Note: Descriptions are shown in the official language in which they were submitted.
~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
- 2 ~
8CH-1989
~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
- 5 -
. . ., ,:, .
'`'
- , , . . . . . . . . ' . . ~ . . .. . . . . ; . . . . .. . . .
8CH-1989
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
- 6 -
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
- 8 -
:
, , , .. , ~ ~ , . " , i . . . " . - . ~
8CH-1989
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 --
. . :- ~
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~
. .:
