CA1191147A - Process for preparing tetramethyloxirane - Google Patents
Process for preparing tetramethyloxiraneInfo
- Publication number
- CA1191147A CA1191147A CA000410656A CA410656A CA1191147A CA 1191147 A CA1191147 A CA 1191147A CA 000410656 A CA000410656 A CA 000410656A CA 410656 A CA410656 A CA 410656A CA 1191147 A CA1191147 A CA 1191147A
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- reaction
- oxygen
- dimethyl
- butene
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D303/00—Compounds containing three-membered rings having one oxygen atom as the only ring hetero atom
- C07D303/02—Compounds containing oxirane rings
- C07D303/04—Compounds containing oxirane rings containing only hydrogen and carbon atoms in addition to the ring oxygen atoms
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D301/00—Preparation of oxiranes
- C07D301/02—Synthesis of the oxirane ring
- C07D301/03—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds
- C07D301/04—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds with air or molecular oxygen
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Epoxy Compounds (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Tetramethyloxirane is prepared by reacting 2,3-dimethylbutene with oxygen or with an oxygen-containing gas at temperatures of 40 to 180°C and for residence times of 5 to 150 minutes without the addition of catalysts and separating off tetramethyloxirane.
Tetramethyloxirane is prepared by reacting 2,3-dimethylbutene with oxygen or with an oxygen-containing gas at temperatures of 40 to 180°C and for residence times of 5 to 150 minutes without the addition of catalysts and separating off tetramethyloxirane.
Description
~ 318')-5423 Ihe presollt invelltion -r~lates to n procoss tor prel)arirlg tetra-metllyloxiralle ~2,3-cl:imetllyl-2,3-epoxyl)utLllle) :Eroln 2,X-cl:imothylbuterles ancl oxygell or oxygen-con-tainiilg gases.
Oxiranes are used in the paint field, for the preparation oE poly-ethers, poLyurethanes, epoxy resins, detergents and glycols and as intermediate products (see, for example, U.S. 2,412,136).
Ethylene oxide, an important compound from the group comprising the oxiranes, is prepared industrially by oxidizing ethylene with molecular oxygen in the gas phase in the presence of silver catalysts ~see, Eor example, U.S.
Oxiranes are used in the paint field, for the preparation oE poly-ethers, poLyurethanes, epoxy resins, detergents and glycols and as intermediate products (see, for example, U.S. 2,412,136).
Ethylene oxide, an important compound from the group comprising the oxiranes, is prepared industrially by oxidizing ethylene with molecular oxygen in the gas phase in the presence of silver catalysts ~see, Eor example, U.S.
2,693,474). This method has not yet been transferred successfully to higher olefins since then secondary reactions take place to a large extent and criti-cally reduce the profitability oE such a process ~see U.S. 2,412,136).
It is known to prepare oxiranes by co-ox:iclizing alkenes and aldehydes with oxygen. I`hus~ Eor example, one C.lll prepare tetrametilyloxircme by co-oxidi~ing 2,3-dime-thyl-2-butene ancl acetaldehyde in chloroben~ene as solvent at 40 C in a yield of up to 84% ~determined by gas chromatography) ~see ~l. Krapf and M.R. Yazdanbakch, Synthesis _977, page 172, fourth example in the tab;le).
It is a great disadv~mtage for the economic feasibility oE this pro-cess that one mol of acetic acid is formed per mole of oxirane. The acetic acid must be removecl before further working up from the reaction mixture, for example by extraction with sodium hydrogen carbonate solution, since the tetra-methyloxirane formed is split by acetic acid and can therefore be isolated only with losses of material ~see I. Swern "Organic Peroxides", Volume 2, Wiley Interscience, 1971, page 430, lines 9-ll).
Another synthetic route is described in U.S. 3,641,066, ~256,649
It is known to prepare oxiranes by co-ox:iclizing alkenes and aldehydes with oxygen. I`hus~ Eor example, one C.lll prepare tetrametilyloxircme by co-oxidi~ing 2,3-dime-thyl-2-butene ancl acetaldehyde in chloroben~ene as solvent at 40 C in a yield of up to 84% ~determined by gas chromatography) ~see ~l. Krapf and M.R. Yazdanbakch, Synthesis _977, page 172, fourth example in the tab;le).
It is a great disadv~mtage for the economic feasibility oE this pro-cess that one mol of acetic acid is formed per mole of oxirane. The acetic acid must be removecl before further working up from the reaction mixture, for example by extraction with sodium hydrogen carbonate solution, since the tetra-methyloxirane formed is split by acetic acid and can therefore be isolated only with losses of material ~see I. Swern "Organic Peroxides", Volume 2, Wiley Interscience, 1971, page 430, lines 9-ll).
Another synthetic route is described in U.S. 3,641,066, ~256,649
3,856,826 and 2,856,827 and involves liquid phase oxidation of olefins with oxygen or oxygen-containing inert gases in the presence of heterogeneous cata-Ge/UG~Gai) Le A 21 068-CA
7.
I','~, ~
lys-ts. 'Ihese l~atellts do not contlirl data conce-rning convelsion and solectivi--ties. Ilowever, the use oE expellsivo catalysts a~d the expense of thc:ir isola--tion, working-up and return is ,aiways unEIvourable.
Arlo-ther method Eor the catalytic oxidat;on of olefins with oxygen is described in U.S. 4,182,722. According to Example B 2, 2,3-dimethyl-2-butene is oxidized at 50C and for a reaction time oE Eive hours in the presence of an X zeolite which has been ion-exchanged with copper2 and vanadium4 salts and which is used as a catalyst. 24% olefin conversion produces 1,2-epoxy-3-hydroxy-2,3-dimethylbutane as main product with a selectivity of 46%. The by-products are tetramethyloxirane with a selectivity of ~0%, 3-hydroxy-2,3-dimethyl-l-butene with 9% selec-tivity and acetone with 6% selectivity. In addi--tion to the already mentioned disadvantages of using catalys-ts, the long reac-tion time of Eive hours, when the olefin conversion is only 24%, and the pre-dominant formation of products other thm tetramethyloxirane are ~ur-thor dis-advantages of this process.
A further process for preparing tetramethyloxirane from te-tramethy1-ethylene (2,3-dimethyl-2-butene) involves the use oE a homogeneous catalyst system consisting of complexes of the formula trans-MCl(CO) (Ph3P)2 (M =
rhodium or iridium; and Ph = phenyl) (see J.E. Lyons and J.O. Turner, J. Org.
Chem. Volume 37, 2881-2884 (1972)). A reaction time of four hours and a reac-tion temperature of 50C, when the conversion of tetramethylethylene is 8 to 66%, produces tetramethyloxirane with selectivities of 25 to 37.5% (see litera-ture reference: page 2882, Table 1). Due to the long reaction time of four hours and the very low selectivities, this route is not an economical process for preparing tetramethyloxirane.
