JPH0529232B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to bis(diphenylphosphine)iminium salts useful as catalysts for organic synthesis and polymer reactions, specifically bis(alkyldiphenylphosphine or benzylphenylphosphine). ) Concerning a new method for producing iminium salts. (Prior art and problems to be solved by the invention) The conventionally known method for producing bis(diphenylphosphine) iminium salt is as follows: By reacting bis(diphenylphosphino)amine with n-butyllithium, the following formula This compound is reacted with methyl iodide in an amount of 2 molar ratios to form the following formula: Bis(diphenylmethylphosphine)
A process consisting of producing iminium iodide compounds is
und Allegemeine Chemie", volume 492, pages 122-134 (1982). In this method, the yield of the iminium iodide compound of formula (') is 68% for the starting compound (), which is not necessarily high, and expensive n-butyllithium is used as a reactant. The above-mentioned direction is not preferred as an industrial method because of the drawbacks such as the need for (Means for Solving the Problems) The present inventors have conducted extensive studies in order to develop a novel method for producing bis(diphenylphosphine)iminium salts that does not have the drawbacks of the conventional methods as described above. As a result, we have developed a new production method that avoids the use of organic alkali metal compounds such as n-butyllithium as a reactant, uses a cheaper reactant, and is extremely advantageous in that the reaction operation is simple and safe. I came to find out. That is, in the research conducted by the present inventors, it was found that when bis(diphenylphosphino)amine of formula () is reacted with an equimolar amount of a Grignard reagent, it easily reacts almost quantitatively, and that the reaction product is Furthermore, it has been found that bis(alkyldiphenylphosphine or benzyldiphenylphosphine)iminium salt can be easily produced in high yield under reflux temperature conditions by reacting alkyl halide or benzyl halide in an amount of 2 molar ratios. Therefore, according to the present invention, the following equation The bis(diphenylphosphino)amine represented by [representing an iodine atom] is reacted with a Grignard reagent represented by the following formula RX [] [wherein R represents an alkyl group or a benzyl group, and X represents a chlorine, bromine or iodine atom]. characterized by reacting a halide compound represented by the following formula: [In the formula, R and X have the same meanings as above]
A method for producing a bis(alkyldiphenylphosphine or benzylphenylphosphine) iminium salt represented by is provided. In the method of the present invention, the reaction product obtained as an intermediate in the reaction between the starting compound of formula () and the Grignard reagent (R'MgX') of formula () is expressed by the following formula: It is presumed to be a compound represented by [wherein X' is the same halogen atom as in formula ()]. The reasons for this estimation include the following. That is, based on the known chemical behavior of the Grignard reagent, a -MgX' substitution reaction can occur, and an alkane (R'H) that can be considered liberated from the Grignard reagent used can be detected in the reaction solution. Furthermore, it can be confirmed that the final product of this method obtained by reacting the reaction product with a halide compound of formula () in an amount of 2 molar ratio is a compound that can be represented by formula (). All steps of the reaction of this method can be fully explained by the reaction formula below. Next, implementation of the method of the present invention will be described. As the Grignard reagent of formula () to be reacted with the starting compound (), the group R' can be arbitrarily selected from an alkyl group and an aryl group, unless it is particularly unstable. Usually, examples of the alkyl group (R') include a methyl group, ethyl group, propyl group, butyl group, and examples of the aryl group include a phenyl group. Furthermore, the halogen (') of Grignard reagent R'MgX' is I,
Either Br or Cl may be used. When selecting one of these halides, it is necessary to pay attention to the following points. That is, there is no problem if the halogen (') of the Grignard reagent of formula () is the same as the halogen (X) of the halide compound of formula () used subsequently. However, if they are different, they may induce a halogen exchange reaction with the final product iminium salt (), and when such halogen conversion is undesirable, the halide compound of formula () and the Grignard compound of formula () It is necessary to consider how to combine halogens in reagents. The halide compound of formula () is not particularly limited, but must have reactivity to produce a phosphonium salt compound. In the case of alkyl halide compounds, as the alkyl group becomes higher, the reactivity decreases, so an alkyl group having 1 to 8 carbon atoms is substantially preferable, and as a halogen, iodide has excellent reactivity, and chloride reaction Sex is poor. On the other hand, in the case of highly reactive benzyl halide, high yields can be obtained even in the case of chloride. In this method, according to the standard method, first, bis(diphenylphosphino)amine of formula () is
The Grignard reagent of formula () is added in an equimolar ratio, preferably in a slightly excess amount, and heated to react to produce compound (V), which is a reaction intermediate. Thereafter, a halide compound of formula () is added to this reaction solution in an amount of 2 molar ratio, preferably a slight excess amount, and heated under reflux for 5 to 10 hours. When stirring is continued, the target compound of formula () is produced. The reaction is completed. In this method, the reaction between the bis(diphenylphosphino)amine of the formula () and the Grignard reagent of the formula () can proceed smoothly, and the subsequent reaction with the halide compound of the formula () can proceed smoothly. ()
This is important in obtaining the desired product in high yield. In this case, the organic solvents used as the reaction medium include ethyl ether, butyl ether, tetrahydrofuran, which are commonly used for the preparation of Grignard reagents.
