JPS6130646B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a terminal difluoromethylene olefin compound. Terminal difluoromethylene olefin compounds are important compounds that have various uses as raw material monomers for polymeric compounds, and can also be widely used as raw materials or synthetic intermediates for fluorine-containing organic compounds. Conventionally, the synthesis of terminal difluoromethylene olefin compounds has required multistep reactions. However, only recently has a simple synthesis method been proposed. For example, a terminal difluoromethylene olefin compound can be obtained by reacting a reaction product of difluorodibromomethane and tertiary phosphine with a compound having a carbonyl group or an aldehyde group in the molecule. However, when the reaction was carried out according to the above method, tertiary phosphine dipromide, which was produced as a by-product when difluorodibromomethane and tertiary phosphine were reacted, contained a carbonyl group or an aldehyde group in the raw material compound. It was found that dibromide of the raw material compound was produced as a by-product. This makes separation of the target compound, the terminal difluoromethylene olefin compound, complicated.
Moreover, it has the drawback that no improvement in yield can be expected, and it cannot be said to be an industrially satisfactory method. Furthermore, in the above method, when a difluorohalomethane compound other than difluorodibromethane is used, the reaction hardly proceeds under normal reaction conditions. It has thus been found that the method has a number of drawbacks, such as the narrow range of raw material compounds used for synthesis. The present inventors have been conducting research on the synthesis of fluorine-containing compounds for many years, and have now discovered a method for producing terminal difluoromethylene olefin compounds in good yield under mild reaction conditions. That is, the present invention relates to (a) compounds having at least one carbonyl group or aldehyde group in the molecule (excluding phthaldialdehyde), (b) compounds with the general formula
Difluorohalomethane _compounds represented by CF ₂ This is a method for producing a terminal difluoromethylene olefin compound, which comprises reacting at least one compound selected from the group consisting of metal iodides and alkaline earth metal iodides. According to the reaction of the present invention, the reaction temperature is lower than that of the reaction in the above-mentioned method, the yield is good, and furthermore, a dibromide compound as a by-product is not produced, and the reaction is performed under mild reaction conditions. It is possible to obtain terminal difluoromethylene olefin compounds below. Furthermore, in the reaction of the present invention, difluorohalomethane compounds other than difluorodibromomethane also have the excellent feature of reacting with good yield under similar reaction conditions. One of the raw materials used in the present invention is a compound having at least one carbonyl group or aldehyde group in the molecule (excluding phthaldialdehyde). This compound can be used without particular restrictions. Examples of those generally suitably used are as follows. A compound that is generally preferably used as a compound having a carbonyl group in its molecule is a ketone. The ketone has the general formula

[Formula] (where R represents the same or different atomic group, specifically CH ₃ −,
Alkyl groups such as C ₂ H ₅ −, C ₃ H ₇ −, etc.:

【formula】

【formula】 【formula】

Cycloalkyl groups such as [Formula]; alkenyl groups such as C ₃ H ₅ −, C ₄ H ₇ −;

Cycloalkenyl groups such as [Formula]; Alkynyl groups such as C ₃ H ₃ -;

[Formula] etc. Cycloalkynyl group;

[Formula] etc. Aralkyl group;

【formula】

【formula】

These include aryl groups such as [Formula]. ) are preferably used. Also, the ketone

【formula】

Cyclic ketones such as [Formula] can also be used. In addition, compounds having an aldehyde group in the molecule have the general formula

[Formula] (where R′ is an alkyl group such as CH ₃ −, C ₂ H ₅ −, C ₃ H ₇ −;

【formula】

【formula】

【formula】

Cycloalkyl groups such as [Formula]; Alkenyl groups such as C ₃ H ₅ −, C ₄ H ₇ −;

Cycloalkenyl groups such as [Formula]; Alkynyl groups such as C ₃ H ₃ -;

Cycloalkini such as [formula] Ru group;

Aralkyl groups such as [Formula];

【formula】

【formula】

These include aryl groups such as [Formula]. ) are preferably used. In the case of a compound having two or more carbonyl groups and/or aldehyde groups in the molecule, compounds having a structure that can be easily inferred from the examples described above can generally be used. Compounds having various functional groups as a part of R or R' in the above general formula to an extent that does not interfere with the reaction in the present invention can also be suitably used. Furthermore, compounds in which some or all of the hydrogen atoms contained in the atomic group represented by R or R' are substituted with halogen atoms can also be preferably used. Especially the R or
R′ is