It is also known to react tetramethylethylene with oxygen at 25C in the presence of iron -meso-tetraphenylporphyrine chloride as catalyst (D.R.
I'clulso~ ULII1]I dncl l~.B. Slouno, .I.~..S. Cllelll. Coulm., I(J7~1, p1l~C 187, [~Ibl~).
AE-ter 2~ hours' reclction time, 2,3-climethyl-3-en-2-ol is obtained as ma-irl pro-cluct with a selectivity oE ~5% ancl tetrametllyloxiralle and acetone are obtained as by-produc-ts with a selectivity o-E ~l cmd 14% respectively. 'I'he disadvarlt-ages of this process, in adclition to the catalyst costs, are the long reaction time of 2~ hours and the :Eormation oE 2,3-dimethyl-3-en-2-ol as main product.
Finally, it is known to prepare tetramethyloxirane by oxygen-oxida-tion of te-tramethylethylene a-t 50 C and in a reaction time of 333 minu-tes in the presence of 2,2'-azobis~2-methylpropionitrile) (I.~. Van Sickle, F.R. Mayo, R.M. Arluck and M. Sy~. J. Am. Chem. Soc. 89, 1967, page 971, Table l). This process is not o-E interest industrially, since the tetramethylethylene conver-sion, despite the reaction period oE more than five hours, is only 5% and the tetramethyloxirane selectivi-ty only reaches 15.5%.
'I'here is therefore a neecl Eor a simple ancl effec-tive process Eor pre-paring tetramethylox:ircme.
A process for prepar-i[lg tetrcunethylox:ircme has now been foulld and :it is characterised in that 2,3-climetllylbutenes are reacted with oxygen or an oxygen-containing gas at temperatures o-E ~0 -to 180 C and for residence times oE
5 to 150 minutes without the addition of catalysts and the tetramethyloxirane obtained is separated off.
Possible examples of 2,3-dimetilylbu-tenes which can be used in the pro-cess according to the invention are 2,3-dimethyl-2-butene, 2,3-dime-thyl-1-butene, any mixtures of 2,3-dimethyl-2-butene and 2,3-dimethyl-1-butene and any mixtures of 2,3-dimethyl-2-butene and/or 2,3-dimethyl-1-butene with inert materials.
~xamples of these inert organic diluents are hydrocarbons and chlorinated hydro-carbons of the aliphatic, cycloaliphatic and aromatic series, for example satur-ated aliphatic hydrocarbons, such as n-hexane or dimethylbutane, saturated cyclo-a~ at:LC hyCIrOCa:rl)OI15~ SUCII as decaLi!l, aroma-tic hyclrocarbolls, such a'; L)CnZCnC, toluelle or xylerle ancl clllolinate(l hydrocarbons, :Eor examp]e chlorinatcd arollla-tics. r[`he iner-t organ:ic diluents used preferlbly are n-hexanc, dirnethyl-bu-tane, benzene or chlorinuted hydrocarbons.
2,3-Dimethyl-2-butene and 2,3-dimet}lyl-1-butene àre readily accessible starting materials which can be ob-tained, for example, by dimerizing propylene ~see Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Volume V/Ib, page 550 to 551, Stuttgart (1972)) and can -then be used directly, or if appropriate after prior distillation, in tha process according to the invention. The dehydrating of 2,3-dimethylbutan-2-ol can also produce 2,3-dimethylbutenes which can be used in the process according to the lnvention.
2,3-Dime-thyl-2-butene or 2,3-dimethyl-2-butelle-containing mixtures of the abovementioned -type which contain more than 60%, preferably more than 70%, of 2,3-dimethyl-2-butene are preferably used in the process according to the invention.
Oxygen can be supplied to the process according to the invention as pure oxygen or in the form of an oxygen-contailling gas mixture. When an oxygen-containing gas mixture is used, the latter, in addition to oxygen, preferably only contains inert constituents. Possible examples of these inert constituents are nitrogen, carbon dioxide and/or noble gases, such as helium, neon, argon and/or krypton. It is also possible IO use an inert gas mixture of carbon dioxide and nitrogen, prepared, for example, by combustion of methane with air, as an inert constituent of the oxygen-containing gas mixture. Additions of ozone or atomic oxygen are also possible.
The oxygen-containing gas mixtures preferably contain between 10 and more than 99% of oxygen. The feed used for the process according to the inven-tion preferably is air, oxygen-containing gas mixtures containing more than 50%
of oxygen or pure oxygen.
..../
- s -It CUII bo adv.lnt.Lgeous to add tho oxygorl to bo used in SOVCI'UI SllCCe';-sive portiolls, ~or oxclmplo by injoctirlg oxygon .ulcl/or oxygon-contairling guses several times during tho reaction.
If an oxygen-containillg gas mixture is used, -tho various components of the gas mixture can be suppliecl to the reaction zone toge-ther, separa-tely or combined in suitable combinations. The gas components can be mixecl within or outside of the reaction zone. The mixing of the gas components outside the reaction zone can be effected, for example, in a free jet, in ducts, in mixing apparatuses or in mixing chambers. Suitable examples are injector mixers and jet mixers. Stirred units can also be used for the gas mixing. ~ans can also act as simultaneous mixing device.
It is advantageous to restrict the oxygen content of the gas phase of the reaction space by suitable measures in such a manner that explosive gas mix-tures cannot arise. An example of such measures consists in the adclition o-E
inert gases such as nitrogen, ca-rbon dioxide and/or noble gases.
The process according to the invention is carried ou-t at tompor.ltures of ~0 -to 180 C. The process is preEerably carriecl out at 60 to 160 C, particu-larly preferably at 80 to l~0 C.
In addition to operating under isothermal conditions, that is to say maintaini.ng a uniform temperature during the entire reaction, the reaction can also be carried out wi-th the formation of a so-called temperature gradient, that is to say at a temperature which increases or decreases in the course o-f the reaction.
The process according to the invention is carried out in sucil a manner that the residence time ~when operating discontinuously) or the mean residence time ~when operating continuously) is 5 to 150 minutes. This time is pre:Eerably 10 to 120 minutes~ particularly preferably 15 to 90 minutes.
~,:
The process according to the invention is carried out without the addition o catalysts.
In the process according to the invention, the pressure can be varied within wide limits. The process can be carried outJ for example, under a pres-sure of the system of 0.9 to 90 bar. This pressure prefera~ly is 2.0 to 80 bar, particularly preferably 5.0 to 70 bar. In special cases, it is also possible for the pressure used to fall short of or exceed the pressure ranges indicated.
The pressure is preferably established by establishing the desired reaction pressure by injecting~ for example, nitrogen, carbon dioxide and/or noble gases.I'hereafter, up to 20 bar of oxygen partial pressure are adclitionally injectedJand oxygen consumed dur:ing the reaction is replaced co-ntinuously or discontinu-ous ly .
