JPS6256496A - Production of 3,3,3-trifluoro-1-propynyllithium - Google Patents

Abstract

PURPOSE:To obtain the titled compound useful as an introducing agent of 3,3,3- trifluoro-1-propyl group in one step, by reacting 1,1,2-trichloro-3,3,3-trifluoro-1- propene with an organolithium compound. CONSTITUTION:1,1,2-Trichloro-3,3,3-trifluoro-1-propene is dissolved preferably in an aprotic organic solvent, e.g. ether, and an organolithium compound, e.g. ethyllithium, is dropped thereto and reacted therewith to afford the aimed compound.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention provides 8.8.8-)') fluoro-1 useful as an agent for introducing 8,8.8-)refluoro-1-propynyl group.
-Propynyllithium (hereinafter referred to as trifluoropropynyllithium).

8,8.8-) Lifluoro-1-propyne (trifluoromethylacetylene; hereinafter abbreviated as trifluoropropyne) is the simplest acetylene compound having a trifluoromethyl group. By replacing the hydrogen at the 10th position with various elements or groups, a series of acetylenes having a trifluoromethyl group on one side of the triple bond can be obtained. These acetylenes can be used as monomers for polymeric compounds with semiconducting properties, or as intermediates for synthesizing medicines, agricultural chemicals, and the like. Trifluoropropynyllithium is indeed very useful for synthesizing many of these acetylenes.

Due to its low stability, trifluoropropynyllithium is generally not isolated, but can be prepared as a solution and reacted with appropriate reagents to produce various types of 8.8
．． 8-) Converted to a compound having a refluoro-1-propynyl group. Therefore, as an example of a trifluoropropynyllithium drug, chlorotrimethylsilane is conveniently chosen in this description. The examples also include cases where n-butyraldehyde and acetophenone are used as reagents. However, the reagents that can be reacted with trifluoropropynyllithium are not limited to these reagents.

(b) Prior art method for obtaining trifluoropropynyllithium The most conventionally known method is the lithiation of trifluoropropyne [F, G, Drakesmith, O, J
.

8tewart, 'and P, Tarrant,
J, Org, Chem,, 33°280 (19
68) ]. For this purpose, trifluoropropyne must first be synthesized. There are several methods for synthesizing trifluoropropyne, the most representative of which are 1 and 1.2.
-) Lichloro-8,L 3-trifluoro-1-propene is used as a raw material and zinc powder is applied to it [
W, G, Finneganand W, P, N
orris, J. Org. Chem, 28.
1139 (1968)].

Therefore, trifluoropropynyllithium can be obtained in a total of two steps: the first step to synthesize trifluoropropyne from this raw material and the second step thereafter.

In the first step, 1.1.2-)lichloro-3°a,
a-Trifluoro-1-propene and zinc dust are reacted to produce zinc acetylide of trifluoropropyne. For this purpose, the reaction must be carried out at about 100° C. using dimethylacetamide or dimethylformamide as a solvent. The acetylide is then decomposed by adding water, and the generated l-fluoropropyne is collected and purified.

In the second step, the trifluoropropyne thus obtained is dissolved in ether, and a solution of an organolithium compound is added dropwise to the solution while cooling in a dry ice-acetone bath to produce trifluoropropynyllithium. Then a suitable reagent (in this case chlorotrimethylsila,
The product is isolated after post-treatment. The chemical formulas of the reactions that occur during the operation of the conventional method described above are expressed by formulas (1) to (4). Equations (1) and (2) are the first
Steps, equations (3) and (4) correspond to the second step.

CF3CC1=CC12+2Zn −□CF3C= C
ZnCl +ZnC12(1)OF30=CZnC1+
H2O-1-→CF3C= CH+ZnClOH(2
) CF 30 = CH+ RL i −-→CF3C
CF3CCLiH(3) CF3CmiCLi +018i (OH3)3--→C
F30=08i (CH3)3 + LiC1(4)(
C) Object of the invention 1.1.2-)lichloro-3,3,8-)refluoro-
The method of applying zinc powder to 1-propene as a raw material is as follows:
The present method is considered to be an easy method for synthesizing trifluoropropyne. But the way to go through this is
There is much room for improvement in the method for producing trifluoropropynyllithium. Sunahachiko's synthesis method is based on the formula (1
) to (3), it follows the route [raw material -1 -> zinc acetylide of trifluoropropyne -> trifluoropropyne□trifluoropropynyl lithium (lithium acetylide of trifluoropropyne)]. If trifluoropropynyllithium can be obtained directly from raw materials in good yield, the effect will be significant.

