JPS626574B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing poly-vinylphenols. It is known that when poly-(p-vinylphenol) is used as a curing agent for epoxy resins, the resulting cured product exhibits excellent performance in terms of dimensional stability, glass transition temperature, heat loss, etc. However, vinylphenol monomers are unstable and difficult to handle, making their production difficult. BBCorson et al., as a method for producing p-vinylphenol, acetylated p-hydroxyacetophenone () and obtained p-vinylphenol.
Acetoxyacetophenone () is hydrogenated to form p-acetoxyphenylmethylcarbinol (), then dehydrated to form p-acetoxystyrene (), and further hydrolyzed to obtain the desired p-acetoxystyrene ().
-We are investigating a method to obtain vinylphenol () (“Journal of Organic Chemistry”)
Magazine, vol. 23, p. 544, 1958). In this method, acetylation is performed to avoid side reactions and facilitate the reaction, but acetylation requires a subsequent step of hydrolysis. In this method, acetylation,
This method requires many steps such as hydrogenation, dehydration, and hydrolysis, and a polymerization step is also required to obtain polyvinylphenol, making this method complicated to operate. In particular, the yield in the dehydration step is only 43 to 71%, and the yield of polyvinylphenol throughout the entire process is low. Also, according to US Pat. No. 2,276,138, p-hydroxyacetophenone () is hydrogenated to produce p-
Hydroxyphenylmethyl carbinol () is obtained, this is acetylated, the resulting diacetate () is decomposed to p-acetoxystyrene (), which is polymerized and then hydrolyzed to form poly(p-vinylphenol). )() is known. This method also requires many steps such as acetylation, decomposition, polymerization, and hydrolysis, which not only complicates the operation but also reduces the yield of the target product throughout the entire process. In the process of conducting detailed studies on the dehydration reaction of hydroxyphenylmethylcarbinol and the polymerization reaction of hydroxystyrene, the present inventors discovered that polyvinylphenol can be produced from hydroxyphenylmethylcarbinol in a high yield through a single reaction operation. The present invention was completed by discovering a method for obtaining the same. That is, the gist of the present invention resides in a method for producing polyvinylphenol, which is characterized by heating hydroxyphenylmethyl carbinol in the presence or absence of an acid to dehydrate and polymerize it. The most preferred hydroxyphenylmethylcarbinol (also referred to as 1-(hydroxyphenyl)ethanol) used as a raw material is p-hydroxyphenylmethylcarbinol, but m-hydroxyphenylmethylcarbinol, o- Hydroxyphenylmethylcarbinol (these bulk, meta, and ortho forms each have 1
-(p-hydroxyphenyl)ethanol, 1-
(m-hydroxyphenyl)ethanol, 1-(o
-Hydroxyphenyl)ethanol. ), resulting in polymers of vinylphenol of the corresponding isomers. Also, p contains about 10 mol% or less of the meta-isomer and ortho-isomer, respectively.
- When dehydrating and polymerizing hydroxyphenylmethyl carbinol, it is also possible to recover the ortho form and meta form as o-vinylphenol and m-vinylphenol by making the reaction conditions mild or severe. It is also possible to incorporate it into the polymer chain as a copolymer with p-vinylphenol. The raw material hydroxyphenylmethyl carbinol can be obtained by hydrogenating hydroxyacetophenone. According to the present invention, the heat treatment of hydroxyphenylmethyl carbinol can be carried out in the presence or absence of an acid. Acids include inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, perchloric acid, formic acid, oxalic acid, acetic acid, propionic acid,
Butyric acid, chloroacetic acid, trichloroacetic acid, succinic acid,
Organic acids such as picric acid, phenol, cresol, catechol, salicylic acid, benzoic acid, phthalic acid, benzenesulfonic acid, p-toluenesulfonic acid, boron fluoride, boron fluoride etherate, boron fluoride and phenols. complexes of boron fluoride and water, Friedel-Crafts type acids such as boron chloride, aluminum bromide, aluminum chloride, tin chloride, titanium chloride, zinc chloride, and ferric chloride. be able to. When the reaction is carried out by adding an acid, the reaction rate becomes faster and the reaction can be carried out at a lower temperature. The amount of acid added can be arbitrarily selected in the range of 0 to 100 parts by weight, particularly 0.001 to 1 part by weight, based on 100 parts by weight of the raw material hydroxyphenylmethyl carbinol, but the The amount added can be adjusted for control purposes. When using the produced polymer as a curing agent for epoxy resin, the presence of acid may affect the curing reaction, so it is necessary to remove the acid and purify the produced polymer, for example by subjecting it to an extraction process with hot water. There is. In cases where the presence of acid is undesirable, the reaction according to the present invention may be carried out without adding any acid and by simply performing the dehydration/polymerization reaction using heat alone. The reaction temperature for heat-treating hydroxyphenylmethyl carbinol is usually about 50 to 300°C. Approximately 100 to 250 when carried out in the presence of acid
