WO2003091187A1

WO2003091187A1 - Process for producing perhalogenated alkyl iodide telomer

Info

Publication number: WO2003091187A1
Application number: PCT/JP2003/004877
Authority: WO
Inventors: Jun Miki; Yoshito Tanaka
Original assignee: Daikin Industries, Ltd.
Priority date: 2002-04-24
Filing date: 2003-04-17
Publication date: 2003-11-06

Abstract

A process for producing a compound represented by the general formula (II): X1-CF2CFX2-(CF2CF2)n-I (II) [wherein X1 represents fluorine, chlorine, or iodine; X2 represents fluorine, chlorine, or CF3; and n is a or b (a and b each is an integer of 1 to 5, provided that a≤b)] by reacting a compound represented by the general formula (I): X1-CF2CFX2-I (I) (wherein X1 and X2 are as defined above) with tetrafluoroethylene in a reactor in the presence of a catalyst, characterized by comprising: a step in which the reaction is conducted under such conditions as to yield reaction products containing as a major component a compound represented by the formula (II) wherein n=1 and a liquid reaction mixture comprising the starting material represented by the general formula (I) as a major ingredient is introduced into a distillation column; a step in which a fraction consisting mainly of the starting material represented by the general formula (I) is taken out of the column top through distillation and is returned to the reactor for reuse; and a step in which the bottom residing in the distillation column is introduced into a rectification step to purity it to obtain the compound represented by the formula (II) having a high purity. Also provided is a perhalogenated alkyl iodide telomer produced through those steps which is represented by the general formula (III): X1-CF2CFX2-(CF2CF2)n-H (III) [wherein X1 and X2 are as defined above; and n is c or d (c and d each is an integer of 2 to 6, provided that c≤d)] and has an impurity content of 50 ppm or lower. An optical functional material and/or an intermediate for optical functional materials is further provided which is obtained from or comprises the telomer.

Description

Specification

Method for producing perhalogenated alkyl iodide telomer

Technical field

The present invention relates to a method of producing a perhalogenated alkyl iodide telomer and a high-purity perhalogenated alkyl iodide telomer. The perhalogenated alkyl iodide telomer of the present invention is particularly useful when used as a pharmaceutical intermediate, an optical functional material intermediate, or a polymer raw material. Above all, in the case of an intermediate of an optical functional material, the presence of a hydrogen-containing compound as an impurity is extremely useful because optical characteristics are impaired.

Background art

It is known that the perhalogenated alkyl iodide telomer proceeds according to the following formula (see German Patent Publication No. 1443517 and JP-A-6-305995).

Rf-I + CF ₂ CF ₂ → Rf— (CF ₂ CF ₂ ) _n — I

(In the formula, Rf represents a perhalogenated alkyl group.)

In the reaction, the telomer having n of 6 or more has low utility, so it is important to stop the telomerization reaction at a medium chain (n = 1 to 5), in which case a large amount of the raw material remains in the reaction solution. It is necessary to perform purification in this state. In the case of use in water- and oil-repellent agents, which are the usual applications, the purpose can be achieved with a mixture having an average n number of about 3.5. When used as a raw material, high purity is required as a single component. Therefore, it was important how to efficiently purify compounds having a specific n number.

In some cases, Rf— (CF ₂ CF ₂ ) _n —H was a problem as an impurity. For example, in the case of an intermediate of an optically functional material, a hydrogen-containing compound deteriorated the optical characteristics, and was deteriorated.

The present invention relates to a process for producing a compound of the general formula (II), wherein a reaction mixture containing a large amount of a raw material efficiently produces a medium-chain telomerized product (compound of n = 1 to 5 in the general formula (Π)). The purpose is to provide the law. Another object of the present invention is to provide a perhalogenated alkyl iodide telomer having a low impurity content. It is a further object of the present invention to provide an optically functional material and an intermediate of Z or an optically functional material using them. Disclosure of the invention