Trifluoropropyne, which is the product of the first step and the starting material of the second step, is contaminated with water, solvent, decomposition products of the solvent, etc., and these substances are removed before the second step. I have to remove it, but this is quite a hassle. Moreover, trifluoropropyne has a boiling point of -48 to -4.
It is a gaseous compound at room temperature (7°C/705M) and is not easy to handle.

(d) Structure of the Invention In order to produce trifluoropropynyl lithium more easily than the conventional method, the inventors investigated various methods and conducted repeated experiments. i, 2-trichloro-
The present inventors have discovered a method for producing trifluoropropynyllithium from 8,8,8-trifluoro-1-propene in two steps in a high yield in one step using the same raw materials.

The method of the present invention is 1.1.2-)lichloro-3,3゜3-
The process involves producing propynyllithium by reacting trifluoro-1-propene with an organic lithium compound.

In other words, this raw material is dissolved in an aprotic organic solvent,
By dropping a solution of 2 equivalents of an organic lithium compound while cooling this solution, a solution of trifluoropropynyllithium is obtained. The reaction is shown by formula (5).

CF3CC] =CC12+2RLi -1 → 0F3C
=CLi-4-2RC1+Li01 (5) Generally, in this way, a solution of trifluoropropynyllithium is first prepared and reacted with the appropriate reagent for conversion to the next desired compound. If the reagent is chlorotrimethylsilane, the reaction is expressed by formula (4). However, depending on the type of reagent, it is also possible to first prepare a solution of the mixture with the raw material and then drop the solution of the organolithium compound thereto.

Ethers such as diethyl ether are suitable as the aprotic organic solvent for dissolving the raw materials. The solvent for dissolving the organolithium compound must also be an aprotic organic solvent, and ethers, hydrocarbons, or a mixture of both can be used.

The reaction is suitably carried out by cooling with dry ice-acetone. When the organolithium compound is added using ether as a solvent and keeping the internal temperature below -60°C, a clear solution is obtained. Since no precipitation of chloride or lithium produced as a result of the reaction is observed, the reaction is judged to be incomplete at this point. When cooling is stopped and stirring is continued, a precipitate begins to form and its amount gradually increases as the temperature gradually rises. If you re-cool it immediately when the temperature reaches 0℃,
Reagents for the next reaction can be added. Even if the temperature increase is limited to about -30°C, the reaction of formula (5) can be completed over time.

As the organic lithium compound, alkyl lithium of about 01 to 08 is generally used, but compounds such as phenyl lithium can also be used. The difficulty of isolating the product must also be considered in deciding which organolithium compound to use. As a result of the reaction, the organolithium compound becomes the corresponding chloride, but if the boiling point of the organolithium compound is close to the boiling point of the desired product, it becomes difficult to extract the desired product pure by distillation alone.

(e) Effect of invention The effects of the present invention are listed below.

1) Trifluoropropynyllithium, which conventionally required two steps, can be produced in one step from the same raw material, 1,1,2-)dichloro-8,8,8-1-lifluoro-1-propene. can do. Moreover, the yield is also good, at 80% or more.

2) It is possible to directly produce trifluoropropynyllithium, its lithium acetylide, without producing trifluoropropyne, which has a low boiling point and is difficult to handle.

3) As a result of the reaction, the organolithium compound used as a reagent becomes the corresponding hydrogen compound in the conventional method (see formula (3)), but in the method of the present invention, it becomes the corresponding chloride (formula (5)
)reference). Therefore, after recovering this chloride, it can be reacted with lithium to regenerate the organic lithium compound.

(Example 0) Next, the present invention will be explained in more detail with reference to Examples.