[Formula] When it is an electron-withdrawing atomic group such as CH ₂ = CH-, CH ₃ -O- CH ₂ -, CCl ₃ -CF ₃ -, the carbonyl group or aldehyde group is activated and the reaction proceeds. Easy to do. The most preferred starting material for the present invention is a compound in which R or R' in the above general formula is an aryl group, a fluorine-containing group, particularly a perfluoro group, regardless of the presence or absence of a substituent. Particularly in the case of ketones, when at least one of the R's in the above general formula is a fluorine-containing group or a perfluoro group, the reaction is particularly efficient. The difluorohalomethane compound, which is another compound of the raw material used in the present invention, has _the general formula CF ₂ The compound shown is The difluorohalomethane compound represented by the above general formula can be used without particular limitation, and two or more types of difluorohalomethane compounds can also be used in the reaction. In particular, difluorohalomethane compounds having one or more bromine atoms bonded within the molecule are most preferred since they are more preferable than other types of difluorohalomethane compounds in terms of yield. The tertiary phosphine used in the present invention has the general formula
R″ ₃ P (However, R″ is usually an atomic group such as the same or different alkyl group, cycloalkyl group, alkenyl group, cycloalkenyl group, alkynyl group, cycloalkynyl group, aralkyl group, aryl group, secondary amino group, etc.) Compounds represented by (a) can be suitably used. To be more specific, R'' in the above general formula is
CH ₃ −, C ₂ H ₅ −, C ₃ H ₇ −, C ₄ H ₉ −,

[Formula] C ₄ H ₇ −,

【formula】

【formula】

【formula】

[Formula] (CH ₃ ) ₂ N−,

【formula】

Compounds such as [Formula] are preferably used. From the viewpoint of obtaining raw materials and reaction yield, it is particularly preferable that R'' in the above general formula is

【formula】

[Formula] (CH ₃ ) ₂ N −,

【formula】

It is a compound such as [Formula]. The reducing metal used in the present invention can be used without any particular restriction as long as it has reducing properties. Usually, one type of metal is used, but two or more types of metals can be activated and used in combination. Generally, it is better to use the metal in the form of a powder, and it is also possible to use the metal activated by increasing the surface area, such as an ultrafine powder. As the reducing metal, any known reducing metal may be used, but those that can generally be suitably used include, for example, Na, Mg, Al, Cd, Hg, Cu, Fe, Ni,
There are Raney Nickel, Sn, Zn (Cu) Katupuru, etc. In particular, from the viewpoint of yield, Cu, Fe, Ni,
Raney nickel, Sn, Zn, and Zn(Cu) couples are used, and among these, especially when using Zn and Zn(Cu) couples, the reaction results in good yield. When using the alkali metal iodide or alkaline earth metal iodide used in the present invention, it may be prepared in advance and added to the reaction system, or iodine may be applied to the alkali metal or alkaline earth metal in the reaction vessel. It may also be prepared by letting it dry. in general
Alkali metal iodides such as NaI and KI are more sensitive to MgI ₂
It is preferable in terms of yield than alkaline earth metal iodides such as In the reaction of the present invention, the starting compound (a)
Compounds having at least one carbonyl group or aldehyde group in the molecule (excluding phthaldialdehyde) (b) Specific difluorohalomethane compounds (c) Tertiary phosphine and (d) Reducing metals and alkali metals At least one compound selected from the group consisting of iodides and alkaline earth metals and iodides may be mixed in any order for the reaction. Furthermore, the reaction can be carried out by mixing all of these starting material compounds in one step, or the reaction can be carried out by mixing these starting material component compounds in several stages. The reaction conditions in the present invention are not particularly limited, but the reaction is generally carried out in the presence of a solvent. As the solvent, an anhydrous polar non-aqueous solvent that does not react with the raw materials can be used without particular limitation. Typical examples of the polar non-aqueous solvent include, for example, tetrahydrofuran, dioxane, monoglyme,
Ether solvents such as diglyme, triglyme, and tetraglyme; for example, dimethyl sulfoxide,
Oxosulfur solvents such as sulfolane; nitrile solvents such as acetonitrile, propionitrile, and benzonitrile; amide solvents such as dimethylformamide, diethylformamide, dimethylacetamide, N-methylpyrrolidone, and hexamethylphosphoramide are used. be done. Among the above-mentioned solvents, nitrile solvents or amide solvents are particularly preferred because the desired reaction proceeds quickly. The method and order of mixing the raw material component compound used in the present invention and the solvent are not particularly limited. The reaction temperature in the present invention is not particularly limited, but it is usually preferably selected from a temperature range of -30°C or higher and 250°C or lower. At temperatures below -30°C, the reaction generally progresses extremely slowly. Although the reaction proceeds even at high temperatures exceeding 250°C, there is a tendency for the raw materials or products to undergo deterioration or decomposition, or for side reactions to occur. Therefore, from the viewpoint of yield of the target product, the reaction temperature is preferably -
It is preferable to select from a temperature range of 30 to 250°C, more preferably from a temperature range of -10 to 180°C. The reaction in the present invention is usually conveniently carried out under natural pressure at the reaction temperature with the raw material components and solvent simply charged, but it may be carried out under increased or reduced pressure as necessary. Good too. The reaction atmosphere is not particularly limited, and various substances may be selected, but substitution with an inert gas often gives preferable results. In addition, the reaction time in the present invention varies depending on the raw material component compound used, the type of solvent, the reaction temperature, etc., and cannot be absolutely limited, but it is generally preferable to select it within the range of several minutes to several days. It is preferable to select other conditions so that the reaction time ranges from several minutes to several hours, if necessary. The material of the reaction vessel is not particularly limited as long as it is not involved in the reaction and is resistant to corrosion, but glass, metals such as stainless steel, Teflon, etc. are generally suitable. When carrying out the present invention, it is often better to stir the reaction system in order to uniformly disperse the reaction heat and the raw material components. When a compound having two or more carbonyl groups or aldehyde groups in the molecule is used as a raw material in the reaction of the present invention, some or all of these groups are converted into terminal difluoromethylene olefins. At this time, if two or more types of terminal difluoromethylene olefin compounds are obtained as a mixture, they can be used separately if necessary. In order to separate the terminal difluoromethylene olefin compound produced by the reaction in the present invention from the mixture, ordinary operations such as distillation can be applied. In addition, solvent extraction methods, chromatography methods, etc. can also be applied.
A combination of these separation methods can also be applied. EXAMPLES Examples are shown below to explain the present invention more specifically, but the present invention is not limited to these Examples. Note that, except in the case of Example 2, yield % is based on the amount of the target product that can be theoretically obtained based on the compound having a carbonyl group or aldehyde group in the molecule used as a raw material. The percentage of the amount of target substance is shown. Example 1 Benzaldehyde in a 100ml three neck flask
Add 2.10g, triphenylphosphine 10.5g, and 3.0g zinc powder, then add 30ml dimethylformamide.
was added and stirred. After replacing the air in the reaction vessel with nitrogen, slowly
8.5 g of CF ₂ Br ₂ was added dropwise. After keeping the reaction vessel at 40° C. and continuing stirring for 90 minutes, the contents of the three-necked flask were analyzed using a gas chromatograph mass spectrometer, and the yield of the desired product was 98%.
Further, the contents of this three-necked flask were transferred to a separating funnel and extracted with 90 ml of diethyl ether. When the obtained extract was distilled, 2.57 g of β・β-difluorostyrene (yield
93%) was obtained. β·β-difluorostyrene was identified by ¹⁹ F-nuclear magnetic resonance spectrum, infrared absorption spectrum, mass spectrometry spectrum, elemental analysis, etc. Example 2 In the method of Example 1, the reaction was carried out using other starting compounds having at least one carbonyl group or aldehyde group shown in Table 1 in the molecule instead of benzaldehyde. When the starting compound contained only one carbonyl group or aldehyde group in the molecule, an equimolar amount (19.8 mmol) of the starting compound as the benzaldehyde used in Example 1 was used in the reaction. If the total number of carbonyl groups and aldehyde groups in the molecule is 2 or more, 19.8
A molar amount of the starting compound was used in the reaction, which was millimoles divided by the total number of carbonyl groups and aldehyde groups. The raw material compounds, products, and yields in gas chromatography were as shown in Table 1. The product was confirmed using a gas chromatograph mass spectrometer.

【table】

【table】

【table】

【table】

[Table] Example 3 4.2 g of benzaldehyde, 21 g of triphenylphosphine, 5.5 g of zinc powder, and 80 ml of dimethylformamide were placed in a 300 ml glass autoclave and stirred. Next, after cooling the reaction vessel with dry ice-methanol, CF ₂ ClBr gas was blown into the reaction vessel and 20 ml of liquid was added thereto. Heat the reaction vessel to 60°C for 90°C.
After stirring for a minute, β·β-difluorostyrene was obtained in 92% yield. Example 4 By the same operation as in Example 3, 4.2 g of benzaldehyde, 21 g of triphenylphosphine, 5.5 g of zinc powder,
When 20 ml of CF ₂ Cl ₂ gas was added in a liquid state and stirred in 80 ml of dimethylformamide at 80° C. for 90 minutes, β·β-difluorostyrene was obtained in a yield of 81%. Example 5 In the method of Example 1, only the type of solvent was changed to
The reaction was carried out with changes as shown in the table. The same volume of solvent as that used in Example 1 was used. Table 2 shows the types of solvents used and the reaction yields.

【table】

[Table] Example 6 In the method of Example 1, a reaction was carried out by replacing zinc with other reducing metals or metal iodides shown in Table 3. Reducing metal or metal iodide is as shown in Example 1.
Only gram equivalents were used that were equal to the gram equivalents of zinc used in . The types of reducing metals or metal iodides used and the reaction yields are shown in Table 3.

【table】

[Table] Example 7 In the method of Example 1, the reaction was carried out by changing only the type of tertiary phosphine as shown in Table 4. The tertiary phosphine was used in an equimolar amount to the triphenylphosphine used in Example 1. Table 4 shows the type of tertiary phosphine used and the reaction yield.

【table】

[Table] Example 8 In the method of Example 1, only the reaction temperature was
The reaction was carried out with changes as shown in the table. The results are shown in Table 5.

【table】

Claims (1)

[Claims] 1 (a) Compounds having at least one carbonyl group or aldehyde group in the molecule (excluding phthaldialdehyde), (b) General formula CF ₂ X ₂ (where X is the same or different chlorine, bromine, (3) tertiary phosphine and (2) reducing metals, alkali metal iodides and alkaline earth metal iodides; A method for producing a terminal difluoromethylene olefin compound, which comprises reacting at least one selected compound.