JPS6039275B2 - Method for purifying 2,2,6,6-tetramethyltetrahydropyran-4-ol - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for purifying 2,2,6,6-tetramethyltetrahydropyran-4-ol.

2,2,6,6-tetramethyltetrahydropyran-4-ol (hereinafter abbreviated as TTPH) represented by the formula:
It is a C compound with a melting point of about 85 to 8, and is a compound useful as a raw material for organic synthesis and a high boiling point solvent.

TTPH can be produced through aldol condensation of acetone, followed by dehydration and hydrogenation. For example, triacetone dialcohol is synthesized by aldol condensation of acetone, and then 2
, 2,6,6-tetramethyltetrahydropyran-4-one (hereinafter abbreviated as TTPK), a method for producing TTPH by hydrogenating it, a method for producing holon by condensation of acetone, dehydration, There is a method in which TTPK is then synthesized by hydration and cyclization, and TTPH is produced by similar hydrogenation. Although it is not clear which of the above reactions takes place, methyl isobutyl ketone (MIBK
) and methylisobutylvinol (MIBC), TTPH or TTPK is obtained as a by-product, so TTPK can be converted to TTPH by hydrogenating in the same way.
It can be PH. TTPH produced by such a method is usually obtained in a form containing impurities, so
Depending on the application, it may be necessary to further increase the purity.

The inventors of the present invention conducted intensive research on the method for purifying the crude TTPH, and as a result, discovered a recrystallization method using a hydrocarbon solvent. That is, the present invention is a method for purifying TTPH, which is characterized by recrystallizing crude TTPH obtained by condensation, dehydration, and hydrogenation of acetone using a hydrocarbon solvent. The recrystallization solvent used in the present invention is a hydrocarbon solvent, preferably having 5 carbon atoms, 12 carbon atoms, and 12 carbon atoms.
belongs to.

Specifically, aliphatic hydrocarbons such as n-bentane, n-hexane, isohexane, n-hebutane, n-octane, isooctane, n-decane, kerosene, cyclobentane,
Examples include alicyclic hydrocarbons such as cyclohexane, and aromatic hydrocarbons such as benzene, toluene, and xylene. These recrystallization solvents do not need to be a single compound, and may be a mixture of two or more. In addition, other organic solvents may be included as long as they are in small amounts. Particularly preferred among these are aliphatic hydrocarbons. The crude TTPH' used as the raw material of the present invention is produced through the steps of condensation of acetone, dehydration, and hydrogenation as described above, and usually has a purity of about 80% or more, preferably about 9.
At 0% or more, it contains TTPK and other acetone conductors as impurities.

When recrystallizing crude TTPH, the amount of solvent used is
The pH varies depending on the melting temperature and type of solvent, but
In general, a method is adopted in which TTPH is dissolved at a temperature of about 100°C to 100°C per 100°C of solvent, and then cooled to about 120° to 130°C. . As a crystallization method, a crude TTPH solution is continuously supplied to a crystallization tank maintained at a predetermined temperature,
On the other hand, a continuous method in which the slurry is continuously discharged from the crystallization tank, a batch method in which the crude TTPH solution is charged into the crystallization tank and then cooled to crystallize TTPH, or a modified method thereof may be adopted. I can do it. In order to isolate the crystals, methods employed as ordinary crystal separation methods such as filtration and centrifugation can be used. If necessary, the recrystallization operation may be performed two or more times. According to the invention, T.T.
The recovery rate of PH is very high, and high purity products can be easily obtained. Example 1 MI through the steps of acetone condensation, dehydration and hydrogenation
A reaction mixture containing BK as a main component was obtained.

After MIBK was distilled off, the mixture was hydrogenated, and diisobutyl ketone and lower boiling point substances were distilled off. The residue was cooled, and the precipitated crystals were collected in a furnace to obtain crude TTPH with a purity of 92.8%. Mitsui Hexane (manufactured by Mitsui Petrochemical Co., Ltd.) 100, and the above crude TTPH9. After heating to dissolve at 50° C., the mixture was cooled to 0° C. to obtain crystals. By filtering through a glass filter and drying under reduced pressure, 4.7 g of purified TTPH with a purity of 99.9% was obtained (Fumushi point: 85.1°C). Example 2 40 g of crude TTPH used in Example 1 was added to 100 g of cyclohexane, dissolved at 50 g, and then cooled to 2000 g.

Claims (1)

[Claims] 1. Recrystallization of crude 2,2,6,6-tetramethyltetrahydropyran-4-ol obtained by condensation, dehydration and hydrogenation of acetone using a hydrocarbon solvent. A characterized method for purifying 2,2,6,6-tetramethyltetrahydropyran-4-ol. 2. The method according to claim 1, wherein a hydrocarbon solvent having 5 to 12 carbon atoms is used. 3. The method according to claim 1 or 2, wherein an aliphatic hydrocarbon is used as the hydrocarbon solvent.