JPH0559142A - Production of organic ferromagnetic substance - Google Patents

Abstract

PURPOSE:To produce an organic ferromagnetic substance, having a high radical concentration and capable of exhibiting ferromagnetism. CONSTITUTION:A polymer having a triarylmethane structure and the methine carbon atom substituted by an alkali metal is reacted with a silane compound having at least one halogen atoms. The above-mentioned polymer is produced by reacting the polymer having the triarylmethane structure with an organic alkali metal. Tritium, etc., are included in the alkali metal. The polymer substituted with the alkali metal is reacted with the above-mentioned silane compound such as chlorotriphenylsilane to produce a radical at the site of the methine carbon atom.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an organic ferromagnet which can be used as a magnetic recording material, a magneto-optical material, a magnetic toner material and the like.

[0002]

2. Description of the Related Art In recent years, various organic magnetic materials having excellent workability have been reported in place of inorganic magnetic materials. For example, it has been reported that a polyradical is generated by substituting a hydrogen atom at a methine carbon site of an oligomer having a triarylmethane structure with lithium and reacting with iodine (J.
Am. Chem. Soc. 1990, 112, 5889-5890).

In this method, lithium iodide is produced by the reaction with iodine, but it is extremely difficult to stop the reaction by one-electron oxidation. Therefore, a two-electron oxidation reaction occurs, a cation is generated at the methine site and an iodine anion is also generated, and the radical generation efficiency is low.

Therefore, it is an object of the present invention to provide a method for producing an organic ferromagnet which has a high radical concentration and is capable of producing ferromagnetism.

[0005]

As a result of intensive studies, the present inventor found that a polyradical is efficiently produced by substituting a hydrogen atom bonded to a methine carbon with an alkali metal and reacting it with a halosilane. Was completed.

That is, the present invention provides a method for producing an organic ferromagnetic material in which a polymer having a triarylmethane structure and having a methine carbon substituted with an alkali metal is reacted with a silane having a halogen atom.

The polymer used in the present invention has a triarylmethane structure, and the methine carbon is substituted with an alkali metal. This polymer functions as an organic ferromagnetic precursor and contains, for example, a structural unit represented by the following general formula.

[0008]

[Chemical 1] (In the formula, Ar1 represents a divalent aromatic group which may be substituted with a substituent, Ar2 represents a monovalent aromatic group which may be substituted with a substituent, and M represents an alkali metal. Represents a positive integer) The proportion of the structural unit represented by the general formula is 25 to 100%, preferably 50% or more in the organic ferromagnetic precursor.
In the structural unit represented by the above general formula, an aromatic group Ar1
And Ar2 may be the same or different.

As the aromatic compounds constituting the aromatic groups Ar1 and Ar2, benzene, naphthalene, azulene,
Indacene, acenaphthylene, anthracene, phenanthrene, triphenylene, pyrene, chrysene, naphthacene, benzophenanthrene, perylene, benzopyrene,
Monocyclic or condensed polycyclic hydrocarbons such as hexacene and heptacene; aromatic hydrocarbons having a heterocycle containing nitrogen atom, sulfur atom, oxygen atom and the like as a hetero atom such as isoquinoline, quinoline, carbazole, acridine and phenazine Is exemplified.

The substituents on the aromatic groups Ar1 and Ar2 include methyl, ethyl, propyl, isopropyl,
A lower alkyl group having 1 to 6 carbon atoms such as butyl, pentyl, hexyl group; a hydroxy group; a lower alkoxy group having 1 to 6 carbon atoms such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, pentyloxy, hexyloxy group; Examples thereof include dialkylamino groups having an alkyl group having 1 to 6 carbon atoms such as dimethylamino, diethylamino and dipropylamino groups. These substituents are
One or more may be substituted depending on the type of aromatic group.

Of these substituents, an electron-donating group such as a lower alkyl group, a hydroxy group or a lower alkoxy group is preferable. The electron-donating group is preferably substituted at the conjugated position of the aromatic group bonded to the methine group, for example, at the 2-position, 4-position and 6-position. Examples of the alkali metal M include lithium, sodium, potassium and the like. Preferred alkali metals include lithium.

In the organic ferromagnetic precursor, the repeating unit n of the structural unit represented by the above general formula is preferably 5 or more. When n is 4 or less, the stability of the generated radicals is likely to be impaired by the low-molecular weight compound having large mobility. It is preferable that the organic ferromagnetic precursor has a large molecular weight in the range of being soluble and fusible. The preferred repeating unit n is 5 to
It is about 100. The number average molecular weight of the organic ferromagnetic precursor cannot be uniquely determined because it depends on the structural unit represented by the general formula, but is 700 or more, preferably about 1000 to 20000 in terms of polystyrene by gel permeation chromatography. .. In addition, n = 5
An organic ferromagnetic precursor of about 10 is B- which is an initial condensate.
It becomes the stage polymer. The B-stage polymer usually has a softening point of about 30 to 120 ° C.

