CA1037486A - Process for preparing tetrahydrofuran - Google Patents
Process for preparing tetrahydrofuranInfo
- Publication number
- CA1037486A CA1037486A CA211,038A CA211038A CA1037486A CA 1037486 A CA1037486 A CA 1037486A CA 211038 A CA211038 A CA 211038A CA 1037486 A CA1037486 A CA 1037486A
- Authority
- CA
- Canada
- Prior art keywords
- butanediol
- carboxylic acid
- catalyst
- silica
- grams
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
- C07D307/02—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings
- C07D307/04—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having no double bonds between ring members or between ring members and non-ring members
- C07D307/06—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having no double bonds between ring members or between ring members and non-ring members with only hydrogen atoms or radicals containing only hydrogen and carbon atoms, directly attached to ring carbon atoms
- C07D307/08—Preparation of tetrahydrofuran
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Furan Compounds (AREA)
- Catalysts (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A process for preparing tetrahydrofuran which comprises heating a carboxylic acid diester of 1,4-butanediol with water in the presence of a hydrolysis-dehydroacyloxylation catalyst.
A process for preparing tetrahydrofuran which comprises heating a carboxylic acid diester of 1,4-butanediol with water in the presence of a hydrolysis-dehydroacyloxylation catalyst.
Description
~CH-1989 ~03174B6 This invention relates to a pro~es3 for preparing tetrahydrofuran which comprises heating a carboxylic acid .!
diester of 1~4-butansdiol with water in the presence ~f a hydrolysis-dehydroacyloxylation catalyst.
I~ is known in the ar~ that ~etrahydrofuran may bs made by a number o~ di~ferent methods; the more prominent method~ are by the catalytic hydrogenation of ~uran or by the dehydration o~ 1,4-butanediolO
In praatice, the tetrahydrofuran is most o~tan produced by a series of reactions ~tarting with the reaction of ~ormaldehyde and acetylene in the presen¢e o~ a cuprous acetylid~ complex to orm butynediol. Butynediol i8 converted on hydrogenation to butanediol~ The 1,4-butanedlol is converted ~o tetrahydrofuran as indicat0d abo~e.
Additionally, tetrahydro~uran i~ prepared ~rom maleia acid, its e~ters, maleic anhydride, fu~aric acid, its esters, ~;
~uccinic aaid, it~ esters, succinic anhydrideJ ~-butyrolactone, or mixtures of these compounds by hydrogenation over a hydro-generation catalyst.
However, these methods involve con~iderably expenæive equipmen~ and the handling of hazardous materia~s. Al~o, cataly~ts in some ~a~es may be expensive, and in other ~-instance~ may be ea~ily poisoned.
T~trahydrouran i~ a use~ul solvent ~or natural and ` ;~
synthetic resins, particularly vinyls. Also, it is used as an intermediate in the manu~acture o~ nylon, 1,4-dichlorobutane a '1 . -anu polyure~nanes.
It has been discovered that tetrahydrofuran may be inexpensively prepared rom a carboxylic acid diester of 1,4-butanediol by heating it with water in the presence of a hete-rogeneou~ hydrolysis-dehydroacyloxylation catalyst. By thi~
~ethod, tetrahydrofuran i9 prOd aed in esscntially qyantitative ., ; .:
8C~-1989 ~ .
~03~4B6 yields. Also, the hydrolysis-dehydroacyloxylation catalyst of the instant invention is stationary and perman~nt and there-fore may be continually reused.
Ancther object of this invantion is to pro~uce tetra-hydro~uran from inexpen~ive starting matexials, i.~., propylene, carbon monoxide, hydrogen and oxygen, by way o~ several inter- :
mediate steps.
The hydroly~is-dehydroacyloxyla~ion catalysts which may be employed in the practice o thi~ invention are those which promote hydrolysis, evolution o~ the carboxylic acid and ring closure. In the case o~ the diacetat~ es~or, the catalyst is a hydrolysis-dehydroacetoxylation cataly~t. Suitable hyaroly~is-dehydroacyloxylation catalysts include zeolite~, silica, alumina, silica-alumina~, silica-magnesia~, acidic alays, and the like.
The zeolite hydrolysi~-dehydroacyloxylation catalysts .
which may be used in the instant invention include the synthetic .
and natural zeolites, al~o known as molecular sieves. These zeolites axe well Xnown in the art and are detailed in ~olecular .~ 20 Sieves, Charles K. Hsrsh, Reinhold Publishing Company, New York (1961). Reprasentati-~e nautral zeolites which may be employed .:
- in the instant invention include those in Table 3-1 on page 21 ; .o~ the Hersh reerence ~hile representative molecular siev8s :
in~lude tho~e in Table 5-1 on page 54 o~ the Hersh reference.
- AdaitionAl zeoli~e catalysts are se~ forth in Orqanic Catal~sis .
Over_Crystalline A uminosil~ es, P.B. Venuto and P.S. Landis, Advanaes in Catalysi~, Vol. 18, pp. 259 to 371 (1968).
~ he silica-alumina hydrolysis-dehydroacyloxylation cataly8t8 which may be u~ed vary in compostion from pure silica to pura alumina whereas the ~ilica-magnegias vary in composition ~rom pure silica to predominantly magnesia.
The acidic clay hydrolysi~-dehydroacyloxylation
diester of 1~4-butansdiol with water in the presence ~f a hydrolysis-dehydroacyloxylation catalyst.
I~ is known in the ar~ that ~etrahydrofuran may bs made by a number o~ di~ferent methods; the more prominent method~ are by the catalytic hydrogenation of ~uran or by the dehydration o~ 1,4-butanediolO
In praatice, the tetrahydrofuran is most o~tan produced by a series of reactions ~tarting with the reaction of ~ormaldehyde and acetylene in the presen¢e o~ a cuprous acetylid~ complex to orm butynediol. Butynediol i8 converted on hydrogenation to butanediol~ The 1,4-butanedlol is converted ~o tetrahydrofuran as indicat0d abo~e.
Additionally, tetrahydro~uran i~ prepared ~rom maleia acid, its e~ters, maleic anhydride, fu~aric acid, its esters, ~;
~uccinic aaid, it~ esters, succinic anhydrideJ ~-butyrolactone, or mixtures of these compounds by hydrogenation over a hydro-generation catalyst.