Example 1 1.1.2-) Ri-ro-ro-3, 8, 8
-) Stir with Rifle Owo and dry ainu.
Cool for 1' in an acetone bath (calculated from the nominal concentration: 0.
(containing 60 moles of ethyllithium) was added dropwise over about 1 hour. After removing the refrigerant from the cooling bath, stirring was continued, and when the temperature reached 0°C, the dark brown suspension was recooled to -30°C, 85 g (0.32 mo/v) of chlorotrimethylsilane was added, and cooling was stopped and further stirred. Stirred for 2 hours. The reaction mixture was diluted with concentrated hydrochloric acid 60
- and crushed ice, the whole was shaken in a separatory funnel, and the ether layer was washed once with water and once with a saturated aqueous solution of sodium sulfate, and then dried over anhydrous sodium sulfate. 98% of the ether solution was fractionated to obtain trimethy/L/(3,8,3-trifluoro-1-propynyl)silane, boiling point 73-75°C, 84g
mol, yield 82%).

As a modification of the above method, 1.1.2-)! J Kuroro 3
．． 8. ethertV (25
After the solution is cooled with dry ice-acetone and 350ml of an ether solution of ethyllithium is added dropwise, cooling may be stopped and stirring may be continued until the reaction is completed. In this case, almost no coloring is observed in the reaction mixture, and the operation is simple and takes only a short time. However, trimethi/l/(8
The yield of ,8,8-)lifluoro-1-proviny/L/)silane is somewhat low, and the formation of a compound formed by addition of ethyllithium to this compound is also observed 1, Example 2 1, 1 ．． 2-) ri ri ro ro -3,
8,3-) Rifle Ower-1-Propene 10g
(0,050 mo) v ) no k-te/' (50 mg
) The solution was stirred with a magnetic cooler under a nitrogen atmosphere, cooled with a dry ice-acetone bath, and an ether solution of ethyllithium 697! (containing o, t i 5 moles of ethyllithium, calculated from the nominal concentration) was added dropwise at an internal temperature below -60°C. Stop cooling and continue stirring when the temperature reaches 09°C, cool again, and when the temperature reaches -64°C, n-
Butyraldehyde 6.9 g (0,095 mo/l/)
was added, cooling was stopped, and the mixture was stirred for 3 hours. The reaction mixture was treated as in Example 1, 93% of the ether solution was distilled and 7.7.7-trifluoro-5-heptyne-
4-ol, boiling point 60°C/19ff, 5.
5 g (0.083 mol, yield 70%) was obtained.

Example 8 '1, 1.2 - Tori Ro Ro -3, 3, 3
-Trifluoro-1-propene 10g (0,05
A hexane solution of n-butyllithium was prepared by cooling the ether)v(50i) solution at 0mol/L/) with dry ice-acetone under a nitrogen atmosphere, keeping the internal temperature below -50°C. 70m7 (calculated from the nominal concentration: 0.
(containing 109 mol of n-butyllithium) was added dropwise.

Stop cooling and continue stirring, and when the temperature reaches 0°C, cool again.
After adding 7 g (0,058 mo) of acetophenone, cooling was stopped and the mixture was stirred until the temperature reached 26°C. The reaction mixture was treated as in Example 1 and the resulting ether-
Distill 91% of the hexane solution and boil at 78℃ 15jl
8.6 g of liquid was obtained.

According to the infrared absorption spectrum and gas chromatogram, 87% (7.4 g, yield 75%) of this is the addition product 5,5.5-)! J Fluoro 2-Funi2/
It was found that most of the residue was V-8-pentyn-2-ol and acetophenone. Crystals of this adduct were obtained by seeding this liquid with crystals. The melting point was 69.5 to 71°C, which was almost the same as the literature value (71 to 73°C, mentioned in the 1968 literature).

designated agent +1□　(- Agency of Industrial Science and Technology Nagoya Industrial Technology Laboratory q, -“Toshito Nagase”! : ・

Claims (1)

[Claims] 1,1,2-trichloro-3,3,3-trifluoro-
A method for producing 3,3,3-trifluoro-1-propynyllithium, which comprises reacting 1-propene and an organolithium compound.