CA1162511A - Process for the preparation of 2-chloro-1,1,1,2,3,3,3- heptafluoropropane - Google Patents
Process for the preparation of 2-chloro-1,1,1,2,3,3,3- heptafluoropropaneInfo
- Publication number
- CA1162511A CA1162511A CA000376831A CA376831A CA1162511A CA 1162511 A CA1162511 A CA 1162511A CA 000376831 A CA000376831 A CA 000376831A CA 376831 A CA376831 A CA 376831A CA 1162511 A CA1162511 A CA 1162511A
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- Prior art keywords
- heptafluoropropane
- chlorine
- chloro
- preparation
- gas
- Prior art date
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Classifications
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
- C07C17/093—Preparation of halogenated hydrocarbons by replacement by halogens
- C07C17/10—Preparation of halogenated hydrocarbons by replacement by halogens of hydrogen atoms
Abstract
Abstract:
Process for the preparation of 2-chloro-1,1,1,2,3,3,3-heptafluoropropane The invention relates to a process for the sel-ective preparation of 2-chloro-1,1,1,2,3,3,3-heptafluoro-propane, wherein 1,1,1,2,3,3,3-heptafluoropropane is reacted in the gas phase with elementary chlorine in the presence of high-energy radiation at reaction temperatures in the range of from -30° to +500°C.
Process for the preparation of 2-chloro-1,1,1,2,3,3,3-heptafluoropropane The invention relates to a process for the sel-ective preparation of 2-chloro-1,1,1,2,3,3,3-heptafluoro-propane, wherein 1,1,1,2,3,3,3-heptafluoropropane is reacted in the gas phase with elementary chlorine in the presence of high-energy radiation at reaction temperatures in the range of from -30° to +500°C.
Description
~ 162~11 The presen-t in-~entlon relates -tc a process for the selective preparation o~ 2-chlo~o-1,1,1,~,3,~,3-heptafluoro-propane ("2~chloro-heptafluoroprop~ne") by photochlorination of 1,1,1,2 3 3,3,3--heptafluoropropane ("2H-heptafluoropropane").
2~Chloro-heptafluoropropane (boiling point -2C) belongs to the category of the completely halo-genated alkanes, which is distinguished by exceptional thermal and chemical stability, non-flammability and special electrical and other physical properties.
2-Chloro-heptaf]uoropropanecanbe ernployed,inter alia, as a coolant or heat transfer medium, as an inert sol~ent-or cleaning agent for low temperature use, as a gasecus or liquid inert medium, for example as a dielectric or insulating medium, as a fire-extinguishin~ agent or additive to fire~extinguishing agents, or as an etchan-t for silicon dioxide layers on silicon. In the patent literat-ure, 2~chloro-heptafluoropropane has been pro-posed as a blowin~ agent or blowing agent componen-t (U.S. Patent 4,057,973), and for the preparation of sol-uble, fusible polymers of :low flammability from more easily fla~mable polymers by irradiation (Ge man Paten-t 1,213,117). Accordingly, there is considerable interest in a simple and economical process, which does not pollute the environment, for the preparation of the compound shown in the title.
2-Ch~oro-heptafluoropropane has already been described repeatedly in the litera-ture. Most pro-cesses for its prepara-tion are based on -the :~luorination ~.
of a C3-compour.d:
~ lUS~ accordin~ toU S.Patent 2,466,i89, the com-poundCF~CCl~CF3 canbe obtairledby fluorinating 2-chloro-pentafluoropropene with hydrogen fluoride and l~ad diox de in an au-toclave, whilst according to British Patent 839,0~4 it can be obtained by an addition reac-tion of elementary fluorine with 2-chloro-pentafluoro-propene. The fluorination of l,l,l-trifluoro-tri-chloropropene by means of cobalt trifluoride, in accord-ance with U.S. Pa-tent 2,670,387 also produces 2~chloro-heptafluoropropane, in low yield.
The fluorination of 3-chloro-prop-2-ene with hydro~en fl~loride at temperatures above 500C, in accordance ~ith the process of U.S. Patent 3,047,6~
results i.n a yield of about 50~6 of the title compound.
According to U.S. Patent 2,831,035, -the reaction of fluorlne or of chlorine trifluoride with CF3CC12CClF2 or CF3CC12CC12F in the presence of an aluminum fluoride catalyst ~esults in the formation of no-t only octa-fluoropropane but also 2-ch]oro-heptafluoropropane.
On a labo.ratory scale, the title compowld can be prepared in yields of over ~0% by an addi.-tion reac-tion of chlorine fluoride with hexalluoropropene (D. D.
Moldavski.~ Y. G. Temchenko e-t a]., Zh. Org. Khim. ~, 2~ 673)- Howevel, transfer of this process -to an indus-trial scal.e is difficul.t, since by-products which are difficult to separate off are for~ed and the chlorine fluoride employed is highly toxic, is awkward -to handle, since, for exa~ple9 it reacts vigorously with glasr; and 2~
e~plosively with hydrogen-containing compounds, and must~ furthermore, in its turn be prepared from ~le--mantary fluorine and chlorine.
None of the known processcs is suitable for the selective preparation of 2-chloro-heptafluoropropane in high yields. ln all the processes, fragmentation reactions or other competitlve reactions occur to a con-siderable degree. The undesired by~products reduce the yield and make extensive distillation operations necessary. Furthermore, the known methods of pre-paration require starting compour.ds which are difficult to obtain, ~meconomical fluorinating agents or high reaction temperatures, which resu]t in increased cor-rosion of the reactor materials and short lives of catalysts.
Accordingly, there existed the problem o:~ pro-viding a sil~ple process for the selective preparation of 2 chloro-heptafluolopropane, which is based on easily accessible starting materials and proceeds with high yields.
