Process for preparing adamantane polyol

#This Application is a U.S. National Stage Application filed under 35 U.S.C. §371 of International Application PCT/JP2011/076228, filed Nov. 15, 2011, designating the United States, which claims priority from Japanese Patent Application 2010-259910, filed Nov. 22, 2010, the complete disclosures of which are hereby incorporated herein by reference in their entirety for all purposes.

#The present invention relates to a process for preparing an adamantane polyol which is useful as an intermediate material for a highly functional polymer, a synthetic lubricant, a plasticizer or the like, or as an intermediate for an organic chemical such as, for example, a pharmaceutical or agricultural drug.

#According to a process for preparing an adamantane polyol (adamantane diol, adamantane triol, etc.), an adamantane is reacted with a ruthenium compound and a hypochlorite in a biphasic water/organic solvent system (see Patent Documents 1 through 3). However, a ruthenium compound is costly and thus needs to be recovered and reused. Ruthenium may have various valences and is difficult to be recovered as a single compound. This causes a problem that the recovery ratio is low.

#Now, the present invention will be described more specifically by way of examples. The present invention is not limited to the following examples. The amount of generated adamantane polyol contained in the water phase was analyzed by a gas chromatographer provided with an FID detector. The quantization of the ruthenium compound contained in the water phase was performed by ICP emission spectrometry after the sample was dissolved in hydrochloric acid to provide a uniform solution. The recovery efficiency of ruthenium was found as follows: after the solid-liquid separation, the amount of ruthenium which flowed into the waste water was measured, and the concentration was used to find the efficiency.

#The following substances were put into a jacket-attached glass separable flask having a capacity of 2 L and provided with a magnet induction stirrer, a thermometer, a Dimroth condenser, and a pH electrode: 54 g of adamantane, 3.6 g of tricalcium phosphate as an inorganic adsorbent (for chemical use; produced by Wako Pure Chemical Industries, Ltd.; hereinafter, referred to simply as “TCP”), 2.7 g of ruthenium chloride-n hydrate (produced by N. E. Chemcat Corporation; the Ru content is 43%, i.e., about 1.2 g of Ru), 415 ml of ethyl acetate and 400 ml of water. 1200 g of 12 wt. % aqueous solution of sodium hypochlorite was dripped. At the same time, 10 wt. % sulfuric acid was dripped so that the pH value of the reaction solution would be 3.5. The time required to drip sodium hypochlorite was about 12 hours. During the dripping of sodium hypochlorite, the temperature was adjusted to be 55° C.±5° C. After the reaction was finished, 25% sodium hydroxide solution was dripped until the pH value of the reaction solution became 7. Next, the reaction solution was kept still, the organic phase mainly containing ethyl acetate was removed by distillation, and thus a water phase containing a ruthenium compound (catalyst) and an adamantane polyol was obtained. This water phase was analyzed by gas chromatography. As a result, the yield of 1,3,5-adamantane triol was 64%. Then, the resultant water phase was treated with suction filtration to separate the ruthenium catalyst together with the inorganic adsorbent, and thus 1800 g of water phase containing the adamantane polyol was obtained as a mother liquid. The concentration of ruthenium in the water phase was quantized by ICP emission spectrometry. The result was 5.0 ppm.

#The same operation as in Example 1 was performed except that tricalcium phosphate having the ruthenium catalyst adsorbed thereto, which was separated by filtration in Example 1, was used with no further treatment, instead of newly adding tricalcium phosphate and ruthenium chloride-n hydrate. Like in Example 1, the water phase was analyzed by gas chromatography. As a result, the yield of 1,3,5-adamantane triol was 66%. The concentration of ruthenium in the resultant water phase was quantized by ICP emission spectrometry. The result was 3.7 ppm. The results are shown in Table 1.