Note: Descriptions are shown in the official language in which they were submitted.
~9~ ~9
CATALYSIS OF CONDENSATION REACTIONS
This application is a division of copending Canadian
Patent Application No. 405,618, filed June 21, 1982, and is
also related to copending Canadian Patent Application No.
400,220, filed March 31, lg82.
TECH~ICAL FIEI,D OF THE INYENTION
The present invention relates to organic condensation
reactions effected in the presence oi novel pyrophosphate
and hydrogen phosphate catalysts and is more particularly
concerned with the production of amine compounds in enhanced
yields.
BACKGROUND OF THR PRIOR ART
-
Organic synthesis by condensation reactions resulting
in the loss of a molecule of water or of ammonia are well
known in the art. Certain of such reactions are generally
effected in the presence of acidic catalysts. An important
area in which such acid catalysis has been employed is in
cycliæation reactions as in the synthesis of triethylenediamine
and its C-substituted homologues. The catalysts more generally
2~ used or proposed for use in such cyclization reactions are
solid products of the Lewis acid type.
Triethylenediamine, also called diazabicyclo -[2.2.2]-
octane, has been widely employed commercially as a catalyst
in organic isocyanate reactions with compounds containing
labile hydrogen, as in the production of urethane polymers.
Triethylenediamine (sometimes hereinafter referred to as
TEDA) was initially prepared
-- 1 --
119~i29
in significant q~lantities by methods such as that
described in U.S. Patent No. 2,937,176, by passing
aliphatic amines in vapor phase over acidic cracking
catalyst, such as silica-alumina dried gel or acid
activated clays. Numerous other feed stocks as well as
other catalysts are disclosed in subsequent patents for
preparation ~f TEDA as well as C-alkyl derivatives
thereof.
Typical among these are U.S. Patents 2,985,658 and
3,166,558 employing preferably silica-alumina type
catalyst, but listing also other useful solid acid
catalysts that can be employed such as alumina in which
phosphate or fluoride ion is incorporated (U.s. 2,985,658~.
Among other catalysts proposed in the patent art
for preparation of triethylene diamine and/or C-alkyl
homologues there~f, are certain phosphate compounds,
particularly aluminum phosphate.
The use of aluminum phosphate as a catalyst in the
preparation of heterocyclic compounds from aliphatic
amines was early disclosed in U.S. Patent 2,467,205,
particularly for the preparation of piperazine from
ethylenediamine or from polyethylene polyamine. The
use of aluminum phosphate as catalyst in the preparation
of triethylenediamine accompanied by piperazine among
other by-products is further described in U.S. ~atent
3,172,891; while U.S. Patent 3,342,820 describes the
use of complex phosphates of alkali metal and trivalent
metals in the preparation of C-alkyl TEDA.
U.S. Patent 3,297,701 discloses as catalysts for
preparation of TEDA and C-alkyl TEDA, in addition to
the preferred aluminum phosphate stated to be superior,
other phosphate compounds including calcium and iron
phosphates among other listed metal phosphates. In the
conversion of N-aminoethylpiperazine to triethylenedi-
amine over aluminum phosphate catalyst, at most up to39 mol% triethylenediamine is said to be obtained.
Other of the named metal phosphate catalysts in the
~iL98~2~
examples of the patent obtain yieids of less than 10 mol% TEDA.