However, these methods involve con~iderably expenæive equipmen~ and the handling of hazardous materia~s. Al~o, cataly~ts in some ~a~es may be expensive, and in other ~-instance~ may be ea~ily poisoned.
T~trahydrouran i~ a use~ul solvent ~or natural and ` ;~
synthetic resins, particularly vinyls. Also, it is used as an intermediate in the manu~acture o~ nylon, 1,4-dichlorobutane a '1 . -anu polyure~nanes.
It has been discovered that tetrahydrofuran may be inexpensively prepared rom a carboxylic acid diester of 1,4-butanediol by heating it with water in the presence of a hete-rogeneou~ hydrolysis-dehydroacyloxylation catalyst. By thi~
~ethod, tetrahydrofuran i9 prOd aed in esscntially qyantitative ., ; .:
8C~-1989 ~ .
~03~4B6 yields. Also, the hydrolysis-dehydroacyloxylation catalyst of the instant invention is stationary and perman~nt and there-fore may be continually reused.
Ancther object of this invantion is to pro~uce tetra-hydro~uran from inexpen~ive starting matexials, i.~., propylene, carbon monoxide, hydrogen and oxygen, by way o~ several inter- :
mediate steps.
The hydroly~is-dehydroacyloxyla~ion catalysts which may be employed in the practice o thi~ invention are those which promote hydrolysis, evolution o~ the carboxylic acid and ring closure. In the case o~ the diacetat~ es~or, the catalyst is a hydrolysis-dehydroacetoxylation cataly~t. Suitable hyaroly~is-dehydroacyloxylation catalysts include zeolite~, silica, alumina, silica-alumina~, silica-magnesia~, acidic alays, and the like.
The zeolite hydrolysi~-dehydroacyloxylation catalysts .
which may be used in the instant invention include the synthetic .
and natural zeolites, al~o known as molecular sieves. These zeolites axe well Xnown in the art and are detailed in ~olecular .~ 20 Sieves, Charles K. Hsrsh, Reinhold Publishing Company, New York (1961). Reprasentati-~e nautral zeolites which may be employed .:
- in the instant invention include those in Table 3-1 on page 21 ; .o~ the Hersh reerence ~hile representative molecular siev8s :
in~lude tho~e in Table 5-1 on page 54 o~ the Hersh reference.
- AdaitionAl zeoli~e catalysts are se~ forth in Orqanic Catal~sis .
Over_Crystalline A uminosil~ es, P.B. Venuto and P.S. Landis, Advanaes in Catalysi~, Vol. 18, pp. 259 to 371 (1968).
~ he silica-alumina hydrolysis-dehydroacyloxylation cataly8t8 which may be u~ed vary in compostion from pure silica to pura alumina whereas the ~ilica-magnegias vary in composition ~rom pure silica to predominantly magnesia.
The acidic clay hydrolysi~-dehydroacyloxylation
- 2 ~
~3'7~
catalyi~ts which may be u~ed in the instant inven~ion include clays containing th~ minerals kaolinite, halloy~ite, montmoril-lonite, illite, ~uartz, calci~e, liminomite, gypsumi, muscavita and the like, either in naturally acidic orm~ or after treatment with acid.
The catalyst i8 preferably used in tha form of a bed through which the reactants are passe,d.
The carboxylic aaid diesters of 1,4-butan~diol which are suitable in the instant invention preferably contain 2 to 8 carbon atom~. A pre~erred carboxylic acid diester of 1,4-butanediol i8 the diacetate of 1,4-butanediol.
The amount o~ water used i~ only that necessary to cause the reaction to proceed to a ~atis~actory ~xtent. In absence o~ added water, the conversion of the d~ac~tate to tetrahydrouran does not proceed and ~t ii~ pa~se~ through the tube e~sentially unchanged. Generally, we have ~ound that the ` ;
water and diacetate may be present in proportions varying from about 1 part water to about 10 parts diacetata, to about 10 parts water to 1 part diaceta~e. ~ the amount of water used increaises, thiis adds to tha volume o~ the reaction product from .
which ~he totrahydrofuran mu~t be isolated. Accordingly, one ~hould employ only the minimum amount o~ water needed to cau~e the r~action to go at optimum rates and yields. Preferably, the water employed in the instan~ inven~ion is in the orm of steam~
The tempera~ure at which the proc6ss can be carried out varies widely. ~emp~ratur~s ranging from about 12$C~ to about 300C. are generally adequate although higher temperatures can be usad. Pr0~erably, the reaction is carried out at a tempera-ture o~ ~rom about 180C. to about 270C. The maximum depends ;~
upon destruction of the product, olein formation occurring under too rigorous conditions.
~3'7~
catalyi~ts which may be u~ed in the instant inven~ion include clays containing th~ minerals kaolinite, halloy~ite, montmoril-lonite, illite, ~uartz, calci~e, liminomite, gypsumi, muscavita and the like, either in naturally acidic orm~ or after treatment with acid.
The catalyst i8 preferably used in tha form of a bed through which the reactants are passe,d.
The carboxylic aaid diesters of 1,4-butan~diol which are suitable in the instant invention preferably contain 2 to 8 carbon atom~. A pre~erred carboxylic acid diester of 1,4-butanediol i8 the diacetate of 1,4-butanediol.
The amount o~ water used i~ only that necessary to cause the reaction to proceed to a ~atis~actory ~xtent. In absence o~ added water, the conversion of the d~ac~tate to tetrahydrouran does not proceed and ~t ii~ pa~se~ through the tube e~sentially unchanged. Generally, we have ~ound that the ` ;
water and diacetate may be present in proportions varying from about 1 part water to about 10 parts diacetata, to about 10 parts water to 1 part diaceta~e. ~ the amount of water used increaises, thiis adds to tha volume o~ the reaction product from .
which ~he totrahydrofuran mu~t be isolated. Accordingly, one ~hould employ only the minimum amount o~ water needed to cau~e the r~action to go at optimum rates and yields. Preferably, the water employed in the instan~ inven~ion is in the orm of steam~
The tempera~ure at which the proc6ss can be carried out varies widely. ~emp~ratur~s ranging from about 12$C~ to about 300C. are generally adequate although higher temperatures can be usad. Pr0~erably, the reaction is carried out at a tempera-ture o~ ~rom about 180C. to about 270C. The maximum depends ;~
upon destruction of the product, olein formation occurring under too rigorous conditions.