This problem is solved by the invention defined in the main claim.
The process according to the inven-tior can be operated continuously in the manner of conventional gas/gas reactions. A solid catalyst is not required for -this purpose. The preferred -tempera-hlre range is from 20 to 450C, especially from 30 to 400C, and more particularly from 4-0 to 350C.
~ igh-energy light means, in the present context, ~ 5 -radiatio-n w~lich is capable of decomposing chlorine molecules in-to chlorine atoms, in particular visible light and ultraviolet ligh-t in the range of from 450 to 260 nm. The process according to the invention can be described by the equation CF3-CH~-CF3 ~ C12 ~ CF -CClE'-CF + HCl The reaction can be carried out in a corven-tional irradiationapparatus, such as is used, for example, for chlorinating toluene to give benzyl ]o chloride. Such an apparatus consistsS for e~ample, of a glass flask into whlch a mercury high-pressure immersion lamp provided with a quartz tube is in-tro-duced. The glass flask is additionally equipped ^rith a gas inlet tube, an internal thermometer, a condenser ~Jhlch is cooled with carbon dioxide1 and a drainage stopcock attached to the bottom. The glass flask should be capable of being externally heated at the level of theimmersion lamp and a-t the level of the drainage stopcock.
In general, the meterèd gaseous starting pro-ducts are ir.-troduced as a mixture into the glass flask.
m e gas mix-ture leaving the reactor is washed with wa-ter, whereby hydrogen chloride formed is absorbed.
Thereaf-ter, the residual ch]orine is rernoved with thio-sulfate solution and dilute sodium hydroxide solution and -the produc-t is dried by means of -towcrs which are Iilled wi-th calcium chloride or with phosphorus pen-t-- oxide. The crude product can be condensed in suitable cold traps.
1 ~2~11 The boiling points of starting materials and end products are summarized in the -table below:
Product or Formula Molecular Boiling material weight point/
1 bar ... . . .
2H-Heptafluoropropane CF3CHFCF3 170.03 -18C
Chlorine C12 70.96 -34.1 Hydrogen chloride HCl 36.46 -~5 2Cl-HeptafluoropropaneCF3CClFCF3 204.47 -2 . . .
m e 2H-heptafluoropropane emplcyed is of technical-grade purity and is advantageously anhydrous, ie. it is preferably clried with phosphorus pen-to;~ide.
2H-Heptafluoropropane is easily obtainable b~r the quantitative addition reaction of hydrogen fluoride with hexafluoropropene, for example in accordance with German Offenlegungsschrift 2,7]2,732. Chlorine is taken from a commercial steel cylinder and is advan-tageously employed in the anhydrous form, ie. it is dried with, for example, concentrated sulfuric acid.
The conversion of 2H-heptafluoropropalle at 300 and atmospheric pressure is abou-t 0.1 to 3 moles/l of reactor volume per hour, depending on the radiation intensity. Lower throughputs are readily achieva~]e.
At higher pressures, the conversion can be correspond-ingly higher. In generals the chlorine is added without ~ilution; the amount of ch]orine is in general between 0.1 and 3.5 moles/l of reac-tor volume per hour.
The amo~mt ofshlorine shouldbe at leas-tequivalent to the an~ount Of 2H-heptafluoropropan~ which is added simul+aneously J1~2511 and contjnuously. A slight excess of chlorine is preferred. The molar ratio of 2H-heptafluoroprop~ne/
chlorine is, for example, be-tween 1 : 1.5 and 1 : 1, preferably bet~Yeen 1 :1.15 and 1 : 1.05. Quantitat-ive conversion of ~H-heptafluoropropane can be achieved by uslng an excess of chlorine. Whilst larger excesses of chlorine are feasible, they are no-t advan-tageous, since, if an efficient condenser is used, there is the danger that unconverted chlorine liquefi~d in the condenser and flowing back into the irraclia-tion reactor may lower the temperature in the reactor and accordingly lead to a reduction in the rate of r~action.
Furthermore, the excess of chlorine increases the effort en-tailed in wor~ing up by distillation. Any maJor excess of chlorine is advantageously removed ~rom the ~aseous reaction products by fractional distil-lation; the recovered chlorine can be re-used.
Whilst it is possible to employ a less than equival~nt amount of chlorine, this reduces the conversion and increases the effort entailed in working up.
In general, the process is carried ou-t without addition of an inert gas. Whilst dilution with an iner-t gas, such as, for examp]e, ni-trogen, is ~easible, i-t does not offer any significan-t advantages.
The irradiation reac-tlon can be carried out over a wide tempera-ture range, of from 30 to ~500C;
however, the reaction proceeds only slowly in the range of Irom -30 to -~l~0C. Accordingly, temperatures - above 40C are preferred. ~,~ils-t temperatures in the ~1~;251~
range oI from 350 -to 500C are fcasible they are dis-advantageous from the point of view of energy consumption.
The residence time o~ the starting materials and of the end products in -the reac-tor is not critical;
it can, for example, vary bet~een a few seconds and a few minu-tes, without the composition of the crude pro~ j ducts being adversely affected by the occurrence of side-reactions or secondary reactions. On -the other hand, econornical considera~ions impose an upper limit on the residence time. Accordingly, it is advantage-ous, for a high space--time yield, that the reaction products formed should be removed trom the reactor as promptly as possible.
~he hydrogen chloride formedisin general dis-charged at the top, through a condenser cooled with solid carbon dioxide. ~le 2-chloro-hep~afluoropro-pane formed, which collects at the bottom of the reactor, can also be taken off continuously, through a stopcock.
