Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITLE
DIMETHYLACETAMIDE FROM CARBONYLATION
OF TRIMETHYLAMINE
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BACKGROUND OF THE INVENTION
Field of the Invention
.
The present invention relates to reacting
trimethylamine with carbon m~noxide to form
dimethylacetamide.
Prior Art
U.S. Patent 3,412,151 discloses reacting
trimethylamine with carbon monoxide to ~orm
dimethylformamide at elevated pressure and temperature
in the--presence an amount of water about equimolar to
the trimethylamine reactant using dicobalt
octacarbonyl as the catalyst.
Japanese Patent Publication No. 1971-43,526
of Yoshio I~i (Ni~x~ Gas), published 1971 DK~er 23,
discloses r~ing trimethylamine with c~*~n mnnoxide to form
d~thylaoe~de using dioobalt carbonyl as the catalyst.
Summary of the Invention
The present invention relates to the
discovery that when reacting trimethylamine with
carbon monoxide using dicobalt octacarbonyl as the
catalyst that the reaction can be effectively promoted
with a hydrogen donor, ~uch as water, while
suppressing the formation of dimethylformamide by
using from 0.5 2.0 moles of hydrogen donor per mole of
dicobalt octacarbonyl.
Detailed Description
~ he present invention relates to the
production of dimethylacetamide from trimethylamine
and carbon monoxide. In accordance with the present
invention from 0.5-2.0 and preferably 0.5-1~5 moles of
a hydrogen donor per mole of Co2(CO)8 is present
to form the active catalyst species. Thus, when using
water as the hydrogen donor, the reaction is as
follows:
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C2(C)8 + ~2 ~ CO -> 2HCo(CO)4 ~ C02
HCo (CO) 4 + (CH3 ) 3N~ CH3Co (CO) 4 ~ E~ (CH3 ) 2N
0
CH3Co (CO) 4 ~ CO~ CH3CCo (CO) 4
O O
CH3CCo (CO) 4 + (CH3) 3N~ CH3CN (CH3) 3 + Co (CO) 4
O O
n ,~. _ n
CH3CN(CH3)3 + Co(CO)4 >CH3CN(CH3)2 + CH3Co~C0)4
Thus CH3Co (CO) 4 is the active catalyst
speciesO This reaction has been found to depend on
catalyst concentration and not CO concentration for
its rate. Thus moderate pressures of as low as 400
psi (2.7 X 106 pascals) can be used. While high
pressures such as 4000 psi (27.5 X 106 pascals) can
be used, doing so is uneconomical. The preferred
pressure range is from 600-2000 psi (4.1 X 106 to
13.8 X 106 pascals)~ Generally the temperature
used will be from 175-275C with from 220-250C being
the preferred range.
Generally the process of the present
invention produces less than 44 dimethylformamide and
in its preferred mode less than 2% dimethylformamideO
The product dimethylacetamide is widely used as a
solvent and for most of these uses the presence of
more than a few percent of dimethylformamide cannot
be tolerated. Thus the process of the present
invention provid~s a process for converting
trimethylamine, which normally is a wa~te stream
generated in the production of dimethylamine, into a
useful product.
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The process of the present invention can be
performed as either a batch process or continuously.
The process can be carried out neat or using
a solvent. Dimethylacetamide is the preferred
solvent.
In a preferred aspect of the invention from
0.005-0.10 mole of a lower alkyl halide per mole of
trimethyl amine is present in the reaction mixture.
The preferred lower alkyl halide is methyl iodide
used in a molar ratio of 0.5-2.0 moles of methyl
iodide per mole of cobalt carbonyl.
EXAMPLES
Example 1
To a 200 ml reactor was charged 20 grams
dimethylacetamide and 5 grams dicobalt octacarbonyl
and 0.25 gram water in an atmosphere of nitrogen.
The molar ratio of water to catalyst in this example
was 0.95. The reactor was cooled to -80C, evacuated
and 50 grams trimethylamine was then addad. The
reactor was warmed to room temperature and pressured
to 1000 psi (6.9 X 106 Pa) with carbon monoxide.
The vessel and contents were heated and maintained at
250C for 6 hours. On reaching reaction temperature,
carbon monoxide was added to bring the pressure to
2500 psig (17.2 X 106 Pa). After the pressure
dropped to about 2300 psig (15.8 X 106 Pa) it was
repressured ts 2500 psig (17.2 X 106 Pa). The
total amount of repressuring amounted to 2230 psig
~15.4 X 106 Pa). After 5 hours, CO absorption
stopped. At the conclusion of the run, the reactor
was cooled to room temperature and unreacted
trimethylamine was vented into a cold trap maintained
at -B0C. Unreacted trimethylamine amounted to 4.1
grams. The remaining product was then recovered and
analyzed. The liquid product amounted to 74.9
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grams. Dimethylacetamide amounted to 67.6 grams for
a net conversion of trimethylamine to
dimethylacetamide of 92%. Dimethylformamide
represented 1% of the product. This example shows
the beneficial effect of water.
Example 2
Example 1 was repeated but with 0.8 gram of
water added to 5 grams dicobalt octacarbonyl. The
molar ratio of water to catalyst in this example was
3.0q The reactor was also charged with 20 grams
dimethylacetamide and 40 grams trimethylamine. The
reactor was pressured to 1500 psig (10.3 X 106 Pa)
with carbon monoxide at room temperature. The
reaction was run at 240C and 3500 psig (24 X 106
Pa) pressure for 2 hours. After the pressure dropped
significantly the reaction was repressured to 3500
psig (24 X 106 Pa). This was done repeatedly until
the total amount of repressuring amounted to 4580
psig (31.6 X 106 Pa). The product was recovered as
beforeO Unreac~ed trimethylamine amounted to 5.1
grams. The liquid product amounted to 86.7 grams.
Dimethylacetamide amounted to 71.5 grams for a net
conversion of trimethylamine to dimethylacetamide of
85~. Dimethylformamide represented 9% of the
product. This example shows the beneficial effect of
a higher water/catalyst ratio on productivity but
with more byproduct dimethylformamide.
Example 3
Example 1 was repeated but with only 0.07
gram water added to 5 grams dicobalt octacarbonyl.
The molar ratio of water to catalyst in this example
was 0.3. As before, the reactor was charyed with 20
grams dimethylacetamide and 40 grams trimethylamine~
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The reactor was pressured to 1500 psig (10.3 X 106
Pa) with CO at room temperature. The reaction was
run at 250C and 3000 psig (24 X 106 Pa) pressure
for 8 hours. CO absorption was complete in 4 hours.
After the pressure dropped significantly, the reactor
was repressured to 3000 psig (20.7 X 106 Pa). This
was done repeatedly until the total amount of
repressuring amounted to 2860 psig (19.7 X 106
Pa). Th~ product was recovered as before. Vnreacted
trimethylamine amounted to 3.2 grams. The liquid
product amounted to 69.4 grams. Dimethylacetamide
amounted to 60.3 grams for a net conversion of
trimethylamine to dimethylacetamide of 88%.
Dimethylformamide represented 3~ of the product.
lS This example shows both lower productivity and higher
byproduct formation at low water/catalyst ratios.
Example 4
Example 1 was repeated but with no water
added to the S grams of dicobalt octacarbonyl. The
reactor was charged with 20 grams dimethylacetamide
and 40 grams trimethylamine. The reactor was
pressured to 500 psig (3.45 X 106 Pa) with CO at
room temperature The reaction was run at 250C and
2000 psig (13.8 X 106 Pa) pressure for 8 hours~
After the pressure dropped significantly, the reactor
was repressured to 2000 psig (18.3 X 106 Pa). This
was done repeatedly until the total amount of
repressuring amounted to 1450 psig (10 X 106 Pa)
and was complete in 7 hours. The product was
recovered as before. Unreacted trimethylamine
amounted to 9.0 grams. The liquid product weighed
55.9 grams. Dimethylacetamide amounted to 44.6 grams
for a net conversion of trimethylamine to
dimethylacetamide of 93~. Dimethylformamide
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represented 3% of the product. ThiS example shows
low activity of the catalyst in the absence of water.
Example 5
Example 1 was repeated with 0.3 gram of
water added to 5 grams dicobalt octacarbonyl. The
molar ratio of water/catalyst was 1.3. The reactor
was charged with 20 grams dimethylacetamide and 40
grams trimethylamine. The reactor was pressured to
1500 psig (10.3 X 106 Pa) with CO at room
temperature. The reaction was run at 250C and an
initial CO pressure of 3800 psig (26.2 X 106 Pa).
There was no replenishment of COO Rather, ir. this
example the pressure was allowed to decrease as CO
was absorbed. After 4 hours CO absorption was
complete and the final pressure was 450 psig ~3.1 X
106 Pa). CO absorption totaled 3350 psig (23.1 X
106 Pa). The product was recovered as before.
Unreacted trimethylamine amounted to 1.5 grams. The
liquid product totaled 76.9 grams. Dimethylacetamide
amounted to 70.3 grams for a net conversion of
trimethylamine to dimethylacetamide of 94~.
Dimethylformamide represented 2% of the product.
This example shows the beneficial effect of water on
productivity and yield over a range of reactor
pressure.
Example 6
In this example dimethylacetamide containing
50 g/gal (0.13 kg/m2) dicobalt octacarbonyl and 2
g/gal (0.005 kg/m2~ water was fed to a 2 liter
reactor at the rate of 2.4 liters/hour continuously
- over a 10 hour period. Trimethylamine was also fed
at the rate of 1.3 lbs/hour (0.59 kg/hour). The
reactor was stirred and maintained at 250C and 1000
psig ~6.9 X 10~ Pa) with carbon monoxide. Product
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was removed continuously through a low pressure
separator. During this time, 5720 grams of
trimethylamine was fed. Unreacted trimethylamine
amounted to 2932 grams. The liquid product weighed
11,335 grams. Dimethylacetamide amounted to 10,219
grams for a net production of 2205 grams.
Productivity was 0.73 lbs dimethylacetamide/gal/hour
(53 kg/m2/hr). Conversion of trimethylamine to
dimethylacetamide was 28%. The product contained
1.8% dimethylformamide. This example shows the
beneficial effect of water for a continuous reac~ion.
Example 7
Example 1 was repeated but with ~ome alkyl
halide added with water to the catalyst. Methyl
iodide (2.0 grams) was added to 0.5 gram water and
5.0 grams dicobalt octacarbonyl. The molar ratio of
water/catalyst was 1.9. As before, the reactor was
charged with 20 grams dimethylacetamide and 40 grams
trimethylamine. The reactor was pressured to 2000
psig (13.8 X 106 Pa) with carbon monoxide at room
temperature. The reaction was run at 250C and 5000
psig (34.5 X 106 Pa) for 2 hours. CO absorption
was complete after 68 minutes. After the pressure
dropped significantly, the reactor was repressured to
2000 psig (13.8 X 106 Pa). This was done
repeatedly until the total amount of repressuring
amounted to 5640 psig (38.9 X 106 Pa). Unreacted
trimethylamine amounted to 3.7 grams. Liquid product
totaled 90.5 grams~ Dimethylacetamide amounted to
81.4 grams and represents a 93~ conversion of
trimethylamine to dimethylacetamide. Dimethyl-
formamide represented 4% of the product. This
example shows the further improvement in reaction
rate resulting from methyl iodide addition with
water.
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