Acid metal phosphate catalysts, particularly phosphates of boron,
aluminum and trivalent iron, have also been proposed for use in intramolecular
cyclic dehydration reactions and other condensation reactions involving
amino compounds. Examples of such reactions are found in U.S. Patent
4,117,227, which discloses conversion of an N-substituted diethanolamine
to the corresponding N-substituted morpholine. U.S. Patent 4,036,881
describes preparation of non-cyclic polyalkylene polyamines by condensation
of an alkylene diamine with an ethanolamine. N-hydroxethylmorpholine is
condensed with morpholine in the presence of aluminum phosphate catalyst
to form dimorpholino ethane according to U.S. Patent 4,103,087. Similarly,
dimorpholinodiethyl ether is obtained by condensation of hydroxyethyl
morpholine with aminoethyl morpholine over iron, aluminum or boron
phosphate in U.S. Patent 4,0g5,022. Reaction of piperazine with ethanolamine
over such acidic metal phosphate pro~duces N-aminoethyl pipera~ine according
to U.S. Patent 4,049,657. V.K. Patent 1,492,359 discloses the preparation
of morpholine compounds by reacting an aminoalkoxyal~anol compound over
phosphoric acid and similar types of phosphorus-containing substances.
Pyrophosphates of lithium, sodium, strontium and barium have been
used as dehydration catalysts; see U.S. Patent 3,957,900. Phosphates
and pyrophosphates of strontium and nickel have been used for the dehydrogenation
of, for example, n-butene to butadiene under the conditions described in
U.S. Patent 3,541,172.
SUMMARY OF THE INVENTION
In its broadest aspect the present application, a division of
copending Canadian Application No. 405,618, filed June 21, 1982, is
concerned with the provision in methods for the synthesis of organic
compounds by condensation reactions in the presence of phosphate catalysts,
by the improvement which comprises the use as such of catalysts which
are selected from the group consisting of the pyrophosphate and dihydrogen
~'
~ 4 ~ 11984Z9
phosphate of strontium, and mix~ures thereof, together with mixtures of
at least one of the pyrophosphate and dihydrogen phosphate of strontium
with the monohydrogen phosphate of strontium.
DETAILED DESC~IPT~O~ OF ~E INVEN~ION
The monohydrogen and dihydrogen phosphate catalysts of the present
invention are prepared by reaction of a mono- or diphosphate of an
alkali metal or a~monium with a soluble salt of strontium, copper,
magnesium, calcium, barium, zinc, aluminium, lanthanum, cobalt, nickel,
cerium or neodymium at ambient temperatures. The highest purity and
best yields of the present invention are obtained when using the soluble
metal salts of a strong acid such as the metal nitrates, in substantially
stoichiometric proportion to the phosphate. In aqueous media under
these conditions, the reaction mixture is at a pH of about 3.5 to 6.5.
In general, to obtain a precipitate of desired high content of the metal
monohydrogen or dihydrogen phosphate~ the ratio of phosphate to metal
salt in the reaction mixture should be such as to have a pH of 5 ~ 3,
or the mixture should be adjusted to that pH range.
The pyrophosphate form of the catalysts of the present invention
are prepared by heat treating the metal monohydrogen or dihydrogen
phosphate product at temperatures above about 300C up to 750C in the
presence of a mixture of steam and air, preferably at least about 20% by
volume of steam.
For use as a catalyst, the metal pyro-, monohydrogen or dihydrogen
phosphate product may be employed in the form of irregular particles of
the desired size range prepared by breaking up the washed and dried
filter cakè or in the form of regular shaped pellets obtained by known
methods of casting or extruding or the product
~'..`'
8~i~9
may be deposited or otherwise impregnated into the
pores of a microporous substrate such as alumina,
silica, silica-alumina, and the like. In using the
catalyst of the present invention to catalyze organic
condensation reactions, substantially the same condi-tions
may be employed as when using the ~nown catalysts for
the particular synthesis. For optimum results, however,
some adjustment in temperature, diluent and/or spac~
rate may be ound beneficial.