[~ :is ~lso aclvr)llt.lgeous to cl~sllre, ~luri.ng tllo roacti.on, that thc roac-ti.OIl co~ )ollollts art~ tllorol~lgllly Ini.xod~ Eor ~xall~ lc~ I)y vi~roroLI.~i st.i.rr~ r or ~l~S~
c)l u gLIS dist~ l;i.oll scirrc~r.
'I'lle process accorcli)lg to the invelltioll ccm be car:riecl out, wi-thin the parameters indicatedJ in such a manner that the conversion of 2,3-dimethyl-butenes is, for example, 5 to 99.9%. At the end of the reaction this conver sion preferably is 15 to 95%, particularly pre:Eerably 20 to 90%.
It is advantageous to carry out the oxidation of 2,3-d:imetllylbutc,~nes w:ithout the acldition of water. SlTIaLL amoullts oE wLIter, for ex~ )le up to O.nO9'!0 by w~i.ght, presellt :ill thQ ~eecl l~roclucts or t`ormecl cluri.llg tllc :reactioll clo not :ilnl)a:Lr the Eo:rmat:ion ot tetramethyloxirane.
Tlle process according to the invention can be carriecl out not only in the liquid phase but also in the gas phase. It is advantageously carried out in the liquid phase.
An example of an inclustrially preferable embodiment of the process acco:rLI~ g to tho illVCllti.On coml)rises :reactillg 2,.5-d:i.lllotlly:LbuLellcs, or m:ixtures COll'ta.il'l:i.llg thelll, 1t toml)oraturos oE 80 to 140C, Wlder pressuros oi' ~ to 70 bar and Eor reaction timos o:E 10 to S() m:i.nlltos w;.th oxyge11 or oxygen containing g15eS wit]loUt catalyst ill such a mam1er that the conversion of 2,3~-d:ilnethyl-butene is 20 -to 85Uo. T}1e composi-tion of ti1e result:ing reaction mixture can be, for example, 5 to 15~o by weight o:E 2,3-dimethylbutenes, 55 to 65% by weight oftetramethyloxi.rane, 3 to 7% by weight o:E 2,3-climethy:l-l-buten-3-ol, 0.l to 1.5%
by weight of 2,3-dime-thylbutan-2-diol, 3.0 to 1~.5% by weight of compounds which have a lower boiling point than 2,3-dimethylbutenes and 3 to 11.5% by weight of compounds which have a ~higher boiling point than 2,3-dimethylbutan-2,3-diol.
For conversions of 2,3-dimethylbutene of up to 90%, the process according to the inve11tio11 achieves -tetramethyloxi:raIle selecti-vi.ties of, for example, 70 to 80%. Ihe process according to the :invention can a]so be carried out with 2,3-dimethylbute11e conversions of greater thal1 90%, bu-t a-t h;.gher con-versi.ons the tetrame-thyloxi.rane selecti.v:ity may decrease somewh--t.
The proces-; according to -the inven-t:ion can be carried out discontinu-ously or continuously in dev:i.ces customary :Eor reactions of thi.s type. Suitable examples are stirred kettles, boiling reactors, -tube reactors, loop reactors, bypass-reactors, thin-film reactors, st:irred kettle cascades and bubble columns.
Various ma-terials can be used as constructional materials for the apparatuses in which the process according to the invention is carri.ed out.
Suitable examples are glass, stainless steel, nickel alloys, zirconium, tantalumand enamelled materials.
The heat of reaction can be conducted away in various ways, for example by internal or external coolers or by boiling under reflux, for example in boiling reactors.
The 2,3-dimethylbutenes, or the mixtures containing them, can be intro-r3 ~
ducecl :ill V~Ll`.iO-IS W-lyi :illtO the clevi.co prov:iclecl :Eor tho ronct:i.on. It :i.s poss:ible to feecl :ill the 2,3-cli.111otl1yll)utcnes, or tl1o m:ixtLlres conta.ir1:ing thc1ll, at -vari.ous pOi11ts in the react:ion ~.one. Whell USillg a multipl:ic:ity o:f reacto:rs wh:ich are arrallged 1S a cascade :i-t can be aclvLntageous to feed the 2,3-cliMethylbutenes, or the mixtures contail1iJ1g then1~ exclusively to the :f:irst reactor. ilowever, cheir addition can also be subdividecl among various or all reactors.
When using a multiplicity ot reactors which are arranged as a cascade, oxygen or oxygen-containing gas m:ixtures and/or 2,3-dimethylbutenes or mixtures containing them can be fed separately or together into all or only some of the kettles of the cascade.
The working-up of the reaction mixtures present a:fter the process according to the invention has been carried ou-t and the separlti.on of the tetra-methyloxiral1e ob-tained can be e:ffectecl in various ways. Ic the react:ion W15 carried out a.t temperatures above the bo:il:ing po:int ~u1lder atn1ospheIic pressure~
of the 2,3-dimet11ylbLItelles culd under an elevated pressure, it Call be advalltage-ous fi.rst -to cool the reaction mixtu:re down to temperatures below the boiling pOiJ1t (unc1er atmosphe:r:ic pressure) o:F the 2,3-dimethylbutenes, to ].et down the pressure and therea:fter to separate o:f:E the tetrame-thyloxirane. It may be advantageous, to avoid the :formltior1 o:t explosi-ve gas mixtures, to pass in inert gases, such as nitrogen, carbon di.oxide or noble gases, while letti.ng down the pressure. The gas mixture released on letting down the pressure, if necessary after purification and enrichment with oxygen, can be returned to the reaction.
The tetrame-thyloxirane formed, unreacted 2,3-dimethylbutenes and by-products which have a lower boiling point than 2,3-dimethylbutenes can be separated from the reaction mixture obtained after the reaction. This separa-tion can be carried out jointly or successively, for example by distillation and/or extraction. In this separation, small amounts of water which may have LC)rlllO(I dll:rLng tho rc~lct:i.on Ol WOL~e i.ntl'O(IUCOCl togother w:ith the foocl products call bo rcmoved comp,Letc:Ly 0:1` ~ lrt:ially.
I~hen jo:intLy soL~aIati.llg ox:irallo, ullcorlver-tecL 2,3-cl:imetllyll)utenes ancl otheI reactioll procLucts, i~ prescnt, this m.ix-ture can be separatecl .into :its com-ponents, for example, by clist:illation, extractiorl, absorption, adsorption or extractive distillat:ion. Ihe ~mconverted 2,3-dimethy].butenes, if necessary a:Lter prior purification and after repletion of the amount of 2,3-dimethyl-butenes consumed in the reaction, can be returned afresh to the reaction ~one.
Te-tramethyloxirane thus obtained can already be used as such for many purposes, for example for preparing polyethers, polyureth~mes, epoxy resins, detergents, glycols and a large number of organic intermediate products (see, for example, U.S. Patent Speci:L~icat:ion ~,~12,136).
