KR100822146B1 - Preparation of high purity fluorinated peroxides - Google Patents

Abstract

The present invention relates generally to an improved process for the preparation of high purity fluorinated peroxides formed by the reaction of carbonyl fluoride with hypofluorite. This method is characterized by a simplified method for the synthesis and recovery of high purity fluorinated high purity products.

(a) the carbonyl fluoride and the hypofluorite under conditions such that a gaseous reaction product consisting of fluorinated peroxide and unreacted carbonyl fluoride is formed which is substantially free of unreacted hypofluorite. Reacting;

(b) removing the unreacted carbonyl fluoride and byproducts from the gas phase reaction product under gas phase conditions, thereby producing a gaseous product stream containing fluorinated peroxides; And

(c) collecting the fluorinated peroxide produced from step (b) in the gas phase

It includes.

Carbonyl fluoride, hypofluorite, fluorinated peroxide

Description

Process for producing high purity fluorinated peroxide {PREPARATION OF HIGH PURITY FLUORINATED PEROXIDES}

Fluorinated peroxides are powerful oxidants and are useful as free radical generators and etchants in the manufacture of electronic components. Perfluorodimethyl peroxide, often referred to as bis (trifluoromethyl) peroxide, is one example of a common fluoroperoxide used in this field.

One of the many requirements in the electronics industry is the high purity requirement. The final product should be substantially free of unreacted contaminants. Reactants and by-products formed during synthesis have many safety problems due to their high reactivity and hazards, and extreme care should be taken in the synthesis and recovery of high purity products.

The following documents and patents are representative examples of techniques related to fluorinated peroxides, including the preparation and recovery of perfluorodimethyl peroxides.

USP 3,100,803 and USP 3,230,264 (CIP of '264) disclose methods for synthesizing perfluorodimethyl peroxide by reacting equimolar amounts of carbonyl fluoride with trifluoromethyl hypofluorite in the presence of a metal fluoride catalyst. The reaction temperature generally exceeds 200 ° C. Samples of the product are collected by condensation in a trap cooled with liquid oxygen. The condensate is then separated by distillation. In another method, carbon monoxide and fluorine are reacted in various ratios to produce carbonyl fluoride and trifluoromethyl hypofluorite in situ.

USP 3,202,718 reacts bis (perfluorodimethyl) by reacting carbonyl fluoride (COF ₂ ) with chlorine trifluoride (ClF ₃ ) at a temperature of 0-300 ° C., preferably 100-250 ° C., in the presence of a fluoride salt. Disclosed is a method of making peroxide (BTMP). Separation and purification of BTMP involves passing the reaction product through a tube of granular calcium chloride, washing with water and dilute caustic to remove residual chlorine, hydrogen fluoride and carbonyl fluoride, and trapping the cleaned stream at -80 ° C. To freeze the water and condense the bis (trifluoromethyl) peroxide, followed by passing the liquid stream through a liquid nitrogen trap to prevent loss of bis (trifluoromethyl) peroxide. do. If tetrafluoromethane is present as a by-product, it is removed using distillation as the last step.

Roberts, HL, Preparation of Bis (trifluoromethyl) Peroxide and its Reduction with Hexafluoropropene, J. Chem. Soc. (1964) 4538 discloses a process for preparing BTMP by reacting COF ₂ with CF ₃ OF (molar ratio 1.47: 1) at high temperature and high pressure (275 ° C. and 780 psig) in a nickel autoclave. The autoclave is cooled to room temperature, the product remaining in the autoclave is removed, and the gas is passed through a liquid air trap. The condensate is then distilled off in a Podbielniak column. The recovered product is then reacted with hexafluoropropene to form a product consisting of telomer CF ₃ O] C ₃ F ₆ ] _n OCF ₃ , where n ≧ 2.

Gard, GL et al., Reactions of Xenon with Certain Strong Oxidizing Agents, The University of Chicago Press, Chicago, 1963 (p. 109-111) disclose various reactions of xenon and various oxidants. As an example, xenon is reacted with trifluoromethyl hypofluorite to produce non-fluorinated dinon and BTMP. In the recovery step, the reaction product at 225 ° C. is cooled in a water bath and then cooled to −78 ° C., and the volatile product is ejected and passed through a liquid nitrogen trap. Volatiles other than xenon are found to be CF ₃ OF and CF ₃ OOCF ₃ , and the substance remaining in the tube is non-fluorinated difluoride.

US 4,499,024 discloses a process for producing bisfluorooxydifluoromethane (BDM) by reacting fluorine with carbon dioxide in the presence of a cesium fluoride catalyst. The main impurities are CF ₃ OF, CO ₂ and CF ₄ , but there may be residual (trace) CF ₃ OOCF ₃ . Separation to produce high purity products is carried out by liquefying and releasing gaseous impurities.

US Pat. No. 4,654,444 discloses fluorine-containing diacyl peroxes by reacting acyl halides (eg, α, α-difluoro-β-t-butoxypropionyl chloride) with sodium peroxide in water and extracting the product with an appropriate solvent. Disclosed is a method of making a seed.

The present invention generally relates to an improved process for the production of high purity fluorinated peroxides by reacting carbonyl fluoride with hypofluorite. It is a feature of the present invention to provide a simplified process for the synthesis and gas phase recovery of high purity fluorinated peroxide products,

(a) the carbonyl fluoride and the hypofluorite under conditions such that a gaseous reaction product consisting of fluorinated peroxide and unreacted carbonyl fluoride is formed which is substantially free of unreacted hypofluorite. Reacting;

(b) removing the unreacted carbonyl fluoride and any byproducts from the gas phase reaction product under gas phase conditions to produce a gaseous product stream containing fluorinated peroxides; And

(c) collecting the fluorinated peroxide produced from step (b) in the gas phase

It includes.

Important advantages can be obtained using the simplified gas phase recovery method described above.

The ability to produce fluorinated peroxides with sufficiently high purity for immediate use in the electronics field;

The low temperature condensation step and the distillation step that accompany the prepurification process are not required;

That high purity fluorinated peroxides can be prepared without undergoing a distillation step; And

Reduces the risks associated with cold recovery processes using condensation in the production of high purity fluorinated peroxides

It includes.

The present invention relates to an improved process for the preparation of high purity fluorinated peroxides formed by reacting carbonyl fluoride with fluoro hypofluorite. The process generally consists of two steps, the first being the synthesis of the reaction product containing the fluorinated peroxide and the second being the gas phase recovery of the fluorinated peroxide from the reaction product.

The first step in the process consists of reacting carbonyl fluoride with hypofluorite such as trifluoromethyl hypofluorite to form fluorinated peroxide. The hypofluorite may be prepared prior to contact with carbonyl fluoride or formed in situ by reacting fluorine with carbon monoxide in the presence of a catalyst such as, for example, a fluoride salt. Likewise, carbonyl fluoride may be formed prior to reaction with hypofluorite or in situ, for example by reacting carbon monoxide with fluorine. Depending on the reaction mechanism, the selected reactants may be formed in advance or, if necessary, in situ.

Examples of suitable hypofluorites for the reaction include C _1-8 alkylhypofluorites and C _1-8 bisalkylhypofluorites such as trifluoromethyl hypofluorite, chlorodifluoromethyl hypofluorite, pentafluoroethyl Hypofluorite, heptafluoropropyl hypofluorite and bis (fluorooxy) difluoromethane.

The preferred route for obtaining the desired fluorinated peroxide is shown in the following scheme.

Scheme A

[과잉 COF₂를 R_fOOCF₃ 및 미반응 COF₂가 형성되도록 하는 조건 하에서 R_fOF와 반응시킴 (여기서, R_f는 C_xF_2x+1이고, x는 1 내지 8임)]

[Reacted with R _f OF Sikkim under the condition that the excess COF ₂ R _{f 3} and unreacted OOCF to COF ₂ is formed (wherein, R _f is C _x F _{2x + 1, x} is 1 to 8);

Scheme B

[과잉 COF₂를 R'_f(OOCF₃)₂ 및 미반응 COF₂가 형성되도록 하는 조건 하에서 R'_f(OF)₂와 반응시킴 (여기서, R'_f는 C_xF_2x이고, x는 1 내지 8임)]

[Excess COF ₂ is reacted with R ' _f (OF) ₂ under conditions such that R' _f (OOCF ₃ ) ₂ and unreacted COF ₂ are formed, where R ' _f is C _x F _2x and x is 1 To 8)]

The inventors have found that by initially controlling the reaction conditions associated with the synthesis, the risks associated with the recovery of fluorinated peroxides can be reduced, including the simplification of the recovery process. The initial goal in the synthesis of fluorinated peroxides is to substantially completely convert the hypofluorite used in the reaction. The reaction conditions are controlled to direct the equilibrium reaction towards completion of the reaction so that substantially no hypofluorite remains in the reaction product. The reaction product contains less than 0.5% by weight of hypofluorite and generally contains less than 0.1% by weight, preferably less than 0.05% by weight of hypofluorite.

