JP3911705B2 - Method for producing azobiscyanocarboxylic acid chloride - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a novel process for producing an azobiscyanocarboxylic acid chloride useful as a raw material for an azo polymer polymerization initiator (hereinafter abbreviated as MAI) and a macromonomer.
[0002]
BACKGROUND OF THE INVENTION
In recent years, the development of polymer compounds has progressed from general-purpose ones to high-value-added functional polymers, and in particular, the effective expression of various functions is expected by taking a multiphase structure derived from a microphase separation structure. Production of block polymers and graft polymers is becoming increasingly popular.
[0003]
As for the production method of these block polymers and graft polymers, for example, the living polymerization method, the segment bonding method, the polymer initiator method and the like are known for the block polymer, but the polymer initiator method is particularly convenient for the production of the block polymer. In particular, a method of obtaining a block polymer by polymerizing a second monomer using a prepolymer containing an azo group in a trunk polymer as a polymerization initiator is known as an azo polymer polymerization initiator [MAI] method. It is in the limelight.
[0004]
As a method for producing this MAI, for example, as described in J. Furukawa, S. Yamashita, Angew. Makromol. Chem., 1 , 92 (1967), two hydroxyl groups and one A method of synthesizing MAI having a urethane bond using azobiscyanopentanol having an azo group is known.
However, in recent years, H. Inoue, A. Ueda, S. Nagai, J. Polym. Sci., A26 , 1077 (1988), J. Apply. Polym. Sci., 35 , 2039 (1988), Akira Ueda, Nagai Block, as described in Susumu, Polymer Journal, 33 , 131 (1976), 44 , 469 (1987), J. Polym. Sci. Polym. Chem. Ed., 22 , 1611 (1984), etc. From the viewpoint of easy molecular design of the polymer, a method using azobiscyanocarboxylic acid chloride having an acid chloride group that is more reactive than a hydroxyl group as a raw material for MAI has become the mainstream.
[0005]
On the other hand, in the graft polymer, a reactive functional group (for example, a hydroxyl group) is introduced into the trunk polymer, and a branch polymer having a functional group (for example, an acid chloride group) that reacts therewith is reacted. A macromonomer method or the like in which a monomer and a monomer serving as a backbone polymer are copolymerized to form a graft polymer is known. In particular, the macromonomer method has attracted much attention in recent years in terms of graft efficiency and simplicity.
[0006]
As a method for producing this macromonomer, a method in which a reactive monomer such as methacrylic acid chloride, 2-hydroxyethyl methacrylate, 4-hydroxystyrene, or vinylpyridine is bonded to a terminal reactive polymer is generally used. The reactive polymer is obtained by using a radical polymerization initiator having a reactive functional group such as azobiscyanopentanoic acid chloride, azobiscyanopentanol, or azobis [2- (2-imidazolin-2-yl) propane]. In particular, the method using azobiscyanopentanoic acid chloride is in the spotlight because a highly reactive acid chloride group can be introduced into the polymer terminal.
[0007]
As a production method of azobiscyanocarboxylic acid chloride used for the production of these MAI and macromonomers, 4,4′-azo is described in D. Smith, Makromol. Chem., 103 , 301 (1967). A method of reacting biscyanopentanoic acid with phosphorus pentachloride in a benzene solvent, a method of reacting thiol chloride with pyridine as a dehydrochlorinating agent in ethyl ether described in East German Patent No. 100710, British Patent No. 2115810 The method of reacting with thionyl chloride using pyridine as a catalyst in the tetrahydrofuran (THF) solvent described in the book, and further, the thionyl chloride described in Akira Ueda, Susumu Nagai, Kobunshi Shigshu, 33 , 131 (1979) A method of using it as a chlorinating agent and a solvent is known.
[0008]
[Problems to be solved by the invention]
However, in the method described in Makromol. Chem., 103 , 301 (1967) using phosphorus pentachloride, the phosphorus pentachloride used is a highly toxic compound, and phosphorus oxychloride as a reaction byproduct is also highly toxic. There is a problem that removal from the product is difficult.
In addition, although the method described in the collection of polymer papers is less toxic than phosphorus pentachloride, irritating thionyl chloride must be used in a large amount of 5 equivalents to 4,4'-azobis (4-cyanopentanoic acid). In addition, the yield was as low as 42.3% when the reaction time was as long as about 10 hours.
Furthermore, in the method described in the East German patent, although the target product is obtained in a high yield, it is difficult to remove pyridine as a dehydrochlorination agent and pyridine hydrochloride as a by-product, and in the method described in the British patent, Since THF is used as the solvent, the resulting hydrochloric acid reacts with the THF of the solvent to produce α, ω-butanechlorohydrin, which further reacts with the desired acid chloride to form an ester. , Had the disadvantage that the content was reduced.