The process according to the invention is in general carried out under a-tmospheric pressure, but the use of reduced pressure or superatmospheric pressure (for eY.ample up to 10 barS preferably up to 3 bar) is also possible, within wide limits. In order to achieve high space-time yields, it is preferred to use superatrnospheric pressureO
For reac-tions on an industrial scale, a continu-ous and uniform method of opeiation is desirable. In '~ 162~11 ~ 9 _ the process accc,rding to the invention, continuous introduction of chlorine and 2H-~heptafluoropropane, continuous conduct of the reaction, continuous dis-charge of the reactlon products and continuous working up are readi.ly possible. Further particular advan--tages of the conti.nuous procedure are the improved utilization of the s-tarting materials and the small amount of effluent and waste gas produced.
..In the process according to the invention, the conversion of 2H-heptafluoropropane is in general abcve 90% and often above 99jo.
Because of the high selec-tivity of the process according to the invention, the yields of 2-chloro-heptafl.uoropropane are also above 90,~ and often above 98% of theory. The 2-chloro-heptafluoropropane pro--duced i.s obtained in high purity. Workin~ up is therefore extremely simple.
In view of literature statements concerning the lack of reactivity towards chlorine of hydrogen atoms in the immediate vicinity of tri.fluorome-thyl groups, it is surprising -that the subs-titution of hydrogen by chlorine in 2H-he~afluoroprop.lne proceeds so s~noothly in the process according to the invention.
It is known tha-t in comparable compournds such as C~3~CrI2-CF3 and CF3-CH--CF~, hydrogel~ is no-t replaced CCl~ -by chlorlne (Houben-Weyl 5 Methoden der organi.schen Chemie (~ethods of Or~anic Chemistry), 1962~ volume V/3, pages 59/l-598).
1A ~; 2 5 1 ~
'rhe process is illustra-ted by the Examples which follow.
Example 1 r~le experimental arrangement consists of a mu]ti-neck irradiation flask made of~ DURAN glas.s, which has a capacity of 2 liters and into which an ultraviolet high-pressure mercury i~nersion lamp pro-vided with a thin-walled quartz glass tube is intro-duced. m e irradiation flash is additionally equipped with a gas i.nlet tube, which terminates near the in~ersion lamp, an internal thermometer, which extends into the vicinity of the immersion lamp, a con-denser filled with solid C02, which is placed on one of the ground-glass connections attached to the top, and a drainage stopcock located at the bo-ttom of the irradi.ation flask. l~e outer walls can be addition-ally heated externally,by means of electrical radian-theaters, at the level of the immersion lamp and a-t the level oI
the drainage stopcock. Both the upper exi-t o.f the condenser and the exit of the drailnage cock lead to a wash vessel, fil.led wi.th water, to take up the hydrogen chloride formed. m ese wash vessels are followed by wash vessels filled with aqueous lO~o strength Na2S203 solution to take up the excess chlorine5 and vessels filled with aqueous lO~o strength NaOH for the final wash. m ese are then followed by two drying towers, one filled with CaC12 for pre-drying and the other filled with ~25 ior final drying. The gaseous crude prod.uc-t is fillally condensed in a high efficiency cold ~ 3 trap, cooled ~ith C02 Elel~entary chlorine is taken from a cor~,ercial steel cylinder, dried with concentrated H2S04, metered by means of a flowme-ter and mixed with the stream of 5 CF3CI-IFCF3 gas.
2H-Heptafluoropropane is prepared in accordance with German Offenlegungsschrift 2,712,732, by hydro-fluorination of hexafluoropropene in the presence of a chromium oxyfluoride catalyst. I-t is dried with P205, metered by means of a flo~eter and mixed with tne stream of C12.
BefoIe starting the photochlorination, the reac-tion chamber, which has beforehand been flushed with N2, is pre-heate~ by switching on the ultraviolet lamp;
this results in temperatures of about 150 to 180C in the reactor chamber. In the immediate vicinity of the immersion lamp, tempera-tures of 260 to 300C are measured on the quartz glass.
To pho-tochlorinate 2iI-heptafluoropropane, a tot;al of 76 g (0.45 mole) of CF3C~IFCF3 and 33 g (0./i6 mole) of ch~orine, corresponding to a molar ratio of CF3CIIFCF3: C12 of 1 : 1.02, is introduced in -the course of 2 hoursi at temperatures of 120 to 90C. During the e~periment; the hydrogen chloride evolved which is not retained by the condenser is absorbed in the wash water receiver. After completion oI`-the reaction, flushing with N2 is employed in order to wash -the entire hydrogen chloride into the wash water. In the pre-sent example (1) the other gaseous reaction p-oduc-ts, i 1~251 1 which collect at the bot-tom of the irradlation vessel, are discharged through the drainage stopcock, located at the bottom, onl-~ after completion of the reaction.
0.44 mole of HCl is found, by titration, in the wash water; HF is not found. m e condensed crude product is examined by gas chromatograph~ on a ~ PORAPAK
c~lwnn. This reveals the following:
CF3CCl~CF398.1%
CF3CHECF3 1.7%
CF3CClFCClF2 0.1%
c~3cF3 ~ 0-05%
CF3CF2CF3< 0.05%
The two last-mentioned components are uncon~
verted impurities of the heptafluoropropane employed;
CF3CClFCClF2 is produced by chlorina-tion of C3F6, which is also present in traces in the starting material.
The liquid crude product weiglls 88 g. Accord-ingly the yield of CF3CClFCF3 is 95.4% of theory, based on CF3CHFCF3 conver-ted. The 2-çhloro-1,1,1,2,3,3,3-hepta-fluoropropane is addi-tionally identified by 19F-NMR
measuremen-t, infrared recordings and determination of the boiling point, which is -2C.