The method for producing the polymer having the structural unit represented by the above general formula is not particularly limited. For example, an aromatic compound which may have a substituent and an aromatic compound which has at least one formyl group. An aldehyde compound is condensed in the presence of an acid catalyst, and the obtained product having a triarylmethane structure is reacted with an organic alkali metal,
It can be obtained by replacing the hydrogen atom bonded to the methine carbon with an alkali metal.

As the substituent of the aromatic compound, for example, a hydroxy group, a lower alkoxy group having 1 to 6 carbon atoms,
Examples thereof include a lower alkyl group having 1 to 6 carbon atoms and a dialkylamino group having a lower alkyl group having 1 to 6 carbon atoms.

Examples of the aromatic compound include aromatic compounds constituting the aromatic groups Ar1 and Ar2, phenol, resorcinol, hydroquinone, pyrogallol,
Cresol, methoxybenzene, ethoxybenzene, m
-Dimethoxybenzene, m-diethoxybenzene, 4-
Examples are monocyclic or condensed polycyclic hydrocarbons such as methoxyphenol, 4-hydroxy-2,6-dimethylphenol, and naphthol. At least one of these aromatic compounds can be used.

The aromatic aldehyde compound having a formyl group may have the same substituent or alkylamino group as described above. Examples of such aromatic aldehyde compounds include benzaldehyde, terephthalaldehyde, isophthalaldehyde, p-hydroxybenzaldehyde, salicylaldehyde, p-methoxybenzaldehyde, 2,5-dihydroxybenzaldehyde, 2,
Examples thereof include 5-dimethoxybenzaldehyde, p-N, N-dimethylaminobenzaldehyde, pyrene aldehyde, benzaldehyde dimethyl acetal and the like. At least one of these aromatic aldehyde compounds can be used.

When an aromatic aldehyde compound having a hydroxyl group and a formyl group, such as p-hydroxybenzaldehyde or salicylaldehyde, is used, since it has self-condensation, it may have the above-mentioned substituent. Group compounds are not necessary.

The aromatic aldehyde compound is usually used in an amount of 0.1.0 per mol of the aromatic compound which may have a substituent.
It is used in an amount of 5 to 2.5 mol, preferably 1 to 2 mol.

The acidic catalyst used in the condensation reaction is
Examples thereof include inorganic acids such as hydrochloric acid, sulfuric acid and nitric acid, and organic acids such as p-toluenesulfonic acid and fluoromethanesulfonic acid. The amount of the acidic catalyst varies greatly depending on the type and reactivity of the starting material, but is usually 0.0 with respect to the total amount of the aromatic compound and the aromatic aldehyde compound.
It is about 1 to 10% by weight. Note that when a starting material having an electron-donating group is used, the amount of acidic catalyst can be small. More specifically, when m-dimethoxybenzene and benzaldehyde are condensed, the amount of p-toluenesulfonic acid added is about 1 to 7% by weight.

The condensation reaction is carried out in air, preferably in an atmosphere of an inert gas such as nitrogen or helium. The condensation reaction may be carried out in the presence of an organic solvent, but usually in the absence of a solvent, room temperature to 200 ° C., preferably 100 to 1
It can be carried out at a temperature of about 50 ° C. for about 10 minutes to 12 hours, preferably for about 30 minutes to 6 hours. When the reaction time is short, for example, about 10 minutes to 1 hour, a B-stage precondensate can be obtained.

Examples of the organic alkali metal used in the substitution reaction include alkyl lithium such as methyl lithium, ethyl lithium, ethyl sodium, ethyl potassium, propyl lithium, butyl lithium, butyl sodium, butyl potassium, hexyl lithium and octyl lithium. -Aryl-alkali metals such as alkali metals, phenyllithium, phenylsodium, and naphthyllithium are exemplified. These organic alkali metals can be used alone or in combination of two or more. Preferred organic alkali metals include organolithium.

The ratio of the polymer having a triarylmethane structure to the organic alkali metal is 1 to 5 equivalents, preferably 1.
It is used in 2-3 equivalents.

The reaction is usually carried out in a solvent inert to the reaction. As the solvent, for example, aromatic hydrocarbons such as benzene, toluene and xylene, ethers such as dioxane, ethyl ether, propyl ether and tetrahydrofuran, and mixed solvents thereof can be used. The reaction is
It can be carried out at -45 ° C to 50 ° C, preferably about -25 ° C to 25 ° C.

The polymer having the structural unit represented by the above general formula can also be obtained by another sail method. For example, the aromatic compound and an aromatic compound having a trihalogenomethyl group such as a trichloromethyl group are condensed in the presence of a Lewis acid, and a polymer produced by the condensation reaction is reacted with an alkoxy alkali metal to give a methine carbon. The halogen atom of is substituted with an alkyl ether group. Then, it is reacted with an alkali metal to replace the alkyl ether group with the alkali metal.

Examples of the Lewis acid include conventional compounds such as AlCl ₃ , FeCl ₃ , ZnCl ₂ and TiCl ₂ .
₃ , TiCl ₄ , SnCl ₂ , SnCl _{4 and the} like. Examples of the alkoxyalkali metal include sodium alkoxide such as sodium methoxide, sodium ethoxide, sodium propoxide and sodium butoxide, and lithium alkoxide and potassium alkoxide corresponding to these. Examples of the alkali metal include lithium, sodium, potassium, etc., as described above, and lithium is preferable.

After the reaction is completed, the produced polymer is usually
It is subjected to a removal step of removing impurities by a purification method using a good solvent and a poor solvent. By reacting the thus obtained polymer having the structural unit represented by the general formula with a silane compound having a halogen atom, an organic ferromagnet in which radicals are generated can be obtained.

The silane compound may have a halogen atom. The silane compound having a halogen atom is, for example, (R) ₃ SiX (wherein R is the same or different,
A hydrogen atom, an alkyl group, an alkenyl group, an aryl group, or a cycloalkyl group, and X represents a halogen atom).

Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl,
Includes t-butyl, pentyl, hexyl groups and the like. The alkenyl group includes, for example, a vinyl group having 2 to 6 carbon atoms.
Some lower alkenyl groups are included. The aryl group includes a phenyl group and the like, and the cycloalkyl group includes a cyclohexyl group and the like. These substituents may have a halogen atom such as a fluorine atom or a cyano group. The halogen atom X includes a chlorine atom, a bromine atom and the like.

Examples of such monohalosilane compounds include chlorotrimethylsilane, chlorodimethyl-t-butylsilane, chlorodimethyltrifluoropropylsilane, chlorotriphenylsilane, chlorodimethylphenylsilane and the like. These silane compounds may be used either individually or in combination of two or more. The silane compound also includes polysilane having two or more silicon atoms as long as the halogen atom is bonded to silicon. Preferred silane compounds include silane compounds having a phenyl group. As the number of phenyl groups in the silane compound increases, the radical generation efficiency at the methine site tends to increase.

The silane compound having a halogen atom is, for example, 1 to 5 with respect to the structural unit represented by the above general formula.
The equivalent is used, preferably about 1.2 to 3 equivalents. The reaction is usually performed in a solvent that does not adversely influence the reaction.
As such a reaction solvent, the same solvent as that which can be used in the reaction between the polymer having the structural unit represented by the above general formula and the organic alkali metal is exemplified. The reaction is carried out at an appropriate temperature, for example, −45 to 80 ° C., preferably −30 to 30 ° C.
It can be performed at about 50 ° C., and is usually completed in about 30 minutes to 24 hours.

By thus reacting the polymer with the silane compound, radicals are efficiently generated at the methine site and the generated radicals are stabilized. This means that the silane radicals produced by the reaction are extremely unstable and recombine rapidly to produce stable disilane,
It is presumed that this does not adversely affect the radicals at the methine site.

It is preferable to remove tetramer or lower low-molecular compounds contained in the polymer. The removal of the low molecular weight compound may be carried out at an appropriate stage, for example, a condensation reaction, an alkali metal substitution reaction or a reaction with a silane compound. By removing low molecular weight compounds of tetramer or less,
It is possible to suppress the disappearance of radicals and stabilize the radicals for a long period of time. The low molecular weight compound can be removed by a conventional method, for example, solvent fractionation method, adsorption method, molecular sieve, liquid chromatography, gel filtration chromatography, column chromatography and the like.

The good solvent and poor solvent used in the solvent fractionation method can be selected according to the solubility of the polymer. Examples of the good solvent include halogenated hydrocarbons such as dichloromethane and chloroform, ethers such as tetrahydrofuran, and ketones such as acetone. Examples of the poor solvent include aliphatic hydrocarbons such as hexane and octane, alicyclic hydrocarbons such as cyclohexane, alcohols such as methanol, ethanol, propanol, isopropanol and cyclohexyl alcohol, and mixed solvents thereof. It is illustrated.

Examples of the adsorbent used in the adsorption method include silica gel, clay, alumina, activated carbon, zeolite, and synthetic zeolite. Examples of the molecular sieve include zeolite and synthetic zeolite having a pore size suitable for removing low molecular weight compounds.

Removal of low molecular weight compounds by column chromatography is carried out by a conventional method, for example, a method of eluting an organic solvent solution of the product through a column packed with an adsorbent or the like; After supporting the product, the low molecular weight component is eluted with a poor solvent, and then the high molecular weight component is eluted with a good solvent.

Of these removal methods, column chromatography is preferred.

Since the organic ferromagnet exhibits thermoplasticity or thermosetting property, it can be easily molded into a molded product, film or fiber, and when used as an organic solvent solution, a thin film can be easily formed. Can be formed. Further, when the molding process is performed in the state where the magnetic field is applied, the magnetism becomes large.
The organic ferromagnet may be compounded with a metal such as iron, cobalt or nickel.

The radical of the organic ferromagnetic substance has only to be present in at least the methine carbon site, and the site of the structural unit represented by the above general formula that can have a resonance structure may be radicalized. Even if a radical is generated at a methine carbon site or a site capable of adopting a resonance structure, the radical is stably present in the organic ferromagnet having a triarylmethane structure.
Therefore, magnetism is developed for a long period of time due to the stable radicals.

It suffices for the organic ferromagnet to have an appropriate radical concentration within a range necessary for exhibiting magnetism, and the radical concentration is usually 10 ¹⁷ / g or more, preferably 10 ¹⁷ / g or more.
¹⁸ / g or more. The radicals of the organic ferromagnet can be confirmed by ESR.

The magnetism of the organic ferromagnetic material can be confirmed as follows. As a simple method, there is a method in which an organic ferromagnetic material is crushed, a magnet is arranged under a petri dish into which water is injected, and a resin powder is floated on the water surface and allowed to stand. In this method, the resin powder on the water surface moves to a portion of the magnet having a large magnetic flux density and gathers around the magnet. As another method, the magnetic characteristic of the organic ferromagnet can be measured using a magnetization characteristic measuring device.

[0041]

According to the method of the present invention, since the alkali metal at the methine carbon site is eliminated by the silane compound, an organic ferromagnet having a high radical concentration and exhibiting ferromagnetism can be easily and reproducibly produced.

[0042]

EXAMPLES The present invention will be described in more detail based on the following examples.

Example 1 1 mol of m-dimethoxybenzene and 1.
25 and mixed with 5% by weight of p-
Toluenesulfonic acid was added, and the temperature was set to 12 in a nitrogen atmosphere.
The mixture was stirred at 0 ° C. for 1 hour and dehydrated and condensed. The obtained polymer was dissolved in dichloromethane and filtered to remove insoluble matter, and then the filtrate was poured into 20 times volume of methanol to collect a precipitate. The recovered polymer is dissolved in benzene, supported on silica gel (merk 60), washed thoroughly with methanol, and then eluted with benzene, which is a good solvent,
Low molecular weight material was removed. When the molecular weight of the obtained polymer having a triarylmethane structure was measured by gel permeation chromatography (solvent: tetrahydrofuran), the degree of polymerization was about 50.

22.6 g of the polymer was dissolved in 1 L of tetrahydrofuran, and 0.2 mol of n-butyllithium was added. The mixture was stirred at -20 ° C for 1 hour, then heated to room temperature over 1 hour to form a precursor polymer, and 0.2 mol of chlorotriphenylsilane was added to a tetrahydrofuran solution containing the precursor polymer. , -10 degreeC was made to react. The reaction solution was added dropwise to 20 times volume of diethyl ether, and the formed precipitate was collected by filtration and dried to obtain an organic ferromagnetic material.

Example 2 An organic ferromagnet was obtained in the same manner as in Example 1 except that 0.2 mol of chlorodimethylphenylsilane was used instead of chlorotriphenylsilane.

Example 3 An organic ferromagnetic material was obtained in the same manner as in Example 1 except that 0.2 mol of chlorotrimethylsilane was used instead of chlorotriphenylsilane.

Comparative Example An organic ferromagnet was prepared in the same manner as in Example 1 except that 0.2 mol of iodine was added to the tetrahydrofuran solution containing the precursor polymer obtained in Example 1 and the reaction was carried out at -40 ° C. Obtained. The reaction solution turned green, which indicates the presence of cations.

The spin concentrations of the organic ferromagnets obtained in Examples 1 to 3 and Comparative Example were measured by ESR, and the results shown in the table were obtained.

[0049]

[Table 1] From the table, the reaction with the silane compound increases the radical concentration of the organic ferromagnetic material.

Claims (3)

[Claims] 1. A method for producing an organic ferromagnetic material, which comprises reacting a polymer having a triarylmethane structure, in which a methine carbon is substituted with an alkali metal, with a silane compound having a halogen atom. 2. The alkali metal is lithium.
A method for producing the described organic ferromagnetic material. 3. The method for producing an organic ferromagnetic material according to claim 1, wherein the silane compound has a phenyl group.