As a result of repeated investigations in view of the above problems, the present inventors have found that a large amount of the raw material remains in the reaction mixture, and the reaction product under the reaction conditions in which the compound of the general formula (II) of n = l is the main component. The compound of formula (I), which is a starting material, is reacted with tetrafluoroethylene, the reaction mixture is introduced into a distillation column, and the overhead is reduced by distilling off a fraction mainly composed of the raw material compound of formula (I). It has been found that a highly pure compound of the general formula (II) can be efficiently produced by introducing the bottom liquid to the next rectification step. By adopting such a method, at least one of the compounds of n = 1 to 5 can be efficiently synthesized, and even when all of the five compounds of n = 1 to 5 are simultaneously produced, such a method can be used. It is advantageous to manufacture under such conditions.

The invention relates to a process for preparing a compound of the general formula (I):

Xi—CFsCFX ² — I (I)

(In the formula, X ¹ represents F, C, I, and X ² represents F, C, CF _3. )

Is reacted with tetrafluoroethylene in the presence of a catalyst to give the following formula (Π): X ¹ — CF ₂ CFX ² — (CF ₂ CF ₂ ) _n — I (II)

(Wherein X ¹ and X ² are as defined above, and n = a to b (a and b each represent an integer of 1 to 5, a ≦ b).)

In the method for producing the compound represented by

(a) The reaction is carried out under the condition that the compound of the formula (II) where n = l as the reaction product is the main component, and the reaction solution containing the raw material of the general formula (I) as the main component is fed to the distillation column. Guiding process,

A step of distilling a fraction containing the raw material of the general formula (I) as a main component from the top of the column, returning the fraction to the reactor for reuse, and

A step of introducing the bottom liquid of the distillation column to a rectification step to purify the compound of formula (II) (n = 2 to 5) with high purity.

_C The present invention is to provide a method for producing a compound represented by the general formula (II) which comprises a can, as an impurity, the general formula (III):

X ¹ — CF ₂ CFX ² — (CF ₂ CF ₂ ) _n — H (III)

(Wherein X ¹ and X ² are as defined above, and n = c to d (c and d each represent an integer of 2 to 6, and c ≦ d).) The present invention also relates to a perhalogenated alkyl iodide telomer characterized in that the content of the compound represented by the following formula (hereinafter abbreviated as Rf-H) is 50 ppm or less.

The perhalodialkyl alkyl iodide telomer according to the present invention is particularly useful when used as a pharmaceutical intermediate, an intermediate of an optically functional material, or a polymer raw material. Above all, in the case of an intermediate of an optical functional material, the presence of a hydrogen-containing compound as an impurity is extremely useful because optical characteristics are impaired. Here, the optical functional material is, for example, an organic material for optical communication, such as an optical waveguide material, an optical switch, a modulator, a filter, an optical cross connect, an optical amplifier, a multiplexer / demultiplexer, a wavelength converter, 0ADM, a photonic crystal, and a non-linear type. Examples of optical materials include optical recording materials such as holographic materials, photochromic materials, photorefractive materials, and liquid crystal materials. Examples of display materials include organic EL materials, liquid crystal materials, and LEDs.

Further, the obtained perhalogenated alkyl iodide telomer can be reacted with phosphorus to synthesize high-purity alkyl perphosphoric acid and / or bis-perhalogenated alkyl phosphoric acid. These high-purity fluorinated phosphoric acids are extremely useful as intermediates for optically functional materials. For example, these fluorinated phosphoric acid and rare earth metal ions, such as erbium (Er) ion, thulium (Tm) ion, praseodymium (Pr) ion, holmium (Ho) ion, neodymium (Nd) ion, europium ( Complexes with Eu) ions, cerium (Ce) ions, samarium (Sm) ions, dysprosium (Dy) ions, and terbium (Tb) ions can be expected as highly efficient light-emitting materials and optical amplification materials. . This is because the presence of R f _ (CF ₂ CF ₂ ) _n — H transfers the energy of light emission to the C-H bond and lowers the light emission efficiency, but the perhalogenated alkyl iodide telomer of the present invention It is thought that energy transfer can be suppressed by using as a raw material.