Some specific examples of the type of organic
compounds selectively obtained by the method of this
invention include T~DA, the aliphatic alkylamines such
as methylamine, methylethylamine, dimethylethylamine,
morpholine, and dimethylaminoethylmorpholine. In the
production of these compounds, the temperature is in
the range of about 285 to 420~C, the pressure is in
the range of about G.1 to 1.5 atmospheres, and the
liquid hourly space velocity (LHSV) of the organic feed
stock per ~olume of catalyst is in the range of about
0.05 to 1.5. Preferably depending on the particular
reaction, the temperature is in the range of about 300
to 400~C, the pressure is in the range of about 0.3 to
1.O atmospheres and the LHSV is in the range of about
0.1 to 0.3 to obtain the highest yields and most econom-
~5 ical process. The operable ratio of the organic feedsto water diluent is about 10 to 90% on a weight basis
and preferably, 20 to 80% by weight. The optimum yield
of these compounds is likely to be obtained using the
highest temperature in the preferred range at the
lowest LHSV.
In the preparation of TEDA, the preferred catalyst
is selected from the group consisting of monohydrogen
phosphate of calcium, magnesium, zinc, mixtures of
strontium and ~arium in the ratio of Sr to Ba o about
1 to 5 to 5 to 1 and mixtures of lanthanum and strontium
in the ratio of La to Sr of about 15 to 1 to 15. The
organic feed stock used in this reaction to produce
119~4Z~
TEDA is a substituted piperazine compound selected from
the group consisting of hydroxyethylpiperazine and
aminoethylpiperazine. The catalysts of this invention
are relatively uneffected by the purity of the feed
stock. For example, high conversion and go~d yields
can be obtained from crude hydroxyethylpiperazine which
contains minor quantities of piperazine and bis hydroxy-
ethylpiperazine.
In the preparation of dimethylaminoethylmorpholine
(DMAEM), the preferred catalyst is a mixture of strontium
and nickel monohydrogen phosphate in the ratio of Sr to
Ni of about 1 to 5 to 5 to 1. The feed stock is morpholine
and dimethylethanolamine in the molar ratio in the
range of about 1 to 3 and 3 to 1. Preferably, the
reaction takes place in the presence of hydrogen in the
molar ratio of hydrogen to organic feed of about 1 to 1
to 20 to 1 and an inert gas such as nitrogen, argon or
helium in the molar ratio of inert gas to organic feed
of about 1 to 1 to 20 to 1.
In the preparation of morpholine co~pounds, e.g.
morpholine and alkyl morpholine, wherein the alkyl
group has from 1 to 6 carbon atoms, diglycolamine
compounds, e.g. diglycolamine and alkyl diglycolamines,
wherein the alkyl group has from 1 to 6 carbon atoms
are preferably carried out in the presence of strontium
monohydrogen phosphate at about 300 to 370C with the
other conditions remaining the same as that discussed
above. ~his reaction also preferably takes place in
the presence of the inert gas in ratios of 2 to 1 to 10
to 1 inert gas to liquid organic feed stock.
The methods and catalysts of this invention are
also capable of reacting an alcohol and a nitrogen-
containing compound selected from the group consisting
of ammonia, aliphatic primary and secondary amines, and
aromatîc primary and secondary amines to selectively
con~ert this compound to the corresponding symmetrical
or unsymmetrical higher molecular weight amine with
1~l91~'~29
little, if any, conversion to the correspondinq ~y-products of
thermodynamic amine equilibration. The amines and alcohol in
the feed stock each contain 1 to 20 carbons per molecule~
Preferably, the catalyst is lanthanum or copper monohydrogen
phosphate and the molar ratio of alcohol to nitrogen-containing
compound ranges from about 1 to 6 to 6 to 1.
CATALYST PREPARATION
Example 1
200 grams of strontium nitrate [Sr(NO3)2] was dissolved
in distilled water and brought to a total volume of 800 cc with
distilled water. To this solution there was added 10 cc of 8S%
phosphoric acid followed by 34.5 cc of 50% sodium hydroxide
added rapidly with vigorous stirring. The resultant fine
white precipitate was stirred for 10 minutes, vacuum-filtered
and water-washed. The obtained filter caXe was air dried in a
static oven at approximately 110C and extruded into 1/8 inch
pellets for evaluation.
The obtained product had a surface area of 10-15 m /g.