[0009]
OBJECT OF THE INVENTION
The present invention has been made in view of the above-described situation, and without using a highly toxic halogenating agent such as phosphorus pentachloride. It is an object of the present invention to provide a novel and extremely effective production method of azobiscyanocarboxylic acid chloride from which chloride can be obtained.
[0010]
[Means for solving problems]
In order to achieve the above object, the present invention comprises the following arrangement.
“General Formula [I]
[Chemical 1]
(Wherein, R represents an alkyl group of C ₁ ~C _4, n is an integer of 1-5.)
The general formula [II], characterized in that azobiscyanocarboxylic acid represented by the formula and thionyl chloride are reacted using acetonitrile as a reaction solvent
[Chemical 2]
(In the formula, R and n are the same as described above.)
The manufacturing method of azobis cyanocarboxylic acid chloride shown by this. "
[0011]
That is, as a result of intensive studies to achieve the above object, the present inventors have found that when azobiscyanocarboxylic acid and thionyl chloride are reacted using acetonitrile as a reaction solvent, the problems of the conventional method described above. All the points were overcome, and it was found that high-quality azobiscyanocarboxylic acid chloride can be produced easily and in good yield in a short time, and the present invention was completed.
[0012]
In the general formulas [I] and [II], examples of the C1-C4 alkyl group represented by R include a methyl group, an ethyl group, a propyl group, and a butyl group. Either a chain shape or a branched shape is possible.
[0013]
The amount of acetonitrile used in the present invention is not particularly limited as long as the reaction is not hindered. However, if it is too small, it takes time for the reaction, and if it is too much, it is economically disadvantageous. Accordingly, the amount of acetonitrile used is appropriately selected from the range of usually 1 to 100 times, preferably 2 to 50 times, more preferably 5 to 20 times the volume of azobiscyanocarboxylic acid.
It goes without saying that other solvents may be appropriately mixed in acetonitrile as long as the reaction does not hinder the reaction. In other words, the reaction solvent that can be used in the present invention includes not only acetonitrile alone but also a mixed solvent mainly composed of acetonitrile.
The other reaction solvent that can be used in combination with acetonitrile may be any solvent as long as it does not inhibit the reaction of producing azobiscyanocarboxylic acid chloride by reacting azobiscyanocarboxylic acid with thionyl chloride. It is preferable to use a solvent that does not react with hydrochloric acid. Examples of other reaction solvents that can be used in combination with acetonitrile include aromatic hydrocarbons such as benzene, toluene, and xylene, aliphatic hydrocarbons such as n-hexane and n-heptane, and halogens such as chloroform and dichloroethane. Hydrocarbons such as ethers such as diethyl ether and diisopropyl ether.
[0014]
The amount of thionyl chloride used in the present invention is not particularly limited, but usually about 1.1 to 2.0 equivalents are sufficient for the azobiscyanocarboxylic acid. That is, in the present invention, the amount of thionyl chloride used can be remarkably reduced as compared with that in the conventional method. About reaction temperature, it is 0-50 degreeC normally, Preferably it is 0-30 degreeC, Although reaction time changes a little with reaction temperature etc., about 1-8 hours are usually enough.
[0015]
For example, the present invention may be performed as follows.
That is, azobiscyanocarboxylic acid and about 1.1 to 2.0 equivalents of thionyl chloride are reacted in acetonitrile at 0 to 50 ° C., preferably 0 to 30 ° C. for 1 to 8 hours. After completion of the reaction, the reaction solution is concentrated under reduced pressure, and the solvent and the like are distilled off, whereby high-quality azobiscyanocarboxylic acid chloride can be obtained.
If necessary, it is optional to recrystallize this with a suitable solvent such as dichloromethane-isopropyl ether.
[0016]
In the production method of the present invention, the azobiscyanocarboxylic acid used as a raw material is, for example, 4,4′-azobis (4-cyanopentanoic acid) (manufactured by Wako Pure Chemical Industries, Ltd., trade name V-501). Commercially available products such as the above may be used after drying, or those synthesized by the following method according to the method described in JP-B-55-34162, for example, may be used.
That is, the corresponding ketocarboxylic acid is reacted with hydrazine hydrate in the presence of an alkali to form ketazine, then hydrogen cyanide is added to form a hydrazo, and then oxidized with an oxidizing agent such as bromine. Biscyanocarboxylic acid is obtained. It is optional to purify this by recrystallization or the like as necessary.
[0017]
Hereinafter, the present invention will be described in more detail with reference to reference examples and examples, but the present invention is not limited thereto.