The process according -to the inventi.on enables -tetrametllyloxirane to be prepared :in a s:imple alld econom:ical manner. T}le selectiv.it:ies which can be achieved are high, the use o:L` hydroge1l peroxicle, Wh.iCIl :is expens:ive comparecl to oxygen or air, :is avoidecl, cata.l.ysts a:re not reqllired, and the react:i.on timos are short.
It is definitely surprising that it is poss:ible to obta:in these bene-fits by means o:E the process according to the invention, since, in view o:L theliterature reference J. Org. Chenm. 37, 2881 to 288~l (1972) and from U.S.
~,182,722, it could not be expected that it would be possible to prepare tetra-methyloxirane without catalysts and in short reaction times.
The process according to the invention is illustrated by the examples which follow but i.t is not restricted to them. Unless otherwise indicated, all percentage data are percentages by weight.
Examples Example 1 "~ r~ ~ r~
I ( ) '55 g ol' a mixtu~c colniisLillg of 98"., ol~ 2,3-clilnetllyL-2~l)utcnc, 1% o~
2,3-dillletllyL-I-I)utclle alld 1o of n-llex,llle were illtrocluced into 1 stainLess steel autocl.lve c(~uipl)ecL with a gas clLstribLItioll stirrel, a thermometer arl L a valvc.
'I'he autoclave was heatecL with stirring (400 rpm) to 100C. While stirring was continued, 28 bar oE air were injected f'or f'ive minutes cmd s-tirring was con--tinued Eor another five minutes at 100C. 'I'he autoclave was -then cooled down Wi't]l stirring to room temperature and the reaction products were analyzed. The result was an 8.1% conversion of 2,3-dimethylbu-tene with a selectiv:ity of 76%, relative to tetramethyloxirane prepared. Also found were 2,3-dimethyl-1-buten-3-ol with 18.8% selectivity and 2,3-dimethyl-2,3-butadiene with 3.3% selectivity.
Example 2 The procecLure of Example L was Eollowed, but -the autoclave was heated to 117 C. Wh:ile stirring (1,000 rpm), 6.5 bar oE oxygen were injected Eor 15 m:inutes. 'I'he autoc]ave was -thell cooled ùown to room temperature, and tlle reac--tion products analysed. 'I'he result was a 40.3% conversion oE 2,3-dimetilyl-butene with a seLec-tivity oE 71%, re]ative to tetrametllyloxirane prepared. Also fou]ld were 2,3-dimethyl-1-buten-3-ol with 15.5% selectivity, 2,3-dimetllylbutan-2-ol with 0.5% selectivity, 3,3-cLimethylbutan-2-o]le wi-th 0.4% selectivity and 2,3-dimethylbutadiene with 0.3% selectivity.
Example 3 255 g of a mixture consisting of 80% of 2,3-dimethyl-2-butene, 15% of 2,3-ùimethyl-1-butene, 2% of 2,3-dimethylbutane and 3% of n-hexane were intro-duced into the autoclave described in Example l. After heating to 87C and while stirring (1,400 rpm), 20 bar of a gas mixture consisting of 35% of oxygen and 65% of nitrogen were injected and, after a further 5 minutes, 3 bar of pure oxygen were injected for 25 minutes. The autoclave was then cooled down to room temperature, and the reaction products were analysed. The result was an 83.1%
., I I
convc~riioll oE 2,3-dillletllyll)utello witll Ll seloctivity oE 72'~, rolativo to totr.l-mC`thYIOXI:ral~O l)rel~lreCI~ A150 :EO~D1CI were 2,3-dilllotllyl~l-butoll-3-c)l with L6.1%
selec-tivity, 2,3-clillletllyl-2,3-butallecliol Wit]l 1.2% seloctiv;ty, 273-dimethyl-bu-t.-n-2-ol with 0.G% selectivity, 3,3-dimethyll)utan-2-olle with 0.5% selectivity ~md 3,3-dime-t}lylblltan-2-ol with 0.3% selec-tivity.
_a~
T}le procedure of Example 3 was Eollowed, but the reaction mixture ob-tained was separated by distillatioll in-to the components and the 2,3-dimethyl-butenes recovered were used afresh in the reaction. The experimental result was an 85.6% conversion of 2,3-dimethylbutene with a selectivi-ty of 69.2%, rela-tive to tetramethyloxiralle isolated.
Example 5 208 g oE a mixture cons:is-t:ing o-f ')5% oE 2,3-dimet}lyl-2-butelle, 3% oE
2,3-dimethyl-1-butene, 1.5% of 2,3-dilllethyLbutalle ancl 0.5% oE n-hexalle we~re introduced into the autoclave clescribed in ExampLe 1. AEter heating to 128 (, and while stirring ~2,000 rpm), 5.3 bar oE oxygen were :injected for 20 millutes.
Ihe autoclave was then cooled dow-rl to room temperature. 'i'he experimental re-sult was 65.3% conversion of 2,3-dimethylbutene with a selec-tivity of 71.3%, rela-tive to tetrame-thyloxirane prepared. Also -found were 2,3-dimethyl-1-bu-ten-3-ol with 13.3% selectivity, 2,3-dimethylbutane-2,3-diol with 5.9% selectivity, 2,3-dimethylbutan-2-ol wi-th 2.3% selectivity, 2,3-dimethylbutan-2-one with 2.2%
selectivity and 3,3-dimethylbutan-2-ol with 1.7% selectivity.
le 6 930 g/h of a mixture consisting of 97% of 2,3-dimethyl-2-butene, 1.3%
of 2,3-dimethyl-1-butene, 0.8% of 2,3-dimethylbutane and 0.9% of n-hexane were introduced into a cascade consisting oE three stirred pressure reactors each of which was equipped with a gas distribution stirrer (1,500 rpm) and had a capac-.L2 -ity o( 17~ ml. Illlc Ei.rst rcacto:r ot- the cascllcle was ope-ratocl at 1()5 (, thc sccorlcl at :L00 C and the th:i-rd at ')5 (,. A~Ete-r the rcaction temperatures incl-i-cated had becll reached, su:ft`ic;ent oxygen W15 :injecte(l :into eacll reactor via a valve to ensure that the overal] prcssure :in the cascaclc- was 7.5 bar, Ille pres-sure oE the react:ion mixture was let down aftcr the cascade by adding nitrogen to avoid explosive gas mixtures. The reaction mixture was then cooled down to 60C and fed -to a sieve tray colunm to separate o:Ef unconverted 2,3-dimethyl-butenes and compounds having a lower boiling poin-t than 2,3-dimethylbutenes.
A:L-ter the addition o-F :Eresh 2,3-dimethylbutene mixture, the 2,3-dimethylbutenes recovered were retu-rned to the first reactor of the cascade. In a second column, the tetramethyloxirane -formed and constituen-ts of the remaining reac--tion mixture which under atmospher:ic pressure bo:il at less than ].80C were separatecl distillatively in vacuo.
The analytical result was 72.5% conversion o:E 2,3-dimethylbutene with a selectivity of 73%, rel.lt;ve to te-tramethyloxira.ne prepared. 293.5 g o:E tetr"-methyloxirane we:re obta:ined per hour.
7.
I','~, ~
lys-ts. 'Ihese l~atellts do not contlirl data conce-rning convelsion and solectivi--ties. Ilowever, the use oE expellsivo catalysts a~d the expense of thc:ir isola--tion, working-up and return is ,aiways unEIvourable.
Arlo-ther method Eor the catalytic oxidat;on of olefins with oxygen is described in U.S. 4,182,722. According to Example B 2, 2,3-dimethyl-2-butene is oxidized at 50C and for a reaction time oE Eive hours in the presence of an X zeolite which has been ion-exchanged with copper2 and vanadium4 salts and which is used as a catalyst. 24% olefin conversion produces 1,2-epoxy-3-hydroxy-2,3-dimethylbutane as main product with a selectivity of 46%. The by-products are tetramethyloxirane with a selectivity of ~0%, 3-hydroxy-2,3-dimethyl-l-butene with 9% selec-tivity and acetone with 6% selectivity. In addi--tion to the already mentioned disadvantages of using catalys-ts, the long reac-tion time of Eive hours, when the olefin conversion is only 24%, and the pre-dominant formation of products other thm tetramethyloxirane are ~ur-thor dis-advantages of this process.
A further process for preparing tetramethyloxirane from te-tramethy1-ethylene (2,3-dimethyl-2-butene) involves the use oE a homogeneous catalyst system consisting of complexes of the formula trans-MCl(CO) (Ph3P)2 (M =
rhodium or iridium; and Ph = phenyl) (see J.E. Lyons and J.O. Turner, J. Org.
Chem. Volume 37, 2881-2884 (1972)). A reaction time of four hours and a reac-tion temperature of 50C, when the conversion of tetramethylethylene is 8 to 66%, produces tetramethyloxirane with selectivities of 25 to 37.5% (see litera-ture reference: page 2882, Table 1). Due to the long reaction time of four hours and the very low selectivities, this route is not an economical process for preparing tetramethyloxirane.
It is also known to react tetramethylethylene with oxygen at 25C in the presence of iron -meso-tetraphenylporphyrine chloride as catalyst (D.R.
I'clulso~ ULII1]I dncl l~.B. Slouno, .I.~..S. Cllelll. Coulm., I(J7~1, p1l~C 187, [~Ibl~).
AE-ter 2~ hours' reclction time, 2,3-climethyl-3-en-2-ol is obtained as ma-irl pro-cluct with a selectivity oE ~5% ancl tetrametllyloxiralle and acetone are obtained as by-produc-ts with a selectivity o-E ~l cmd 14% respectively. 'I'he disadvarlt-ages of this process, in adclition to the catalyst costs, are the long reaction time of 2~ hours and the :Eormation oE 2,3-dimethyl-3-en-2-ol as main product.
Finally, it is known to prepare tetramethyloxirane by oxygen-oxida-tion of te-tramethylethylene a-t 50 C and in a reaction time of 333 minu-tes in the presence of 2,2'-azobis~2-methylpropionitrile) (I.~. Van Sickle, F.R. Mayo, R.M. Arluck and M. Sy~. J. Am. Chem. Soc. 89, 1967, page 971, Table l). This process is not o-E interest industrially, since the tetramethylethylene conver-sion, despite the reaction period oE more than five hours, is only 5% and the tetramethyloxirane selectivi-ty only reaches 15.5%.
'I'here is therefore a neecl Eor a simple ancl effec-tive process Eor pre-paring tetramethylox:ircme.
A process for prepar-i[lg tetrcunethylox:ircme has now been foulld and :it is characterised in that 2,3-climetllylbutenes are reacted with oxygen or an oxygen-containing gas at temperatures o-E ~0 -to 180 C and for residence times oE
5 to 150 minutes without the addition of catalysts and the tetramethyloxirane obtained is separated off.
Possible examples of 2,3-dimetilylbu-tenes which can be used in the pro-cess according to the invention are 2,3-dimethyl-2-butene, 2,3-dime-thyl-1-butene, any mixtures of 2,3-dimethyl-2-butene and 2,3-dimethyl-1-butene and any mixtures of 2,3-dimethyl-2-butene and/or 2,3-dimethyl-1-butene with inert materials.
~xamples of these inert organic diluents are hydrocarbons and chlorinated hydro-carbons of the aliphatic, cycloaliphatic and aromatic series, for example satur-ated aliphatic hydrocarbons, such as n-hexane or dimethylbutane, saturated cyclo-a~ at:LC hyCIrOCa:rl)OI15~ SUCII as decaLi!l, aroma-tic hyclrocarbolls, such a'; L)CnZCnC, toluelle or xylerle ancl clllolinate(l hydrocarbons, :Eor examp]e chlorinatcd arollla-tics. r[`he iner-t organ:ic diluents used preferlbly are n-hexanc, dirnethyl-bu-tane, benzene or chlorinuted hydrocarbons.
2,3-Dimethyl-2-butene and 2,3-dimet}lyl-1-butene àre readily accessible starting materials which can be ob-tained, for example, by dimerizing propylene ~see Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Volume V/Ib, page 550 to 551, Stuttgart (1972)) and can -then be used directly, or if appropriate after prior distillation, in tha process according to the invention. The dehydrating of 2,3-dimethylbutan-2-ol can also produce 2,3-dimethylbutenes which can be used in the process according to the lnvention.
2,3-Dime-thyl-2-butene or 2,3-dimethyl-2-butelle-containing mixtures of the abovementioned -type which contain more than 60%, preferably more than 70%, of 2,3-dimethyl-2-butene are preferably used in the process according to the invention.
Oxygen can be supplied to the process according to the invention as pure oxygen or in the form of an oxygen-contailling gas mixture. When an oxygen-containing gas mixture is used, the latter, in addition to oxygen, preferably only contains inert constituents. Possible examples of these inert constituents are nitrogen, carbon dioxide and/or noble gases, such as helium, neon, argon and/or krypton. It is also possible IO use an inert gas mixture of carbon dioxide and nitrogen, prepared, for example, by combustion of methane with air, as an inert constituent of the oxygen-containing gas mixture. Additions of ozone or atomic oxygen are also possible.
The oxygen-containing gas mixtures preferably contain between 10 and more than 99% of oxygen. The feed used for the process according to the inven-tion preferably is air, oxygen-containing gas mixtures containing more than 50%
of oxygen or pure oxygen.
..../
- s -It CUII bo adv.lnt.Lgeous to add tho oxygorl to bo used in SOVCI'UI SllCCe';-sive portiolls, ~or oxclmplo by injoctirlg oxygon .ulcl/or oxygon-contairling guses several times during tho reaction.
