Method for preparing 1,3-dihydroxy-4,6-bis(.alpha.-methyl-.alpha.(4'-hydroxyphenyl)ethyl)benz ene

A method for preparing 1,3-dihydroxy-4,6-bis.alpha.-methyl-.alpha.-.alpha.(4'-hydroxyphenyl)ethy l!benzene represented by the following formula (1): ##STR1## comprising the step of initiating a reaction of resorcin with 4-isopropenylphenol in a mixed solvent which comprises a non-polar solvent and a polar solvent in the presence of an acidic catalyst. The method can easily be handled, ensures a high yield, permits the reduction of impurity content and can provide highly pure 1,3-dihydroxy-4,6-bis.alpha.-methyl-.alpha.-(4'-hydroxyphenyl)ethyl!benze ne. The resulting phenolic compound is useful as, for instance, a branching agent for polycarbonates, polyesters or the like; a raw material for radiant ray-sensitive components for use as resist materials; a raw material for epoxy resins; and a hardening agent for epoxy resins.

BACKGROUND OF THE INVENTION 
(a) Field of the Invention 
The present invention relates to a method for preparing 
1,3-dihydroxy-4,6-bis.alpha.-methyl-.alpha.-(4'-hydroxyphenyl)ethyl!benze 
ne. 
More specifically, the present invention relates to a method for preparing 
1,3-dihydroxy-4,6-bis.alpha.-methyl-.alpha.-(4'-hydroxyphenyl)ethyl!benze 
ne which is useful as, for instance, a branching agent for polycarbonates, 
polyesters or the like; a raw material for radiant ray-sensitive 
components for use as resist materials; a raw material for epoxy resins; 
and a hardening agent for epoxy resins. 
(b) Description of the Prior Art 
Japanese Un-examined Patent Publication No. Hei 4-364147 discloses a method 
for preparing 
1,3-dihydroxy-4,6-bis.alpha.-methyl-.alpha.-(4'-hydroxyphenyl)ethyl!benze 
ne which comprises the step of reacting resorcin with 4-isopropenylphenol 
in a single non-polar solvent or a single polar solvent in the presence of 
an acidic catalyst. 
However, this method suffers from the following problems. Resorcin has a 
low solubility in a non-polar solvent and the majority of resorcin is 
dispersed in the solvent in its solid state. As a result, the reaction of 
resorcin with 4-isopropenylphenol is initiated in a heterogeneous reaction 
system and the solid resorcin remaining in the reaction system is 
dissolved in the system as the reaction proceeds. For this reason, the 
reaction is greatly influenced by the shapes and sizes of the solid 
resorcin particles dispersed in the reaction system. Moreover, control of 
the reaction is quite difficult since a part of the solid resorcin 
remaining in the reaction system is covered with the crystals of the 
intended product when it is crystallized in the system. On the other hand, 
if the reaction is performed in a polar solvent, these starting materials 
are reacted in a homogeneous solution system from the beginning to the end 
of the reaction. Therefore, the intended product, 
1,3-dihydroxy-4,6-bis.alpha.-methyl-.alpha.-(4'-hydroxyphenyl)ethyl!benze 
ne, does not crystallize and therefore, the chemical equilibrium in the 
liquid phase does not cause a shift. This accordingly leads to a low 
reaction yield and reduction in the purity of the resulting product. 
SUMMARY OF THE INVENTION 
The object of the present invention is generally to solve the foregoing 
problems associated with the conventional technique and more specifically 
to provide a method for easily preparing highly pure 
1,3-dihydroxy-4,6-bis.alpha.-methyl-.alpha.-(4'-hydroxyphenyl)ethyl!benze 
ne in a high yield. 
The inventors of this invention have conducted various studies to 
accomplish the foregoing object, have found out that the foregoing 
problems can be solved by reacting resorcin with 4-isopropenylphenol in a 
mixed solvent comprising non-polar and polar solvents in the presence of 
an acidic catalyst and thus have completed the present invention. 
One aspect of the present invention is a method for preparing 
1,3-dihydroxy-4,6-bis.alpha.-methyl-.alpha.-(4'-hydroxyphenyl)ethyl!benze 
ne comprises the step of initiating the reaction of resorcin with 
4-isopropenylphenol in a homogeneous system in a mixed solvent comprising 
a non-polar solvent and a polar solvent in the presence of an acidic 
catalyst. 
Another aspect of the present invention is a method comprising the steps of 
dissolving 4-isopropenylphenol or a mixture of 4-isopropenylphenol with a 
linear polymer thereof in a mixed solvent comprising non-polar and polar 
solvents, then converting the 4-isopropenylphenol into an oligomer thereof 
in the presence of an acidic catalyst, adding resorcin to dissolve it in 
the oligomer solution and thereafter adding an acidic catalyst to cause a 
reaction of the resorcin with the resulting oligomer. 