Specific examples of the compound of the general formula (I) used as a raw material include CF ₃ CF ₂ I,

C1CF ₂ CF ₂ I, ICF ₂ CF ₂ I, C1CF ₂ CFC1I, (CF ₃ ) ₂ CFI are preferably exemplified CF ₃ CFC1 I, ICF ₂ CFC1I, C1CF ₂ CF (CF ₃ ) I, ICF ₂ CF ( CF ₃ ) I can also be used.

Specific examples of the target compound of the general formula (Π) include

CF ₃ CF ₂ — (CF ₂ CF ₂ ) _n -I (n = l to 5);

_{_{_{C1CF 2 CF 2 I- (CF.CF 2}}} ) n - I (n = l~5); ICF ₂ CF ₂ I- (CF ₂ CF ₂ ) _n — I (n = l to 5);

C1CF ₂ CFC1I— (CF ₂ CF ₂ ) _n — I (n = l to 5);

(CF ₃ ) ₂ CFI— (CF ₂ CF ₂ ) _n -1 (n = l to 5);

CF ₃ CFC1I— (CF ₂ CF ₂ ) _n — I (n = l to 5);

5 ICF ₂ CFC1I— (CF ₂ CF ₂ ) _n _I (n = l ~ 5);

ClCF ₂ CF (CF ₃ ) I_ (CF ₂ CF ₂ ) _n — I (n = l to 5); and

ICF ₂ CF (CF ₃ ) I— (CF ₂ CF ₂ ) _n — I (n = l ~ 5)

Can be exemplified.

As the catalyst used for the telomerization reaction, known catalysts, in particular, metal catalysts can be widely used. 10 Examples of the metal type of the metal catalyst include copper, tin, zinc, magnesium, vanadium, renium, rhodium, ruthenium, platinum, silver, alloys of these metals, and mixtures of these metals. Alternatively, an alloy obtained by adding a small amount of a transition metal to these metals can be used. As the transition metal, it is possible to use a metal which does not show a catalytic action itself or a catalyst having a very small catalytic action, such as iron, nickel, chromium, molybdenum, tungsten,

15 Titanium etc. can be used.

In particular, when copper, tin, or tin using copper as a cocatalyst is used as a catalyst, the catalytic activity and the selectivity of the medium-chain telomer are improved. As for tin using copper as a cocatalyst, a mixture of tin powder and copper powder, a tin-copper alloy, or the like can be used. Since both tin and copper can be used as catalysts for the telomerization reaction, the ratio of both can be arbitrarily determined. For example, if the ratio of tin is 0.

The ability to use a catalyst in the range of about 200 to 100% by mass It is preferable to set the amount of tin to about 2 to 35% by mass, especially from the viewpoint of processability, cost reduction, and availability.

The size of tin powder, copper powder, tin-copper alloy powder, etc. used as a catalyst is not particularly limited, but may be, for example, 0.1 μm or more: about Lmm, preferably 20 μm to 0.3 mm. Particle size of about 20 μη! About 200 μm, preferably 45 to 100 μm

25

The reaction can be carried out batchwise or continuously.

When the reaction is carried out in a continuous manner, for example, a tubular reactor filled with a catalyst metal composed of spherical metal powder or sintered metal is used as the reactor, and the raw material of the formula (I) and tetrafluoride are added to the reactor. The telomerization reaction can be carried out by continuously supplying ethylene to the mouth. When the reaction is carried out in a batch system, the amount of the catalyst used is not particularly limited, but is preferably about 0.2 to 50 raass% based on the weight of the compound of the formula (I) as the raw material. If the amount of the catalyst used is too large, it is uneconomical, and if the amount is too small, the reaction speed is undesirably slow.

These catalysts may be used in the form of a catalyst metal supported on a carrier such as alumina or zeolite.

