;

s2: preparation of adiponitrile:

taking 0.003mol of zero-valent nickel catalyst, and enabling the concentration of zero-valent nickel in a catalyst mixing system to be 300mg/L, wherein the molar ratio of zero-valent nickel/monodentate phosphorus ligand/1- (diphenylphosphine) -2- (ethyldiphenylphosphine) ferrocene is 1:2:4; under the protection of nitrogen, dissolving Lewis acid in a certain amount of 3-pentenenitrile, and adding the solution into a reaction bottle with a mechanical stirring and condensing reflux pipe; wherein the molar ratio of the 3-pentenenitrile to the zero-valent nickel catalyst is 160:1, the molar ratio of the Lewis acid to the zero-valent nickel catalyst is 2:1, starting stirring a monodentate phosphorus ligand trimethyl phosphite, heating to 70-90 ℃, and then blowing liquid hydrocyanic acid into a reaction bottle at a certain flow rate by using nitrogen; after the hydrocyanic acid feeding is finished, preserving the temperature of the reaction liquid for 4.5 hours at normal pressure; after the heat preservation is finished, evaporating and recovering unreacted hydrocyanic acid, 3-pentenenitrile, a product adiponitrile and other byproducts by reduced pressure distillation, and extracting and recovering a zero-valent nickel catalyst and a phosphorus ligand by using an extracting agent;

the product adiponitrile is analyzed by gas chromatography, and calculated by taking hydrocyanic acid as a reference, the reaction reaches the conversion rate of 96 percent and the selectivity of 92 percent;

s3: continuous preparation of adiponitrile

Continuously and repeatedly carrying out secondary hydrocyanation reaction according to the operation step S2, after continuously operating for 120 hours, extracting and recovering the zero-valent nickel catalyst and the phosphorus ligand by using an extracting agent, supplementing 0.001mol of zero-valent nickel, and carrying out the same reaction in the single kettle simulation cycle test mode to obtain a product;

the structural formula of the 1- (diphenyl phosphine) -2- (ethyl diphenyl phosphine) ferrocene is as follows:

wherein R and R' are phenyl.