A still further aspect of the present invention is a method comprising the 
steps of dissolving 4-isopropenylphenol or a mixture of 
4-isopropenylphenol with a linear polymer thereof, and resorcin in a mixed 
solvent comprising non-polar and polar solvents, then converting the 
4-isopropenylphenol into an oligomer thereof in the presence of an acidic 
catalyst and thereafter adding an acidic catalyst to cause a reaction of 
the resorcin with the resulting oligomer. 
1,3-Dihydroxy-4,6-bis.alpha.-methyl-.alpha.-(4'-hydroxyphenyl)ethyl!benzen 
e prepared by the methods of the present invention is represented by the 
following formula (1): 
##STR2## 
The method of the present invention is characterized by the use of a mixed 
solvent comprising non-polar and polar solvents and, in particular, the 
reaction is initiated in a homogeneous system in the method. This makes 
the control of the reaction quite easy. Moreover, the method ensures a 
quite high effect of recrystallization observed during separation of the 
desired product from the reaction system and this in turn results in the 
formation of the desired product having high purity.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The method of the present invention will hereunder be described in more 
detail. 
Resorcin usable in the present invention may be those available on the 
market. As the 4-isopropenylphenol, there may be used, in the present 
invention, those obtained by cleaving, and for instance, 
dihydroxydiphenylpropane at 220.degree. C. 50 mm Hg in the presence of 
sodium hydroxide to give a mixture of phenol, 4-isopropenylphenol and 
polymers of 4-isopropenylphenol (number of repeating units: 2 to 10) and 
then removing phenol from the mixture. In addition, it is also possible to 
use monomeric 4-isopropenylphenol isolated from the mixture, linear dimeric 
4-methyl-2,4-bis(4-hydroxyphenyl)pentene-1 or 
4-methyl-2,4-bis(4-hydroxyphenyl)pentene-2, or mixtures thereof. Moreover, 
the 4-isopropenylphenols usable herein may further include an oligomer 
obtained by oligomerizing 4-isopropenylphenol under the oligomerization 
conditions as will be detailed below. Further, the 4-isopropenylphenols 
usable herein may be those having properties identical to those of the 
foregoing 4-isopropenylphenols even if they are prepared by other methods. 
The acidic catalysts usable in the present invention include, for instance, 
inorganic acids such as hydrobromic acid, hydrochloric acid and nitric 
acid. The amount of the acidic catalyst varies depending on the kinds of 
non-polar and polar solvents constituting the reaction solvent system used 
herein and mixing ratio of the former to the latter, but in general ranges 
from 0.0001 to 0.01% by weight for hydrobromic acid; 0.001 to 0.1% by 
weight for hydrochloric acid; and 0.01 to 1.0% by weight for nitric acid, 
on the basis of the weight of the reaction solution. 
The amount of the 4-isopropenylphenol, the linear polymers of 
4-isopropenylphenol (those having 2 to 10 repeating units and including 
the foregoing oligomers) or mixtures thereof relative to that of resorcin 
in general ranges from 1.8 to 2.5 moles and preferably 1.9 to 2.2 moles of 
the former (the molar number of the linear polymer of 4-isopropenylphenol 
is expressed in terms of the molar number of 4-isopropenylphenol units) 
per mole of resorcin. This is because if the former is used in an amount 
of less than 1.8 moles, the amount of 
2-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)propane remaining in the 
reaction system increases, while if it exceeds 2.5 moles, the amount of 
4-isopropenylphenol oligomers increases and this makes the purification 
step complicated. 
The mixed solvent herein used as the reaction solvent comprises a mixture 
of a non-polar solvent and a polar solvent. Examples of non-polar solvents 
are aromatic hydrocarbons such as benzene, toluene and xylene; halogenated 
hydrocarbons such as dichloromethane and carbon tetrachloride; aliphatic 
hydrocarbons such as hexane; and alicyclic hydrocarbons such as 
cyclohexane. In addition, examples of polar solvents usable herein include 
alcohols such as methanol and ethanol. As such mixed solvents, there may be 
used those comprising one or two kinds of non-polar solvents and one or two 
kinds of polar solvents. Among these, mixed solvents preferably used 
comprise benzene and methanol. 
Regarding the mixing ratio of the non-polar solvent to the polar solvent in 
the mixed solvent, the amount of the polar solvent is in general not more 
than 20% by weight and preferably 0.5 to 10% by weight based on the total 
weight of the mixed solvent. 
The mixed solvent is used in such an amount that it can form a homogeneous 
reaction system at the beginning of the reaction and the amount thereof 
varies depending on the mixing ratio of the non-polar solvent to the polar 
solvent. The amount thereof is in general at least two times and preferably 
3 to 10 times that of the total weight of resorcin and 4-isopropenylphenol, 
linear polymers of 4-isopropenylphenol or mixture thereof. If the amount is 
less than two times, the concentration of crystals in the reaction system 
is too high to agitate the reaction system. 
The reaction temperature ranges from 0.degree. to 100.degree. C. and 
preferably 30.degree. to 70.degree. C. This is because if it is less than 
0.degree. C., the reaction requires a long time period, while if it 
exceeds 100.degree. C., a large amount of impurities are formed. 
The reaction time in general ranges from 0.5 to 20 hours and preferably 1 
to 15 hours. 
The reaction is generally carried out by charging, in a batch, 
4-isopropenylphenols, resorcin and a mixed solvent in a reactor, 
dissolving the reactants in the solvent, then reacting them over a 
predetermined time while adding an acidic catalyst to the reaction system, 
followed by removing crystals from the reaction system to give a desired 
product. If 4-isopropenylphenol, or a mixture of 4-isopropenylphenol and a 
linear polymer thereof is used, however, the reactants undergo a vigorous 
exothermic reaction. For this reason, they are introduced into the reactor 
continuously or in portions, but this operation is quite complicated. 
If 4-isopropenylphenol, or a mixture of 4-isopropenylphenol and a linear 
polymer thereof is introduced into the reactor in a batch, it is preferred 
to oligomerize 4-isopropenylphenol in advance and then react the resulting 
oligomer with resorcin. This is because the heat of reaction can easily be 
dissipated, any abrupt generation of heat can be prevented and thus the 
reaction temperature can easily be controlled. 
The oligomerization of 4-isopropenylphenol can be carried out by 
dissolving, for instance, 4-isopropenylphenol, or a mixture of 
4-isopropenylphenol and a linear polymer thereof in the foregoing mixed 
solvent used as the reaction solvent, maintaining the solution at 
30.degree. to 60.degree. C., adding hydrobromic acid, hydrochloric acid or 
nitric acid in an amount generally ranging from 0.00005 to 0.0005% by 
weight, 0.0005 to 0.005% by weight or 0.005 to 0.05% by weight 
respectively and then maintaining the reaction mixture at that temperature 
for 10 to 30 minutes. After the oligomerization, resorcin is added to and 
dissolved in the mixture, then the foregoing acidic reaction catalyst is 
added thereto to thus react the resorcin with the resulting oligomer to 
give the desired product. 
Alternatively, 4-isopropenylphenol, or a mixture of 4-isopropenylphenol and 
a linear polymer thereof, and resorcin are dissolved in the foregoing mixed 
solvent used as the reaction solvent, followed by oligomerization under 
conditions similar to the aforementioned oligomerization conditions, 
addition of the foregoing acidic reaction catalyst and reaction of the 
resorcin with the resulting oligomer. In this case, the 
4-isopropenylphenols slightly undergo a reaction with resorcin during the 
oligomerization. 
The acidic catalyst used in the oligomerization may be identical to or 
different from that used in the reaction. In general, it is preferred to 
use the same acidic catalyst in these processes from the viewpoint of the 
management of catalysts and the post-treatment of waste liquor. 
After completion of the reaction, the reaction solution is filtered and the 
resulting crude crystals are washed with, for instance, benzene, toluene, 
cyclohexane and dichloromethane. Then the crystals are in general 
subjected to vacuum drying at a temperature ranging from 100.degree. to 
120.degree. C. If the crystals are additionally washed with warm water 
after the washing with, for instance, benzene, the purity of the crystals 
can further be improved. 
The present invention will be explained in more detail with reference to 
the following non-limitative working examples. 
EXAMPLE 1 
To a 1 l volume separable flask equipped with a reflux condenser, a 
thermometer and a stirring machine, there were added 80.4 g (0.6 mole) of 
4-isopropenylphenol, 650 g of benzene and 14 g of methanol, followed by 
dissolution at 35.degree. C., addition of 0.02 g of 36% by weight 
hydrochloric acid and stirring for 10 minutes to oligomerize 
4-isopropenylphenol. Then 33 g (0.3 mole) of resorcin was added to and 
dissolved in the oligomer solution and then 0.3 g of 36% by weight 
hydrochloric acid was added to the solution to thus cause a reaction of 
resorcin with the oligomer at 45.degree. C. for one hour with stirring. 
After completion of the reaction, the resulting slurry was subjected to 
suction filtration to separate crystals formed and the crystals were 
washed with 200 g of benzene. After air-drying, the crystals were dried at 
120.degree. C. for 3 hours in a vacuum dryer to give 97 g of the desired 
crystalline product having a melting point ranging from 217.degree. to 
219.degree. C. 
The crystals thus prepared were subjected to elemental analysis, mass 
spectrometric analysis and .sup.1 H-NMR spectroscopic analysis and the 
following results were obtained. 
______________________________________ 
Elemental Analysis: 
C H N 
______________________________________ 
Found 76.0% 6.9% &lt;0.05% 
Calculated 76.2% 6.9% -- 
______________________________________ 
Mass Spectrometric Analysis (EI-MS): M.sup.+ =378 
.sup.1 H-NMR spectroscopic analysis in CD.sub.3 COCD.sub.3 ; Reference 
Material: tetramethylsilane (TMS)! 
______________________________________ 
.delta. (ppm) Attribution* 
______________________________________ 
1.68 (s, 12H) 
(a) 
6.18 (s, 1H) (b) 
6.53-7.24 (q, 8H) (c), (d) 
6.90 (s, 2H) (e) 
7.33 (s, 1H) (f) 
8.02 (s, 2H) (g) 
______________________________________ 
The results of the foregoing analyses clearly indicate that the product 
prepared in Example 1 is 
1,3-dihydroxy-4,6-bis.alpha.-methyl-.alpha.-(4'-hydroxyphenyl)ethyl!benze 
ne represented by the following formula (1): 
##STR3## 
and the product has a purity of 99.5% by weight as determined by liquid 
chromatography. The conditions for the reaction and the results obtained 
are summarized in Table 1 given later. 
EXAMPLE 2 
To the same container used in Example 1, there were added 80.4 g (0.6 mole 
as expressed in terms of the molar number of 4-isopropenylphenol unit) of 
a linear dimer of 4-isopropenylphenol, 33 g (0.3 mole) of resorcin, 600 g 
of benzene and 16 g of methanol, followed by dissolution while stirring 
the mixture at 45.degree. C. for one hour. Then the reaction was carried 
out at 45.degree. C. for one hour with stirring, while adding 0.3 g of 36% 
by weight hydrochloric acid. After completion of the reaction, the reaction 
system was neutralized by addition of 1.3 ml of a 2N methanol solution of 
KOH. The resulting slurry was subjected to suction filtration to separate 
crystals formed and the crystals were washed with 200 g of benzene. The 
resulting wet crystals and 800 g of water were introduced into a flask, 
then the benzene was distilled off by increasing the temperature to 
80.degree. C., followed by suction filtration at 50.degree. C. and washing 
with 200 g of warm water maintained at 50.degree. C. The resulting crystals 
were dried at 120.degree. C. for 3 hours in a vacuum dryer to give 90 g of 
the desired crystalline product. The product has a purity of 99.8% by 
weight as determined by liquid chromatography. The conditions for the 
reaction and the results obtained are summarized in Table 1 given later. 
EXAMPLE 3 
To the same container used in Example 1, there were added 107.2 g (0.8 
mole) of 4-isopropenylphenol, 44 g (0.4 mole) of resorcin, 650 g of 
benzene and 15 g of methanol, followed by dissolution at 50.degree. C. and 
oligomerization of 4-isopropenylphenol for 20 minutes with stirring while 
adding 0.02 g of 20% by weight hydrochloric acid. Then the reaction was 
carried out at 60.degree. C. for 2 hours with stirring while adding 0.25 g 
of 20% by weight hydrochloric acid and then cooling the reaction system to 
50.degree. C. for an additional one hour with stirring. The resulting 
slurry was subjected to suction filtration to separate crystals formed and 
the crystals were washed with 300 g of benzene. The resulting crystals were 
air-dried and then dried at 120.degree. C. for 3 hours in a vacuum dryer to 
give 130 g of the desired product as crystals. The product has a purity of 
99.4% by weight as determined by liquid chromatography. The conditions for 
the reaction and the results obtained are summarized in Table 1 given 
below. 
EXAMPLES 4 AND 5 
The same procedures used in Example 3 were repeated except for the 
conditions shown in Table 1 to prepare 
1,3-dihydroxy-4,6-bis.alpha.-methyl-.alpha.-(4'-hydroxyphenyl)ethyl!benze 
ne. The conditions for the reaction and the results obtained are summarized 
in Table 1 given below. 
COMATIVE EXAMPLE 1 
To the same container used in Example 1, there were added 80.4 g (0.6 mole) 
of 4-isopropenylphenol and 650 g of benzene, followed by dissolution at 
35.degree. C. and oligomerization of 4-isopropenylphenol for 10 minutes 
with stirring while adding 0.02 g of 36% by weight hydrochloric acid. Then 
33 g (0.3 mole) of resorcin was added to the oligomer solution and the 
reaction was carried out at 45.degree. C. for one hour with stirring while 
adding 0.3 g of 36% by weight hydrochloric acid. After completion of the 
reaction, the resulting slurry was subjected to suction filtration to 
separate crystals formed and the crystals were washed with 200 g of 
benzene. The resulting crystals were air-dried and then dried at 
120.degree. C. for 3 hours in a vacuum dryer to give 102 g of the desired 
crystalline product. The product has a purity of 97.7% by weight as 
determined by liquid chromatography. The conditions for the reaction and 
the results obtained are summarized in Table 1 given below. 
COMATIVE EXAMPLE 2 
To the same container used in Example 1, there were added 80.4 g (0.6 mole) 
of 4-isopropenylphenol, 33 g (0.3 mole) of resorcin and 400 g of methanol, 
followed by dissolution at 45.degree. C. and reaction at 45.degree. C. for 
one hour with stirring while adding 5 g of 36% by weight hydrochloric acid. 
After completion of the reaction, 250 g of water was added to the reaction 
system, owed by cooling down to 10.degree. C. to crystallize, suction 
filtration to separate crystals formed and washing them with 200 g of 
water. The resulting crystals were dried at 120.degree. C. for 3 hours in 
a vacuum dryer to give 63 g of the desired crystalline product. The 
product has a purity of 89.5% by weight as determined by liquid 
chromatography. The conditions for the solution and the results obtained 
are summarized in Table 1 given below. 
TABLE 1 
__________________________________________________________________________ 
Kind of Catalyst Used 
Solv. 
Concn. 
Amount in 
Amount in 
Mixing 
of Reac. Temp. .times. 
Purity 
Yield 
Ex. No. 
Olig. S..sup.1) 
Reac. S..sup.2) 
Ratio.sup.3) 
MeOH.sup.4) 
Reac. Time 
(%) (%).sup.5) 
__________________________________________________________________________ 
1 36% by weight HCl 
5.86 2.1 45.degree. C. .times. 1 hr. 
99.5 85.5 
0.02 g 0.3 g 
2 36% by weight HCl 
5.43 2.6 45.degree. C. .times. 1 hr. 
99.8 83.8 
-- 0.3 g 
3 20% by weight HCl 
4.40 2.3 60.degree. C. .times. 2 hr. + 
99.4 86.0 
0.02 g 0.25 g 50.degree. C. .times. 1 hr. 
4 5% by weight HBr 
4.40 2.3 60.degree. C. .times. 2 hr. + 
99.5 87.0 
0.02 g 0.25 g 50.degree. C. .times. 1 hr. 
5 61% by weight HNO.sub.3 
4.40 2.3 60.degree. C. .times. 4 hr. + 
99.2 80.0 
0.25 g 2.5 g 50.degree. C. .times. 2 hr. 
1* 36% by weight HCl 
5.73 -- 45.degree. C. .times. 1 hr. 
97.7 89.9 
0.02 g 0.3 g 
2* 36% by weight HCl 
3.53 100 45.degree. C. .times. 1 hr. 
89.5 55.6 
-- 5.0 g 
__________________________________________________________________________ 
Note: 
.sup.1) This means the amount of the catalyst used in the oligomerizaion 
step (Olig. S.). 
.sup.2) This means the amount of the catalyst used in the reaction step 
(Reac. S.). 
.sup.3) Weight ratio: solvent/(4isopropenylphenol + resorcin). 
.sup.4) The amount of methanol in solvent (% by weight). 
.sup.5) The amount (mole) of the product per mole of the charged resorcin 
(mole %). 
*: Comparative Example. 
As seen from the results obtained in Examples, the method of the present 
invention can easily be handled, ensures a high yield, permits the 
reduction of impurity content (for instance, the impurity concentration in 
the product obtained in Example 1 is 0.5%, while that in the product 
obtained in Comparative Example 1 is 2.3%, i.e., it is reduced by a factor 
of 1/5) and can provide highly pure 
1,3-dihydroxy-4,6-bis.alpha.-methyl-.alpha.-(4'-hydroxyphenyl)ethyl!benze 
ne. The resulting phenolic compound is useful as, for instance, a branching 
agent for polycarbonates, polyesters or the like; a raw material for 
radiant ray-sensitive components for use as resist materials; a raw 
material for epoxy resins; and a hardening agent for epoxy resins.