In the method of the present invention, in the reaction mixture supplied to the distillation column,

Feedstock from 80 to 98 mole ^_0/0 of formula (I), preferably 85 to 96 Monore ^_0/0,

Compounds of n = l is a formula (II), 1: 12 Monore ⁰ I preferably 3: 10 mole ^_0/0,

The compound of the formula (の) wherein n is 2 or more is present under such conditions that 0.1 to 10 mol%, preferably 0.3 to 5 mol% is present (the compound of the formula (I) as a raw material and The reaction is preferably carried out under the following conditions: ethylene ratio, pressure, temperature, time, type and amount of catalyst. By subjecting the reaction mixture thus obtained to separation in a distillation column and subsequent purification steps, at least one compound of the desired compound of the formula (II) (n = l to 5), preferably can Rukoto give the compound of five (n = 1 to 5) At the same time, and, eta 5 mol% of the total product the production of 6 or more compounds or less, preferably 2 mol ^_0/0 or less, more preferably 0 - 5 mole ^_0/0 or less, in particular can be suppressed to 0.1 mole ^_0/0, it is possible to manufacture various telomers of interest efficiently.

Tetrafluoroethylene Compound of formula (I) (molar ratio) = 0.01-1 It is preferable to be about 0.1-0.5.

The reaction temperature is usually about 60 to 200 ° C, preferably about 60 to 160 ° C, and more preferably about 100 to 140 ° C.

The pressure during the reaction is preferably about 0.1 to 5 MPa (gauge pressure). The reaction proceeds at a pressure lower than this, which is not preferable because the space time yield decreases. If the reaction pressure is higher than the above range, the telomerization reaction proceeds, but safety risks and costs are increased.

In the production method of the present invention, the reactor is, for example, a reactor having a pressurized temperature control device so that the compound of the formula (I) can exist in a liquid phase, and having a stirring device, The internal pressure is increased from 0.5 to 1.5M so that tetrafluoroethylene, the compound of formula (I), can exist mainly as a liquid

A tank reactor that can be adjusted within the range of Pa (gauge pressure) is suitable. Using such a reactor, The telomerization reaction can be performed by introducing tetrafluoroethylene in a gas phase into a device in which a liquid phase containing the raw material of the formula (I) is stirred.

Alternatively, the reaction may be carried out by dissolving tetrafluoroethylene in the raw material of the formula (I), and then supplying this solution from a reactor introduced into the reactor. In this case, a reactor equipped with a pressure controller at the outlet and having a temperature controller is suitable. In this case, the internal pressure is about 0.5 to 3 MPa (gauge pressure) so that tetrafluoroethylene, which is a taxogen, is dissolved in telogen, for example, parafluoroethyl iodide, and can remain as a liquid. It is preferable to adjust in the range of.

The reaction mixture obtained by the above reaction is supplied to a distillation column to distill a fraction containing the i-adduct of the formula (I), which is a starting material at the top, as a main component. The reaction mixture contains the compound represented by the formula (II)! In general, compounds containing n = 1 to 5 are included, but the conversion is low, in which case n is large and the ratio of the compounds is reduced. In the case of producing a compound having a small n, the reaction may be terminated in a state where the conversion is low and led to a distillation column. For example, in formula (II), when five compounds of n = l to 5 (a = l, b = 5) are obtained at the same time, the conversion (reaction ratio of the compound of formula (I)) is 5 to: 15% When a compound of n = 3 (a = b = 3) is obtained, the conversion is preferably about 2 to 10%. When a compound of n = l (a = b = l) is obtained, The conversion is preferably 3% or less. The overhead fraction generally contains at least 85 mol%, preferably at least 90 mol% of the compound of the formula (I), and the compound of the formula (II) wherein n = 1 : About 15 mol%, preferably about 7 to 11 mol%, and the compound of the formula (II) where n = 2 or more is usually 3 mol% or less, preferably 1.5 mol% or less.

