JP2003238461A - Process for producing perfluoroolefins - Google Patents

Abstract

(57) [Summary] Tetrafluoro useful as a raw material monomer for fluororesin
Production of fluoroethylene and hexafluoropropylene
Providing a method. The fluorine content is 30% by mass or more (R¹
CH₂CH (R²) CH ₂OCO)_nQ in the liquid phase
React with element (R^1FCF₂CF (R^2FCF₂O
CO)_nQ^FAnd then decompose the ester bond to R
^1FCF₂CF (R ^2F) COF
R by solving^1FCF = CF₂Manufacturing method. n is
An integer greater than or equal to 1. R¹, R²Each independently represents a hydrogen atom
Or a methyl group, at least one of which is a hydrogen atom. R
^1F, R^2FIs a fluorine atom or trifluoromethyl
Group. Q^FIs a group in which Q is perfluorinated, and
Is the same group as Q.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing tetrafluoroethylene (hereinafter referred to as TFE) and hexafluoropropylene (hereinafter referred to as HFP) useful as a precursor of a fluororesin raw material or a monomer of a fluororesin. .

[0002]

2. Description of the Related Art TFE uses 6 parts of chlorodifluoromethane.
It is industrially produced by a method in which a difluorocarbene is heated by heating at a high temperature of 00 to 900 ° C. and the difluorocarbene is subjected to a dimerization reaction. In addition, HFP is TFE
Is industrially produced by a method of carrying out a disproportionation reaction at 700 to 900 ° C. under reduced pressure. As a laboratory manufacturing method of HFP, an electrochemical fluorination method (hereinafter referred to as ECF
Described as the law. ) Is known, the method of thermally decomposing the salt of perfluorobutyric acid is known.

[0003]

The difluorocarbene dimerization reaction has a drawback that the reaction temperature is extremely high. In addition, chlorodifluoromethane, which is a raw material, is an ozone depleting substance, and there is a problem that its use is limited.

On the other hand, in the method for producing HFP, the reaction temperature is extremely high, which is a drawback. Further, there is a problem that perfluoroisobutene (PFIB), which is a problem in the work environment, is produced as a by-product by about 10%.

When a compound containing an etheric oxygen atom and a hydrogen atom is fluorinated by the ECF method, C-
Since the O bond is cleaved, the target compound cannot be obtained in good yield, and there is a problem that many by-products are generated. Further, the method of pyrolyzing a solid salt of perfluorobutyric acid is difficult to scale up.

[0006]

DISCLOSURE OF THE INVENTION The present inventors have developed a fluorine compound (3) having both an n-valent fluorine-containing organic group (n is an integer of 1 or more) and a carbon skeleton corresponding to the target compound. It was found that n molecules of the perfluoroolefins can be produced at one time by a method in which the ester bond is decomposed, and then the ester bond is decomposed, followed by thermal decomposition.

That is, the present inventors have selected, as a raw material for the production method, a raw material derived from a hydrocarbon alcohol which is inexpensive and widely used industrially. Further, for the fluorination reaction of the compound (3), a liquid phase fluorination method that can solve the problem of the ECF method, that is, the production of by-products, was selected. Further, for the production reaction of perfluoroolefins, a method by thermal decomposition that can be carried out in a continuous reaction and is easy to scale up was selected. It was found that this thermal decomposition reaction can be carried out at a lower temperature than the conventional method, and that it does not generate a by-product which is a problem in the working environment.

Furthermore, the present inventors have found that the method of recycling the produced compound becomes an industrially advantageous continuous process.

That is, according to the present invention, a compound (3) having a fluorine content of 30% by mass or more is reacted with fluorine in a liquid phase to form a perfluoropolymer and the following compound (4) is obtained.
Then, the ester bond of the compound (4) is decomposed into the following compound (5), and then the compound (5) is thermally decomposed, and the following perfluoroolefins (7) are produced. provide.

(R ¹ CH ₂ CH (R ² ) CH ₂ OCO) _n Q ... (3) (R ^1F CF ₂ CF (R ^2F ) CF ₂ OCO) _n Q ^F ... (4) R ^{1F _{CF 2 CF (R 2F) COF}} ··· (5) R 1F CF = CF 2 ··· (7) provided that the symbols in the formula have the following meanings. n: An integer of 1 or more, which represents the number of groups bonded to Q. R ¹ and R ² : each independently represent a hydrogen atom or a methyl group, at least one of which is a hydrogen atom. R ^1F , R ^2F : R ^1F corresponds to R ¹ , R ^2F corresponds to R ² , and when R ¹ and R ² are each a hydrogen atom, it is a fluorine atom, and R ¹ and R ² are each a methyl group. Is a trifluoromethyl group. Q: n-valent fluorine-containing organic group. Q ^F : When Q is a fluorinated group, Q ^F is a perfluorinated group, and when Q is a non-fluorinated group, Q ^F is the same as Q.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the compound (3) of the present invention,
Q is an n-valent fluorine-containing organic group. What is a fluorinated organic group?
It means an organic group having at least one or more fluorine atoms. n represents the number of groups bonded to Q, is an integer of 1 or more, and the upper limit of n is preferably 5, and particularly preferably 1 or 2 from the viewpoint of versatility.

When n is 1, Q may be a fluorine-containing alkyl group or a fluorine-containing (etheric oxygen atom-containing alkyl) group. The carbon number of Q is 1 to 1
20 is preferable, and particularly from the viewpoint of solubility in the liquid phase during the fluorination reaction, the number of carbon atoms is preferably 3 to 20, and particularly 3 to
10 is preferable.

The fluorine-containing alkyl group has a linear structure,
Examples thereof include groups in which one or more hydrogen atoms of an alkyl group having a branched structure, a ring structure, or a partial ring structure is substituted with a fluorine atom. Examples of the linear structure alkyl group include a methyl group, an ethyl group, a propyl group and a butyl group. As the branched alkyl group, an isopropyl group,
Examples thereof include an isobutyl group, a sec-butyl group and a tert-butyl group. Examples of the alkyl group having a ring structure (that is, a cycloalkyl group) include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a group in which a carbon atom forming a ring of these groups is substituted with an alkyl group. . Examples of the alkyl group partially having a ring structure include a linear alkyl group substituted with a cycloalkyl group and a branched alkyl group substituted with a cycloalkyl group. Specific examples of these groups include the groups shown in the following specific examples.