°C is preferred, and when carried out in the absence of acid, approximately
100-300°C, especially about 150-300°C is preferred. Since the resulting polymer has a melt point of about 150 DEG to 220 DEG C., it is preferable to gradually increase the reaction temperature within this temperature range so that the product becomes melt-like. If the reaction temperature is too low, the reaction rate will be slow, and if the reaction temperature is too high, side reactions will occur, which is undesirable. The reaction time can be appropriately determined as necessary, but is usually about 0.1 hour or more, preferably about 1 to 5 hours. The higher the reaction temperature, the shorter the reaction time;
The lower the reaction temperature, the longer the reaction time. The progress of the reaction can be determined by inspecting the reaction product or by checking the amount of water distilled out. The reaction pressure is also not particularly restricted, and can be carried out under reduced pressure, normal pressure, or increased pressure. However, if carried out under strong reduced pressure that would distill off the vinylphenol monomer, the yield of the desired polymer may be impaired. Generally, it is about 0.1Kg/cm2 or ^more , especially about 0.5 to 5Kg/cm2, because the rate decreases and there is a risk of clogging pipes, etc.
It is preferable to carry out within the range of cm ² . During the reaction, oxygen gas or air is undesirable as it inhibits polymerization or causes coloration of the produced polymer, so the reaction should be carried out in an atmosphere of inert gas such as nitrogen gas or argon gas, or in an atmosphere of vapor of raw materials or solvent. is preferable. Some small amount of oxygen gas in the reactor at the beginning of the reaction is acceptable. The reaction may also be carried out in the presence of a solvent if necessary. Examples of solvents include alcohols such as methanol, ethanol, and octanol, esters such as ethyl acetate and butyl acetate, hydrocarbons such as n-heptane, light oil, and lubricating oil, trichloroethane, trichloroethylene, and carbon tetrachloride. There are halogenated hydrocarbons, etc. Those that inhibit polymerization under the reaction conditions are not suitable for use. Even if all raw materials, acid, inert gas, and solvent are charged into the reactor at the start of the reaction,
It may be supplied in small quantities. The produced polymer may be taken out from the reactor as it is being formed or after the reaction is completed, and the light substances containing water produced by dehydration may be distilled out of the system as the reaction progresses, or the reaction may be carried out without being distilled out. You can also do it. According to the present invention, poly-vinylphenol can be obtained from hydroxyphenylmethyl carbinol in one step, and the yield is also high. Therefore, multiple steps as seen in conventional methods are not necessary, and acetylation, such as protecting an active group with an acetyl group prior to the reaction, is not necessary. According to the IR spectrum, the structure of the polymer obtained by the method of the present invention is equivalent to that of a standard polymer of poly(p-vinylphenol) obtained by radical polymerization or cationic polymerization of p-vinylphenol.
Furthermore, a thermosetting resin obtained by reacting the resulting polymer with an epoxy resin exhibits excellent heat resistance. The present invention will be further explained below with reference to Examples. Reference Example 1 Hydrogenation of p-hydroxyacetophenone In an autoclave with a volume of 100 ml, 10 g of p-hydroxy acetophenone (manufactured by Tokyo Kasei Co., Ltd.) was dissolved in 50 ml of ethanol, and a palladium-carbon catalyst (palladium content: 5% by weight) was dissolved in 50 ml of ethanol. ) was added along with 0.5g. After the interior was completely replaced with hydrogen gas, the contents were reacted at 25° C. for 6 hours with stirring under hydrogen pressure of 10 kg/cm ² gauge pressure. Analysis of the product was performed by gas chromatography. In order to prevent the target product carbinol from undergoing reactions such as dehydration during analysis, the product was acetylated in advance before being subjected to analysis. As a result of analysis, the composition of the product was 90% by weight of p-hydroxyphenylmethylcarbinol, 5% by weight of p-ethylphenol, and 5% by weight of p-hydroxyacetophenone. Example 1 p-hydroxyphenylmethyl carbinol 90