For the overhead fraction, it is possible to recover only the raw material of formula (I) by increasing the number of theoretical plates in the distillation column and performing precise distillation.Recover the compound of formula (II) with a force n = l. Even in this case, it is not appropriate to recover only the raw material of the formula (I) at this stage, since the raw material is predominantly present in the compound of the formula (II) where n = l. And the majority of the raw material disappears, the overhead fraction containing a small amount of the compound of the formula (II) of n = l is distilled and reused in the telomerization reaction, and the compound of the formula (II) of n = l Is preferably further purified by a purification step.

n = 2 to 5 (a = 2, b = 5) at least one compound of the formula (II), preferably n = 3 or more compounds of the formula (II) (a = 3, b = 3 to 5) At least one compound of formula (II) wherein n = 3 to 5 (a = In the case of separating and recovering 3, b = 5), it is not necessary to recover the compound of formula (II) where n = l, and the overhead containing the compound of formula (Π) with η = 1 It is advantageous to reuse the minutes. The bottom liquid is guided to the next rectification step and further purified. As the rectification step, purification by a distillation column is exemplified. The distillation column may be a single distillation column or may be purified using two or more distillation columns.

Since a large amount of the raw material of the formula (I) is contained in the reaction mixture, the bottom liquid may contain a small proportion of V as a raw material.

In the purification step, when one distillation column is used, when only the compound of the formula (II) where η == 1 is purified, when the starting compound is not contained in the bottom liquid, η = 1 The distillation may be carried out under the conditions of the number of theoretical plates, temperature and pressure necessary to obtain the compound of the formula (II) of the formula (1) as a top distillate. The raw material of the formula (I) is separated as the top fraction, and the compound of the formula (I) with η = 1 is supplied to the second distillation column as the bottom cut liquid and the force obtained by side cutting, and the second distillation column May be collected as a top distillate.

In order to obtain a compound of the formula (II) (a≥2) with η = 2 or more, the raw material of the formula (n = 0) or the product of the formula (II) (n = l ~ (A-1) and a≥2) are withdrawn as a top power or a side cut fraction of the distillation column and reused in the telomerization reaction, and the desired compound of the formula (II) with n = 2 or more is obtained. What is necessary is just to separate and collect. Specifically, the compound of the formula (II) in which n = 2 or more is obtained by using the second rectification column or, if necessary, further using the (b−a + 1) th rectification column. (1) Fractionation column The desired compound of the formula (II) of n = ab can be separated and recovered from the bottom liquid.

Compounds of formula (II) where n = 3-5 are particularly useful.

When obtaining the compound of the formula (II) (a = 3, b = 5) of n = 3 to 5, in the rectification step, the compounds of n = l and 2 are separated, and the compound of the formula (I) When the raw material is contained, the raw material compound is recovered, and the precursor conjugate (the raw material and the product of n = l, 2) is returned to the reactor and reused. In the telomerization reaction, even for the purpose of obtaining the compound of the formula (II) of n = 3 to 5, the reaction is carried out under the condition where the compound of the formula (II) of n = l is most often produced, so that it is supplied to the distillation column. The reaction mixture contains the largest amount of the raw material compound of the formula (I) (usually 80 mol% or more), and as the product, the component with n = 1 is the largest, and as η increases from 1 to 5, The ratio will decrease as a product. Therefore, there are many precursor compounds having η of 0 to 2. In the purification step, the precursor compound is recovered and reused using one or two distillation columns, and the compound having η = 3 to 5 is obtained. Is preferably withdrawn as a bottom liquid of a distillation column, and further recovered using a distillation column for separating these objective substances. The bottom liquid containing the target compound of the formula (II) where n = 3 to 5 is separated by distillation according to a conventional method. Specifically, the rectification step can be performed by the following steps (i) to (iii):

(i) The bottom liquid having the distillation column power is led to the first rectification column and separated as a top fraction containing a compound of n = 0 to 2, and a compound of the formula (11) of 11 = 2 to 5 is obtained. Introducing the bottom liquid containing the compound of the formula (II) of η = 0 to 2 into the second rectification column and reusing it in the reactor;

(ii) The compound of the formula (II) of n = 2 is separated as a top distillate of the second distillation column, and the bottom liquid containing the compound of the formula (II) of η = 3 to 5 is supplied to the third rectification column. Deriving the overhead fraction containing the compound of formula (II) with η = 2 by returning it to the reactor for reuse; and

(iii) a step of separating and recovering the compound of the formula (II) of n = 3 to 5 using a third rectification column and, if necessary, fourth and fifth rectification columns.

Further, the present invention also has a feature that Rf-IH, which is an impurity contained in the conventional method for producing a telomer, is 50 ppm or less.

Here, Rf-H of 50 ppm or less is determined by gas chromatography with FID detection.

SE-30, filler 15% Uniport HP 60/80, length 3m, inner diameter 3ram, sample amount 2mg) shows no detection when analyzed. For this, when a calibration curve was prepared in advance with Rf_H, the detection limit under the above conditions was separately confirmed to be approximately 0.1 μg (for a sample volume of 2 m, the detection limit was 0.1 to 50 ppm. Hit).

In addition, in order to prepare, for example, an optically functional material using these telomers as intermediates, various conventional synthesis methods can be employed. By using the telomer of the present invention, the properties of the optical functional material can be improved.

According to the production method of the present invention, it is possible to efficiently produce and purify a desired medium-chain telomer (n = l to 5). Furthermore, high-purity medium-chain telomers (n == l-5) with Rf-H of 50 ppm or less can be produced as impurities. They are particularly useful when used as intermediates for pharmaceuticals, intermediates for optically functional materials, and raw materials for polymers. Among them, they are extremely useful as intermediates for optically functional materials. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1

A 3Z8-inch stainless steel tube filled with 46 g of spherical copper powder (Mitsui Metals Co., Ltd., particle size of 330 mesh or less) was used as a reaction tube, and tetrafluoroethylene (TFE) was used as a perfluoroethyla. The raw material solution (tetrafluoroethylene concentration (TFE / (telogen + TFE)) = 4.25 mol%) dissolved in iodide was continuously supplied to the stainless steel tube, and the reaction pressure was 3 MPa (gauge pressure). The telomeri-dani reaction was performed at a supply rate of 9. OmlZ. The reaction temperature was 60 to 120 ° C. The reaction solution flowing out of the stainless tube was cooled, and the composition was analyzed by gas chromatography. The results are shown in Table 1 below.

From the obtained reaction mixture, the starting compound of the formula (I) and the precursor compound of n = 1 or 2 in the formula (II) were separated under the following conditions using the first to third distillation columns.

1st distillation column

Still temperature 120 ° C, tower top temperature 60 ° C, number of theoretical plates 12 stages, pressure 0.15MPa

Distillate composition: n = 0 (90 mol%), n = 1 (9 mole%), n = 2 (1. 0 mole ^_0/0) still temperature 120 ° C, column top temperature 65 ° (:, theoretical plate number 23 stages, fine, low pressure (almost normal pressure)

Distillate composition: n = 0 (7. 9 Monore ^{0 / o), n = l} (49. 7 mol ^{_{0/0), n = 2}} (42. 0 mol ^{_{0/0), n = 3}} (0. 4 mole ^_0/0) still temperature 118. C, overhead temperature 58 ° C, number of theoretical plates 23, pressure-0.087 MPa Distillate composition: n = 2 (99. 9 mole ^{_{0 / o), n = 3}} (0. 1 mole ^_0/0)

Note Rf-H which is an impurity in the gas chromatography FID detector (conditions: column SE - 30, filler 15% Uniport HP 60/80, length 3m, inner diameter 3 negation, sample volume 2m _g) when analyzed On the other hand, it was not detected.

The bottom liquid of the third distillation column was led to a further distillation column to separate and purify each compound of n = 3, 4, and 5. Rf-H, an impurity, was not detected on gas chromatography for each compound.

The top fraction of the first distillation column was returned to the reactor and reused.

