Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
This invention relates to a process for hydro-
lyzing and hydrogenating cyclic acetal-aldehyde compounds
in one step.
As disclosed in U.S. Patent 2,888,492 issued
May 26, 1969 to Fiæcher et al., it is well known that
six-membered acetal rings can be hydrolyzed and hydrogenated
in the presence of a weak soluble acid using a hydrogenation
catalyst. It i9 also well known that acetal groups form
ether linkage3 on hydrogenation as see, for example,
Reactions o~ Hydrogen with Organic Compounds over Copper,
Chromium Oxide and Nickel Catalysts by Homer Adkins, p. 75.
As disclosed in Organic Chemistry By Fieser and
Fieser, 1957, p. 157, it iB also well known that aldehydes
condense in the presence o~ acids to yield high molecular
weieht resinou~ materials. Since, chemically, the six-
membered acetal ring can also be described as a masked
aldehyde, it can be expected that acetal-aldehydes would
polymerize in the presence of an acid to yield polymeric
resinou~ materials. Depending on the strength of the acid,
the acetal-aldehyde would be expected to condense to a
greater or lesser degree, producing higher degrees o~
polymerization ~n the presence of strong acids. In addi-
tion, ~ome important hydroeenation catalysts such as Raney
nickel are attacked by acids, particularly strong acids.
- U.S. Patent 3,578,609 issued May 11, 1971 to
Naag and Whitehurst and British Patent 1,236,615 issued
June 23, 1965 to Mobile Oil Corporation disclose the
v preparation and use o~ dual function catalysts in which
metals are deposited on ion exchange resins~ Howe~er,
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10667Z3
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when these catalysts are applied to acetals the expected
conversion of the acetal groups to ether linkages is
observed.
SUMM~RY OF THE INVENTION
It has now been found that organic compounds con-
taining one six-membered acetal ring and one aldehyde group
can be hydrolyzed and hydrogenated in a single step to yield
;~ the ct)rresponding polyols in an aqueous medium in the presence
of hydrogen and a catalyst system of a hydrolytic amount of
a strongly acid water insoluble ion exchange resin and a
catalytic amount of a hydrogenation metal or metal compound
catalyst. If desired, the reaction may be allowed to con- ~ -
tinue beyond the polyol formation to achieve cyclization of
any polyols formed which are capable of cyclizing in the
presence of a strong acid, such as, for example, the cycliza-
.~ ~.. .... -
tion of 1,4-butanediol (BAD) to tetrahydrofuran (THF).
DETPlLED DESCRIPTION OF THE INVENTION
., ` ~ .
As used herein, the term polyol is intended to
include diols as well as tri- and higher hydroxy containing
~ 20 compounds.
s~ The acetal-aldehydes which may be hydrolyzed,
hydxogenated and, if desired, cyclized in accordance with
this invention contain one six-membered acetal ring and
one aldehyde functional gro~p attached to the acetal ring
directly or, indirectly, through a cyclic or acycllc,
saturated or unsaturated group which is, in turn, attached -
to the acetal ring at the carbon atom which separates the
oxygen atoms in the acetal ring.
The acetal-aldehydes to be processed in accord-
ance with this invention have the general formula
- 3 -
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R4 Rl
~ 'C-X
~/~.0~
~ R6 3
O O
ll ll
X is -CH or -MCH in which M i3 an alkyl group,
pre~erably having one to twenty carbon atom~, with the
,0,
proviso that the -CH group, may be attached to any M carbon
atom having a replaceable hydrogen; and Rl, R2, R3, R4, R5
and R6 may be the same or di~ferent and may be ~vdrogen or
an alkyl group, preferably having one to 20 carbon atoms.
Although 81kyl groups having more than 20 carbon
atoms can also be used as M and Rl, R2, R3, R4, R5 and ~ ,
10 the upper limit of ~0 carbon atoms is pre~erred to preclude
too high a molecular weight. The alkyl groups m~y also con-
tain any substituents which will not inter~ere with the
hydrol~sis-hydrogenation reaction o~ the invention.
Some speci~ic examples o~ acetal-aldehydes which
may be hydrolyzed and hydrogenated in accordance with thls
inventiOn include (Cl C20)
;;j O ~
~`` ~ & ( 1 20 ~ CH0
~` t--- ~ / H-CH-C ~ -
/CH-CH2-CH2-CHO \_o , .
O
CHgC~H-CH2~CH2~CHO C~3C)~H-CH-CH3
-CH2-CN2-CHC ~O~CH-CH-CH3
~ ~-CH2-CH2-CH0
( ~ )2 o 0~ CH0
(C ~ )2 ~ /CH-CH-CH
- 4 -
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The catalytic liquid hydrolysi~-hydrogenation
reaction o~ this inve~ntion is carried out in an aqueous
medium at elevated temperature under superatmospheric
hydrogen pressure. Generally a molar ratio of water to the
acetal-aldehyde of 1:1 - 100:1, preferably 1:1 - 10:1,
at a hydrogen pressure o~ 500 - 10 000 psig, preferably
1 000 - 5 000 psig and a temperature of 65 - 150C. are
employed.
Any strongly acidic water insoluble ion exchange
resin can be u~ed in the practice of this invention.
T~pical such resins are those containing sul~onic acid
groups such as the resins disclosed in U.S Patent
2 366 007 issued December 26, 1944 to G.F. D~Alelio
~hich include sulfonated styrene-divinyl benzene copolymers
commercially available as nDowex~ G-l, 50 and 50WX8
;~
"Amberlystn* 15,nDuoliten* C-20 and the like resin~. Other
sultable cation-exchange resins include, for example, the
phenol sul~onic acid-formaldehyde reaction products.
`~` Optionally small amounts of basic resins can be used to
absorb any slight amount o~ soluble scid components that
may be present in fresh ion exchange resins. This serves
to reduce catalyst corrosion due to acid attack and in no
;~, way influences the proç~88.
~ Any of the metal or metal compound cataly~ts of
i;~ the type well known and customarily referred to in the art
as hydrogenation cataly~ts can be used. It is desirable
to employ as the hydroge~atlon cataly~t a metal or a -
compound o~ a metal which ~ay be ea~ily and econ~mically
prepared, which has a high degree o~ activity, and which
~ 30 retains its acti~ity under the cond~tions of the proce~s - --
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1066723
for a length of time sufficient to avoid the necesgity of
reactivating or replacing the ca~alyst at too ~requent
intervals. Generally speaking, hydrogenation catalysts
which may be employed in the execution of the process of the
invention include the metal hydrogenation catalysts, such
as platinum, pa'ladium, gold, silver, copper, vanadium,
tungsten, cobalt, nickel, ruthenium, rhodium, manganese,
chromium, molybdenum, iridium, titanium, zirconium, and the
like and mixtures of the same and compounds and alloys
thereof, particularly oxides and sulfides thereof, and
like hydrogenation catalysts. Because of the ease and
economy with which they may be prepared~ the base metal
hydrogenation catalysts, particularly the pyrophoric base
metal hydrogenation catalyst~ such as nickel, cobalt, and
iron, are advantageous. Most important are nickel-aluminum
alloys which are activated by partial removal of the
aluminum with NaOH. The hydrogenation catalyst may be
employed in a finely divided form and dispersed in and
throughout the reaction mixture, or it may be employed in
a more massive state, either in essentially the pure ~tate
or ~upported upon or carried by an inert or catalytically
active supporting or carrier material, such &S pumice, ~ -
kieselguhr, diatomaceous earthJ clay, alumina, charcoal,
carbon, or the like, and the reaction mixture contacted
therewith as by flowing the mixture over or through a bed
o~ the catalyst or according to other methods that are
known in the art.
The insoluble resin and the hydrogenation catalyst
which form the catalyst system o~ this invention may exist
in various interrelationships with one another as desired
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but typically a weight ratio of insoluble reæin to hydro-
genation catalyst of 0.1:1 to 100:1, preferably 1:1 to
10:1 is used.
Depending on the product desired and the kind of
reaction system employed (slurry, ~ixed bed and so on),
any hydrolytic-catalytic amount of the catalyst system Or
this invention may be employed. Generally, amounts of the
acid-catalyst system are employed such that 1~ by weight
of hydrogenation catalyst based on the weight of the acetal-
aldehyde i~ present. In a slurry system 1-10% by weight
based on the contents Or the reactor are optimum and in a
~ixed bed reactor, 10 to 20 times as much may be used.
The reaction of this invention may be carried
out either continuously or batchwise. In either case, the
time during which the reactor contents are in contact
with the catalyst system depends on the product desired.
By manlpulating temperature and contact time, one may
produce either polyol product or the cyclized form of any
polyol which is capable o~ being cyclized in a strongly
acid medium or any combination thereof. As temperature and
contact time increase, the cyclization reaction i5 favored.
Taking BAD a~ an example, greater than 90% yields of cyclized -
BAD (THF) can be obtained at higher temperature~ and
contact times while 99% yields of BAD can be obtained at
loNer temperatures and contact times. Any interrelationship
bet~een temperature and contact time of up to 3 hours at
~; 60C. and up to one half hour at 150C. can be observed. ~-
At 130C. or higher~ THF forms very rapidly and preferentially.
Other methods ~or producing THF using cation exchange
regins are disclosed in U.S. Patent 3,467,679 issued
.
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September 16, 1969 to A. 0. Rogers and German Patent 850 750
issued September 29, 1952 to I. G. Farbenindustrie.
The polyols produced by the process o~ this
invention may be used for any application for which polyol~
are sultable such as reactants with isocyanates to form
urethanes and polyurethanes, with acids to form esters and
polyesters and so on.
The invention i~ further illustrated but ls not
intended to be limlted by the following examples in which
all parts and percentages are by weight unles~ otherwise
speclfied.
EXAMPLE 1
' A 300 ml. stirred autoclave ls charged wlth:
isomeric mixture of 2(~ andr
; formyl ethyl~-5,5-dimethyl-
1,3-dioxane (70~ of ~ 50 grams
water 50 gm.
Raney nickel (wet solids) 5 gm.
"Dowex" 50W~8 10 gm.
"Dowex" 21E 1 gm.
' The autoclave is then sealed, pressurized with
hydrogen and maintained at 1500 psig o~ hydrogen pressure
at 90C. for 30 minutes. At the end of this time, ~3s
chromatograph ana}ysis shows that 95~ of the dioxane is
converted to a mixture of glycols. A 97% yield of 1,4-
butanediol (BAD) i~ obtained and only trace amounts of
tetrahydrofuran (1~) are present.
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EXAMPLE 2
A 300 ml. stirred autoclave i~ charged with
the formyl dioxane mixture of Example 1 45 g.
water 50 g.
Raney nickel (wet solid) 5 g.
"Dowex" 50WX8 resin 10 g.
The autoclave i8 sealed, pressurized with hydrogen
and maintained at 1500 psig of hydrogen pressure at 100 C.
for 25 minutes. At this point a gas chromatograph ~can
shows essentially complete con~ersion of the dioxane essen-
tlally to 1,4-butanediol. The temperature is rai~ed to
120C. and maintained for 30 minutes. At the increased
temperature, 60~ of the 1,4-butanediol is converted to Th~.
Example 1 i8 repeated except that the quantity
of "Dowex" 50WX8 resin is increased from 10 to 20 grams.
At the end of 30 minutes, 100% of the dioxane is converted.
Ga~ chromatograph analysis shows that the product contains
15% of THF based on the concentration of 1,4-butanediol in
~ 20 the final mixture.
'``' EXAMPIE ~ ":.. ,
`~ Example 1 is repeated except that the quantity of Raney nickel is increased from 5 to 12 grams. Substantially
the same result~ are obtained as reported in Example 1.
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EXAMPLE 5
A continuous process is carried out as follows:
The autoclave is charged with:
Ethylene glycol 30 g.
Water 3o g.
Raney Nickel (wet ~olid) 5 g.
"Dowe~'50WX8 resin 10 g.
~Dowex~ 21K re~in o.5 g.
The autoclave is then sealed and the pres~ure and
temperature ad~usted to 1600 pslg and 90C. maintained at
those l~ve's. An isomeric mixture of 2-(~ r -formyl ethyl)-
5,5-dlmetby1-1,3-dio~ane (60%1r) is then pumped into the
autoclave at a rate of 60 grams per 40 minutes. A sample
taken at 40 m~nutes shows that the conversion of dioxane
i8 80% at this point. Afterlthe feed is completed the
reaction is allowed to conti~ue for 30 minutes. At the
end of this period the dioxane conversion to glycol~ i8
` 97%. At this point the nickel is removed and the reaction
mixture heated to 140C. in a still to convert all the -
1,4-butanediol to THF which is distilled off overhead.
The yield of 'ln~ ~ased on the y isomer in the dioxane
charged i8 91%.
EXAMPIE 6_
To a stirred 300 cc. autoclave i~ added ~he
following:
2 (~,r formyl ethyl)-5-met~yl-1,3-dioxane
(80% ~) 5 g.
Water 5o g,
Do~ex" MSC-l Resin (a ~ulfonic acid ion
i exchange reQin) 15 ~.
r~1 30 Nickel(Raney, wet solids) 10 g.
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The temperature is raised to 130C. and the
pressure to 2000 psig. At the end of one hour under these
conditions the conversion of the dioxanes is complete,
The 1,4-butanediol produced is cyclized to T~F to the
extent of 93%. The yield of T~IF and butanediol based
on the amount of y formvl ethyl isomer charged is 97%.
It is to be understood that any of the components
and conditions mentioned as suitable herein can be substi-
tuted for its counterpart in the foregoing examples and that
similar advantageous results can be expected. Further,
; although the invention has been described in considerable
detail in the foregoing, such detail is solely for the
purpose of illustration. Variations may be made in the
invention by those skilled in the art without departing
from the spirit and scope of the invention except as set
forth in the claims.
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