- 3 -,: :
. . .
~037486 8CH-1989 Although only atmospheric pressure is normally required, it will be of course apparant to those skilled in the art that superatmospheric pre~ ure or ~ubabmospheric pressure may be u~ed wherc conditions and concentrations so dic~a~e.
The process may bs illustrated, taking the diacetate of 1,4-butanediol as an example, by khe ~ollowing equation:
O O ', " ................................................... :.
CH CO~CH )4OCCH3 ~ H o ~ CH - cH2 + 2cH3CooH
C~ CH '~' O
The above transormation is actually the net result o~ two con~ecutive reactions repre~ented by the ~ollowing eyuations:
o o O O
CH3CO(cH2)40ccH3 ~ ~2 - > H0~cH2)40ccH3 ~ C 3 O o :
HO~CH2)40CCH3 ?CH2 - CH2 ~ CH3COH ~ .
C~ CH2 0/ '' .
In Canadian application Serial No. 203,212 o~ ;
William E~ S~ith, filed June 24, 1974 and aesigned to ~he same as~ignee as the present invention, there i~ disclosed and claimed a proces~ ~or making butanediols by reacting propylene, oxygen and acid to produce an allyl carboxylate which is then hydroformylated to produce the mixture of the corresponding aldehydes. Hydrogenation o~ the mixtuxe produces a mixture of the ester~ o~ the corresponding diols. In Canadian application Serial No. lgS,892 o~ William E. Smith, filed .
March 25, 1974 and assigned to the ~ame assigne~ a~ khe present ~.
invention, there i8 disclosed and claimed a process wherein th~ hydrogenation is accomplished during the hydroformylation reaction. De-es~erification o the diol e~ter muxture ::-, " ' '~"''' '''`"'''`"'"`"""`'''"'''~''"t'`;' i"'"` I`i ' ..";.,.",, ~,,",,,;,,",;.
`` 8C~-l9~g 748~;
- produces the desired butanediol~ which can be separated by di~tillation.
In carrying out the preparation of tetrahydrofuran starting fxom propylene, oxygen and a carboxylic acid, the ~
procedures disclosed in the above-mentioned Canadian applications .;
may be used to obtain the carboxylic acid esters of lo 4~ -:
buta~ediol. These involve ~a) reacting propylene, oxygen and a carboxylic acid to form the corresponding allyl carboxylate;
(b) conver~ing the allyl carboxylate under hydroformylation-hydrogenation conditions to a mixture comprising the carboxylic acid ester~ of 1,4-butanediol, 1,2-butanediol and 2-methyl-1)~-propanediols (c) heating the dlol esters with water in the presence o a hydrolysis-dehydroacyloxylation catalyst to ~orm ~;
tetrahydro~uran and the car~oxylic aaid~ and (d) isola~ing the carboxylic acid in a form ~uitable for recycling to ~a~
To varying extents depending on reaction conditions 1,4-butanediol diacetate i9 formed in this se~ue nce, either by .
disproportionation o~ the monoacetate (which a~fords the :
diacetate and diol) or by esterification of the monoacetate with ac~ti~ acid present as a decomposition product.
Specifically, thi~ overall process for preparing -tetrahydro~uran comprises ~a) reacting propylene, oxygen, and a carboxylic a~id in th~ preæence o~ a catalyst compri-~ing a Group .-~
VI~I nobla meta~,. or its salt~, or it~ oxides or mixtures thereof at a temperature suf~iciently high to provide the .
desired rate of formation o~ the correspDnding allyl ~arboxylate but below the temperature at which sub~tantial degradation of the allyl carboxylate occurs; tb) converting the allyl carboxylate under hydroormylation-hydrogenation conditions to a mixture comprising the carboxylic acid esters o~ 1, 4-butanediol, 1,2-butanediol and 2-methyl-1,3-propanediol; (c) heating said mixture with water in the presence of a hydrolysis-dehydro-acyloxylation catalyst to conv~rt the 1,4-butanediol diester . . ., ,:, .
'`' - , , . . . . . . . . ' . . ~ . . .. . . . . ; . . . . .. . . .
lq~3~4B6 prasent, as well as the monoester and diol, to tetrahydrofuran and the carboxylic acid; and (d) isolating the carboxylic acid in a form suitable for recycling to (a)~
More speci~ically, the proces~ of producing tetrahydro- .
furan comprises (a) reacting propylene, oxygen and acetic acid in the presence of a catalyst comprising a Group VIII noble metal, or its ~alts or its oxides or mixtures thereo~, at a temperature ~ufficiently high to provide the desirsd rate of formation of allyl acetate but below the temperature at which substantial degradation of allyl acstate occurs; (b) converting ::.
the allyl acetate under hydrogenation-hydroformylation condition~ to a mixture comprising a signiicant amount of 1,4-butanediol diacetate in addition to the monoacetate and diol and the corresponding derivatives o~ 2-methyl~1,3- ;
propanediol and 1,2-butanediol; tc) heating ~aid mlxture with :.
watar in the presence of a hydroly~is-d0hydroacyloxylation catalyst to convert the diacetate o 1,4-butanediol pre~ent a~ well as the monoacetate and diol to tetrahydrofuran and acetic acidt (d) isolating the acetic acid in a form sui~able for recycling to ~a).
The conditions under which the carboxylic acid esters of l,4-butanediol, 1,2-butanediol and 2-methyl-1~3-propanediol `~
are formed from propylene, oxygen and acids by way of an intermediate step are disclosed in Canadian applications discussed above.
The hydrolysis-dehydroacyloxylation mixture can be passed over the catalyst in the li~uid phase, vapor phase or liquid-vapor phasa. Preferably, it is used in the vapor phase.
For most instances, the reaction is carried out by passing the carboxylic acid esters of 1,4-butanediol and water through a heated catalyst bed~ Thereafter, tha product is dis-tilled to e~ct isolation of acetic acid and an azeotrope 8C~-1983 103~74~
containing tetrahydrofuran and water. Well-known techniques of purifica~ion of the fractions can be u~ed to obtain the maximum yield of tetrahydrofuran.
The following examples are set ~orth to illustrate more clearly the principle and pxactice o this invention to tho~e skil}ed in the art. Unles~ otherwise specified, where parts or percent~ are mentioned, they axe part~ or percents by weight.
Ap~aratus -- ~ vertical hot tube reactox ~16 mm ID x 70 cm ef~ective length) is constructed ~rom heavy wall glass, with 24/~0 male and female joints. Vigreaux points are in-dented just above the male joint to support catalyst pellets.
Thermocouple leads are fa~tened into three other Vigreaux indentations at points along the length. Three 4 ~t~ x 1 inch Bri~kheat gla~s in~ulated heating tapes ara wound onto the tube, covered with glass wool and gla~s tape, and connected to separate variable transoxmers. The tube exit i5 connected by a gooseneck lalso hea~ed) to an e~icient condenser and collection vessel. A three necked 1ask serve~ as the evaporator, with the reactants added ~r~m addition unne}s in side necks. Nitrogen carrier gas is passed through to provide ra~idence times on the order of 3 to 10 second~.
Example 1 The tube reactor described above is chargsd with 89 `~
grams of silica-alumina catalyst 187% ~ilica - 13~ alumina, 3/16" x 3/16" pill~, Davison Chemical Grade 970~ and is main-tained at 220-250C while S0.0 grams o~ 1,4-butanediol diacetate and 50 ml. of water, admitted to the evaporator simultaneou~ly ~rom ~eparate addition ~unnels, are copassed through over a one hour period. Quantitative glpc analy~is (propionic acid in-ternal ~tandaxd) o the e~fluent shows the presence of 9.0 grams o 1,4 butanediol diacetate (18% recovery), 16.3 gram~ of tetra-hydrofuran (96% yield based on 82% conver~ion), and 28~2 griams .
' . " . ' ,' ' : ', ' .,', "' `. .. ". '.. ~ ' .' :'.
8C~ 1989 ~L~13~86 ~
of acetic acid (100% yield based on 82% conversion)~ ~o butanediol or butanediol monoacetate is detected.
- On dis~illa~ion, the tetrahydrofuran-water azeotrope i~ ea~ily ~eparated, leaving a watar-acetic acid-butanediol diacetate residue which can be further distilled to a~ford materials for r~cycle.
~ :,. ..
The tube xeactor is charged with 85 grams of ~ilica-magne~ia cataly3t (70% silica- 30% magnesia, 3/16" x 3/16" pil~ , Davison Chemical) and maintained at 220-250C. As in Example 1, 50.0 gram~ of 1~4-butanediol diacetate and 50 ml. of water are copas~ed over one hour. Ths effluent contains, as shown by quantitative glpc analy~is, 12.2 grams of the unconverted butane-diol diacetate ~24% recovery), 15.1 gram~ o tetrahydro~uran and 24.4 grams of ace~ic acid ~96% and 93% yields, resp~ctively, based on 76% con~er~ion), and 0.1 g~am~ of 4-acetoxybutanol ~0.3% yield).
~ '', '', ,, ' The kube reactor, charged with 110 grams of alumina catalyst ~1/8" pellets, Harshaw Al-OlO~T), is maintained at 250C while 25.0 grams of 1,4-buta~ediol diacetate and 50 ml.
of water ~xe admitted to th~ evaporator simultaneously from dif~erent addition funnel~ over a ~0 mlnuts period. The aqueous effluent collec~ed contains tatrahydrofuran, acetic acid, and about 10% of the original diacetate. The mixture is again taken through the tube. The effluent from this second pass contains, ;~
as founa by guantitative glpc analysis, 0.3 gram~ o~ residual butanediol diacetate ~1% unconvexted), 9~2 grams o tetra-hydrofuran (90~ yield), and 15.9 gxa~5 o~ acetic acid (93% yield).
!~
A 50.0 gram mixture containing 31,7 grams of :
, , , .. , ~ ~ , . " , i . . . " . - . ~
103~74~
. . .
~037486 8CH-1989 Although only atmospheric pressure is normally required, it will be of course apparant to those skilled in the art that superatmospheric pre~ ure or ~ubabmospheric pressure may be u~ed wherc conditions and concentrations so dic~a~e.
The process may bs illustrated, taking the diacetate of 1,4-butanediol as an example, by khe ~ollowing equation:
O O ', " ................................................... :.
CH CO~CH )4OCCH3 ~ H o ~ CH - cH2 + 2cH3CooH
C~ CH '~' O
The above transormation is actually the net result o~ two con~ecutive reactions repre~ented by the ~ollowing eyuations:
o o O O
CH3CO(cH2)40ccH3 ~ ~2 - > H0~cH2)40ccH3 ~ C 3 O o :
HO~CH2)40CCH3 ?CH2 - CH2 ~ CH3COH ~ .
C~ CH2 0/ '' .
In Canadian application Serial No. 203,212 o~ ;
William E~ S~ith, filed June 24, 1974 and aesigned to ~he same as~ignee as the present invention, there i~ disclosed and claimed a proces~ ~or making butanediols by reacting propylene, oxygen and acid to produce an allyl carboxylate which is then hydroformylated to produce the mixture of the corresponding aldehydes. Hydrogenation o~ the mixtuxe produces a mixture of the ester~ o~ the corresponding diols. In Canadian application Serial No. lgS,892 o~ William E. Smith, filed .
March 25, 1974 and assigned to the ~ame assigne~ a~ khe present ~.
invention, there i8 disclosed and claimed a process wherein th~ hydrogenation is accomplished during the hydroformylation reaction. De-es~erification o the diol e~ter muxture ::-, " ' '~"''' '''`"'''`"'"`"""`'''"'''~''"t'`;' i"'"` I`i ' ..";.,.",, ~,,",,,;,,",;.
`` 8C~-l9~g 748~;
- produces the desired butanediol~ which can be separated by di~tillation.
In carrying out the preparation of tetrahydrofuran starting fxom propylene, oxygen and a carboxylic acid, the ~
procedures disclosed in the above-mentioned Canadian applications .;
may be used to obtain the carboxylic acid esters of lo 4~ -:
buta~ediol. These involve ~a) reacting propylene, oxygen and a carboxylic acid to form the corresponding allyl carboxylate;
(b) conver~ing the allyl carboxylate under hydroformylation-hydrogenation conditions to a mixture comprising the carboxylic acid ester~ of 1,4-butanediol, 1,2-butanediol and 2-methyl-1)~-propanediols (c) heating the dlol esters with water in the presence o a hydrolysis-dehydroacyloxylation catalyst to ~orm ~;
tetrahydro~uran and the car~oxylic aaid~ and (d) isola~ing the carboxylic acid in a form ~uitable for recycling to ~a~
To varying extents depending on reaction conditions 1,4-butanediol diacetate i9 formed in this se~ue nce, either by .
disproportionation o~ the monoacetate (which a~fords the :
diacetate and diol) or by esterification of the monoacetate with ac~ti~ acid present as a decomposition product.
Specifically, thi~ overall process for preparing -tetrahydro~uran comprises ~a) reacting propylene, oxygen, and a carboxylic a~id in th~ preæence o~ a catalyst compri-~ing a Group .-~
VI~I nobla meta~,. or its salt~, or it~ oxides or mixtures thereof at a temperature suf~iciently high to provide the .
desired rate of formation o~ the correspDnding allyl ~arboxylate but below the temperature at which sub~tantial degradation of the allyl carboxylate occurs; tb) converting the allyl carboxylate under hydroormylation-hydrogenation conditions to a mixture comprising the carboxylic acid esters o~ 1, 4-butanediol, 1,2-butanediol and 2-methyl-1,3-propanediol; (c) heating said mixture with water in the presence of a hydrolysis-dehydro-acyloxylation catalyst to conv~rt the 1,4-butanediol diester . . ., ,:, .
'`' - , , . . . . . . . . ' . . ~ . . .. . . . . ; . . . . .. . . .
lq~3~4B6 prasent, as well as the monoester and diol, to tetrahydrofuran and the carboxylic acid; and (d) isolating the carboxylic acid in a form suitable for recycling to (a)~
More speci~ically, the proces~ of producing tetrahydro- .
furan comprises (a) reacting propylene, oxygen and acetic acid in the presence of a catalyst comprising a Group VIII noble metal, or its ~alts or its oxides or mixtures thereo~, at a temperature ~ufficiently high to provide the desirsd rate of formation of allyl acetate but below the temperature at which substantial degradation of allyl acstate occurs; (b) converting ::.
the allyl acetate under hydrogenation-hydroformylation condition~ to a mixture comprising a signiicant amount of 1,4-butanediol diacetate in addition to the monoacetate and diol and the corresponding derivatives o~ 2-methyl~1,3- ;
propanediol and 1,2-butanediol; tc) heating ~aid mlxture with :.
watar in the presence of a hydroly~is-d0hydroacyloxylation catalyst to convert the diacetate o 1,4-butanediol pre~ent a~ well as the monoacetate and diol to tetrahydrofuran and acetic acidt (d) isolating the acetic acid in a form sui~able for recycling to ~a).
The conditions under which the carboxylic acid esters of l,4-butanediol, 1,2-butanediol and 2-methyl-1~3-propanediol `~
are formed from propylene, oxygen and acids by way of an intermediate step are disclosed in Canadian applications discussed above.
The hydrolysis-dehydroacyloxylation mixture can be passed over the catalyst in the li~uid phase, vapor phase or liquid-vapor phasa. Preferably, it is used in the vapor phase.
For most instances, the reaction is carried out by passing the carboxylic acid esters of 1,4-butanediol and water through a heated catalyst bed~ Thereafter, tha product is dis-tilled to e~ct isolation of acetic acid and an azeotrope 8C~-1983 103~74~
containing tetrahydrofuran and water. Well-known techniques of purifica~ion of the fractions can be u~ed to obtain the maximum yield of tetrahydrofuran.
The following examples are set ~orth to illustrate more clearly the principle and pxactice o this invention to tho~e skil}ed in the art. Unles~ otherwise specified, where parts or percent~ are mentioned, they axe part~ or percents by weight.
Ap~aratus -- ~ vertical hot tube reactox ~16 mm ID x 70 cm ef~ective length) is constructed ~rom heavy wall glass, with 24/~0 male and female joints. Vigreaux points are in-dented just above the male joint to support catalyst pellets.
Thermocouple leads are fa~tened into three other Vigreaux indentations at points along the length. Three 4 ~t~ x 1 inch Bri~kheat gla~s in~ulated heating tapes ara wound onto the tube, covered with glass wool and gla~s tape, and connected to separate variable transoxmers. The tube exit i5 connected by a gooseneck lalso hea~ed) to an e~icient condenser and collection vessel. A three necked 1ask serve~ as the evaporator, with the reactants added ~r~m addition unne}s in side necks. Nitrogen carrier gas is passed through to provide ra~idence times on the order of 3 to 10 second~.
Example 1 The tube reactor described above is chargsd with 89 `~
grams of silica-alumina catalyst 187% ~ilica - 13~ alumina, 3/16" x 3/16" pill~, Davison Chemical Grade 970~ and is main-tained at 220-250C while S0.0 grams o~ 1,4-butanediol diacetate and 50 ml. of water, admitted to the evaporator simultaneou~ly ~rom ~eparate addition ~unnels, are copassed through over a one hour period. Quantitative glpc analy~is (propionic acid in-ternal ~tandaxd) o the e~fluent shows the presence of 9.0 grams o 1,4 butanediol diacetate (18% recovery), 16.3 gram~ of tetra-hydrofuran (96% yield based on 82% conver~ion), and 28~2 griams .
' . " . ' ,' ' : ', ' .,', "' `. .. ". '.. ~ ' .' :'.
8C~ 1989 ~L~13~86 ~
of acetic acid (100% yield based on 82% conversion)~ ~o butanediol or butanediol monoacetate is detected.
- On dis~illa~ion, the tetrahydrofuran-water azeotrope i~ ea~ily ~eparated, leaving a watar-acetic acid-butanediol diacetate residue which can be further distilled to a~ford materials for r~cycle.
~ :,. ..
The tube xeactor is charged with 85 grams of ~ilica-magne~ia cataly3t (70% silica- 30% magnesia, 3/16" x 3/16" pil~ , Davison Chemical) and maintained at 220-250C. As in Example 1, 50.0 gram~ of 1~4-butanediol diacetate and 50 ml. of water are copas~ed over one hour. Ths effluent contains, as shown by quantitative glpc analy~is, 12.2 grams of the unconverted butane-diol diacetate ~24% recovery), 15.1 gram~ o tetrahydro~uran and 24.4 grams of ace~ic acid ~96% and 93% yields, resp~ctively, based on 76% con~er~ion), and 0.1 g~am~ of 4-acetoxybutanol ~0.3% yield).
~ '', '', ,, ' The kube reactor, charged with 110 grams of alumina catalyst ~1/8" pellets, Harshaw Al-OlO~T), is maintained at 250C while 25.0 grams of 1,4-buta~ediol diacetate and 50 ml.
of water ~xe admitted to th~ evaporator simultaneously from dif~erent addition funnel~ over a ~0 mlnuts period. The aqueous effluent collec~ed contains tatrahydrofuran, acetic acid, and about 10% of the original diacetate. The mixture is again taken through the tube. The effluent from this second pass contains, ;~
as founa by guantitative glpc analysis, 0.3 gram~ o~ residual butanediol diacetate ~1% unconvexted), 9~2 grams o tetra-hydrofuran (90~ yield), and 15.9 gxa~5 o~ acetic acid (93% yield).
!~
A 50.0 gram mixture containing 31,7 grams of :
, , , .. , ~ ~ , . " , i . . . " . - . ~
103~74~
4-acetoxybutanol, 10.2 grams of 1,4-butanediol diacetate, a very small amount of l,4-butanediol, and oxo by-products ~about 6 grams o acetate derivatives of 2-methyl 1,3-propanediol and 1,2-butanediol) is copassed with 50 ml. of water through the tube reactor and alumina catalyst described in Example 3, at 250-270C~ over a one-hour period. A glpc analysis of the effluent show~ the presence of tetrahydrofuran, acetic acid and a ~ew other minor components, but no l,4-butanediol ,: .
derivatives. The product mixture is distilled through a 300 mm. ~ -Vigreaux column. The first 54 grams taken off (boiling over th2 64-100C. range) contains, as shown by quantitative glpc analysis, all of the tetrahydrofuran formed - 20~4 gram~, corresponding to a 95% yield based on conversion o~ all 1,4-butanqdiol monoacetate and diacetate initially pres~nt.
~nalysis o the total di~tillate ~hows the presence o~ Z4.3 grams o acetic acid.
Example 5 The tube reactor is charged with 88.1 grams o~
Linde 13X zeolite (1/8" pellets, pretreated at 200C. with a tetrahydrofuran-acetic acid vapor mixture) and maintained at 190-230C. while 50.0 grams of 1,4-butanediol diacetate and 60 -~
ml. of water are copassed, as in Examples 1-3, over a one-hour period. The e~fluent is recycled three times until the .. ~; .
diacetate is ecsentially ~onverted. Quantitative glpc analysis o~ the ~inal effluent shows the presence of 0,4 grams of butanediol diacetate (1% recovery), 9.5 grams of tetrahydrofuran 147% yield) and 30.4 grams of acetic acid ~89% yield). A
considerable amount o~ low boiling material is produced using this method.
Example 6 A mixture of completely acetylated oxo acetates compDsed o~ 37.8 grams of 1,4-butanediol diacetate, 4.7 grams of 2-methyl-1,3-propanediol diacetate and 7.5 grams of _ 9_ '. '.
,: . ' ;`
i~3~486 8CH-1989 1~2-butanediol diacetate is copassed with 50 ml. of water through the tube and the silica-alumina catalyst deseribed in Example 1, at 220-250C., over a o~e hour period. Quantitative glpc ~nalysis of the effluent indieatas the presence of 4.9 grams of the 1,4-butanediol diaeetate ~13% unconverted), 12.9 grams of tetrahydrofuran (95% yield based on 87% conversion), 29.1 grams of aeetie acid, and small quantities of the byproduct diols (2-methyl-1,3-propanediol and 1,2-butanediol), and their various acetate derivatives and olefinie deeomposition products. -Example 7 A miniplant is eonstructed and operated for theproduetion of tetrahydrofuran from propylene via the diselosed eyelie proeess. An 8 t. x 1 in~ diameter stainless steel tube i8 charged with one liter (lOQO grams) o~ aatal~st eomposed of alumina impregn~ted with palladium (0.3%) and potassium aeetate (3%), The reaetor temperature is maintained at 180C~ (circulating oil jacket) while a mixture per hour of 2000 grams of propylene, 600 grams o~ acetic acid, 170 grams of oxygen and 900 grams of water is passed through. The output per hour is a mixture of about 960 grams of allyl acetate and 1050 grams of water, in addition to 18 grams of carbon dioxide and the excess propylene and oxygen, which are reeycled.
The allyl acetate phase, which contains about 0~1% acetic acid, is separated and used diractly in the second stage of the process, A two liter stirred autoclave heated at 125C. is pressurized with 3000 psi o~ 2~1 hydrogen/earbon monoxide and eharged with a mixture of 400 grams of the allyl acetate, 8.0 grams of ~obalt oetaearbonyl and 400 ml. of benzene. An exothermic reaction and gas uptake ensue. After 15 minutes at 125-145C., the product mixture is pumped from the auto-clave, cooled and vented. It is then decobalted by heating at . . :- ~
10~48~ 8CH-1989 110C. for 10 minutes in a closed vessel, the addition of acetic acid being unnecessary because of its presence as a ~ ~
decomposition product. (The cobaltous acetate which forms is ~ -filtered off and trans~ormed to cobalt octacarbonyl by subjection to hydrogen/carbon monoxide at elevated temperature and pressure [160C., 3000 psi] ). The bsnæene solution is concentrated and the products are flash distilled, affording 474 grams (91% yield) o~ oxo aldehyd0s containing minox amounts of the butanediol acetate compounds. A glpc analysis indicates the pressnce o~ 4-acetoxybutyraldehyde, 3-acetoxy-2-methyl-propionaldehyde and 2-acetoxybutyraldehyde in 7 : 1.5 : 1.5 ratio.
The aldehyde mixture i8 combined in a stirred autoclave with 50 grams o a 13% cobalt on silica catalyst, ubjected to 3000 p~i o~ hydrogen and heated Eor 15 minutes at 190C. Reduction to the diol derivatives is complete, in essentially quantitative yield.
After removal of the hydrogenation catalyst by filtra-tion, the product mixture is examined by glpc and found to contain 4-acetoxybutanol, 3-acetoxy-2-methylpropanol and ~-acetoxybutanol, in addition to substantial amounts of the corresponding diacetate and diol disproportionation products (including about 140 grams of lp4-butanediol diacetate).
The acetate product is combined with 100 ml of water: ;
the mixture is passed directly through an 8 ft~ x 1 in.
diameter tube containing one liter of the catalyst described ,;
in Example 1, at 220-250C, over a 30 minute period (contact time 3-10 seconds). Distillation of the e~fluent affords the tetrahydrofuran-water azeotrope (containing, as indicated by glpc analysis, 176 grams o~ tetrahydrofuran, 61% yield in the conversion from allyl acetate) and 224 grams o~ acetic acid ;
(92% yield). The small higher boiling component of the effluent - 11 - ' .
.
8~1-1989 contains minor accounts of the byproduct acetates, diols and olefinic decomposition products. ~o 1,4~butanediol derivatives remain unconverted~
The ac~tic acid produced in the final step is recycled to the propylene oxidation stage for pxoduction of allyl acetate.
The process as described is operated semi-continuously to provide tetrahydrofuran at about one pound per hour.
It should, of course, be apparent to those skilled .;
in the art that changes may be made in the particular embodiments oE the invention described which are within the full intended scope of the invention as defined by the appended claim~
. .:
derivatives. The product mixture is distilled through a 300 mm. ~ -Vigreaux column. The first 54 grams taken off (boiling over th2 64-100C. range) contains, as shown by quantitative glpc analysis, all of the tetrahydrofuran formed - 20~4 gram~, corresponding to a 95% yield based on conversion o~ all 1,4-butanqdiol monoacetate and diacetate initially pres~nt.
~nalysis o the total di~tillate ~hows the presence o~ Z4.3 grams o acetic acid.
Example 5 The tube reactor is charged with 88.1 grams o~
Linde 13X zeolite (1/8" pellets, pretreated at 200C. with a tetrahydrofuran-acetic acid vapor mixture) and maintained at 190-230C. while 50.0 grams of 1,4-butanediol diacetate and 60 -~
ml. of water are copassed, as in Examples 1-3, over a one-hour period. The e~fluent is recycled three times until the .. ~; .
diacetate is ecsentially ~onverted. Quantitative glpc analysis o~ the ~inal effluent shows the presence of 0,4 grams of butanediol diacetate (1% recovery), 9.5 grams of tetrahydrofuran 147% yield) and 30.4 grams of acetic acid ~89% yield). A
considerable amount o~ low boiling material is produced using this method.
Example 6 A mixture of completely acetylated oxo acetates compDsed o~ 37.8 grams of 1,4-butanediol diacetate, 4.7 grams of 2-methyl-1,3-propanediol diacetate and 7.5 grams of _ 9_ '. '.
,: . ' ;`
i~3~486 8CH-1989 1~2-butanediol diacetate is copassed with 50 ml. of water through the tube and the silica-alumina catalyst deseribed in Example 1, at 220-250C., over a o~e hour period. Quantitative glpc ~nalysis of the effluent indieatas the presence of 4.9 grams of the 1,4-butanediol diaeetate ~13% unconverted), 12.9 grams of tetrahydrofuran (95% yield based on 87% conversion), 29.1 grams of aeetie acid, and small quantities of the byproduct diols (2-methyl-1,3-propanediol and 1,2-butanediol), and their various acetate derivatives and olefinie deeomposition products. -Example 7 A miniplant is eonstructed and operated for theproduetion of tetrahydrofuran from propylene via the diselosed eyelie proeess. An 8 t. x 1 in~ diameter stainless steel tube i8 charged with one liter (lOQO grams) o~ aatal~st eomposed of alumina impregn~ted with palladium (0.3%) and potassium aeetate (3%), The reaetor temperature is maintained at 180C~ (circulating oil jacket) while a mixture per hour of 2000 grams of propylene, 600 grams o~ acetic acid, 170 grams of oxygen and 900 grams of water is passed through. The output per hour is a mixture of about 960 grams of allyl acetate and 1050 grams of water, in addition to 18 grams of carbon dioxide and the excess propylene and oxygen, which are reeycled.
The allyl acetate phase, which contains about 0~1% acetic acid, is separated and used diractly in the second stage of the process, A two liter stirred autoclave heated at 125C. is pressurized with 3000 psi o~ 2~1 hydrogen/earbon monoxide and eharged with a mixture of 400 grams of the allyl acetate, 8.0 grams of ~obalt oetaearbonyl and 400 ml. of benzene. An exothermic reaction and gas uptake ensue. After 15 minutes at 125-145C., the product mixture is pumped from the auto-clave, cooled and vented. It is then decobalted by heating at . . :- ~
10~48~ 8CH-1989 110C. for 10 minutes in a closed vessel, the addition of acetic acid being unnecessary because of its presence as a ~ ~
decomposition product. (The cobaltous acetate which forms is ~ -filtered off and trans~ormed to cobalt octacarbonyl by subjection to hydrogen/carbon monoxide at elevated temperature and pressure [160C., 3000 psi] ). The bsnæene solution is concentrated and the products are flash distilled, affording 474 grams (91% yield) o~ oxo aldehyd0s containing minox amounts of the butanediol acetate compounds. A glpc analysis indicates the pressnce o~ 4-acetoxybutyraldehyde, 3-acetoxy-2-methyl-propionaldehyde and 2-acetoxybutyraldehyde in 7 : 1.5 : 1.5 ratio.
The aldehyde mixture i8 combined in a stirred autoclave with 50 grams o a 13% cobalt on silica catalyst, ubjected to 3000 p~i o~ hydrogen and heated Eor 15 minutes at 190C. Reduction to the diol derivatives is complete, in essentially quantitative yield.
After removal of the hydrogenation catalyst by filtra-tion, the product mixture is examined by glpc and found to contain 4-acetoxybutanol, 3-acetoxy-2-methylpropanol and ~-acetoxybutanol, in addition to substantial amounts of the corresponding diacetate and diol disproportionation products (including about 140 grams of lp4-butanediol diacetate).
The acetate product is combined with 100 ml of water: ;
the mixture is passed directly through an 8 ft~ x 1 in.
diameter tube containing one liter of the catalyst described ,;
in Example 1, at 220-250C, over a 30 minute period (contact time 3-10 seconds). Distillation of the e~fluent affords the tetrahydrofuran-water azeotrope (containing, as indicated by glpc analysis, 176 grams o~ tetrahydrofuran, 61% yield in the conversion from allyl acetate) and 224 grams o~ acetic acid ;
(92% yield). The small higher boiling component of the effluent - 11 - ' .
.
8~1-1989 contains minor accounts of the byproduct acetates, diols and olefinic decomposition products. ~o 1,4~butanediol derivatives remain unconverted~
The ac~tic acid produced in the final step is recycled to the propylene oxidation stage for pxoduction of allyl acetate.
The process as described is operated semi-continuously to provide tetrahydrofuran at about one pound per hour.
It should, of course, be apparent to those skilled .;
in the art that changes may be made in the particular embodiments oE the invention described which are within the full intended scope of the invention as defined by the appended claim~
. .:
Claims (8)
1. A process for preparing tetrahydrofuran which comprises heating a carboxylic acid diester of 1,4-butanediol with water in the presence of a solid phase hydrolysis-dehydroacyloxylation catalyst.
2. The process of claim 1 wherein the carboxylic acid diester of 1,4-butanediol is the diacetate of 1,4-butanediol.
3. The process of claim 1 wherein the hydrolysis-dehydroacyloxylation catalyst is selected from the group consisting of natural zeolites, synthetic zeolites, silica, alumina, silica-aluminas, silica-magnesias, and acidic clays.
4. A process for preparing tetrahydrofuran which comprises the steps of (a) reacting propylene, oxygen and a carboxylic acid to form the corresponding allyl carboxylate;
(b) converting the carboxylate under hydroformylation-hydrogenation conditions to a mixture comprising the carboxylic acid diesters of 1,4-butanediol, 1,2-butanediol and 2-methyl-1,3-propanediol;
(c) heating the diol esters with water in the presence of a solid phase hydrolysis-dehydroacyloxylation catalyst to form tetrahydrofuran and the carboxylic acid; and (d) isolating the carboxylic acid in a form suitable for recycling to (a).
(b) converting the carboxylate under hydroformylation-hydrogenation conditions to a mixture comprising the carboxylic acid diesters of 1,4-butanediol, 1,2-butanediol and 2-methyl-1,3-propanediol;
(c) heating the diol esters with water in the presence of a solid phase hydrolysis-dehydroacyloxylation catalyst to form tetrahydrofuran and the carboxylic acid; and (d) isolating the carboxylic acid in a form suitable for recycling to (a).
5. The process of claim 4 wherein said solid phase hydrolysis-dehydroacyloxylation catalyst is selected from the group consisting of natural zeolites, synthetic zeolites, silica, alumina, silica-aluminas, silica-magnesias, and acidic clays.
6. The process of claim 4 or 5 wherein said carboxylic acid is acetic acid.
7. The process of claim 1, 3 or 4 wherein said solid phase hydrolysis-dehydroacyloxylation catalyst is contained in a bed, through which said carboxylic acid diesters pass.
8. The process of claim 1, 3 or 4 wherein said heating is in the range of about 180°C to about 300°C.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US42085373A | 1973-12-03 | 1973-12-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1037486A true CA1037486A (en) | 1978-08-29 |
Family
ID=23668103
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA211,038A Expired CA1037486A (en) | 1973-12-03 | 1974-10-09 | Process for preparing tetrahydrofuran |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS5093961A (en) |
| BR (1) | BR7409959A (en) |
| CA (1) | CA1037486A (en) |
| DE (1) | DE2456780A1 (en) |
| FR (1) | FR2266700B1 (en) |
| GB (1) | GB1487200A (en) |
| IT (1) | IT1026704B (en) |
| NL (1) | NL7415775A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2442886B2 (en) * | 1974-09-07 | 1976-09-30 | Basf Ag, 6700 Ludwigshafen | METHOD FOR MANUFACTURING TETRAHYDROFURAN |
| DE2856455A1 (en) * | 1978-12-28 | 1980-07-17 | Basf Ag | METHOD FOR PRODUCING TETRAHYDROFURAN |
| DE4005295A1 (en) * | 1990-02-20 | 1991-08-22 | Basf Ag | THF recovery from butane-diol butyrolactone and succinate ester mixts. - by heating with layer silicate at 100-250 deg. C, distilling off THF water and sepg. THF from distillate |
-
1974
- 1974-10-09 CA CA211,038A patent/CA1037486A/en not_active Expired
- 1974-11-28 BR BR995974A patent/BR7409959A/en unknown
- 1974-11-29 FR FR7439176A patent/FR2266700B1/fr not_active Expired
- 1974-11-30 DE DE19742456780 patent/DE2456780A1/en not_active Withdrawn
- 1974-12-02 JP JP49137073A patent/JPS5093961A/ja active Pending
- 1974-12-02 GB GB5202074A patent/GB1487200A/en not_active Expired
- 1974-12-02 IT IT3006974A patent/IT1026704B/en active
- 1974-12-03 NL NL7415775A patent/NL7415775A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| AU7585974A (en) | 1976-06-03 |
| FR2266700B1 (en) | 1980-04-11 |
| IT1026704B (en) | 1978-10-20 |
| BR7409959A (en) | 1976-05-25 |
| JPS5093961A (en) | 1975-07-26 |
| FR2266700A1 (en) | 1975-10-31 |
| NL7415775A (en) | 1975-06-05 |
| DE2456780A1 (en) | 1975-06-05 |
| GB1487200A (en) | 1977-09-28 |
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