JPS60126292A - Method for preventing crystal deposition of grignard reagent - Google Patents

Abstract

PURPOSE:To prevent the crystal deposition of a Grignard reagent even on storage in a high concentration and low temperature for a long term, by adding a hydrocarbon to a solution of the Grignard reagent in tetrahydrofuran (THF). CONSTITUTION:A hydrocarbon, preferably an aromatic hydrocarbon such as toluene or benzene, in an amount of preferably 10-35vol% is added to a solution of a Grignard reagent, particularly an alkylmagnesium chloride, in tetrahydrofuran (THF). The time for adding the above-mentioned hydrocarbon is preferably just after the synthesis or before crystal deposition during the storage avoiding the synthesis of the Grignard reagent.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing crystal precipitation of Grignard reagents, particularly magnesium dichloride, alkylmagnesium chloride, etc. in an alkylma solution during long-term storage at low temperatures.

Many studies have been conducted on the synthesis of Grignard reagents and synthetic reactions using Grignard reagents.
. As a result, tetrahydrofuran is generally used as a solvent during the synthesis of Grignard reagents because of its ease of industrial handling and the fact that Grignard reagents can be obtained in good yields under mild conditions. But 11. Grignard reagents, especially tetrahydrofuran solutions of alkylmagnesium chlorides, are stored for long periods at a density of 7% (at a certain temperature, they remain transparent, but below that temperature, crystals such as magnesium dichloride and alkylmagnesium chloride precipitate). When crystals precipitate, they are deposited at the bottom of the storage tank [7] and solidify, which not only causes inconveniences such as harming μ during transfer through piping, but also reduces the uniformity of the solution composition in the storage tank. In other words, since the chemical composition of the supernatant liquid portion and the crystal portion are different, variations may occur in the subsequent chemical reaction using the Grignard reagent, which is extremely undesirable.

Conventionally, there was no way to prevent crystal precipitation other than to lower the concentration of alkylmagnesium chloride in the solution to a large lIJ, or to keep it warm so that the temperature did not drop too much.

However, lowering the pressure increases the volume and reduces the number of reaction moles in a constant 8M reactor.
It's not 11 measures. In addition, H is also a high-value tetrahydrofuran.
It also requires the use of trtc, which is not economical. on the other hand,
Even if crystal precipitation can be prevented by raising the temperature, it is necessary to keep the temperature above the temperature at which crystal precipitation does not occur when it is cold, so it is necessary to prevent crystal precipitation of argylmagnesium chloride from an industrial perspective. No fundamental technical solution was found.

As a result of extensive research, the present inventors have discovered that by adding a hydrocarbon to a tetrahydro-7 run solution of alkylmagnesium chloride, precipitation of crystals can be prevented even when the solution is stored at high concentrations and at low temperatures for long periods of time. In this case, if the hydrocarbon is -tetrahydrofuran and the total number of said hydrocarbons,
The present invention was completed by confirming that the effect is remarkable when the number of 0 to 55 vo is used.

The present invention will be explained in more detail below.

Examples of the alkyl group of the alkylmagnesium chloride used in the present invention include methyl, ethyl, -1So-
Propyl, n-propyl, n-tet-t.

thyl, nec-butyl, -→-phthyl, n-hegysyl,
Examples include n-octyl and n-desol. These alkylmagnesium chlorides are synthesized from a corresponding alkyl chloride having an alkyl group and metallic magnesium flakes in tetrahydro7rane as a solvent according to a conventional method.

Conditions for precipitation of crystals from a tetrahydrofuran solution of alkylmagnesium chloride vary depending on the iA3 degree of the alkylmagnesium chloride and the temperature during storage, and also vary depending on the species 61 of the alkyl group. for example,
In the case of a solution obtained by dissolving n-butylmagnesium chloride in tetrahydrofuran, the n-butylmagnesium chloride contained per 1e of the solution has a concentration of 3 mo/JL, at a temperature of about 15°C or less, and 1.5 mof. It has been confirmed that crystal precipitation occurs at concentrations below about 0°C.