By X-ray diffraction the principal component was identified as
~-SrHPO4 with minor quantities of Sr5(OH~ (PO4)3 and unreacted
Sr(NO3~2. Infrared spectroscopy showed a spectrum consistent
with SrHPO4. SRef: Richard A. Nygurst and Ronald O. Kagel,
"Infrared spectra of Inorganic Compounds", page 163, 1971).
Example 2
212 grams of Sr(NO3)2 were dissolved in distilled water
and diluted to 500 cc. 115 grams of ammonium dihydrogen
phosphate --NH4H2PO4-- were dissolved in distilled water and
diluted to 500 cc. The salt solutions were then combined with
heat and stirrPd. The combined solution was vacuum filtered
and the resulting precipitate was washed with distilled water
and air dried overnight in a static oven at approximately 110
C. The resulting catalyst was believed to contain less than 5
strontium dihydrogen phosphate --Sr(H2PO4)2-- with the balance
8 ~1~8~9
being SrHPO4. The surface pH of this catalyst mixture was
4-4.6 in comparison to substantially pure strontium
monohydrogen phosphate which has a surface pH of 4.8-5.4.
Substantially pure strontium dihydrogen phosphate was found to
have a surface pH of 0.2-1.2; see Example 5.
The product of this example was deposited on
silica-alumina spheres by placing the amount of catalyst to be
coated into a jar with Alundum spheres and rotating on a
jar-mill for several days to cause the catalyst powder to
adhere to the spheres.
Example 3
A catalyst preparation procedure was employed in which
212 grams of Sr(NO3)2 was dissolved in distilled water and
thereafter diluted with distilled water. Di basic ammonium
phosphate was also dissolved in distilled water and diluted
with distilled water with heat. The salt solutions were then
combined with heat and stirre~d. The combined solution was
vacuum filtered and the resulting precipitate was washed with
distilled water and air dried overnight in a static oven at
approximately llO~C. The resulting strontium monohydrogen
phosphate catalyst had a surface pH o~ 4.8-5.2.
~9~4~
g
Control s 1- 3
The followin~ salts were also combined in the manner ~f
the Exampl e 1 pr epa rat i o n .
Catalyst
Control Salt Solutions Formulatior
(a) (b)
261g. Ba (N03)2 :BaS04
2 75g . CsCl40g . (NH4) 2HP04 CsHP04*
3 106g. Sr(N03)40g. SO% NaOH~ . SrHAsO4
2 80e (~H4)2H2A54
*Did not fonn a precipitate.
lo 119~3 ~Z9
Control 4
200 grams of Sr(NO3)2 were dissolved in distilled water
and diluted to 400 cc. 92 grams of H2SO4 were diluted in 200
cc. of distilled H2O. 75 grams of 50 wt. % NaOH solution were
diluted to 200cc. with distilled water. The H2SO4 and NaOH
solutions were mixed together slowly. The Sr~NO3)2 solution
was stirred into the solution containing H2SO4 and NaOH. The
solution was stirred for 10 minutes and the precipitate was
filtered, washed and dried. The surface pH of the resulting
catalyst was less than 3 which was believed to be substantially
all SrSO4.
Example 4
The SrHPO4 catalyst of Example 3 was heat treated for 2
hours in the presence of a mixture 20% by volume steam and the
balance air at 350C. The resulting strontium pyrophosphate
tSr2P2O7) had a crushing strength of 0.47 kg./mm of length and
a packed bulk density of 1.01 kg./l.
Example 5
132.5 grams of strontium hydroxide octahydrate
--Sr(OH)2.8H2O-- were dissolved in a solution of 750 cc. of 85~
phosphoric acid and 1500 cc. of distilled water. The resulting
solution was slowly evaporated to a total volume of about 900 cc.