A mixed solvent with ethers such as tetrahydropyran and diglyme, or aromatic hydrocarbons such as benzene and toluene is used. Both this exchange reaction using a Grignard reagent and the subsequent iminization reaction using a halide compound of formula (2) are particularly performed in a tetrahydrofuran solvent to significantly accelerate the reaction and give good results. In order to simplify the reaction operation, this method can often be carried out by simultaneously adding the bis(diphenylphosphino)amine of formula (), the halide compound of formula (), and the Grignard reagent of formula (). Furthermore, when the same compound is used for the halide compound R′X′ used in the Grignard reagent of formula () and the halide compound RX of formula (), the bis(diphenylphosphino)amine and magnesium box of formula () are used. The preparation of the Grignard reagent, the reaction of the Grignard reagent with the raw material compound of formula (), and the subsequent iminium salt reaction are the same, by adding the corresponding halide compound dropwise into a solvent such as tetrahydrofuran and reacting. It can also be carried out all at once in a reaction system. Regardless of which order the reaction is carried out, iminium salt () and magnesium salt (MgXX') will precipitate after the reaction, but if the inorganic salt is dissolved with dilute hydrochloric acid or solvent substitution is carried out, The desired bis(diphenylphosphine)iminium salt of formula () can be easily extracted by the operation. The iminium salt of formula () thus obtained can be purified by operations such as recrystallization with a solvent such as water. (Action of the invention) The Grignard reagent of the formula () is first prepared by the formula ()
bis(diphenylphosphino)amine to form the reaction intermediate of formula (V) almost quantitatively. This intermediate is subsequently reacted without separation with a halide compound of formula (), resulting in formula ()
A bis(diphenylphosphine)iminium salt of formula () is obtained in the same manner as when the compound of formula (2) is reacted with a halide of formula () directly. (Effects of the Invention) The method of the present invention is improved and advantageous in the following points compared to the method described in the above-mentioned German document. First, the desired iminium salt can be obtained in high yield. Second, expensive organic alkali metal compounds such as n-butyllithium can be avoided. Thirdly, the reaction operation is simple, such as simultaneously reacting the compounds of the formulas (), (), and () used. Fourthly, this reaction has the flexibility to be applied not only to the production of a specific compound, but also to the production of related compounds. Therefore, the present method can obtain the bis(alkyldiphenylphosphine or benzyldiphenylphosphine) iminium salt of formula () with a simple operation, in high yield, and at low cost, and can be carried out on an industrial scale. This manufacturing method is suitable for Example 1 Synthesis of bis(benzyldiphenylphosphine)iminium chloride 38.5 g (0.1 mol) of bis(diphenylphosphino)amine and 200 ml of tetrahydrofuran were placed in a 500 ml flask and dissolved therein. To that solution, a solution of phenylmagnesium chloride (Grinard reagent) (0.11 mol) in tetrahydrofuran
ml was added, and the mixture was reacted under heating and reflux conditions for 0.5 hour.