Examples of hydrocarbons used in the present invention are:

Aromatic hydrocarbons such as benzene, toluene, xylene, alicyclic hydrocarbons such as chlorohexane, methylcyclohexane, aliphatic hydrocarbons such as hexane, hegetane, octane, and the total number of such hydrocarbons. Most preferably, it should be added in an amount of 10 to 55 voJ. This is because below 10 VO, even if the effect of preventing crystal precipitation is recognized, the practical effect is poor55
Even if more than 10% of hydrocarbons are added, a significant increase in the crystal precipitation prevention effect (118t) cannot be expected, and the 1st historical lit of hydrocarbons increases [7. is a requirement that requires particular attention. That is, during the synthesis of the Grignard reagent, hydrocarbons are added.
Crystals are produced as a by-product during synthesis and should be avoided. nothing(
7 filter, it is considered preferable to use it directly after synthesizing the Grignard reagent or before crystals precipitate during storage.

Examples are shown below [71] The present invention will be explained in more detail.

Disaster IEt Example 1: Warp metal magnesium strips in the usual manner, dissolve n-butylmagnesium chloride in tetrahydrofuran, add q+t to the solution, and examine.7.The n-butylmagnesium chloride contained per 1) .01nO
/l! The degree of C (hereinafter used in this sense) is 2. fJ mOA/A). Add 25 mg of dehydrated toluene to 100 mg of this solution,
Diluted and mixed. As a result, the amount of toluene contained in the solution is 2 to the total number of tetrahydrofuran and toluene.
The equivalent of 0 voA% was obtained. The hydrocarbons in the mixture of tetrahydrofuran and hydrocarbons are obtained by hydrolyzing the mixture and quantifying the organic layer components by gas chromatography.

Next, the obtained diluted solution was divided into six 50 ml glass bottles each containing 40 tnl, and the bottles were sealed and stored in five types of thermostats at 10°C, 5°C, and 0°C. After 7 days, the crystals were removed from the incubator and the state of precipitation of each crystal was examined.

No crystal precipitation was observed.

Example 2 Example 1: ``25 ryr1.J of dehydrated toluene.

"The same procedure as in Example 1 was carried out except that 25n+/!J of dehydrated benzene was used. No crystal precipitation was observed at all.

Example 5 [Dehydrated toluene 25mI] of Example fA11 was replaced with [Dehydrated octane 25mI! '' was carried out in the same manner as in Example 1 except that. Although a slight crystal precipitation phenomenon was observed, it was not to the extent that it would be an industrial hindrance.

Example 4 25 ml of dehydrated toluene from Example 1 and 50 ml of dehydrated toluene. The procedure was carried out in the same manner as in Example 1 except that j was used. No crystal precipitation was observed at all.

Example 5 The same procedure as in Example 1 was carried out except that 15 mgJ of dehydrated toluene was used instead of 25 mgJ of dehydrated toluene in Example 1. Although a slight phenomenon of crystallization was observed, it was not considered industrially acceptable. 0 Comparative Example 1 "25 ml of dehydrated toluene" from Example 1 was dehydrated and a solution diluted with 25 ml of water was simply obtained by moving from umbrella to umbrella. The same procedure as in Example 1 was performed except for this. When tetrahydrofuran was used alone, precipitation of crystals was remarkable. As shown in Table 1, in Examples 1 to 5, the effect of preventing crystal precipitation was observed in toluene, benzene, and octane, respectively. In the comparative example, Examples 1 to 5 were
It is clear that the crystallization is not suppressed simply by the dilution effect, as crystals precipitate even though the dilution concentration is almost the same as that of the diluted concentration.

Table 1 Judgment of crystal precipitation state is as follows 1. No crystal precipitation at all + Slight crystal precipitation was observed +10 Significant crystal precipitation

Claims (1)

[Claims] 1. In a tetrahydrofuran solution of Grignard reagent,
A method for preventing crystal precipitation of a Grignard reagent, which comprises adding a hydrocarbon. 2. The method according to claim 1, wherein the Grignard reagent is n-butylmagnesium chloride. 6. The amount of hydrocarbon to be added is 10 to 65 vo, i! based on the total amount of tetrahydrofuran and the hydrocarbon! %.Claim I11] The method according to item 1. Law.