4~
11
with the temperature being maintained at 25 to 30Co The
solution was cooled to 5C overnight and a white precipitate
was recovered by vacuum filtration. The resulting Sr(H2PO4)2
precipitate was washed with 5-300cc. portions of anhydrous
ethanol and with 2-200 cc. portions of anhydrous ether. The
product was dried at room termperature under vacuum for 6
hours~ An elemental analysis of the product showed a P/Sr mol
ratio of 2.04 and the surface pH was found to be ~.2-1.2. The
fine powder was pressed into tablets the size of a typical
"Aspirin" (registered trade mark) tablet and crushed to
granules 1/8 to 1/4 inch in size.
Example 6
The fine powder of the catalyst prepared in accordance
with Example 5 was deposited on silica-alumina spheres in the
manner set forth in Example 2.
Example 7
2000 grams of Sr(NO3)2 were dissolved in 2000 cc of
deionized water and the solution diluted to 4000 cc with
deionized water after dissolution of the Sr(NO3)2 was complete.
In another container, 1342.3 grams of Na2HPO4 were
dissolved in 2000 cc of deionized water. After solution of the
Na2HPO4 was complete, the solutions was diluted to 4000 cc with
deionized water. The pH of this solution was approximately
8.8.
Precipitation of SrHPO4 was effected by slowly adding the
Na2HPO4 solution to the Sr(NO3)2 solution with rapid stirring.
The white SrHPO4 precipitated rapidly from solution forming a
rather thick slurry. This slurry was mixed for one hour, after
which time the pH was measured to be about six.
The solid SrHPO4 was recovered by filtering on an eight
frame filter press using cloth filters. It was washed with
deionized water. After filtering and washing, the solid was
dried in a circulating hot air oven at 250F for four hours.
12 ~ ~ 9~42~
The yield of SrHPO4 was 1680 grams. The solid was wetted and
formed into pellets by extrusion through a 3.1 mm die plate and
cutting the extrudates to about l/4 inch in length. After
drying the extrudate at 250F for four Hours in a circulating
hot air oven, they were heat treated at 662F for two hours in
a 20~ steam, 80~ air atmosphere.
USE OF CATALYST_
Examples 8-15
Several of the products prepared in accordance with the
above Examples and Controls l and 3-5 above were evaluated for
catalytic performance for the preparation of TEDA with either a
feed mixture containing hydroxyethylpiperazine (HEP) or
N-aminoethylpiperazine (AEP) in accordance with the following
test procedure:
(a) 20 cc (approximately 6.2g.) of the catalyst was
loaded into a 3/4" diameter stainless steel reactor.
(b) The reactor was placed in a conventional tube
furnace such that the catalyst bed was near the furnace
center and therefore could be heated to a constant and
uniform temperature.
(c) The catalyst bed termperature was raised to a
termperature of 340- 400C over a period of 15 to 30
minutes while a small flow of gaseous nitrogen was
maintained through the reactor to àid in the removal of
water vapor.
(d) A feed mixture containing HEP and water such
that the organic component made up 60% of the mixture was
than allowed to flow through the catalyst bed at a rate
of 6.5-7.0 cc/hour; the nitrogen flow was discontinued.
(e) The catalyst bed temperature indicated in the
tables set forth below was maintained during the run and
the product samples were collected and analyzed.
I~,r ~ ,
2g
13
Analyses were performed using well-established gas
chromatographic techniques.
The yields of TEDA and piperazine (PIP) as well as
the conversion obtained from the catalysts within the
present invention of the above Examples in Table 1 can be
compared with those of Control Catalysts l and 3-5 in
Table 2 below.
14
~ 9~4Z9
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:Z (~ h h h ~ P~ X X
U~
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h h
~a ~ ~ ~
U~ ~ ~U~ U~ U~ ~ ~
h -( O OOO ~ ~ r-l ~ ~:
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h u~ ~ U) ~ h h S~ ,q .q
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34~9
16
The results set forth in Table 1 where the catalysts
of the examples demonstrate a unique ability to convert
significant amounts of the feed to products the majority of
which is TEDA.
~,