Example 2 CF3CHFCF3 is photochlorinated, at tempe~atures of 115 -to 110C at the beginning of the experiment and temperatures of 35 -to 20C at the end of the experiment, by passing into the apparatus of Example (1), in the course of 5.5 hours, a total of 467 g (2 75 moles) of CF3CHFCF3 and 198 g (2.79 moles~ of C12, corresponding 1 1~2~1 1 to a molar rat:o of CF3CHFCF3 : C12 of 1 : 1.01. The condensed reacti.on produc-ts which collect at the bot-tom of the irradiation flask are, as in Example (1), removed via the drainage s-topcoc~s only after completion of the experiment, and are then washed.
1.84 moles of HCl are found by ti-tration in the wash water of the gases. Ana.lysis by gas chromatog-raphy reveals the following composi.-tion of -the condensed crv.de product:
CF3CClFCF3 67.5%
CF3CHFCF3 32.1%
2-Chloro-heptaf]uoropropanecanbe ernployed,inter alia, as a coolant or heat transfer medium, as an inert sol~ent-or cleaning agent for low temperature use, as a gasecus or liquid inert medium, for example as a dielectric or insulating medium, as a fire-extinguishin~ agent or additive to fire~extinguishing agents, or as an etchan-t for silicon dioxide layers on silicon. In the patent literat-ure, 2~chloro-heptafluoropropane has been pro-posed as a blowin~ agent or blowing agent componen-t (U.S. Patent 4,057,973), and for the preparation of sol-uble, fusible polymers of :low flammability from more easily fla~mable polymers by irradiation (Ge man Paten-t 1,213,117). Accordingly, there is considerable interest in a simple and economical process, which does not pollute the environment, for the preparation of the compound shown in the title.
2-Ch~oro-heptafluoropropane has already been described repeatedly in the litera-ture. Most pro-cesses for its prepara-tion are based on -the :~luorination ~.
of a C3-compour.d:
~ lUS~ accordin~ toU S.Patent 2,466,i89, the com-poundCF~CCl~CF3 canbe obtairledby fluorinating 2-chloro-pentafluoropropene with hydrogen fluoride and l~ad diox de in an au-toclave, whilst according to British Patent 839,0~4 it can be obtained by an addition reac-tion of elementary fluorine with 2-chloro-pentafluoro-propene. The fluorination of l,l,l-trifluoro-tri-chloropropene by means of cobalt trifluoride, in accord-ance with U.S. Pa-tent 2,670,387 also produces 2~chloro-heptafluoropropane, in low yield.
The fluorination of 3-chloro-prop-2-ene with hydro~en fl~loride at temperatures above 500C, in accordance ~ith the process of U.S. Patent 3,047,6~
results i.n a yield of about 50~6 of the title compound.
According to U.S. Patent 2,831,035, -the reaction of fluorlne or of chlorine trifluoride with CF3CC12CClF2 or CF3CC12CC12F in the presence of an aluminum fluoride catalyst ~esults in the formation of no-t only octa-fluoropropane but also 2-ch]oro-heptafluoropropane.
On a labo.ratory scale, the title compowld can be prepared in yields of over ~0% by an addi.-tion reac-tion of chlorine fluoride with hexalluoropropene (D. D.
Moldavski.~ Y. G. Temchenko e-t a]., Zh. Org. Khim. ~, 2~ 673)- Howevel, transfer of this process -to an indus-trial scal.e is difficul.t, since by-products which are difficult to separate off are for~ed and the chlorine fluoride employed is highly toxic, is awkward -to handle, since, for exa~ple9 it reacts vigorously with glasr; and 2~
e~plosively with hydrogen-containing compounds, and must~ furthermore, in its turn be prepared from ~le--mantary fluorine and chlorine.
None of the known processcs is suitable for the selective preparation of 2-chloro-heptafluoropropane in high yields. ln all the processes, fragmentation reactions or other competitlve reactions occur to a con-siderable degree. The undesired by~products reduce the yield and make extensive distillation operations necessary. Furthermore, the known methods of pre-paration require starting compour.ds which are difficult to obtain, ~meconomical fluorinating agents or high reaction temperatures, which resu]t in increased cor-rosion of the reactor materials and short lives of catalysts.
Accordingly, there existed the problem o:~ pro-viding a sil~ple process for the selective preparation of 2 chloro-heptafluolopropane, which is based on easily accessible starting materials and proceeds with high yields.
This problem is solved by the invention defined in the main claim.
The process according to the inven-tior can be operated continuously in the manner of conventional gas/gas reactions. A solid catalyst is not required for -this purpose. The preferred -tempera-hlre range is from 20 to 450C, especially from 30 to 400C, and more particularly from 4-0 to 350C.
~ igh-energy light means, in the present context, ~ 5 -radiatio-n w~lich is capable of decomposing chlorine molecules in-to chlorine atoms, in particular visible light and ultraviolet ligh-t in the range of from 450 to 260 nm. The process according to the invention can be described by the equation CF3-CH~-CF3 ~ C12 ~ CF -CClE'-CF + HCl The reaction can be carried out in a corven-tional irradiationapparatus, such as is used, for example, for chlorinating toluene to give benzyl ]o chloride. Such an apparatus consistsS for e~ample, of a glass flask into whlch a mercury high-pressure immersion lamp provided with a quartz tube is in-tro-duced. The glass flask is additionally equipped ^rith a gas inlet tube, an internal thermometer, a condenser ~Jhlch is cooled with carbon dioxide1 and a drainage stopcock attached to the bottom. The glass flask should be capable of being externally heated at the level of theimmersion lamp and a-t the level of the drainage stopcock.
In general, the meterèd gaseous starting pro-ducts are ir.-troduced as a mixture into the glass flask.
m e gas mix-ture leaving the reactor is washed with wa-ter, whereby hydrogen chloride formed is absorbed.
Thereaf-ter, the residual ch]orine is rernoved with thio-sulfate solution and dilute sodium hydroxide solution and -the produc-t is dried by means of -towcrs which are Iilled wi-th calcium chloride or with phosphorus pen-t-- oxide. The crude product can be condensed in suitable cold traps.
1 ~2~11 The boiling points of starting materials and end products are summarized in the -table below:
Product or Formula Molecular Boiling material weight point/
1 bar ... . . .
2H-Heptafluoropropane CF3CHFCF3 170.03 -18C
Chlorine C12 70.96 -34.1 Hydrogen chloride HCl 36.46 -~5 2Cl-HeptafluoropropaneCF3CClFCF3 204.47 -2 . . .
m e 2H-heptafluoropropane emplcyed is of technical-grade purity and is advantageously anhydrous, ie. it is preferably clried with phosphorus pen-to;~ide.
2H-Heptafluoropropane is easily obtainable b~r the quantitative addition reaction of hydrogen fluoride with hexafluoropropene, for example in accordance with German Offenlegungsschrift 2,7]2,732. Chlorine is taken from a commercial steel cylinder and is advan-tageously employed in the anhydrous form, ie. it is dried with, for example, concentrated sulfuric acid.
The conversion of 2H-heptafluoropropalle at 300 and atmospheric pressure is abou-t 0.1 to 3 moles/l of reactor volume per hour, depending on the radiation intensity. Lower throughputs are readily achieva~]e.
At higher pressures, the conversion can be correspond-ingly higher. In generals the chlorine is added without ~ilution; the amount of ch]orine is in general between 0.1 and 3.5 moles/l of reac-tor volume per hour.
The amo~mt ofshlorine shouldbe at leas-tequivalent to the an~ount Of 2H-heptafluoropropan~ which is added simul+aneously J1~2511 and contjnuously. A slight excess of chlorine is preferred. The molar ratio of 2H-heptafluoroprop~ne/
chlorine is, for example, be-tween 1 : 1.5 and 1 : 1, preferably bet~Yeen 1 :1.15 and 1 : 1.05. Quantitat-ive conversion of ~H-heptafluoropropane can be achieved by uslng an excess of chlorine. Whilst larger excesses of chlorine are feasible, they are no-t advan-tageous, since, if an efficient condenser is used, there is the danger that unconverted chlorine liquefi~d in the condenser and flowing back into the irraclia-tion reactor may lower the temperature in the reactor and accordingly lead to a reduction in the rate of r~action.
Furthermore, the excess of chlorine increases the effort en-tailed in wor~ing up by distillation. Any maJor excess of chlorine is advantageously removed ~rom the ~aseous reaction products by fractional distil-lation; the recovered chlorine can be re-used.
Whilst it is possible to employ a less than equival~nt amount of chlorine, this reduces the conversion and increases the effort entailed in working up.
In general, the process is carried ou-t without addition of an inert gas. Whilst dilution with an iner-t gas, such as, for examp]e, ni-trogen, is ~easible, i-t does not offer any significan-t advantages.
The irradiation reac-tlon can be carried out over a wide tempera-ture range, of from 30 to ~500C;
however, the reaction proceeds only slowly in the range of Irom -30 to -~l~0C. Accordingly, temperatures - above 40C are preferred. ~,~ils-t temperatures in the ~1~;251~
range oI from 350 -to 500C are fcasible they are dis-advantageous from the point of view of energy consumption.
The residence time o~ the starting materials and of the end products in -the reac-tor is not critical;
it can, for example, vary bet~een a few seconds and a few minu-tes, without the composition of the crude pro~ j ducts being adversely affected by the occurrence of side-reactions or secondary reactions. On -the other hand, econornical considera~ions impose an upper limit on the residence time. Accordingly, it is advantage-ous, for a high space--time yield, that the reaction products formed should be removed trom the reactor as promptly as possible.
~he hydrogen chloride formedisin general dis-charged at the top, through a condenser cooled with solid carbon dioxide. ~le 2-chloro-hep~afluoropro-pane formed, which collects at the bottom of the reactor, can also be taken off continuously, through a stopcock.
The process according to the invention is in general carried out under a-tmospheric pressure, but the use of reduced pressure or superatmospheric pressure (for eY.ample up to 10 barS preferably up to 3 bar) is also possible, within wide limits. In order to achieve high space-time yields, it is preferred to use superatrnospheric pressureO
For reac-tions on an industrial scale, a continu-ous and uniform method of opeiation is desirable. In '~ 162~11 ~ 9 _ the process accc,rding to the invention, continuous introduction of chlorine and 2H-~heptafluoropropane, continuous conduct of the reaction, continuous dis-charge of the reactlon products and continuous working up are readi.ly possible. Further particular advan--tages of the conti.nuous procedure are the improved utilization of the s-tarting materials and the small amount of effluent and waste gas produced.
..In the process according to the invention, the conversion of 2H-heptafluoropropane is in general abcve 90% and often above 99jo.
Because of the high selec-tivity of the process according to the invention, the yields of 2-chloro-heptafl.uoropropane are also above 90,~ and often above 98% of theory. The 2-chloro-heptafluoropropane pro--duced i.s obtained in high purity. Workin~ up is therefore extremely simple.
In view of literature statements concerning the lack of reactivity towards chlorine of hydrogen atoms in the immediate vicinity of tri.fluorome-thyl groups, it is surprising -that the subs-titution of hydrogen by chlorine in 2H-he~afluoroprop.lne proceeds so s~noothly in the process according to the invention.
It is known tha-t in comparable compournds such as C~3~CrI2-CF3 and CF3-CH--CF~, hydrogel~ is no-t replaced CCl~ -by chlorlne (Houben-Weyl 5 Methoden der organi.schen Chemie (~ethods of Or~anic Chemistry), 1962~ volume V/3, pages 59/l-598).
1A ~; 2 5 1 ~
'rhe process is illustra-ted by the Examples which follow.
Example 1 r~le experimental arrangement consists of a mu]ti-neck irradiation flask made of~ DURAN glas.s, which has a capacity of 2 liters and into which an ultraviolet high-pressure mercury i~nersion lamp pro-vided with a thin-walled quartz glass tube is intro-duced. m e irradiation flash is additionally equipped with a gas i.nlet tube, which terminates near the in~ersion lamp, an internal thermometer, which extends into the vicinity of the immersion lamp, a con-denser filled with solid C02, which is placed on one of the ground-glass connections attached to the top, and a drainage stopcock located at the bo-ttom of the irradi.ation flask. l~e outer walls can be addition-ally heated externally,by means of electrical radian-theaters, at the level of the immersion lamp and a-t the level oI
the drainage stopcock. Both the upper exi-t o.f the condenser and the exit of the drailnage cock lead to a wash vessel, fil.led wi.th water, to take up the hydrogen chloride formed. m ese wash vessels are followed by wash vessels filled with aqueous lO~o strength Na2S203 solution to take up the excess chlorine5 and vessels filled with aqueous lO~o strength NaOH for the final wash. m ese are then followed by two drying towers, one filled with CaC12 for pre-drying and the other filled with ~25 ior final drying. The gaseous crude prod.uc-t is fillally condensed in a high efficiency cold ~ 3 trap, cooled ~ith C02 Elel~entary chlorine is taken from a cor~,ercial steel cylinder, dried with concentrated H2S04, metered by means of a flowme-ter and mixed with the stream of 5 CF3CI-IFCF3 gas.
2H-Heptafluoropropane is prepared in accordance with German Offenlegungsschrift 2,712,732, by hydro-fluorination of hexafluoropropene in the presence of a chromium oxyfluoride catalyst. I-t is dried with P205, metered by means of a flo~eter and mixed with tne stream of C12.
BefoIe starting the photochlorination, the reac-tion chamber, which has beforehand been flushed with N2, is pre-heate~ by switching on the ultraviolet lamp;
this results in temperatures of about 150 to 180C in the reactor chamber. In the immediate vicinity of the immersion lamp, tempera-tures of 260 to 300C are measured on the quartz glass.
To pho-tochlorinate 2iI-heptafluoropropane, a tot;al of 76 g (0.45 mole) of CF3C~IFCF3 and 33 g (0./i6 mole) of ch~orine, corresponding to a molar ratio of CF3CIIFCF3: C12 of 1 : 1.02, is introduced in -the course of 2 hoursi at temperatures of 120 to 90C. During the e~periment; the hydrogen chloride evolved which is not retained by the condenser is absorbed in the wash water receiver. After completion oI`-the reaction, flushing with N2 is employed in order to wash -the entire hydrogen chloride into the wash water. In the pre-sent example (1) the other gaseous reaction p-oduc-ts, i 1~251 1 which collect at the bot-tom of the irradlation vessel, are discharged through the drainage stopcock, located at the bottom, onl-~ after completion of the reaction.
0.44 mole of HCl is found, by titration, in the wash water; HF is not found. m e condensed crude product is examined by gas chromatograph~ on a ~ PORAPAK
c~lwnn. This reveals the following:
CF3CCl~CF398.1%
CF3CHECF3 1.7%
CF3CClFCClF2 0.1%
c~3cF3 ~ 0-05%
CF3CF2CF3< 0.05%
The two last-mentioned components are uncon~
verted impurities of the heptafluoropropane employed;
CF3CClFCClF2 is produced by chlorina-tion of C3F6, which is also present in traces in the starting material.
The liquid crude product weiglls 88 g. Accord-ingly the yield of CF3CClFCF3 is 95.4% of theory, based on CF3CHFCF3 conver-ted. The 2-çhloro-1,1,1,2,3,3,3-hepta-fluoropropane is addi-tionally identified by 19F-NMR
measuremen-t, infrared recordings and determination of the boiling point, which is -2C.
Example 2 CF3CHFCF3 is photochlorinated, at tempe~atures of 115 -to 110C at the beginning of the experiment and temperatures of 35 -to 20C at the end of the experiment, by passing into the apparatus of Example (1), in the course of 5.5 hours, a total of 467 g (2 75 moles) of CF3CHFCF3 and 198 g (2.79 moles~ of C12, corresponding 1 1~2~1 1 to a molar rat:o of CF3CHFCF3 : C12 of 1 : 1.01. The condensed reacti.on produc-ts which collect at the bot-tom of the irradiation flask are, as in Example (1), removed via the drainage s-topcoc~s only after completion of the experiment, and are then washed.
1.84 moles of HCl are found by ti-tration in the wash water of the gases. Ana.lysis by gas chromatog-raphy reveals the following composi.-tion of -the condensed crv.de product:
CF3CClFCF3 67.5%
CF3CHFCF3 32.1%
3 other components each 0.1%
The condensate weighs 512 g. m e yield of CF3CClFCF~
i~ accordin~ly 90.5% of theory, based on CF3C~FCF3 con-verted; however, the conversion of CF3C}IFCF3 is onlyabout ~8~.
A total of 495 g (2.91 moles) of CF3CHFCF3 and 217 g ~3 06 moles) of chlorine, corresponding to a molar ra-tio of CF3CHFCF~ : C12 of 1 : 1.05, are introduced as gas, in the course of 5 hours, into the apparatus of Examp]e (1), a-t temperatures of 120 to 110C, which can be mai.ntained over the entire experiment. m e reac ti.on products whlch collect are discharged con-tinuously and uniformly via the drainage stopcock, locateda-t-thebot-tom of-theirradia-tion ~lask, excep-tfor acons-ta.ntly remaining residua~ amoun-t of about 10 to 15 ml, and are then ~ashed.