If an oxygen-containillg gas mixture is used, -tho various components of the gas mixture can be suppliecl to the reaction zone toge-ther, separa-tely or combined in suitable combinations. The gas components can be mixecl within or outside of the reaction zone. The mixing of the gas components outside the reaction zone can be effected, for example, in a free jet, in ducts, in mixing apparatuses or in mixing chambers. Suitable examples are injector mixers and jet mixers. Stirred units can also be used for the gas mixing. ~ans can also act as simultaneous mixing device.
It is advantageous to restrict the oxygen content of the gas phase of the reaction space by suitable measures in such a manner that explosive gas mix-tures cannot arise. An example of such measures consists in the adclition o-E
inert gases such as nitrogen, ca-rbon dioxide and/or noble gases.
The process according to the invention is carried ou-t at tompor.ltures of ~0 -to 180 C. The process is preEerably carriecl out at 60 to 160 C, particu-larly preferably at 80 to l~0 C.
In addition to operating under isothermal conditions, that is to say maintaini.ng a uniform temperature during the entire reaction, the reaction can also be carried out wi-th the formation of a so-called temperature gradient, that is to say at a temperature which increases or decreases in the course o-f the reaction.
The process according to the invention is carried out in sucil a manner that the residence time ~when operating discontinuously) or the mean residence time ~when operating continuously) is 5 to 150 minutes. This time is pre:Eerably 10 to 120 minutes~ particularly preferably 15 to 90 minutes.
~,:
The process according to the invention is carried out without the addition o catalysts.
In the process according to the invention, the pressure can be varied within wide limits. The process can be carried outJ for example, under a pres-sure of the system of 0.9 to 90 bar. This pressure prefera~ly is 2.0 to 80 bar, particularly preferably 5.0 to 70 bar. In special cases, it is also possible for the pressure used to fall short of or exceed the pressure ranges indicated.
The pressure is preferably established by establishing the desired reaction pressure by injecting~ for example, nitrogen, carbon dioxide and/or noble gases.I'hereafter, up to 20 bar of oxygen partial pressure are adclitionally injectedJand oxygen consumed dur:ing the reaction is replaced co-ntinuously or discontinu-ous ly .
[~ :is ~lso aclvr)llt.lgeous to cl~sllre, ~luri.ng tllo roacti.on, that thc roac-ti.OIl co~ )ollollts art~ tllorol~lgllly Ini.xod~ Eor ~xall~ lc~ I)y vi~roroLI.~i st.i.rr~ r or ~l~S~
c)l u gLIS dist~ l;i.oll scirrc~r.
'I'lle process accorcli)lg to the invelltioll ccm be car:riecl out, wi-thin the parameters indicatedJ in such a manner that the conversion of 2,3-dimethyl-butenes is, for example, 5 to 99.9%. At the end of the reaction this conver sion preferably is 15 to 95%, particularly pre:Eerably 20 to 90%.
It is advantageous to carry out the oxidation of 2,3-d:imetllylbutc,~nes w:ithout the acldition of water. SlTIaLL amoullts oE wLIter, for ex~ )le up to O.nO9'!0 by w~i.ght, presellt :ill thQ ~eecl l~roclucts or t`ormecl cluri.llg tllc :reactioll clo not :ilnl)a:Lr the Eo:rmat:ion ot tetramethyloxirane.
Tlle process according to the invention can be carriecl out not only in the liquid phase but also in the gas phase. It is advantageously carried out in the liquid phase.
An example of an inclustrially preferable embodiment of the process acco:rLI~ g to tho illVCllti.On coml)rises :reactillg 2,.5-d:i.lllotlly:LbuLellcs, or m:ixtures COll'ta.il'l:i.llg thelll, 1t toml)oraturos oE 80 to 140C, Wlder pressuros oi' ~ to 70 bar and Eor reaction timos o:E 10 to S() m:i.nlltos w;.th oxyge11 or oxygen containing g15eS wit]loUt catalyst ill such a mam1er that the conversion of 2,3~-d:ilnethyl-butene is 20 -to 85Uo. T}1e composi-tion of ti1e result:ing reaction mixture can be, for example, 5 to 15~o by weight o:E 2,3-dimethylbutenes, 55 to 65% by weight oftetramethyloxi.rane, 3 to 7% by weight o:E 2,3-climethy:l-l-buten-3-ol, 0.l to 1.5%
by weight of 2,3-dime-thylbutan-2-diol, 3.0 to 1~.5% by weight of compounds which have a lower boiling point than 2,3-dimethylbutenes and 3 to 11.5% by weight of compounds which have a ~higher boiling point than 2,3-dimethylbutan-2,3-diol.
For conversions of 2,3-dimethylbutene of up to 90%, the process according to the inve11tio11 achieves -tetramethyloxi:raIle selecti-vi.ties of, for example, 70 to 80%. Ihe process according to the :invention can a]so be carried out with 2,3-dimethylbute11e conversions of greater thal1 90%, bu-t a-t h;.gher con-versi.ons the tetrame-thyloxi.rane selecti.v:ity may decrease somewh--t.
The proces-; according to -the inven-t:ion can be carried out discontinu-ously or continuously in dev:i.ces customary :Eor reactions of thi.s type. Suitable examples are stirred kettles, boiling reactors, -tube reactors, loop reactors, bypass-reactors, thin-film reactors, st:irred kettle cascades and bubble columns.
Various ma-terials can be used as constructional materials for the apparatuses in which the process according to the invention is carri.ed out.
Suitable examples are glass, stainless steel, nickel alloys, zirconium, tantalumand enamelled materials.
The heat of reaction can be conducted away in various ways, for example by internal or external coolers or by boiling under reflux, for example in boiling reactors.
The 2,3-dimethylbutenes, or the mixtures containing them, can be intro-r3 ~
ducecl :ill V~Ll`.iO-IS W-lyi :illtO the clevi.co prov:iclecl :Eor tho ronct:i.on. It :i.s poss:ible to feecl :ill the 2,3-cli.111otl1yll)utcnes, or tl1o m:ixtLlres conta.ir1:ing thc1ll, at -vari.ous pOi11ts in the react:ion ~.one. Whell USillg a multipl:ic:ity o:f reacto:rs wh:ich are arrallged 1S a cascade :i-t can be aclvLntageous to feed the 2,3-cliMethylbutenes, or the mixtures contail1iJ1g then1~ exclusively to the :f:irst reactor. ilowever, cheir addition can also be subdividecl among various or all reactors.
When using a multiplicity ot reactors which are arranged as a cascade, oxygen or oxygen-containing gas m:ixtures and/or 2,3-dimethylbutenes or mixtures containing them can be fed separately or together into all or only some of the kettles of the cascade.