% of the product of Reference Example 1 was placed in a flask and placed under a nitrogen atmosphere without adding any additives.
The mixture was heated and stirred at 250°C for 3 hours. Light substances generated during heating are distilled out of the system through a distillation pipe.
Collected. After the reaction was completed, it was cooled to room temperature. The yield of residue in the flask was 4.3 g, and the yield of distillate was 0.6 g. The residue is a reddish-purple solid that is easily crushed.
Easily and completely dissolved in methanol, acetone, and tetrahydrofuran. The intrinsic viscosity of a solution of the residue in tetrahydrofuran at 30° C. was 0.04, and the weight average molecular weight determined by gel permeation chromatography using polystyrene as a standard material was 1500. No unreacted carbinol was observed in the residue. The IR spectrum of the residue, that is, the produced polymer, is shown in Figure 1, using the method of Colson et al. (“Journal of Organic Chemistry”) for comparison.
Fig. 2 shows the IR spectrum of poly(p-vinylphenol), which was separately synthesized by J.D., Vol. 23, p. 544, 1958). From FIGS. 1 and 2, it was confirmed that the produced polymer was poly(p-vinylphenol). The distillate was also analyzed by gas chromatography. The composition of the distillate was a mixture of 95% by weight water and 5% by weight p-ethylphenol. Example 2 5 g of the same raw material as in Example 1 was placed in a flask,
0.01 g of concentrated hydrochloric acid (37% by weight aqueous solution) was added, and the mixture was heated and stirred at 80° C. for 5 hours under a nitrogen atmosphere. After the reaction is complete, cool to room temperature to remove the residual polymer.
4.2g was obtained. The residue or produced polymer was easily soluble in methanol, acetone, and tetrahydrofuran. The intrinsic viscosity of tetrahydrofuran solution at 30℃ is 0.10
It was hot. The weight average molecular weight of the resulting polymer determined by gel permeation chromatography was approximately 10,000. According to the IR spectrum, the produced polymer was poly(p-vinylphenol), and no unreacted carbinol was detected. Example 3 A reaction was carried out in exactly the same manner as in Example 1 except that the reaction temperature was 275°C. The weight average molecular weight of the obtained poly(p-vinylphenol) was 2,700. Example 4 p-hydroxyphenylmethylcarbinol 90
% and m-hydroxyphenylmethyl carbinol 10% in a flask,
Heated at 170°C for 3 hours. The resulting residue in the flask was analyzed by gas chromatography, IR spectrum, and gel permeation chromatography.
The composition of the residue is m-vinylphenol monomer approx.
It was a mixture of 10% by weight and 90% by weight of poly(p-vinylphenol), and the weight average molecular weight of the poly(p-vinylphenol) was 3,500. Example 5 p-hydroxyphenylmethyl carbinol 90
% and o-hydroxyphenylmethylcarbinol (10%) was added with 0.1 g of hydrochloric acid (37% by weight aqueous solution) and heated in an ampoule at 150° C. for 2 hours. The resulting resinous product was soluble in methanol, acetone, and tetrahydrofuran. According to gas chromatography and IR spectroscopy, p-vinylphenol monomer and o-vinylphenol monomer were not detected in this product, indicating that it was a copolymer of p-vinylphenol and o-vinylphenol. The intrinsic viscosity of a tetrahydrofuran solution of this produced polymer measured at 30°C was 0.03. Examples 6 to 17 p-Hydroxyphenylmethyl carbinol (purity 90 % by weight) was heated and stirred for 3 hours under a nitrogen atmosphere. The residue in the flask obtained in these Examples was poly(p-vinylphenol), and its yield and weight average molecular weight were as shown in Table 1.

[Table] Example 18 A reaction was carried out in the same manner as in Example 2, except that 2-ethylhexanol was used as a solvent in an amount of 4 times the weight of the raw materials, and the reaction time was changed to 3 hours. The yield of the obtained poly(p-vinylphenol) was 95%, and the weight average molecular weight was 8,000.

[Brief explanation of the drawing]

FIG. 1 shows the IR spectrum of the produced polymer obtained in Example 1, and FIG. 2 shows the IR spectrum of poly(p-vinylphenol) obtained by the conventional method.

Claims (1)

[Claims] 1. A method for producing poly-vinylphenol, which comprises heating hydroxyphenylmethyl carbinol in the presence or absence of an acid to dehydrate and polymerize it.