[0018]
【Example】
Reference example 1
In 25 ml of water, 50 g (0.384 mol) of 4-acetylbutyric acid was dissolved, and 61.5 g (0.384 mol) of 25% NaOH aqueous solution was added dropwise at 25-30 ° C. with stirring, and then 12 g (0.192 of 80% hydrazine hydrate) was added. mol) was added and stirred for 3.5 hours. Next, 12.8 g (0.474 mol) of hydrogen cyanide was added dropwise to this reaction solution at 15 to 20 ° C., and the mixture was stirred for 1 hour. After standing overnight, 47.5 g (0.47 mol) of concentrated hydrochloric acid was added, 42.4 g (0.070 mol) of 25% aqueous sodium bromate solution was added dropwise under ice cooling, and the mixture was stirred for 30 minutes, and the precipitated crystals were collected by filtration. The obtained crystals were dispersed in 150 ml of water, adjusted to pH 11 with 10% NaOH aqueous solution, treated with 1.7 g of activated carbon, filtered off the activated carbon, and the filtrate was precipitated with sulfuric acid at pH 2.5. I let you. The precipitated crystals were collected by filtration, washed with water and n-hexane and then dried to obtain 42,9 g of white crystals of 5,5′-azobis (5-cyanohexanoic acid).
IR (KBr): ^2240cm-1 (over CN), 1700cm ^{over 1} (C = O)
NMR (DMSO-d ₆ ): δ 1.65 ppm (meso), 1.67 ppm (racemic) (6H, s, CH ₃ ),
_{1.4~1.6ppm (4H, m, CH 2} ) (CH 2 of position γ with respect to COOH),
_{2.05~2.11ppm (4H, m, CH 2} ) (CH 2 of position β with respect to COOH),
_{2.28~2.34ppm (4H, m, CH 2} ) (CH 2 of position α to COOH)
UV (acetonitrile): λ _max 349nm, E _1cm ^1% = 0.620
mp: 109.6-112.2 ° C (decomposition)
[0019]
Example 1
To 100 ml of acetonitrile, 10 g (0.036 mol) of 4,4′-azobis (4-cyanopentanoic acid) (trade name V-501, manufactured by Wako Pure Chemical Industries, Ltd.) was added. 0.144 mol) was added dropwise over 1 hour, and the reaction was stirred at 5 ± 5 ° C. for 2 hours. After the reaction, the solvent was distilled off under reduced pressure, and the residue was recrystallized from dichloromethane-isopropyl ether to obtain 9.3 g of 4,4′-azobis (4-cyanopentanoic acid) chloride white crystals. Yield 82.2%.
mp 75.6 ℃ (decomposition) Content 99.1% from COCl λ _max 351nm ε = 22.1 (CH ₂ Cl ₂ )
[0020]
Example 2
In a mixed solvent of 30 ml of acetonitrile and 20 ml of 1,2-dichloroethane, 10 g (0.036 mol) of 4,4′-azobis (4-cyanopentanoic acid) (manufactured by Wako Pure Chemical Industries, Ltd., trade name V-501) and 11 g (0.092 mol) of thionyl chloride was added, and the reaction was stirred at 25 ± 2 ° C. for 2 hours. After the reaction, the same treatment as in Example 1 was carried out to obtain 9.1 g of 4,4′-azobis (4-cyanopentanoic acid) chloride as white crystals. Yield 80.4%.
Content 99.4% from COCl λ _max 351nm ε = 22.2 (CH ₂ Cl ₂ )
[0021]
Example 3
To 154 ml of acetonitrile, 15.4 g (0.05 mol) of 5,5′-azobis (5-cyanohexanoic acid) obtained in Reference Example 1 and 24.0 g (0.20 mol) of thionyl chloride were added and reacted with stirring at 20 ° C. for 4 hours. . After the reaction, the solvent was distilled off under reduced pressure, and the residue was recrystallized from dichloromethane-isopropyl ether to obtain 12.9 g of white crystals of 5,5′-azobis (5-cyanohexanoic acid) chloride. Yield 74.8%.
mp 75 ℃ (decomposition) Content 99.8% from COCl λ _max 347nm ε = 27.0 (CH ₂ Cl ₂ )
[0022]
【The invention's effect】
As described above, the present invention provides a method for producing azobiscyanocarboxylic acid chloride used in the production of MAI, macromonomer and the like. According to the production method of the present invention, phosphorus pentachloride Thus, there is no need to use a highly toxic and highly dangerous compound, no need for a dehydrochlorination agent, etc., and there is no risk of formation of by-products that are difficult to remove. Since it produces the effect that it is possible to obtain high-quality azobiscyanocarboxylic acid chloride efficiently, this is a great invention that contributes to this industry.

Claims (2)

Formula [I]

(Wherein, R represents an alkyl group of C ₁ ~C _4, n is an integer of 1-5.)
The general formula [II], characterized in that azobiscyanocarboxylic acid represented by the formula and thionyl chloride are reacted using acetonitrile as a reaction solvent

(In the formula, R and n are the same as described above.)
The manufacturing method of azobis cyanocarboxylic acid chloride shown by this. Azobiscyanocarboxylic acid is 4,4'- Azobis (Four- Cyanopentanoic acid ) Or 5,5'- Azobis (Five- Cyanohexanoic acid ) The process for producing azobiscyanocarboxylic acid chloride according to claim 1.