The key factor for obtaining a reaction product that is substantially free of unreacted hypofluorite is the reaction stoichiometry. A stoichiometric excess of carbonyl fluoride is used for hypofluorite to complete the reaction shown in the above scheme. The molar ratio of carbonyl fluoride to hypofluorite is generally from 1.1 to 3: 1, preferably from 1.2 to 1.7: 1. Other by-products which are typically formed in small to minor amounts in the reaction include carbon dioxide, hydrogen fluoride, fluorine and reacted water. Temperatures of 150 to 350 ° C. and autogenous pressures are usually used. The reaction conditions depend on the hypofluorite used and the fluorinated peroxide produced.

We carry out the reaction of carbonyl fluoride and hypofluorite under conditions such that substantially no unreacted hypofluorite remains, thereby allowing unreacted carbonyl from the reaction product without passing the reaction product through a cold condensation trap. It has been found that a gas phase recovery process can be performed to remove fluoride and by-products and recover fluorinated peroxides. Maintaining gas phase conditions throughout the recovery process avoids the hazards associated with highly reactive compounds in the form of condensates.

In a broad sense, the recovery of the fluorinated peroxide from the gas phase reaction product can be carried out by passing the gas phase reaction product through an adsorption bed capable of removing carbonyl fluoride contaminants and any by-products. Alkali-exchange 3-5 'zeolites and anhydrous soda lime granules are examples of adsorbents capable of removing the contaminants.

In a preferred recovery process, the gas phase reaction product is initially washed with an aqueous medium, typically an aqueous alkaline medium, in order to hydrolyze unreacted carbonyl fluoride and neutralize any acidic compounds present in the gas stream. Alkali solutions containing from 5 to 50% by weight of alkali, such as sodium hydroxide, potassium hydroxide, calcium hydroxide and the like, are preferred cleaning agents.

In the second stage of the recovery process, the aqueous treated reaction product is adsorbed to one or more adsorptions to facilitate removal of unreacted carbonyl fluoride and byproduct carbon oxides (eg, CO ₂ ) and droplets entrained H ₂ O. Pass through the layer. Representative adsorbents suitable for removing contaminants from fluorinated peroxide products include zeolites such as 3 ′ and 4 ′ zeolites and soda lime. Pore zeolites should be used to prevent reaction with the fluorinated peroxide product. If some of the carbon oxide remains after passing through the adsorption bed, the product may be passed through a reactant such as soda lime or another adsorbent bed that may react with the carbon oxide.

The following examples are intended to illustrate various embodiments of the invention and are not intended to limit the scope of the invention.

Example 1

Preparation of Bis (trifluoromethyl) peroxide

Molar ratio 1.52: 1

Reactants carbonyl fluoride COF ₂ and fluorooxytrifluoromethane CF ₃ OF were prepared in a flow system and collected in a clean, dry 600-cc Monel pressure reactor. A total of 500 mmol of COF ₂ and 328 mmol of CF ₃ OF were collected with a molar ratio of COF ₂ : CF ₃ OF of 1.52: 1. The mixture of COF ₂ and CF ₃ OF was heated to 274 ° C. under autogenous pressure for 3.5 hours and then held at 274 ° C. for 2 more hours. After the predetermined time had elapsed, the mixture was cooled to room temperature. Infrared spectra of the reactor contents indicated a mixture of COF ₂ and bis (trifluoromethyl) peroxide (BTMP) (CF ₃ OOCF ₃ ) and no CF ₃ OF was observed.

The gaseous contents of the reactor were passed through a purification train consisting of a column of H ₂ O, then through a bed of thermally activated 4 kM molecular sieve and then collected in a clean, dry collection cylinder at temperatures below room temperature. Infrared analysis of the product in the collection cylinder indicated high purity CF ₃ OOCF ₃ (BTMP) and no CO ₂ , H ₂ O, COF ₂ or CF ₃ OF was present. The BTMP product was 33.3 g and the yield was 60%.

Such reaction and recovery protocols can be used to avoid hazards associated with the presence of CF ₃ OF in the reaction product and associated hazards in the separation process.