The fluorine-containing (etheric oxygen atom-containing alkyl) group having 1 to 20 carbon atoms is the carbon-carbon of the fluorine-containing alkyl group having 1 to 20 carbon atoms (excluding cycloalkyl group) described above. A group in which one or more ethereal oxygen atoms are inserted between single bonds. Here, as the etheric oxygen atom-containing alkyl group, an alkoxyl group, an alkoxyalkyl group or an alkoxyalkoxyalkyl group is preferable. Specific examples of the fluorine-containing (etheric oxygen atom-containing alkyl) group include the groups shown in the following specific examples.

When n is 2, examples of Q include a fluorine-containing alkylene group and a fluorine-containing (etheric oxygen atom-containing alkylene) group. The carbon number of Q is 1 to 20
In particular, the carbon number is preferably 3 to 20 from the viewpoint of solubility in the liquid phase during the fluorination reaction, and particularly the carbon number is 3
-10 is preferable.

Fluorine-containing alkylene group or fluorine-containing (d
As the etheric oxygen atom-containing alkylene) group,
Fluorine-containing alkyl group or fluorine-containing ethereal oxygen source
Hydrogen atoms or fluorine present in the child-containing alkyl group
One of the atoms is a bond. Q where n is 2
As the raw material is cheap and easily available, -CF _Two
CF_TwoCF_TwoCF_Two− Is preferable.

The compound (3) in the present invention has a fluorine content (ratio of the total amount of fluorine atoms to the molecular weight of the compound).
Is 30% by mass or more, and the fluorine content is 3
It is preferable to adjust the structure of Q in the compound (3) so that it is 0% by mass or more. Compound (3) has a fluorine content of 3
It is preferably 7% by mass or more, and particularly preferably 37 to 70% by mass.

The molecular weight of the compound (3) is 200 to 1
A value of 000 is preferable in that the fluorination reaction in the liquid phase can be smoothly carried out, and it is preferable to adjust the molecular weight of Q so that the molecular weight is the same. When the molecular weight is too small, the compound (3) is likely to be vaporized, so that the decomposition reaction may occur in the gas phase during the fluorination reaction in the liquid phase. In the present invention, it is possible to increase the molecular weight and raise the boiling point by including a specific amount of a fluorine atom in the compound (3), but if the molecular weight is too large, it is difficult to purify the compound (3). May be.

The following examples can be given as specific examples of the compound (3). The compound (3) is a compound useful as an intermediate for the fluororesin raw material because it can be introduced into the fluororesin raw material by the reaction described below.

CH_ThreeCH_TwoCH_TwoOCOCF_TwoCF_Three,
CH_ThreeCH_TwoCH_TwoCH_TwoOCOCF_TwoCF_TwoCF_Three,
CH_Three(CH_Three) CHCH_TwoOCOCF (CF_Three) CF
_Three, CH_ThreeCH_TwoCH_TwoOCOCF (CF_Three) OCF_Two
CF_TwoCF_Three, CH_ThreeCH_TwoCH_TwoCH_TwoOCOCF
(CF_Three) OCF_TwoCF_TwoCF_Three, CH_Three(CH_Three) C
HCH_TwoOCOCF (CF_Three) OCF_TwoCF_TwoCF_Three,
CH_ThreeCH_TwoCH_TwoOCOCF (CF_Three) OCF_TwoCF
(CF_Three) OCF_TwoCF_TwoCF_Three, CH_ThreeCH_TwoCH_Two
CH_TwoOCOCF (CF_Three) OCF_TwoCF (CF_Three) O
CF_TwoCF_TwoCF_Three, CH_Three(CH_Three) CHCH_TwoOC
OCF (CF_Three) OCF_TwoCF (CF_Three) OCF_TwoCF
_TwoCF_Three, CH_ThreeCH_TwoCH_TwoOCO (CF_Two)_FourOC
OCH_TwoCH_TwoCH_Three, CH_ThreeCH_TwoCH_TwoCH_TwoOC
O (CF_Two)_FourOCOCH_TwoCH_TwoCH_TwoCH _Three, CH
_Three(CH_Three) CHCH_TwoOCO (CF_Two)_FourOCOCH
_TwoCH (CH_Three) CH_Three.

Of the compounds (3), the following compound (3a)
And the compound (3b) are novel compounds and are particularly preferable.

[0022]   R¹⁰CH_TwoCH (R²⁰) CH_TwoOCOR^Thirty... (3a)   R¹⁰CH_TwoCH (R²⁰) CH_TwoOCO (CF_Two)_FourOCOCH_TwoCH (R ²⁰ ) CH_TwoR¹⁰... (3b) However, the symbols in the formulas have the following meanings. R¹⁰, R²⁰: Hydrogen atom or methyl group, whichever
One of them is a hydrogen atom. R^Thirty: Fluorine-containing alkyl group having 3 to 20 carbon atoms, or
Fluorine-containing (ether ether oxygen atom-containing
Rukiru) group.

The method for obtaining the compound (3) is not particularly limited. The compound (3) in the present invention is preferably obtained by an esterification reaction of the following compound (1) and the following compound (2) because it is easily obtained. R ¹ CH ₂ CH (R ² ) CH ₂ OH ... (1) Q (COX) _n ... (2) where n, R ¹ , R ² and Q have the same meanings as described above, and X Represents a halogen atom. X is a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, preferably a fluorine atom, a chlorine atom or a bromine atom, and particularly preferably a fluorine atom when the continuous process described below is carried out.

The following compounds may be mentioned as specific examples of the compound (1). The following compound (1) is a hydrocarbon alcohol that is widely used industrially, and is inexpensive and easily available. CH ₃ CH ₂ CH ₂ OH, CH ₃ CH
₂ CH ₂ CH ₂ OH, CH ₃ (CH ₃ ) CHCH ₂ O
H.

The following compounds may be mentioned as specific examples of the compound (2) in which n is 1. FCOCF ₂ CF ₃ , F
COCF ₂ CF ₂ CF ₃ , FCOCF (CF ₃ ) C
F ₃ , FCOCF (CF ₃ ) OCF ₂ CF ₂ CF ₃ , F
COCF (CF ₃ ) OCF ₂ CF (CF ₃ ) OCF ₂ C
F ₂ CF _3.

Examples of the compound (2) in which n is 2 include the following compounds. FCO (CF ₂ ) ₄ COF, FC
O (CF ₂ ) ₅ COF, FCO (CF ₂ ) ₆ COF.

As the compound (2), a commercially available product may be used,
In addition, the compound (5) produced by the method of the present invention described below
Alternatively, the compound (6) may be used. Compound in the present invention
As item (2), it is easy to obtain and easy to carry out industrially.
Now, n is 1 because of the chemical stability of the compound.
Compound (2) is preferable, and FCOCF (CF_Three) OCF_Two
CF_TwoCF_ThreeOr FCOCF (CF_Three) OCF_TwoCF
(CF_Three) OCF_TwoCF _TwoCF_ThreeIs particularly preferable. Conversion
Compound is in perfluoro (alkyl vinyl ether)
It is easily available as an intermediate.

The esterification reaction between the compound (1) and the compound (2) can be carried out according to a known method described in WO00 / 1765. In the reaction between the compound (1) and the compound (2), an acid represented by HX is generated. When X of the compound (2) is a fluorine atom, HF is generated. Therefore, an alkali metal fluoride (N
aF and KF are preferable), trialkylamine and the like may be present in the reaction system. The HF scavenger should be used when the compound (2) is a compound containing an etheric oxygen atom. When no HF scavenger is used, the reaction is carried out at a reaction temperature at which HF can be vaporized,
At the same time, it is preferable that HF is entrained in the nitrogen stream and discharged out of the reaction system. The HF scavenger is 1 to the compound (2).
It is preferably a 10-fold molar amount.

In the esterification reaction, it is preferable that the amount of the compound (2) is equal to or more than the equimolar amount of the compound (1) in order to reduce the amount of the unreacted compound (1). The amount of the compound (2) with respect to the compound (1) is particularly preferably 1 to 2.5 times mol. In the usual case, the reaction temperature is preferably -50 ° C to + 100 ° C. Further, the reaction time can be changed appropriately. The reaction pressure (gauge pressure, hereinafter referred to as gauge pressure unless otherwise specified) is preferably 0 to 2 MPa.

The crude product containing the compound (3) produced by the esterification reaction of the compound (1) with the compound (2) is used as it is in the next reaction or the like even after purification according to the purpose. Good. In the present invention, from the viewpoint of stably performing the fluorination reaction, it is preferable to purify the crude product and particularly to separate the compound (1) in the crude product. As a method for purifying the crude product, a known method can be adopted.

In the present invention, the compound (3) is fluorinated in the liquid phase to obtain the compound (4). The fluorination reaction is carried out by a liquid phase fluorination method, and the compound (3) in the solvent is preferably fluorinated with fluorine.

Although it has been reported that the fluorination reaction can also be carried out by the ECF method, in actuality, a C--O bond cleavage reaction occurs and the yield is extremely low, which is extremely disadvantageous for industrial practice. is there. Therefore, in the present invention, fluorination is performed by the liquid phase fluorination method. Liquid phase fluorination is a method capable of preventing the decomposition of the compound and producing the compound (4) in a high yield.

Fluorination in the liquid phase is also possible in WO00 / 176.
It can be carried out by a known method described in, for example, Publication No. 5 and the like, and usually it is preferably carried out by a method of reacting compound (3) with fluorine in a solvent. As fluorine, fluorine gas may be used as it is, or fluorine gas diluted with an inert gas (nitrogen gas, helium gas, etc.) may be used. When diluting the fluorine gas, the concentration of the fluorine gas is preferably 10 vol% or more from the viewpoint of efficiency, and particularly preferably 20 vol% or more.

The solvent in the liquid phase fluorination method is preferably selected from perfluorinated organic solvents. In particular, as the solvent, it is preferable to use a solvent capable of dissolving the compound (3) in an amount of 1% by mass or more, and particularly a solvent in which 5% by mass or more can be dissolved. The amount of the solvent is preferably 5 times by mass or more, and particularly preferably 10 to 100 times by mass with respect to the compound (3). Examples of the solvent, perfluoroalkanes, perfluoroethers, perfluoropolyethers, chlorofluorocarbons, chlorofluoropolyethers, perfluoroalkylamines, known solvents used for liquid phase fluorination reaction of inert fluids, Examples thereof include perfluoroesters and perfluoroacid fluoride compounds. Among these, the use of the below-mentioned compound (4) which is a perfluoroester or the below-mentioned compound (6) which is a perfluoroacid fluoride compound is particularly preferable because it has the advantage of facilitating post-treatment after the reaction. .

The reaction system of the liquid phase fluorination method may be a batch system or a continuous system. Further, the amount of fluorine is preferably maintained under the condition that the amount of fluorine with respect to the hydrogen atom in the compound (3) is always in excess equivalent, and 1.1 times equivalent or more (that is, more than the equivalent of the hydrogen atom in the compound (3) (that is, , 1.1 times or more) is particularly preferable.
It is particularly preferable that the amount is 5 times equivalent or more (that is, 1.5 times mol or more). Further, the amount of fluorine is preferably 3 times or less. The method of using an excessive amount of fluorine is a method that can increase the selectivity of the reaction. Moreover, it is preferable that the fluorine is always in an excessive amount from the start of the reaction to the end of the reaction. For example, when a solvent is charged in the reactor, it is preferable to dissolve fluorine in the solvent in advance.

The reaction temperature for the liquid phase fluorination is usually -60.
℃ ~ (boiling point of compound (3)) is preferable, -50 ℃ ~ from the viewpoint of reaction yield, selectivity, and ease of industrial implementation
+ 100 ° C is particularly preferable, and -20 ° C to + 50 ° C is particularly preferable. The reaction pressure is 0 to 2 MPa, the reaction yield,
It is preferable in terms of selectivity and industrial ease of implementation.

The liquid phase fluorination reaction in the present invention is a reaction for perfluorinating the compound (3). In order not to leave unreacted hydrogen atoms in the compound (3), ultraviolet irradiation is carried out after the fluorination reaction, or a compound containing a C—H bond such as benzene or toluene is added to the reaction system. You may perform the operation of.

In the liquid phase fluorination reaction, H produced as a by-product
For the purpose of removing F, it is preferable to coexist an HF scavenger such as NaF in the reaction system. Or H at the reactor gas outlet
It is preferred to contact the F scavenger with the outlet gas.

The crude product containing the compound (4) obtained by the fluorination reaction may be used as it is in the next step, or may be purified to give a highly pure product. Examples of the purification method include a method of distilling the crude product as it is under normal pressure or reduced pressure.

In the fluorination reaction of compound (3), compound (3) is perfluorinated to form compound (4). That is, when R ¹ and R ² in the compound (3) are each a hydrogen atom, it becomes a fluorine atom, and when R ¹ and R ² are each a methyl group, it becomes a trifluoromethyl group. Further, when Q is a fluorinated group, Q ^F is a group in which Q is perfluorinated,
Is a non-fluorinated group (eg, Q is a perfluorinated group), Q ^F will be the same group as Q.

Specific examples of the compound (4) are as follows:
There is a mixture. CF_ThreeCF_TwoCF_TwoOCOCF_TwoC
F_Three, CF_ThreeCF_TwoCF_TwoCF_TwoOCOCF_TwoCF_TwoC
F_Three, CF_Three(CF_Three) CFCF_TwoOCOCF (C
F_Three) CF_Three, CF_ThreeCF_TwoCF_TwoOCOCF (C
F_Three) OCF_TwoCF_TwoCF_Three, CF_ThreeCF_TwoCF_TwoCF
_TwoOCOCF (CF_Three) OCF_TwoCF_TwoCF_Three, CF_Three
(CF_Three) CFCF_TwoOCOCF (CF_Three) OCF_TwoC
F_TwoCF_Three, CF_ThreeCF_TwoCF_TwoOCOCF (CF_Three)
OCF_TwoCF (CF_Three) OCF_TwoCF_TwoCF_Three, CF_Three
CF_TwoCF_TwoCF_TwoOCOCF (CF_Three) OCF_TwoCF
(CF_Three) OCF_TwoCF_TwoCF_Three, CF_Three(CF_Three) C
FCF_TwoOCOCF (CF_Three) OCF_TwoCF (CF_Three)
OCF_TwoCF_TwoCF_Three, CF_ThreeCF_TwoCF_TwoOCO (C
F_Two)_FourOCOCF_TwoCF_TwoCF_Three, CF_ThreeCF_TwoCF
_TwoCF_TwoOCO (CF_Two)_FourOCOCF_TwoCF_TwoCF_Two
CF _Three, CF_Three(CF_Three) CFCF_TwoOCO (CF_Two)
_FourOCOCF_TwoCF (CF_Three) CF_Three.

Of the compounds (4), the following compound (4a)
And the compound (4b) are novel compounds, and are particularly preferable. ^{_{R 10F CF 2 CF (R 20F}} ) CF 2 OCOR 30F ··· (4a) R 10F CF 2 CF (R 20F) CF 2 OCO (CF 2) 4 OCOCF 2 CF (R 20F) CF 2 R 10F ··· (4b) However, the symbols in the formulas have the following meanings. R ^10F , R ^20F : a fluorine atom or a trifluoromethyl group, one of which is a fluorine atom. R ^30F : Perfluoroalkyl group having 3 to 20 carbon atoms,
Alternatively, a perfluoro (ether-containing oxygen atom-containing alkyl) group having 3 to 20 carbon atoms.

In the present invention, the ester bond of compound (4) is further decomposed to give compound (5). The decomposition reaction of the ester bond is performed by n-CF ₂ O in the compound (4).
It is a reaction in which a CO- bond is decomposed to form 2n -COF. The ester bond decomposition reaction is also WO00 / 17
It can be carried out by a known method described in Japanese Patent Laid-Open No. 65-65. For example, there may be mentioned a method of thermally decomposing the compound (4) in a gas phase, condensing an outlet gas containing the produced compound (5) and continuously recovering it. The reaction temperature of the method is preferably 50 to 350 ° C, particularly preferably 50 to 300 ° C, and particularly 1
50-250 degreeC is preferable. In the reaction, nitrogen,
An inert gas such as carbon dioxide may coexist in the reaction system. The amount of the inert gas is 0.01 with respect to the compound (4).
It is preferably about 50 vol%. If the addition amount of the inert gas is large, the product recovery amount may be reduced.

Alternatively, the compound (5) may be obtained by a reaction in which the compound (4) is heated in a liquid state and decomposed (hereinafter referred to as a liquid phase thermal decomposition reaction). The reaction pressure of the reaction is not limited. The liquid-phase thermal decomposition reaction is preferably performed by a method in which the reaction is carried out in a reaction vessel having a distillation column and the compound (5) is continuously withdrawn from the reaction system by distillation. The reaction temperature of the liquid phase thermal decomposition reaction is preferably 50 to 300 ° C, particularly preferably 100 to 250 ° C. The liquid phase reaction is
It may be carried out without solvent (in this case, the compound (4) itself may act as a solvent) or in the presence of a solvent. As the solvent, a compound which does not react with the compound (4) and is compatible with the compound (4), and which produces a compound (5)
The compound is not particularly limited as long as it does not react with, but it is preferable to select a compound that can be easily separated when the compound (5) is purified. As specific examples, inert solvents such as perfluorotrialkylamine and perfluoronaphthalene, and chlorotrifluoroethylene oligomers having a high boiling point among chlorofluorocarbons and the like are preferable. When the solvent is used, the amount is 10 to 1000 with respect to the compound (4).
Mass% is preferred.

Further, the compound (4) is used as a nucleophile in the liquid phase.
Reacts with an electrophile to split the ester bond.
The compound (5) may be obtained by solving. F as a nucleophile⁻
Is preferred, NaF, NaHF_Two, KF, CsF, etc.
F derived from Lucari metal fluoride ⁻Is preferred, especially economical
From the aspect of F from NaF⁻Is preferred. F⁻Nucleophiles such as
Is preferably 1 to 500 mol% based on the compound (4).
10 to 100 mol% is particularly preferable, especially 5 to
50 mol% is preferable. In addition, the liquid phase reaction can also be performed without solvent.
Alternatively, it may be carried out in the presence of a solvent. The reaction temperature is -3
0 ° C to + 250 ° C is preferable, and -20 ° C to + 250 ° C is
Particularly preferred. This method also uses a reactor with a distillation column.
It is preferable to carry out.

Examples of the compound (5) formed by the decomposition reaction of the ester bond include the following compounds. CF ₃ CF ₂ C
OF, CF ₃ CF (CF ₃ ) COF, CF ₃ CF ₂ CF
₂ COF.

In the decomposition reaction of the ester bond, the following compound (6) is produced together with the compound (5). However,
Q ^F and n have the same meanings as described above. Q ^F (COF) _n ... (6) Specific examples of the compound (6) include the same examples as the compound (2).

In the present invention, the compound (7) can be obtained in a high yield by further thermally decomposing the compound (5). However, R ^1F has the same meaning as above. ^F CF = CF ₂ (7) The compound (7) means CF ₂ = CF ₂ (TFE) or C.
F ₃ CF = CF ₂ (HFP). TFE and HFP are compounds having excellent polymerizability, and polymers obtained by polymerizing these compounds are useful as fluororesins.

The reaction of thermally decomposing compound (5) to give compound (7) can be carried out under known reaction conditions. The thermal decomposition reaction is preferably carried out in a liquid phase reaction or a gas phase reaction,
It is efficient and preferable to carry out by a gas phase reaction.

The thermal decomposition reaction by the gas phase reaction is preferably carried out as a continuous reaction. The continuous reaction is carried out by a method in which the vaporized compound (5) is passed through a heated reaction tube to obtain the produced compound (7) as an outlet gas, which is condensed and continuously recovered. preferable. The reactor used for the reaction is preferably a tubular reactor. The residence time when using a tubular reactor is 0.1
Seconds to 10 minutes are preferable. The reaction temperature of the thermal decomposition reaction by the gas phase reaction is preferably 150 ° C or higher, and 200 ° C to 5 ° C.
00 ° C. is particularly preferred, especially above 250 ° C. to 450 ° C.
Is preferred.

In the thermal decomposition reaction of the compound (5) in which R ^1F and R ^2F are fluorine atoms, TF produced is
Since E has an extremely high polymerizability, it may polymerize explosively during recovery. For the purpose of preventing TFE polymerization and recovering and storing more stably, the oxygen content in the TFE monomer is suppressed to 0.002% or less, and a polymerization inhibitor such as α-pinene is put in a recovery container. It is preferable to add it.

When a gas phase reaction is carried out using a tubular reactor, filling the reaction tube with glass, an alkali metal salt, or an alkaline earth metal salt accelerates the reaction.
preferable. As the alkali metal salt or the alkaline earth metal salt, carbonate or fluoride is preferable. Examples of the glass include general soda glass, and glass beads in the form of beads to improve fluidity are particularly preferable. Examples of the alkali metal salt include sodium carbonate, sodium fluoride, potassium carbonate, or lithium carbonate. Examples of alkaline earth metal salts include calcium carbonate,
Examples thereof include calcium fluoride and magnesium carbonate. Furthermore, when the reaction tube is filled with glass, an alkali metal salt or an alkaline earth metal salt, glass beads, sodium carbonate light ash, etc., having a particle size of 1
It is particularly preferable to use one having a diameter of about 00 to 250 μm because a fluidized bed type reaction system can be adopted.

In the gas phase reaction, it is preferable to carry out the reaction in the presence of an inert gas such as nitrogen, carbon dioxide, helium or argon for the purpose of promoting the vaporization of the compound (5). The amount of inert gas is 0.01 to 5 relative to compound (5)
About 0 vol% is preferable. If the amount of the inert gas is too large, the amount of the product recovered may be low, which is not preferable.

In the method of the present invention, the compound (5) can be efficiently produced by selecting the group in the compound, and the desired compound (7) can be advantageously produced. Specifically, compound (5) is preferably produced by the following method. However, the groups not defined below are
It has the same meaning as above. (Method A); when n is 1, Q and Q ^F
The method is - but _{^{R 1F CF 2 CF (R 2F}} ). Method A
In, the compound (5) and the compound (6) produced by the decomposition reaction of the ester bond are the same compound. Therefore,
There is an advantage that the compound (5) and the compound (6) can be used in the next step without being separated.

(Method B) A method in which the compound (6) produced by the decomposition reaction of the ester bond is used as the compound (2) which is reacted with the compound (1). That is, the compound (3) is
The method is the compound (3) obtained by obtaining the following compound (6) from the decomposition product of the ester bond of the compound (4) and reacting the compound (6) with the compound (1). The method of repeating the method B is a method in which the compound (5) can be produced any number of times simply by adding the compound (1) to the reaction system.

(Method C) A method which is a combination of Method A and Method B, wherein when n is 1 and Q and Q ^F are R ^1F CF ₂ CF (R ^2F )-, the ester bond is decomposed. A method of using a part or all of the compound (5) produced in the reaction as the compound (2) for reacting with the compound (1).

TFE and H produced by the method of the present invention
A useful polymer can be produced by polymerizing FP or by copolymerizing a polymerizable monomer (hereinafter, referred to as a comonomer) capable of copolymerizing with FP.

As the comonomer, a known polymerizable monomer is used.
Can be selected from The polymerization reaction method is also a known reaction.
The method of can be applied as it is. As an example of a comonomer
Is CF_Two= CFCl, CF_Two= CH_TwoFluoroe
Tilenes, CF_Two= CHCF_ThreeSuch as fluoropropylene
Kind, CF_ThreeCF_TwoCF_TwoCF_TwoCH = CH_TwoAnd CF_ThreeC
F_TwoCF_TwoCF_TwoCF = CH_TwoPerfluoroalky etc.
(C) with 4 to 12 carbon atoms
Tylenes, perfluoro (propyl vinyl ether), etc.
Perfluorovinyl ethers, CH_ThreeOC (= O)
CF_TwoCF_TwoCF _TwoOCF = CF_TwoAnd FSO_TwoCF_TwoC
F_TwoOCF (CF_Three) CF_TwoOCF = CF _TwoCarbo etc.
Vinyl ether having a group that can be converted to an acid group or a sulfonic acid group
Ethers, ethylene, propylene, isobutylene, etc.
Examples include reffins.

The polymer obtained by the polymerization reaction is useful as a fluororesin. Fluororesin is used in a wide range of fields because it has excellent heat resistance and chemical resistance.

TF produced by the method of the present invention
E and HFP can be converted to tetrafluoroethylene oxide and hexafluoropropylene oxide, which are useful as raw materials for various functional materials, by oxidizing them by a known reaction.

According to the production method of the present invention, perfluoroolefins can be produced in a short process and at a low temperature by using the compound (1) and the compound (2), which are raw materials that are available at low cost. Further, by selecting the structures of R ¹ , R ² and Q, the method of the present invention can be efficiently carried out,
It can also be implemented as a continuous process. Furthermore, according to the present invention, a novel compound useful as a raw material for a fluororesin raw material and a functional material is provided.

[0062]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. In addition,
Hereinafter, gas chromatography will be referred to as GC and gas chromatography mass spectrometry will be referred to as GC-MS. Also, GC
The purity obtained from the peak area ratio of
The yield obtained from the peak area ratio of the NMR spectrum is referred to as the yield, and is referred to as the NMR yield. In addition, tetramethylsilane is referred to as TMS, and CCl ₂ FCClF _{2 is referred} to as R-113.
Further, the NMR spectrum data is shown as an apparent chemical shift range. Reference substance C in ¹³ C-NMR
The standard value of DCl ₃ was 76.9 ppm. ¹⁹ F-N
C ₆ F ₆ was used as an internal standard in the quantification by MR. The pressure is a gauge pressure unless otherwise specified.

[Example 1] CH ₃ CH ₂ CH ₂ OCOCF ₂
Production Example of CF ₃ CH ₃ CH ₂ CH ₂ OH (268.6 g) was placed in a flask and stirred while bubbling nitrogen gas. CF
₃ CF ₂ COF (743 g) was fed over 3.75 hours while maintaining the internal temperature at 20 to 25 ° C. After completion of the feeding, the mixture was stirred at room temperature for 1.25 hours, and 2 L of saturated aqueous sodium hydrogencarbonate was added at an internal temperature of 20 ° C or lower. The layers were separated, and the organic layer was washed with 1 L of water to obtain a crude liquid (775 g). Then, it was distilled under reduced pressure to obtain a fraction (556 g). Boiling point: 50 ° C./18.6 kPa (absolute pressure). NMR spectrum of fraction ¹ H-NMR (399.8 MHz, solvent CDCl ₃ , reference: TMS) δ (ppm): 0.98 (q, J = 7.3).
Hz, 3H), 1.76 (m, 2H), 4.34 (t,
J = 6.7 Hz, 2H). ¹⁹ F-NMR (376.2 MHz, solvent CDCl ₃ ,
Reference: CFCl ₃ ) δ (ppm): -84.0 (3
F), -122.6 (2F).

Example 2 CF ₃ CF ₂ by fluorination reaction
Production Example of CF ₂ OCOCF ₂ CF _{3 In} a 500 mL nickel autoclave, R-113
(312 g) was added, and the mixture was stirred and cooled to -10 ° C.
At the autoclave gas outlet, a cooler maintained at 20 ° C, a NaF pellet packed bed, and a cooler maintained at -10 ° C were installed in series. In addition, a liquid return line for returning the condensed liquid from the cooler maintained at −10 ° C. to the autoclave was installed. After blowing nitrogen gas into the autoclave for 1.0 hour, fluorine gas diluted with nitrogen gas to 20% (diluted fluorine gas) was supplied at a flow rate of 5.66 L / h.
I blown in for 1 hour. Next, while diluting fluorine gas at the same flow rate, the fraction (12 g) obtained in Example 1 was R-
A solution of 113 (250 g) was injected over 14.75 hours.

Next, while blowing the diluted fluorine gas at the same flow rate, R-1 having a benzene concentration of 0.01 g / mL was used.
13 solution was injected, the outlet valve of the autoclave was closed, and when the pressure reached 0.12 MPa, the inlet valve of the autoclave was closed and stirring was continued for 1.0 hour. Further, the operation was repeated 3 times while the temperature was raised from -10 ° C to room temperature, and then 6 times at room temperature. During this time, 0.323 g of benzene and 5 of R-113 in total.
0 g was injected. Then, nitrogen gas was blown in for 2.0 hours. When the target product was quantified by ¹⁹ F-NMR, the NMR yield of the title compound was 77%.

¹⁹ F-NMR (376.2 MHz, solvent CDCl ₃ , standard: CFCl ₃ ) δ (ppm): −8
2.5 (3F), -83.9 (3F), -88.6 (2
F), -122.8 (2F), -130.9 (2F).

Example 3 CF ₃ CF ₂ C by Liquid Phase Pyrolysis
Production Example of OF CF ₃ CF ₂ CF ₂ OCOCF ₂ CF ₃ (2
0 g) and a chlorotrifluoroethylene oligomer (12
0 g) was charged into a 200 mL nickel autoclave equipped with a reflux condenser and heated to 200 ° C. The reflux condenser was cooled by circulating cooling water, and when the pressure reached 0.1 MPa or higher, the gas was purged while maintaining the pressure to collect a gaseous sample (15 g). CF by GC-MS
It was confirmed that ₃ CF ₂ COF was the main product. GC
The yield was 90%.

[Example 4] CF ₂ = C by a gas phase thermal decomposition reaction
Production Example of F ₂ SUS column (inner diameter 20 mm, length 1 m) and K ₂ C
SU filled with O ₃ (average particle size 160 μm, 280 g)
Fluidized bed reactors made by S (inner diameter 45 mm, height 400 mm) were connected in series and heated to 300 ° C. in a salt bath. The reactor was charged with _{1 part} of the mixed gas of CF ₃ CF ₂ COF and N ₂ (N ₂ / CF ₃ CF ₂ COF = 5/1 (molar ratio)) obtained in Example 3.
Flowing at 600 mL / min, the reactor outlet gas after 1 hour was analyzed by GC. The conversion rate of CF ₃ CF ₂ COF was 99%, and the selectivity rate of CF ₂ = CF ₂ was 90%.

[Example 5] CH_ThreeCH (CH_Three) CH_TwoOC
OCF (CF_Three) OCF_TwoCF (CF_Three) OCF_TwoCF
_TwoCF_ThreeSynthesis example of 2L Hastelloy with a reflux condenser cooled to 25 ° C
Into the autoclave, 150 g of (CH_Three)_TwoCHCH_TwoO
H was charged and the reactor was heated to 30 ° C. CF _ThreeCF_Two
CF_TwoOCF (CF_Three) CF_TwoOCF (CF_Three) COF
(1040 g) was continuously introduced into the reactor. Introduction
The temperature rose due to the heat of reaction, but the temperature inside the reactor was kept at 4
The temperature was kept below 0 ° C. All CF_ThreeCF_TwoCF_TwoOCF
(CF_Three) CF_TwoOCF (CF_Three) Add COF to the chamber
After stirring at the temperature for 2 hours, the reaction solution was bubbled with nitrogen gas.
By-produced HF is purged and removed by ringing, and the crude liquid 11
20 g was obtained. As a result of analysis by GC, CF_ThreeCF_TwoC
F_TwoOCF (CF_Three) CF _TwoOCF (CF_Three) COOC
H_TwoCH (CH_Three)_TwoIs obtained with a GC yield of 99%
It was confirmed.

Example 6 CF ₃ CF by fluorination reaction
(CF ₃ ) CF ₂ OCOCF (CF ₃ ) OCF ₂ CF
Preparation Example of (CF ₃ ) OCF ₂ CF ₂ CF ₃ After preparing the same reaction apparatus as in Example 2 under the same conditions, while diluting fluorine gas at a flow rate of 6.50 L / h, the compound obtained in Example 5 ( 5.0 g) to R-113 (100 g)
The solution dissolved in was injected over 2.7 hours.

Next, while blowing fluorine gas at the same flow rate and keeping the reactor pressure at 0.15 MPa, the R-113 solution having a benzene concentration of 0.01 g / mL was heated from 25 ° C to 40 ° C. 9 mL was injected, the benzene inlet of the autoclave was closed, and stirring was continued for 0.3 hours. Next, while maintaining the reactor pressure at 0.15 MPa and the reactor internal temperature at 40 ° C., 6 mL of the benzene solution was injected, and stirring was continued for 0.3 hours. Further, while maintaining the temperature inside the reactor at 40 ° C., 6 mL of the above benzene solution was injected and stirring was continued for 0.3 hours. The same benzene injection operation was repeated 3 times, and the mixture was further stirred for 1.0 hour.
The total amount of benzene injected was 0.34 g, and the total amount of R-113 injected was 33 mL. Furthermore, nitrogen gas was blown in for 1.0 hour. When the target product was quantified by ¹⁹ F-NMR, the NMR yield of the title compound was 79%.

¹⁹ F-NMR (282.7 MHz, solvent CDCl ₃ , standard: CFCl ₃ ) δ (ppm): -7
3.9 (6F), -79.0 to -81.5 (6F),-
82.1 (8F), -84.3 to -85.5 (1F),
-130.1 (2F), -131.9 (1F), -14
5.5 (1F), -187.9 (1F).

Example 7 CF ₃ CF (C
Production Example of F ₃ ) COF CF ₃ CF (CF ₃ ) CF ₂ OCOCF (C
F ₃ ) OCF ₂ CF (CF ₃ ) OCF ₂ CF ₂ CF
₃ (5 g) was charged together with KF powder (0.08 g) in a 200 mL nickel autoclave equipped with a reflux condenser, and heated to 100 ° C. with vigorous stirring. The reflux condenser was cooled by circulating cooling water, and when the pressure reached 0.06 MPa or higher, the gas was purged and a gaseous sample (1.2 g) was collected. CF ₃ CF (CF ₃ ) CO by GC-MS
It was confirmed that F was the main product.

[Example 8] CH_ThreeCH (CH_Three) CH_TwoOC
O (CF_Two)_FourOCOCH_Two(CH _Three) CHCH_ThreeOf
Example (CH in Example 5_Three)_TwoCHCH_TwoThe amount of OH is 300
Change to g, CF_ThreeCF _TwoCF_TwoOCF (CF_Three) CF
_TwoOCF (CF_Three) COF to FCO (CF_Two)_FourCOF
(625 g), the same reaction was performed, and the crude liquid (82
0 g) was obtained. GC analysis results, GC yield 99%
At (CH_Three)_TwoCHCH_TwoOCO (CF_Two)_FourCOOC
H_TwoCH (CH_Three)_TwoConfirmed the generation of.

Example 9 CF ₃ CF by fluorination reaction
(CF ₃ ) CF ₂ OCO (CF ₂ ) ₄ OCOCF ₂ (C
Preparation of F ₃ ) CFCF ₃ The same reactor as in Example 6 was prepared under the same conditions, and then diluted fluorine gas was blown thereinto at a flow rate of 9.47 L / h to obtain the compound (5.0 g) obtained in Example 8. R-113 (100g)
The solution dissolved in was injected over 5.4 hours.

Then, in the same manner as in Example 6, the benzene injection operation was repeated 7 times, and the mixture was further stirred for 1.0 hour. The total injection amount of benzene is 0.60 g, and the total injection amount of R-113 is 58.
It was mL. Furthermore, nitrogen gas was blown in for 1.0 hour. When the target product was quantified by ¹⁹ F-NMR, the NMR yield of the title compound was 55%.

¹⁹ F-NMR (376.0 MHz, solvent CDCl ₃ , standard: CFCl ₃ ) δ (ppm): -7
3.9 to -74.4 (8F), -118.9 (4F),
-122.8 (4F), -187.9 (2F).

[Example 10] CF ₃ CF by a vapor phase pyrolysis method
= Synthesis example of CF ₂ SUS column (inner diameter 20 mm, length 1 m) and Na ₂ C
SU filled with O ₃ (average particle size 160 μm, 280 g)
A fluidized bed reactor made of S (inner diameter 45 mm, height 400 mm) was connected in series and heated to 250 ° C. in a salt bath. The reactor was allowed to flow obtained in Example 7 _{(CF 3)} 2 CFCOF and a mixed gas of _{N 2 (N 2 / (CF} 3) 2 CFCOF = 5/1 ( molar ratio)) in 1600 mL / min. GC analysis of the reactor outlet gas after 1 hour revealed that (CF ₃ )
The conversion rate of ₂ CFCOF is 100%, and CF ₃ CF =
The selectivity of CF ₂ was 95%.

Example 11 (Reference Example) CF ₃ CF = CF ₂
Production Example of Hexafluoropropylene Oxide (HFPO) by Oxidation Reaction of (HFP) In a Hastelloy C pressure resistant reactor (internal volume: 500 mL), C
Charge ClF ₂ CF ₂ CHClF (700 g) 150
The temperature was raised to ° C. CClF ₂ CF ₂ CHClF 4
The internal pressure of the reactor was adjusted to 3 MPa by adjusting the flow rate at which it was continuously fed at a rate of 05 g / h and overflowed from the reactor and was distilled out with a pressure control valve attached to the outlet. When the internal pressure was stable, HFP obtained in Example 10 was 45 g / h,
At the same time, oxygen was continuously supplied at 1.68 NL / h to carry out a reaction for 6 hours. After the reaction, the reaction crude liquid flowing out from the outlet was analyzed by GC and NMR. As a result, HFP
The conversion was 83% and the selectivity for HFPO was 60%. The reaction crude liquid contained CF ₃ COF and trifluoromethylacetic acid in a total area of 35% in terms of GC area%.

[0080]

INDUSTRIAL APPLICABILITY According to the present invention, TFE and HFP which are useful as fluororesin raw material monomers can be produced from the readily available compound (3) by an economically advantageous method in a short process and in a high yield. Further, as compared with the conventional manufacturing methods, the reaction can be performed at a lower temperature and the manufacturing can be performed while suppressing the by-products. The compound (3) is generally easily available, easy to synthesize, and inexpensive. Further, by allowing a specific amount or more of fluorine atoms to exist in the compound (3), the compound (3) is easily dissolved in the liquid phase during the fluorination reaction, and the reaction can be carried out at a high yield.

Further, by selecting the structures of R ¹ , R ² and Q in the compound (3), only the compound (5) can be produced by the decomposition reaction of the ester bond of the compound (4). Further, by recycling the produced compound (5) as a compound (2) for the reaction with the compound (1), the compound (5) can be produced by a continuous process. Further, according to the present invention, a novel compound useful as a fluororesin raw material is provided.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoichi Takagi             1150 Hazawa-machi, Kanagawa-ku, Yokohama-shi, Kanagawa             Asahi Glass Co., Ltd. (72) Inventor Shin Tatematsu             1150 Hazawa-machi, Kanagawa-ku, Yokohama-shi, Kanagawa             Asahi Glass Co., Ltd. (72) Inventor Takashi Okazoe             1150 Hazawa-machi, Kanagawa-ku, Yokohama-shi, Kanagawa             Asahi Glass Co., Ltd. F-term (reference) 4H006 AA02 AC26 AC30 AC47 AC48                       BB12 BB15 BC10 BC11 BC31                       BE53 BM10 BM71 BP10 BS10

Claims (9)

[Claims] 1. A compound (3) having a fluorine content of 30% by mass or more is reacted with fluorine in a liquid phase to perfluoroenolize into the following compound (4), and then the ester bond of the compound (4) is converted into A method for producing the following perfluoroolefins (7), which comprises decomposing the compound to give the compound (5), and then thermally decomposing the compound (5). ^{_{(R 1 CH 2 CH (R}} 2) CH 2 OCO) n Q ··· (3) (R 1F CF 2 CF (R 2F) CF 2 OCO) n Q F ··· (4) R 1F CF 2 CF (R ^2F ) COF ... (5) R ^1F CF = CF ₂ ... (7) However, the symbols in the formulas have the following meanings. n: An integer of 1 or more, which represents the number of groups bonded to Q. R ¹ and R ² : each independently represent a hydrogen atom or a methyl group, at least one of which is a hydrogen atom. R ^1F , R ^2F : R ^1F corresponds to R ¹ , R ^2F corresponds to R ² , and when R ¹ and R ² are each a hydrogen atom, it is a fluorine atom, and R ¹ and R ² are each a methyl group. Is a trifluoromethyl group. Q: n-valent fluorine-containing organic group. Q ^F : When Q is a fluorinated group, Q ^F is a perfluorinated group, and when Q is a non-fluorinated group, Q ^F is the same as Q. 2. The compound (3) is a compound formed by the reaction of the following compound (1) and the following compound (2).
The manufacturing method described in. R ¹ CH ₂ CH (R ² ) CH ₂ OH ... (1) Q (COX) _n ... (2) However, the symbols in the formulas have the following meanings. X: halogen atom. R ¹ , R ² , Q and n: have the same meanings as described above. 3. The process according to claim 1, wherein the following compound (6) is obtained together with the compound (5) from the decomposition reaction product of the ester bond of the compound (4). Q ^F (COF) _n (6) However, Q ^F and n in the formula have the same meanings as described above. 4. A compound (3) is obtained by obtaining the following compound (6) from a decomposition reaction product of an ester bond of the compound (4) and reacting the compound (6) with the compound (1). The production method according to claim 1, which is compound (3). Q ^F (COF) _n (6) However, Q ^F and n in the formula have the same meanings as described above. 5. The production method according to claim 1, wherein n is 1 or 2. 6. n is 1 and R ^1F CF ₂ CF (R
^2F )-and a perfluorinated monovalent organic group Q ^F
And are the same groups, The manufacturing method in any one of Claims 1-5. 7. The production method according to claim 1, wherein the liquid phase at the time of reacting with fluorine in the liquid phase is the compound (5) or the following compound (6). Q ^F (COF) _n (6) However, Q ^F and n each have the same meaning as described above. 8. The decomposition reaction of an ester bond is a decomposition reaction by heat or a decomposition reaction by reacting with a nucleophile or an electrophile in a liquid phase. Production method. 9. A compound represented by the following formula:   R¹⁰CH_TwoCH (R²⁰) CH_TwoOCOR^Thirty... (3a)   R^10FCF_TwoCF (R^20F) CF_TwoOCOR^30F... (4a)   R¹⁰CH_TwoCH (R²⁰) CH_TwoOCO (CF_Two)_FourOCOCH_TwoCH (R ²⁰ ) CH_TwoR¹⁰... (3b)   R^10FCF_TwoCF (R^20F) CF_TwoOCO (CF_Two)_FourOCOCF_TwoCF (R^20F) CF_TwoR^10F... (4b) However, the symbols in the formulas have the following meanings. R¹⁰, R²⁰: Hydrogen atom or methyl group, whichever
One of them is a hydrogen atom. R^10F, R^20F: Fluorine atom or trifluorome
It is a chill group, and one of them is a fluorine atom. R^Thirty: Fluorine-containing alkyl group having 3 to 20 carbon atoms, or
Fluorine-containing (ether ether oxygen atom-containing
Rukiru) group. R^30FIs a perfluoroalkyl group having 3 to 20 carbon atoms,
Or C3-C20 perfluoro (etheric oxygen
Atom-containing alkyl) groups.