The working-up of the reaction mixtures present a:fter the process according to the invention has been carried ou-t and the separlti.on of the tetra-methyloxiral1e ob-tained can be e:ffectecl in various ways. Ic the react:ion W15 carried out a.t temperatures above the bo:il:ing po:int ~u1lder atn1ospheIic pressure~
of the 2,3-dimet11ylbLItelles culd under an elevated pressure, it Call be advalltage-ous fi.rst -to cool the reaction mixtu:re down to temperatures below the boiling pOiJ1t (unc1er atmosphe:r:ic pressure) o:F the 2,3-dimethylbutenes, to ].et down the pressure and therea:fter to separate o:f:E the tetrame-thyloxirane. It may be advantageous, to avoid the :formltior1 o:t explosi-ve gas mixtures, to pass in inert gases, such as nitrogen, carbon di.oxide or noble gases, while letti.ng down the pressure. The gas mixture released on letting down the pressure, if necessary after purification and enrichment with oxygen, can be returned to the reaction.
The tetrame-thyloxirane formed, unreacted 2,3-dimethylbutenes and by-products which have a lower boiling point than 2,3-dimethylbutenes can be separated from the reaction mixture obtained after the reaction. This separa-tion can be carried out jointly or successively, for example by distillation and/or extraction. In this separation, small amounts of water which may have LC)rlllO(I dll:rLng tho rc~lct:i.on Ol WOL~e i.ntl'O(IUCOCl togother w:ith the foocl products call bo rcmoved comp,Letc:Ly 0:1` ~ lrt:ially.
I~hen jo:intLy soL~aIati.llg ox:irallo, ullcorlver-tecL 2,3-cl:imetllyll)utenes ancl otheI reactioll procLucts, i~ prescnt, this m.ix-ture can be separatecl .into :its com-ponents, for example, by clist:illation, extractiorl, absorption, adsorption or extractive distillat:ion. Ihe ~mconverted 2,3-dimethy].butenes, if necessary a:Lter prior purification and after repletion of the amount of 2,3-dimethyl-butenes consumed in the reaction, can be returned afresh to the reaction ~one.
Te-tramethyloxirane thus obtained can already be used as such for many purposes, for example for preparing polyethers, polyureth~mes, epoxy resins, detergents, glycols and a large number of organic intermediate products (see, for example, U.S. Patent Speci:L~icat:ion ~,~12,136).
The process according -to the inventi.on enables -tetrametllyloxirane to be prepared :in a s:imple alld econom:ical manner. T}le selectiv.it:ies which can be achieved are high, the use o:L` hydroge1l peroxicle, Wh.iCIl :is expens:ive comparecl to oxygen or air, :is avoidecl, cata.l.ysts a:re not reqllired, and the react:i.on timos are short.
It is definitely surprising that it is poss:ible to obta:in these bene-fits by means o:E the process according to the invention, since, in view o:L theliterature reference J. Org. Chenm. 37, 2881 to 288~l (1972) and from U.S.
~,182,722, it could not be expected that it would be possible to prepare tetra-methyloxirane without catalysts and in short reaction times.
The process according to the invention is illustrated by the examples which follow but i.t is not restricted to them. Unless otherwise indicated, all percentage data are percentages by weight.
Examples Example 1 "~ r~ ~ r~
I ( ) '55 g ol' a mixtu~c colniisLillg of 98"., ol~ 2,3-clilnetllyL-2~l)utcnc, 1% o~
2,3-dillletllyL-I-I)utclle alld 1o of n-llex,llle were illtrocluced into 1 stainLess steel autocl.lve c(~uipl)ecL with a gas clLstribLItioll stirrel, a thermometer arl L a valvc.
'I'he autoclave was heatecL with stirring (400 rpm) to 100C. While stirring was continued, 28 bar oE air were injected f'or f'ive minutes cmd s-tirring was con--tinued Eor another five minutes at 100C. 'I'he autoclave was -then cooled down Wi't]l stirring to room temperature and the reaction products were analyzed. The result was an 8.1% conversion of 2,3-dimethylbu-tene with a selectiv:ity of 76%, relative to tetramethyloxirane prepared. Also found were 2,3-dimethyl-1-buten-3-ol with 18.8% selectivity and 2,3-dimethyl-2,3-butadiene with 3.3% selectivity.
Example 2 The procecLure of Example L was Eollowed, but -the autoclave was heated to 117 C. Wh:ile stirring (1,000 rpm), 6.5 bar oE oxygen were injected Eor 15 m:inutes. 'I'he autoc]ave was -thell cooled ùown to room temperature, and tlle reac--tion products analysed. 'I'he result was a 40.3% conversion oE 2,3-dimetilyl-butene with a seLec-tivity oE 71%, re]ative to tetrametllyloxirane prepared. Also fou]ld were 2,3-dimethyl-1-buten-3-ol with 15.5% selectivity, 2,3-dimetllylbutan-2-ol with 0.5% selectivity, 3,3-cLimethylbutan-2-o]le wi-th 0.4% selectivity and 2,3-dimethylbutadiene with 0.3% selectivity.
Example 3 255 g of a mixture consisting of 80% of 2,3-dimethyl-2-butene, 15% of 2,3-ùimethyl-1-butene, 2% of 2,3-dimethylbutane and 3% of n-hexane were intro-duced into the autoclave described in Example l. After heating to 87C and while stirring (1,400 rpm), 20 bar of a gas mixture consisting of 35% of oxygen and 65% of nitrogen were injected and, after a further 5 minutes, 3 bar of pure oxygen were injected for 25 minutes. The autoclave was then cooled down to room temperature, and the reaction products were analysed. The result was an 83.1%
., I I
convc~riioll oE 2,3-dillletllyll)utello witll Ll seloctivity oE 72'~, rolativo to totr.l-mC`thYIOXI:ral~O l)rel~lreCI~ A150 :EO~D1CI were 2,3-dilllotllyl~l-butoll-3-c)l with L6.1%
selec-tivity, 2,3-clillletllyl-2,3-butallecliol Wit]l 1.2% seloctiv;ty, 273-dimethyl-bu-t.-n-2-ol with 0.G% selectivity, 3,3-dimethyll)utan-2-olle with 0.5% selectivity ~md 3,3-dime-t}lylblltan-2-ol with 0.3% selec-tivity.
_a~
T}le procedure of Example 3 was Eollowed, but the reaction mixture ob-tained was separated by distillatioll in-to the components and the 2,3-dimethyl-butenes recovered were used afresh in the reaction. The experimental result was an 85.6% conversion of 2,3-dimethylbutene with a selectivi-ty of 69.2%, rela-tive to tetramethyloxiralle isolated.
Example 5 208 g oE a mixture cons:is-t:ing o-f ')5% oE 2,3-dimet}lyl-2-butelle, 3% oE
2,3-dimethyl-1-butene, 1.5% of 2,3-dilllethyLbutalle ancl 0.5% oE n-hexalle we~re introduced into the autoclave clescribed in ExampLe 1. AEter heating to 128 (, and while stirring ~2,000 rpm), 5.3 bar oE oxygen were :injected for 20 millutes.