2.76 moles of HCl ~re found in the wash wa-ter of 5 ~ J
_ 14 -~the gascs. Gas chromatography rneasurements on the collected condensed crude product show the following composition:
CF3CC] FCF395 3%
CF3CHFCF33~ 9%
Remainder: secondary components 0~8%.
m e condensate weighs 585 g. Accordingly the yield of CF3CClFCF3 is 97.6% of theory, based on CF3CEJFCF~
converted.
Example 4 A total of 1,080 g (6.35 moles) of CF3CHFCF3 and 526 g (7.41 moles) of chlorine, corresponding to a molar ratio of CF3CHFCF3 : C12 of 1 : 1.17, is int;ro-duced, in the course of 7.5 hours, into the apparatus of Example (1), at t~mperatures of 135 to 125C. The outer walls of the flask are additionally heated, at the level of the immersion lamp and of the drainage stop-cock, by means of electrical radiant hea-ters. ~s in Example (3), -the reaction products which collect are discharged continuously and uniformly from the flask.
6. 31 moles of HCl are foun~l in the wash ~a-ter.
.nalysis by gas chromato~raphy reveals -the fol:Lowing composition of the crude product:
CF3CClFCF399. 7%
CF3CHFCF30.15%
CF3CClFCClF2< 0.025' CF3CF2CF3~ 0,05%
CF3CE~FCClF~0.1~6 .
The condense~te ~-eighs 1,289 g; accordi.ngly the yield of CF3CClFCF3 is 99.1% of theory, based on CF3CHFCF3 con verted. The conversion of CF3CIIFCF3 is 99.85% of theory, .
The condensate weighs 512 g. m e yield of CF3CClFCF~
i~ accordin~ly 90.5% of theory, based on CF3C~FCF3 con-verted; however, the conversion of CF3C}IFCF3 is onlyabout ~8~.
A total of 495 g (2.91 moles) of CF3CHFCF3 and 217 g ~3 06 moles) of chlorine, corresponding to a molar ra-tio of CF3CHFCF~ : C12 of 1 : 1.05, are introduced as gas, in the course of 5 hours, into the apparatus of Examp]e (1), a-t temperatures of 120 to 110C, which can be mai.ntained over the entire experiment. m e reac ti.on products whlch collect are discharged con-tinuously and uniformly via the drainage stopcock, locateda-t-thebot-tom of-theirradia-tion ~lask, excep-tfor acons-ta.ntly remaining residua~ amoun-t of about 10 to 15 ml, and are then ~ashed.
2.76 moles of HCl ~re found in the wash wa-ter of 5 ~ J
_ 14 -~the gascs. Gas chromatography rneasurements on the collected condensed crude product show the following composition:
CF3CC] FCF395 3%
CF3CHFCF33~ 9%
Remainder: secondary components 0~8%.
m e condensate weighs 585 g. Accordingly the yield of CF3CClFCF3 is 97.6% of theory, based on CF3CEJFCF~
converted.
Example 4 A total of 1,080 g (6.35 moles) of CF3CHFCF3 and 526 g (7.41 moles) of chlorine, corresponding to a molar ratio of CF3CHFCF3 : C12 of 1 : 1.17, is int;ro-duced, in the course of 7.5 hours, into the apparatus of Example (1), at t~mperatures of 135 to 125C. The outer walls of the flask are additionally heated, at the level of the immersion lamp and of the drainage stop-cock, by means of electrical radiant hea-ters. ~s in Example (3), -the reaction products which collect are discharged continuously and uniformly from the flask.
6. 31 moles of HCl are foun~l in the wash ~a-ter.
.nalysis by gas chromato~raphy reveals -the fol:Lowing composition of the crude product:
CF3CClFCF399. 7%
CF3CHFCF30.15%
CF3CClFCClF2< 0.025' CF3CF2CF3~ 0,05%
CF3CE~FCClF~0.1~6 .
The condense~te ~-eighs 1,289 g; accordi.ngly the yield of CF3CClFCF3 is 99.1% of theory, based on CF3CHFCF3 con verted. The conversion of CF3CIIFCF3 is 99.85% of theory, .
Claims (3)
1. A process for the selective preparation of 2-chloro-1,1,1,2,3,3,3-heptafluoropropane (I), wherein 1,1,1,2,3,3,3-heptafluoropropane (II) is reacted in the gas phase with elementary chlorine in the presence of high-energy radiation at reaction temperatures in the range of from -30° to +500°C.
2. A process as claimed in claim 1, wherein (II) is reacted with chlorine in a molar ratio of 1 : 1.0 to 1 : 1.5, preferably of 1 : 1.05 to 1 : 1.15.
3. A process as claimed in claim 2, wherein the reaction temperatures are from 40° to 450°C.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19803017154 DE3017154A1 (en) | 1980-05-05 | 1980-05-05 | METHOD FOR PRODUCING 2-CHLORINE-1,1,1,2,3,3,3, -HEPTAFLUOR-PROPANE |
| DEP3017154.1 | 1980-05-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1162511A true CA1162511A (en) | 1984-02-21 |
Family
ID=6101633
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000376831A Expired CA1162511A (en) | 1980-05-05 | 1981-05-04 | Process for the preparation of 2-chloro-1,1,1,2,3,3,3- heptafluoropropane |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0039471A1 (en) |
| JP (1) | JPS56169632A (en) |
| BR (1) | BR8102724A (en) |
| CA (1) | CA1162511A (en) |
| DE (1) | DE3017154A1 (en) |
| ES (1) | ES501729A0 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7151197B2 (en) | 2001-09-28 | 2006-12-19 | Great Lakes Chemical Corporation | Processes for purifying chlorofluorinated compounds and processes for purifying CF3CFHCF3 |
| US7216722B2 (en) | 2003-04-17 | 2007-05-15 | Great Lakes Chemical Corporation | Fire extinguishing mixtures, methods and systems |
| AU2003303566B2 (en) * | 2002-12-30 | 2007-07-19 | Great Lakes Chemical Corporation | Materials and methods for the conversion of hydrofluorocarbons |
| US7368089B2 (en) | 2003-08-13 | 2008-05-06 | Great Lakes Chemical Corporation | Systems and methods for producing fluorocarbons |
| US8367879B2 (en) | 2007-11-09 | 2013-02-05 | Mexichem Amanco Holding S.A. De C.V. | Method for the preparation of 2 chloro 1,1,1,2,3,3,3 heptafluoropropane |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0407619A1 (en) * | 1989-02-02 | 1991-01-16 | Asahi Glass Company Ltd. | Process for producing a chlorine-containing 2,2-difluoropropane |
| DE3908551A1 (en) * | 1989-03-16 | 1990-09-20 | Hoechst Ag | FUEL MEDIUM FOR SENSOR SYSTEMS FROM TEMPERATURE-WAY TRANSMITTERS |
| RU2293583C2 (en) * | 1989-08-21 | 2007-02-20 | Грейт Лейкс Кемикал Корпорейшн | Fire-extinguishing method |
| US5057634A (en) * | 1989-12-19 | 1991-10-15 | E. I. Du Pont De Nemours And Company | Multistep synthesis of hexafluoropropylene |
| US5043491A (en) * | 1989-12-19 | 1991-08-27 | E. I. Du Pont De Nemours And Company | Multistep synthesis of hexafluoropropylene |
| JPH0595658U (en) * | 1992-01-21 | 1993-12-27 | 株式会社明星金属工業所 | Mini type crusher for synthetic resin molding runner |
| IT1301758B1 (en) | 1998-06-19 | 2000-07-07 | Ausimont Spa | 227 PREPARATION PROCESS |
| EP1059092B1 (en) | 1999-06-08 | 2005-12-07 | Gentium S.p.A. | Use of complexes among cationic liposomes and polydeoxyribonucleotides as medicaments |
| US6551469B1 (en) * | 2001-11-27 | 2003-04-22 | Honeywell International | Photochlorination of 1,1,1,3,3-pentafluoropropane |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB839034A (en) * | 1945-06-25 | 1960-06-29 | William Taylor Miller | Halogenated hydrocarbons and compositions and methods of production thereof |
| US2658928A (en) * | 1947-03-31 | 1953-11-10 | Minnesota Mining & Mfg | Method of making fluorocarbon chlorides and bromides by thermal chlorination and bromination of fluorocarbon hydrides |
-
1980
- 1980-05-05 DE DE19803017154 patent/DE3017154A1/en not_active Withdrawn
-
1981
- 1981-04-28 ES ES501729A patent/ES501729A0/en active Granted
- 1981-04-29 EP EP19810103200 patent/EP0039471A1/en not_active Withdrawn
- 1981-05-01 JP JP6530781A patent/JPS56169632A/en active Pending
- 1981-05-04 BR BR8102724A patent/BR8102724A/en unknown
- 1981-05-04 CA CA000376831A patent/CA1162511A/en not_active Expired
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7151197B2 (en) | 2001-09-28 | 2006-12-19 | Great Lakes Chemical Corporation | Processes for purifying chlorofluorinated compounds and processes for purifying CF3CFHCF3 |
| US7329786B2 (en) | 2001-09-28 | 2008-02-12 | Great Lakes Chemical Corporation | Processes for producing CF3CFHCF3 |
| US7332635B2 (en) | 2001-09-28 | 2008-02-19 | Great Lakes Chemical Corporation | Processes for purifying chlorofluorinated compounds |
| US7335805B2 (en) | 2001-09-28 | 2008-02-26 | Great Lakes Chemical Corporation | Processes for purifying reaction products and processes for separating chlorofluorinated compounds |
| US7348461B2 (en) | 2001-09-28 | 2008-03-25 | Great Lakes Chemical Corporation | Processes for halogenating compounds |
| AU2003303566B2 (en) * | 2002-12-30 | 2007-07-19 | Great Lakes Chemical Corporation | Materials and methods for the conversion of hydrofluorocarbons |
| US7250539B2 (en) | 2002-12-30 | 2007-07-31 | Great Lakes Chemical Corp. | Materials and methods for the conversion of hydrofluorocarbons |
| US7268261B2 (en) | 2002-12-30 | 2007-09-11 | Great Lakes Chemical Corporation | Production processes |
| US7216722B2 (en) | 2003-04-17 | 2007-05-15 | Great Lakes Chemical Corporation | Fire extinguishing mixtures, methods and systems |
| US7223351B2 (en) | 2003-04-17 | 2007-05-29 | Great Lakes Chemical Corporation | Fire extinguishing mixtures, methods and systems |
| US7368089B2 (en) | 2003-08-13 | 2008-05-06 | Great Lakes Chemical Corporation | Systems and methods for producing fluorocarbons |
| US8367879B2 (en) | 2007-11-09 | 2013-02-05 | Mexichem Amanco Holding S.A. De C.V. | Method for the preparation of 2 chloro 1,1,1,2,3,3,3 heptafluoropropane |
Also Published As
| Publication number | Publication date |
|---|---|
| ES8202530A1 (en) | 1982-02-16 |
| BR8102724A (en) | 1982-01-26 |
| EP0039471A1 (en) | 1981-11-11 |
| DE3017154A1 (en) | 1981-11-12 |
| JPS56169632A (en) | 1981-12-26 |
| ES501729A0 (en) | 1982-02-16 |
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