The fractions of the second distillation column and the third distillation column are led to the distillation column when n = l and 2 telomers are required, and the respective fractions are obtained. If the compound of (1) is important, it is recycled back to the reactor without further purification. Example 2 (Example of intermediate synthesis)

By reacting 5 g of C ₈ F ₁₇ I obtained in the example with red phosphorus at 230 ° C. for 48 hours, about 3 g of (C ₈ F ₁₇ ) ₂ PI was obtained. After that, it was reacted with nitrogen dioxide at the temperature of liquid nitrogen, allowed to cool to room temperature, and then hydrolyzed to obtain about 2.6 g of (C ₈ F ₁₇ ) ₂ P〇OH. . The obtained compound was identified by NMR and IR. Example 3 (Production example of optical functional material)

(C ₈ F ₁₇ ) ₂ POOH obtained in Example 2 (2.5 g, 2.7 ramol) and europium acetate tetrahydrate (1.0 g, 2.5 mmol) were calored in 50 ml of water and kept at room temperature for 3 days. Stirred. The precipitated solid was filtered, washed with water, and then recrystallized with a mixed solvent of water and methanol to obtain a complex (Eu [(C ₈ F ₁₇ CO) ₂ POO] ₃ ). When irradiated with black light, red emission characteristic of europium ion was observed.

Claims

The scope of the claims

1. In a reactor, the general formula (I):

X ¹ — CF ₂ CFX ² — I (I)

(In the formula, X ¹ represents F, C, and I, and X ² represents F, C, and CF _3. )

Is reacted with tetrafluoroethylene in the presence of a catalyst to give the following formula (II): X ¹ —CF ₂ CFX ² — (CF ₂ CF ₂ ) _n — I (II)

In a method for producing a compound represented by

Carrying out the reaction under the condition that the compound of the formula (Π) where n = l as the reaction product is the main component, and introducing the reaction solution mainly containing the raw material of the general formula (I) into the distillation column ,

Distilling a fraction containing the raw material of the general formula (I) as a main component from the top of the column, returning the fraction to the reactor, and reusing the fraction;

Producing the compound represented by the general formula (II), which comprises a step of conducting the bottom liquid of the distillation column to a rectification step to purify the compound of the formula (II) with high purity. Method.

2. The method according to claim 1, wherein the rectification step is performed as follows: The bottom liquid of the distillation column is led to a first rectification column, and is represented by the formula (II). = 0 to (a-1) is withdrawn as a fraction at the top or as a side cut, returned to the reactor and reused, and the target product of formula (II) of n = a to b is obtained as a side cut. The method of claim 1, wherein:

3. The method according to claim 1, wherein the rectification step is carried out as follows: The bottom liquid of the distillation column is led to a first rectification column, and in formula (II), n = 0 to ( extracting the compound of a-1) as a column fraction or a side cut, and leading a bottom liquid containing the target compound of the formula (Π) of n = a to b to a second rectification column,

From the bottom liquid of the first rectification column using the second rectification column or, if necessary, up to the (b−a + 1) th rectification column, the desired formula of n == a to b (II) 2. The method according to claim 1, wherein the compound is separated and recovered.

4. The method according to claim 1, wherein a = 3 and b = 5, and the rectification step is performed by the following steps (i) to (iii): (i) The bottom liquid having the distillation column power is led to the first rectification column and separated as a top fraction containing a compound of n = 0 to 2, and a compound of the formula (II) of n = 2 to 5 is separated. Introducing the bottom liquid containing the compound of the formula (II) of η = 0 to 2 into the second rectification column and reusing it in the reactor;

(ii) Separating the compound of the formula (II) of n == 2 as a top distillate of the second distillation column, and converting the bottom liquid containing the compound of the formula (II) of η = 3 to 5 to the third rectification column Returning the overhead fraction containing the compound of the formula (II) of η == 2 to the reactor for reuse; and

(iii) a step of separating and recovering the compound of the formula (II) of n = 3 to 5 using the third rectification column and, if necessary, the fourth and fifth rectification columns.

5. As impurities

General formula (III):

X ¹ — CF ₂ CFX ² — (CF ₂ CF ₂ ) _n — H (III)

(In the formula, X ¹ and X ² are as defined above, and represent n = c to d (c and d are each an integer of 2 to 6, c ≦ d).)

In more it becomes perhalogenated alkyl iodide telomer to the manufacturing method of claim 1, wherein the compound is characterized in that below 50p _P m represented.

6. An optically functional material and / or an intermediate of an optically functional material using the perhalogenated alkyl iodide telomer according to claim 5 as a raw material.