Ihe autoclave was then cooled dow-rl to room temperature. 'i'he experimental re-sult was 65.3% conversion of 2,3-dimethylbutene with a selec-tivity of 71.3%, rela-tive to tetrame-thyloxirane prepared. Also -found were 2,3-dimethyl-1-bu-ten-3-ol with 13.3% selectivity, 2,3-dimethylbutane-2,3-diol with 5.9% selectivity, 2,3-dimethylbutan-2-ol wi-th 2.3% selectivity, 2,3-dimethylbutan-2-one with 2.2%
selectivity and 3,3-dimethylbutan-2-ol with 1.7% selectivity.
le 6 930 g/h of a mixture consisting of 97% of 2,3-dimethyl-2-butene, 1.3%
of 2,3-dimethyl-1-butene, 0.8% of 2,3-dimethylbutane and 0.9% of n-hexane were introduced into a cascade consisting oE three stirred pressure reactors each of which was equipped with a gas distribution stirrer (1,500 rpm) and had a capac-.L2 -ity o( 17~ ml. Illlc Ei.rst rcacto:r ot- the cascllcle was ope-ratocl at 1()5 (, thc sccorlcl at :L00 C and the th:i-rd at ')5 (,. A~Ete-r the rcaction temperatures incl-i-cated had becll reached, su:ft`ic;ent oxygen W15 :injecte(l :into eacll reactor via a valve to ensure that the overal] prcssure :in the cascaclc- was 7.5 bar, Ille pres-sure oE the react:ion mixture was let down aftcr the cascade by adding nitrogen to avoid explosive gas mixtures. The reaction mixture was then cooled down to 60C and fed -to a sieve tray colunm to separate o:Ef unconverted 2,3-dimethyl-butenes and compounds having a lower boiling poin-t than 2,3-dimethylbutenes.
A:L-ter the addition o-F :Eresh 2,3-dimethylbutene mixture, the 2,3-dimethylbutenes recovered were retu-rned to the first reactor of the cascade. In a second column, the tetramethyloxirane -formed and constituen-ts of the remaining reac--tion mixture which under atmospher:ic pressure bo:il at less than ].80C were separatecl distillatively in vacuo.
The analytical result was 72.5% conversion o:E 2,3-dimethylbutene with a selectivity of 73%, rel.lt;ve to te-tramethyloxira.ne prepared. 293.5 g o:E tetr"-methyloxirane we:re obta:ined per hour.
Claims (9)
1. A process for preparing tetramethyloxirane which comprises contacting a 2,3-dimethylbutene with oxygen or an oxygen-containing gas at a temperature of 40 to 180°C
for residence time of 5 to 150 minutes in the absence of a catalyst and thereafter separating off the tetramethylox-irane so formed.
for residence time of 5 to 150 minutes in the absence of a catalyst and thereafter separating off the tetramethylox-irane so formed.
2. A process according to claim 1 wherein the process is carried out at a pressure within the range of 0.9 to 90 bar.
3. A process according to claim 1 wherein 2,3-dimethyl-2-butene, 2,3-dimethyl-1-butene, a mixture of 2,3-dimethyl-2-butene and 2,3-dimethyl-1-butene or a mixture of 2,3-dimethyl-2-butene and/or 2,3-dimethyl-1-butene with an inert organic diluent is employed as the 2,3-dimethyl butene feed.
4. A process according to claim l wherein air, an oxygen containg gas containing more than 50% of oxygen or pure oxygen is employed.
5. A process according to claim 1 wherein oxygen is added to the reaction mixture in several suc-cessive portions.
6. A process according to claim 1 wherein after the reaction mixture has been obtained the pressure is let down and the tetramethyloxirane is separated off by distillation and unconverted 2,3-dimethylbutenes are partially or completely recycled to the reaction.
7. A process according to claim 1 wherein following the process the pressure in the reaction vessel is let down and the reaction mixture is separated by extraction into its com-ponents and unconverted 2,3-dimethylbutenes are partially or completely recycled to the reaction.
8. A process according to claim 1 wherein after the reaction the pressure in the reaction vessel is let down and the reaction mixture is separated by absorption into its components and unconverted 2,3-dimethylbutenes are partially or completely recycled to the reaction.
9. A process according to claim 1 wherein following the reaction pressure in the reaction vessel is let down, the reaction mixture so obtained is separated by extractive distil-lation to its components and unreacted 2,3-dimethylbutenes are partially or completely recycled to the reaction.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3135112.3 | 1981-09-04 | ||
| DE19813135112 DE3135112A1 (en) | 1981-09-04 | 1981-09-04 | METHOD FOR PRODUCING TETRAMETHYLOXIRAN |
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| CA1191147A true CA1191147A (en) | 1985-07-30 |
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| CA000410656A Expired CA1191147A (en) | 1981-09-04 | 1982-09-02 | Process for preparing tetramethyloxirane |
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| JP (1) | JPS5855477A (en) |
| AT (1) | ATE22560T1 (en) |
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| US4601438A (en) * | 1985-04-29 | 1986-07-22 | Charles C. Worth Corporation | Bait casting reel with braking device |
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| US3153058A (en) * | 1964-10-13 | Direct oxidation of olefins in a solvent | ||
| FR1253829A (en) * | 1959-06-23 | 1961-02-17 | Escambia Chem Corp | Preparation of olefin oxides |
| US3238229A (en) * | 1962-09-24 | 1966-03-01 | Monsanto Co | Process for the liquid phase direct oxidation of olefins to olefin oxides |
| US3232957A (en) * | 1963-11-18 | 1966-02-01 | Monsanto Co | Process for the preparation of olefin oxides |
-
1981
- 1981-09-04 DE DE19813135112 patent/DE3135112A1/en not_active Withdrawn
-
1982
- 1982-08-24 DE DE8282107726T patent/DE3273581D1/en not_active Expired
- 1982-08-24 AT AT82107726T patent/ATE22560T1/en not_active IP Right Cessation
- 1982-08-24 EP EP82107726A patent/EP0074009B1/en not_active Expired
- 1982-09-01 IL IL66693A patent/IL66693A0/en not_active IP Right Cessation
- 1982-09-01 JP JP57150815A patent/JPS5855477A/en active Granted
- 1982-09-02 CA CA000410656A patent/CA1191147A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| IL66693A0 (en) | 1982-12-31 |
| JPS5855477A (en) | 1983-04-01 |
| EP0074009A1 (en) | 1983-03-16 |
| EP0074009B1 (en) | 1986-10-01 |
| DE3135112A1 (en) | 1983-03-24 |
| ATE22560T1 (en) | 1986-10-15 |
| JPH0157113B2 (en) | 1989-12-04 |
| DE3273581D1 (en) | 1986-11-06 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |