JP4038657B2 - Method for producing adamantanone - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing adamantanone by oxidizing adamantane and / or 1-adamantanol with sulfuric acid. Adamantanone is a useful compound as a raw material for highly functional polymers, heat resistant resins, pharmaceuticals and the like.
[0002]
[Prior art]
As a method for producing adamantanone, there is a sulfuric acid method (Organic Synthesis Vol. 53, page 8, HWGeluk and VGKeizer (1973)). Specifically, adamantane or 1-adamantanol is heated and stirred in concentrated sulfuric acid to obtain adamantanone. When adamantane is used as a raw material, the yield is 47 to 48%. When 1-adamantanol is used as a raw material It is reported that the yield is about 70%.
[0003]
The adamantanone production method described above is a very useful method because it can be produced with an easy operation of heating and stirring the raw material in concentrated sulfuric acid, an inexpensive reagent, and equipment, but the yield is low and by-products are produced. Since a large amount of product is produced, purification is difficult and raw material costs are increased.
[0004]
In JP-A-11-189564, when adamantane is oxidized with concentrated sulfuric acid, a temperature is controlled by holding at a low temperature for a certain period of time and then increasing the temperature at a predetermined rate of temperature and reacting at a high temperature to obtain adamantanone. Yes. However, this method has a problem that the reaction time becomes long and a complicated temperature control operation is required.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-described problems in the prior art and to provide a method for producing adamantanone in high yield from adamantane and / or 1-adamantanol as a raw material.
[0006]
[Means for Solving the Problems]
As a result of intensive research, the present inventors have found that when the reaction temperature is lowered and the sulfuric acid concentration is lowered, the selectivity is high but the reaction rate is slow, and conversely, the reaction temperature is raised to raise the sulfuric acid concentration. In this case, it was found that a large amount of resinous material was generated and the selectivity of adamantanone was lowered. Therefore, by maintaining the sulfuric acid concentration that decreases with the progress of the reaction by adding fuming sulfuric acid to the reaction conditions with high selectivity and low sulfuric acid concentration, while suppressing the production of resinous substances as by-products, The present inventors have found that the reaction time can be shortened and have completed the present invention.
[0007]
That is, according to the present invention, in a method for producing adamantanone by oxidizing adamantane and / or 1-adamantanol with sulfuric acid, the sulfuric acid concentration at the start of the reaction is 80 to 90% by weight, and fuming sulfuric acid is added during the reaction. Thus, the present invention relates to a method for producing adamantanone, wherein the reaction is carried out while suppressing a decrease in the sulfuric acid concentration in the reaction solution to within 1% by weight.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
As adamantane and / or 1-adamantanol used as a raw material, those commercially available as industrial grade and reagent grade can be used. Further, as the concentrated sulfuric acid, it is preferable to use sulfuric acid having a concentration of 95 to 98% by weight which is generally used in the reaction. Although it can be used even if the sulfuric acid concentration is less than 95% by weight, a large amount of fuming sulfuric acid is required to make up for it. Further, when sulfuric acid having a concentration of 99% by weight or more is used, a resinous substance tends to be easily generated.
[0009]
The amount ratio of the raw material to sulfuric acid in the reaction is preferably 5 to 15 times the weight of sulfuric acid with respect to 100 g of the raw material. If the amount of sulfuric acid is less than this, the raw material will not be completely dissolved and the amount of sublimation during the reaction will increase. On the other hand, if the amount is larger than this, the production of resinous substances as by-products increases and the selectivity is lowered.
[0010]
In addition, a solvent can be used as necessary for the purpose of preventing sublimation of adamantane during the reaction. However, in that case, it is necessary to select a solvent that is stable against sulfuric acid. Examples of such a solvent include inert solvents such as alkyl halides and halogenated benzenes.
[0011]
Since the reaction in the sulfuric acid method produces sulfur dioxide, it is generally preferable to carry out the reaction at normal pressure. However, it is also possible to react under reduced pressure in order to distill off water and solvent. The reaction apparatus may be any apparatus that can sufficiently heat and heat and uses a material that can withstand sulfuric acid.
[0012]
The reaction temperature is in the range of 20-80 ° C, preferably 40-70 ° C. When the reaction temperature is lower than this range, the reaction rate is remarkably reduced, and a large amount of fuming sulfuric acid needs to be added. On the other hand, if it is higher than this range, a resinous product is produced from the beginning of the reaction, and the effect of the present invention cannot be obtained.
[0013]
The sulfuric acid concentration in the reaction solution containing a raw material such as adamantane varies depending on the charging ratio of the raw material and sulfuric acid, but is preferably 80 to 90% by weight, more preferably 82 to 88% by weight at the start of the reaction. . If the sulfuric acid concentration in the reaction solution is smaller than this range, the effect of shortening the reaction time cannot be obtained. If the sulfuric acid concentration is larger than this range, the amount of resinous product as a by-product increases and the yield of adamantanone decreases. .