Next, 30.4 g (0.24 mol) of benzyl chloride was added dropwise to the reaction solution, and the mixture was further heated under reflux for 10 hours to react. After the reaction was completed, 200 ml of 5% hydrochloric acid water was added to the reaction mixture to dissolve the magnesium salt. After that, the solvent tetrahydrofuran was distilled off under reduced pressure, and after cooling,
500ml of dichloromethane was added to dissolve. The entire mixture was transferred to a separatory funnel and the organic layer was separated from the aqueous layer and washed twice with 200 ml of water to remove inorganic salts. The dichloromethane layer was transferred to an eggplant flask, distilled off under reduced pressure, and replaced with 500 ml of toluene to precipitate white crystals. Apart from this crystal, further
It was washed with 400 ml of toluene and dried under reduced pressure at 80°C. Purification was performed by recrystallization with 10 times the amount of water if necessary. 58.3 g of the title compound was obtained. Yield 96.8% Melting point 257.5-258.0℃ IRν ^KBr _nax (cm ^-1 ): 1255, 1318 (P=N) PMR (δ): 4.03 (4H, d, J=13Hz) Example 2 Bis(diphenylmethylphosph) In) Synthesis of iminium iodide 7.7 g (0.02 mol) of bis(diphenylphosphino)amine and 5 ml of toluene in a 200 ml flask.
was added and dissolved. To the solution was added 25 ml of a solution of methylmagnesium chloride (Grinard reagent) (0.022 mol) in tetrahydrofuran, and the mixture was heated under reflux for 0.5 hour. Add 6.8 g of methyl iodide to the reaction solution.
(0.048 mol) was added and the reaction was carried out by heating under reflux for 8 hours. Thereafter, the same treatment as in Example 1 was performed to obtain 9.62 g of the title compound as pale yellow crystals. yield
89.0%. Melting point 177.5-178℃ IRν ^KBr _nax (cm ^-1 ): 1265, 1310 (P=N) PMR (δ): 2.34 (6H, d, J=13Hz) Example 3 Bis(diphenylethylphosphine)iminium Synthesis of iodide: 7.7 g (0.02 mol) of bis(diphenylphosphino)amine and 50 ml of toluene in a 200 ml flask.
Add and dissolve butylmagnesium bromide (0.022 mol) in tetrahydrofuran solution 22
Added ml. React under heating and reflux conditions for 0.5 hours,
Further, 7.5 g (0.048 mol) of ethyl iodide was added to the reaction solution, and the mixture was heated under reflux for 8 hours to carry out the reaction. Thereafter, the same treatment as in Example 1 was performed to obtain 10.15 g of the title compound as pale yellow crystals. yield
93.0% Melting point 187.5-190℃ IRν ^KBr _nax (cm ^-1 ): 1240, 1280 (P=N) PMR (δ): 1.04 (6H, d-t J=20Hz, 8
Hz) 2.37 (4H, d-q J=11Hz, 8Hz) Example 4 Synthesis of bis(diphenylethylphosphine)iminium bromide 7.7 g (0.02 mol) of bis(diphenylphosphino)amine in a 200 ml flask and 5ml of toluene
was added and dissolved. A solution of butylmagnesium bromide (0.22 mol) in tetrahydrofuran is added to the solution.
ml and 5.2 g (0.048 mol) of ethyl bromide were added.
The mixture was stirred for 10 hours and heated to reflux to react. Thereafter, the same treatment as in Example 1 was carried out to obtain 4.5 g of the title compound as white crystals. Yield 43.0% Melting point 200.5-201.5℃ IRν ^KBr _nax (cm ^-1 ): 1310 (P=N) PMR (δ): 1.08 (6H, d-t J=20Hz8Hz) 2.65 (4H, d-q J=11Hz8Hz) )

[Claims]

linear equation In the presence of an alkali metal carbonate and a lower alcohol, the bis(diphenylphosphino)amine represented by The following formula is characterized by reacting a halide compound represented by A method for producing a bis(alkyldiphenylphosphine or araalkyldiphenylphosphine)iminium salt represented by the formula [wherein R and X have the same meanings as above]. 2 In the patent claim, the alkali metal carbonate is potassium carbonate and the lower alcohol is methanol.

Claims (1)

A method for producing a bis(alkyldiphenylphosphine or benzylphenylphosphine) iminium salt represented by 2. A Grignard reagent of formula () and a halide compound of formula () are simultaneously or substantially simultaneously added to a solution of bis(diphenylphosphino)amine of formula () in an organic solvent, thereby forming a compound of formula () and a halide compound of formula (). 2. The method according to claim 1, wherein the reaction of () with the Grignard reagent and the reaction of the reaction product produced by this reaction with the halide compound of formula () are carried out in the same reaction system.