Example 2

Preparation of Bis (trifluoromethyl) peroxide

Molar ratio 1.25: 1

In an experiment similar to the experiment described in Example 1, 1,443 mmol of COF ₂ and 354 mmol of CF ₃ OF with a molar ratio of COF ₂ : CF ₃ OF was 1.25: 1. The mixture of COF ₂ and CF ₃ OF was heated to> 270 ° C. under autogenous pressure and then maintained at a temperature of 270-280 ° C. for 3.5 hours. After the predetermined time had elapsed, the mixture was cooled to room temperature. Infrared spectra of the reactor contents indicated a mixture of COF ₂ and bis (trifluoromethyl) peroxide (BTMP) (CF ₃ OOCF ₃ ), with no CF ₃ OF observed.

The reaction product was purified and collected according to the method described in Example 1. Infrared analysis of the product in the collection cylinder indicated high purity CF ₃ OOCF ₃ (BTMP) and no CO ₂ , H ₂ O, COF ₂ or CF ₃ OF was present. The BTMP product was 36.9 g and the yield was 61%.

Example 3

Preparation of Bis (trifluoromethyl) peroxide

Molar ratio 1.99: 1

Reactants carbonyl fluoride COF ₂ and fluorooxytrifluoromethane CF ₃ OF were distilled into a clean, dry 600-cc Monel pressure reactor. A total of 558 mmol of COF ₂ and 281 mmol of CF ₃ OF were used with a molar ratio of COF ₂ : CF ₃ OF of 1.99: 1. The mixture of COF ₂ and CF ₃ OF was heated to 275 ° C. under autogenous pressure for 5.5 hours, and then maintained at> 269 ° C. for 1 hour. After the predetermined time had elapsed, the mixture was cooled to room temperature. Infrared spectra of the reactor contents showed a mixture of CO ₂ , COF ₂ and bis (trifluoromethyl) peroxide (BTMP) (CF ₃ OOCF ₃ ), with no CF ₃ OF observed.

The contents of the reactor were passed through a purification train consisting of a column of H ₂ O and then passed through a bed of thermally activated 4 kPa molecular sieves, after which the treated contents were collected in a clean, dry collection cylinder at temperatures below room temperature. Infrared analysis of the product in the collection cylinder indicated that it was a mixture of CF ₃ OOCF ₃ (BTMP) and CO ₂ . It was clear that the molecular sieve was not completely effective at removing CO ₂ . The contents of the collecting cylinder were then passed through a lime soda column and collected in a clean, dry cylinder. Analysis of the cylinder contents indicated high purity CF ₃ OOCF ₃ (BTMP) and no CO ₂ , H ₂ O, COF ₂ or CF ₃ OF was present.

This example, although increasing the molar ratio of carbonyl fluoride to trifluoromethyl hypofluorite to at least about 1.7, is effective in reducing the trifluoromethyl hypofluorite concentration in the reaction product, the unreacted carbonyl It not only increases the fluoride concentration but also increases the carbon oxide content, and shows that the increased load can place unnecessary burden on the cleaning and adsorption system in addition to causing the loss of reactant carbonyl fluoride.

Example 4

Purification of Crude Bis (trifluoromethyl) peroxide Using Soda Lime

Crude sample containing a mixture of BTMP and COF ₂ was passed through a soda lime column and then collected in a clean, dry collection cylinder. Analysis of the cylinder contents indicated high purity CF ₃ OOCF ₃ (BTMP) and no CO ₂ , H ₂ O, COF ₂ or CF ₃ OF was present.

This example demonstrates that a single adsorbent can be used to substantially eliminate all contaminants from reaction organisms containing fluorinated peroxides.

Example 5

Purification of Crude Bis (trifluoromethyl) peroxide Using Water and Soda Lime

Crude sample containing a mixture of BTMP and COF ₂ was passed through a soda lime column and then collected in a clean, dry collection cylinder. Analysis of the cylinder contents indicated high purity CF ₃ OOCF ₃ (BTMP) and no CO ₂ , H ₂ O, COF ₂ or CF ₃ OF was present.

Comparative Example 6

Purification of Crude Bis (trifluoromethyl) peroxide Using Soda Lime

Attempts to purify the crude sample containing a mixture of BTMP and CF ₃ OF, by passing the mixture through a soda lime column, were unsuccessful because the process generated oxygen as well as a large amount of local heat. to be. The heat caused subsequent decomposition of residual BTMP.

This comparative example shows inadequate gas phase recovery of fluorinated peroxide products from gaseous reaction products containing unreacted hypofluorite, such as when COF ₂ and CF ₃ OF react in equimolar amounts. The reaction product was washed in contact with a water column to remove carbon oxides.

According to the method for producing a high purity fluorinated peroxide according to the present invention, a low temperature condensation step and a distillation step accompanying the preliminary purification step are not necessary, and a high purity fluorinated peroxide can be prepared without undergoing a distillation step, It is possible to reduce the risks associated with the cold recovery process employed.

Claims (20)

A method of preparing high purity fluorinated peroxide by reacting carbonyl fluoride with hypofluorite, (a) reacting carbonyl fluoride with hypofluorite to form a gas phase reaction product consisting of fluorinated peroxide and unreacted carbonyl fluoride and containing less than 0.5% unreacted hypofluorite; (b) removing the unreacted carbonyl fluoride from the gas phase reaction product formed in step (a) under gas phase conditions, thereby producing a gaseous product stream containing the fluorinated peroxide; And (c) collecting the fluorinated peroxide produced from step (b) in the gas phase How to include. The method of claim 1, wherein the reaction synthesis described in step (a) is selected from the group consisting of: (a1) an excess COF ₂ a R _f OOCF ₃ and unreacted COF ₂ is reacting R _f OF, and under conditions in which to form (wherein, R _f is C _x F _{2x + 1,} x is 1 to 8, Im); And (a2) and the excess _{COF 2 R 'f (OOCF 3} ) 2 , and under conditions such that the unreacted COF ₂ formation R' _f (OF) ₂ and reacting (where, R _'f is C _x F _2x, x Is 1 to 8). The process of claim 1 wherein the molar ratio of carbonyl fluoride to hypofluorite is from 1.1 to 3: 1. The process of claim 3 wherein the gaseous reaction product formed in step (a) is contacted with an aqueous medium under conditions for hydrolyzing unreacted carbonyl fluoride. 5. The method of claim 4, wherein water is removed from the contacted gaseous reaction product by passing the contacted gaseous reaction product through an adsorbent in the adsorption bed under conditions effective to remove residual water. The method of claim 5 wherein the adsorbent is a zeolite molecular sieve. The method of claim 6, wherein the molecular sieve is a 3 ′ or 4 ′ molecular sieve. The method of claim 1 wherein the hypo-fluorite is C _1-8 alkyl hypo-fluorite and C _1-8 alkyl hypo-fluoro bis selected from the group consisting of light. The method of claim 8, wherein the hypofluorite is trifluoromethyl hypofluorite, chlorodifluoromethyl hypofluorite, pentafluoroethyl hypofluorite, heptafluoropropyl hypofluorite and bis (fluorooxy) di. And fluoromethane. The process of claim 1 wherein the molar ratio of carbonyl fluoride to hypofluorite is 1.2 to 1.7: 1. The process of claim 3 wherein the reaction product formed in step (a) contains less than 0.05% by weight unreacted hypofluorite. As a method of preparing bis (trifluoromethyl) peroxide, (a) reacting carbonyl fluoride with trifluoromethyl hypofluorite, consisting of bis (trifluoromethyl) peroxide, unreacted carbonyl fluoride and by-product, with less than 0.5% trifluoromethyl hypofluorite Forming a gas phase reaction product containing the light; (b) removing the unreacted carbonyl fluoride and byproduct from the gas phase reaction product formed in step (a) under gas phase conditions, thereby producing a gaseous product stream containing said bis (trifluoromethyl) peroxide. step; And (c) collecting the bis (trifluoromethyl) peroxide produced from step (b) in the gas phase How to include. The method of claim 12, wherein the unreacted trifluoromethyl hypofluorite in the gas phase reaction product is present in an amount of less than 0.1 wt%. The process of claim 12, wherein the gas phase reaction product of step (a) is contacted with an aqueous medium under conditions for hydrolyzing the carbonyl fluoride and forming an acidic compound. 15. The method of claim 14, comprising removing any acidic compounds and carbon oxides from the contacted gaseous reaction product by contacting with an adsorbent in the adsorption bed. 13. The process of claim 12 wherein the unreacted carbonyl fluoride and by-products are removed from the gas phase reaction product of step (a) by contact with molecular sieves or soda lime. 13. The process of claim 12 wherein the molar ratio of carbonyl fluoride to trifluoromethyl hypofluorite used in step (a) is from 1.1 to 3: 1. The method of claim 15, wherein the adsorbent is 3 ′ or 4 ′ zeolite. 13. The method of claim 12, wherein the carbonyl fluoride and trifluoromethyl hypofluorite are preformed before the reaction. 13. The process of claim 12 wherein the molar ratio of carbonyl fluoride to trifluoromethyl hypofluorite used in step (a) is 1.2 to 1.7: 1.