[0014]
In the present invention, fuming sulfuric acid is added in order to suppress the decrease in sulfuric acid concentration within 1% by weight. If the decrease in the sulfuric acid concentration exceeds 1% by weight, the effect of shortening the reaction time cannot be obtained, and a decrease in conversion and an increase in by-products are observed. Further, the amount and rate of fuming sulfuric acid added is preferably adjusted so as to maintain the sulfuric acid concentration at the start of the reaction.
[0015]
Specifically, the amount of fuming sulfuric acid added is in the range of 0.5 to 10 mol, preferably 1.0 to 5.0 mol, with respect to 1 mol of adamantane and / or 1-adamantanol as raw materials. When the amount of fuming sulfuric acid to be added is less than this range, the effect of shortening the reaction time cannot be obtained, and when it is more than this range, the amount of by-product resinous product increases and the yield of adamantanone decreases. .
[0016]
The rate of fuming sulfuric acid to be added is 0.01 to 1 mol / hour, preferably 0.05 to 0.5 mol / hour, with respect to 1 mol of adamantane and / or 1-adamantanol charged. If the amount and speed of the fuming sulfuric acid added is less than this range, the effect of shortening the reaction time cannot be obtained. If it exceeds this range, the sulfuric acid concentration in the initial stage of the reaction becomes high, and the amount of resinous product that is a by-product Increases and the yield of adamantanone decreases. Since the sulfuric acid concentration tends to increase immediately after the start of the reaction, it is more preferable to add fuming sulfuric acid after 0.5 to 6 hours without adding fuming sulfuric acid. Although there is no restriction | limiting in particular about fuming sulfuric acid, It is preferable to use fuming sulfuric acid of 10 to 60 weight% density | concentration which is easy to handle and is easy to obtain.
[0017]
Since the reaction time depends on the amount of fuming sulfuric acid added and the addition rate, it cannot be determined unconditionally, but it is preferably about 4 to 100 hours. After completion of the reaction, adamantanone can be separated from the reaction system according to a conventional method. That is, after completion of the reaction, the produced mixture containing adamantanone is poured into cold water or ice, and then the separated crude adamantanone can be isolated by filtration or extraction. If further purification is required, it can be purified by a method such as recrystallization, vacuum distillation, steam distillation or sublimation purification.
[0018]
【Example】
In order to describe the present invention specifically, examples and comparative examples will be described below, but the present invention is not limited to these examples.
[0019]
Example 1
17.0 g (126 mmol) of adamantane and 100 ml of 96 wt% sulfuric acid were placed in a 200 ml four-necked flask equipped with a stirrer, a thermometer, and a leak tube, and heated and stirred at 65 ° C. for 12 hours. Meanwhile, addition of fuming sulfuric acid was started 2 hours after the start of the reaction. The addition rate was 30 mmol / hour and a total of 240 mmol was added. The sulfuric acid concentration in the solution at the start of the reaction was 87.0%, and the range of the sulfuric acid concentration during the reaction was 86.4 to 87.0%. After allowing to cool, the reaction mixture was poured into 200 ml of ice and extracted twice with 200 ml of ether. The ether layer was washed twice with 200 ml of saturated brine and then dried over anhydrous magnesium sulfate, and the ether was distilled off under reduced pressure to obtain 12.8 g (yield 76%) of adamantanone.
[0020]
Example 2
1-adamantanol (18.9 g, 124 mmol) and 96 wt% sulfuric acid (100 ml) were placed in the same reaction apparatus as in Example 1, and the mixture was heated and stirred at 55 ° C for 8 hours. Meanwhile, a total of 70 mmol of fuming sulfuric acid was added at an addition rate of 10 mmol / hour from the start of the reaction. The sulfuric acid concentration in the solution at the start of the reaction was 86.9%, and the range of the sulfuric acid concentration during the reaction was 86.5-86.9%. After allowing to cool, 15.5 g (yield 92%) of adamantanone was obtained in the same manner as in Example 1.
[0021]
Comparative Example 1
In the same reactor as in Example 1, 16.9 g (124 mmol) of adamantane and 100 ml of 96 wt% sulfuric acid were added and stirred with heating at 65 ° C. for 12 hours. No fuming sulfuric acid was added. The sulfuric acid concentration in the solution at the start of the reaction was 86.9%, and the sulfuric acid concentration dropped to 85.6% during the reaction. After allowing to cool, 7.8 g (yield 42%) of adamantanone was obtained in the same manner as in Example 1.
[0022]
【The invention's effect】
According to the present invention, adamantanone can be obtained by a simple method with good yield.

Claims (1)

In the method for producing adamantanone by oxidizing adamantane and / or 1-adamantanol with sulfuric acid, the sulfuric acid concentration at the start of the reaction is 80 to 90% by weight, and fuming sulfuric acid is added during the reaction to A method for producing adamantanone, wherein the reaction is carried out while suppressing a decrease in sulfuric acid concentration within 1% by weight.